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<li id="toc-Forerunners" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Forerunners"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1</span> <span>Forerunners</span> </div> </a> <ul id="toc-Forerunners-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Publication_and_refinement" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Publication_and_refinement"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.2</span> <span>Publication and refinement</span> </div> </a> <ul id="toc-Publication_and_refinement-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-After_Fresnel" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#After_Fresnel"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.3</span> <span>After Fresnel</span> </div> </a> <ul id="toc-After_Fresnel-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Design" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Design"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Design</span> </div> </a> <ul id="toc-Design-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Lighthouse_lens_sizes" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Lighthouse_lens_sizes"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Lighthouse lens sizes</span> </div> </a> <ul id="toc-Lighthouse_lens_sizes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Types" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Types"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Types</span> </div> </a> <ul id="toc-Types-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Uses" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Uses"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Uses</span> </div> </a> <button aria-controls="toc-Uses-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Uses subsection</span> </button> <ul id="toc-Uses-sublist" class="vector-toc-list"> <li id="toc-Illumination" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Illumination"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Illumination</span> </div> </a> <ul id="toc-Illumination-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Imaging" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Imaging"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>Imaging</span> </div> </a> <ul id="toc-Imaging-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Projection" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Projection"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.3</span> <span>Projection</span> </div> </a> <ul id="toc-Projection-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Solar_power" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Solar_power"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.4</span> <span>Solar power</span> </div> </a> <ul id="toc-Solar_power-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Bibliography" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Bibliography"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Bibliography</span> </div> </a> <ul id="toc-Bibliography-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">10</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Fresnel lens</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 48 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-48" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">48 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-als mw-list-item"><a href="https://als.wikipedia.org/wiki/Fresnel-Linse" title="Fresnel-Linse – Alemannic" lang="gsw" hreflang="gsw" data-title="Fresnel-Linse" data-language-autonym="Alemannisch" data-language-local-name="Alemannic" class="interlanguage-link-target"><span>Alemannisch</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%B9%D8%AF%D8%B3%D8%A9_%D9%81%D8%B1%D9%8A%D9%86%D9%84" title="عدسة فرينل – Arabic" lang="ar" hreflang="ar" data-title="عدسة فرينل" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Lente_de_Fresnel" title="Lente de Fresnel – Asturian" lang="ast" hreflang="ast" data-title="Lente de Fresnel" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-ba mw-list-item"><a href="https://ba.wikipedia.org/wiki/%D0%A4%D1%80%D0%B5%D0%BD%D0%B5%D0%BB%D1%8C_%D0%BB%D0%B8%D0%BD%D0%B7%D0%B0%D2%BB%D1%8B" title="Френель линзаһы – Bashkir" lang="ba" hreflang="ba" data-title="Френель линзаһы" data-language-autonym="Башҡортса" data-language-local-name="Bashkir" class="interlanguage-link-target"><span>Башҡортса</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%A4%D1%80%D0%B5%D0%BD%D0%B5%D0%BB%D0%BE%D0%B2%D0%B0_%D0%BB%D0%B5%D1%89%D0%B0" title="Френелова леща – Bulgarian" lang="bg" hreflang="bg" data-title="Френелова леща" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Lent_de_Fresnel" title="Lent de Fresnel – Catalan" lang="ca" hreflang="ca" data-title="Lent de Fresnel" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Fresnelova_%C4%8Do%C4%8Dka" title="Fresnelova čočka – Czech" lang="cs" hreflang="cs" data-title="Fresnelova čočka" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Fresnellinse" title="Fresnellinse – Danish" lang="da" hreflang="da" data-title="Fresnellinse" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Fresnel-Linse" title="Fresnel-Linse – German" lang="de" hreflang="de" data-title="Fresnel-Linse" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Fresneli_l%C3%A4%C3%A4ts" title="Fresneli lääts – Estonian" lang="et" hreflang="et" data-title="Fresneli lääts" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Lente_de_Fresnel" title="Lente de Fresnel – Spanish" lang="es" hreflang="es" data-title="Lente de Fresnel" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Fresnel-lenso" title="Fresnel-lenso – Esperanto" lang="eo" hreflang="eo" data-title="Fresnel-lenso" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Fresnel_leiar" title="Fresnel leiar – Basque" lang="eu" hreflang="eu" data-title="Fresnel leiar" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B9%D8%AF%D8%B3%DB%8C_%D9%81%D8%B1%D8%B3%D9%86%D9%84" title="عدسی فرسنل – Persian" lang="fa" hreflang="fa" data-title="عدسی فرسنل" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Lentille_de_Fresnel" title="Lentille de Fresnel – French" lang="fr" hreflang="fr" data-title="Lentille de Fresnel" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Lente_de_Fresnel" title="Lente de Fresnel – Galician" lang="gl" hreflang="gl" data-title="Lente de Fresnel" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%ED%94%84%EB%A0%88%EB%84%AC_%EB%A0%8C%EC%A6%88" title="프레넬 렌즈 – Korean" lang="ko" hreflang="ko" data-title="프레넬 렌즈" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%AB%E0%A5%8D%E0%A4%B0%E0%A5%87%E0%A4%B8%E0%A4%A8%E0%A5%87%E0%A4%B2_%E0%A4%A4%E0%A4%BE%E0%A4%B2" title="फ्रेसनेल ताल – Hindi" lang="hi" hreflang="hi" data-title="फ्रेसनेल ताल" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Fresnelova_zrcala" title="Fresnelova zrcala – Croatian" lang="hr" hreflang="hr" data-title="Fresnelova zrcala" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Lensa_Fresnel" title="Lensa Fresnel – Indonesian" lang="id" hreflang="id" data-title="Lensa Fresnel" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Lente_di_Fresnel" title="Lente di Fresnel – Italian" lang="it" hreflang="it" data-title="Lente di Fresnel" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A2%D7%93%D7%A9%D7%AA_%D7%A4%D7%A8%D7%A0%D7%9C" title="עדשת פרנל – Hebrew" lang="he" hreflang="he" data-title="עדשת פרנל" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%A4%D1%80%D0%B5%D0%BD%D0%B5%D0%BB%D1%8C_%D0%BB%D0%B8%D0%BD%D0%B7%D0%B0%D1%81%D1%8B" title="Френель линзасы – Kazakh" lang="kk" hreflang="kk" data-title="Френель линзасы" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%A4%D1%80%D0%B5%D0%BD%D0%B5%D0%BB%D0%BE%D0%B2%D0%B0_%D0%BB%D0%B5%D1%9C%D0%B0" title="Френелова леќа – Macedonian" lang="mk" hreflang="mk" data-title="Френелова леќа" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Kanta_Fresnel" title="Kanta Fresnel – Malay" lang="ms" hreflang="ms" data-title="Kanta Fresnel" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-mn mw-list-item"><a href="https://mn.wikipedia.org/wiki/%D0%A4%D1%80%D0%B5%D0%BD%D0%B5%D0%BB%D0%B8%D0%B9%D0%BD_%D0%BB%D0%B8%D0%BD%D0%B7" title="Френелийн линз – Mongolian" lang="mn" hreflang="mn" data-title="Френелийн линз" data-language-autonym="Монгол" data-language-local-name="Mongolian" class="interlanguage-link-target"><span>Монгол</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Fresnellens" title="Fresnellens – Dutch" lang="nl" hreflang="nl" data-title="Fresnellens" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%95%E3%83%AC%E3%83%8D%E3%83%AB%E3%83%AC%E3%83%B3%E3%82%BA" title="フレネルレンズ – Japanese" lang="ja" hreflang="ja" data-title="フレネルレンズ" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-frr mw-list-item"><a href="https://frr.wikipedia.org/wiki/Fresnel-Lins" title="Fresnel-Lins – Northern Frisian" lang="frr" hreflang="frr" data-title="Fresnel-Lins" data-language-autonym="Nordfriisk" data-language-local-name="Northern Frisian" class="interlanguage-link-target"><span>Nordfriisk</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Fresnel-linse" title="Fresnel-linse – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Fresnel-linse" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Fresnel_linzalari" title="Fresnel linzalari – Uzbek" lang="uz" hreflang="uz" data-title="Fresnel linzalari" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Soczewka_Fresnela" title="Soczewka Fresnela – Polish" lang="pl" hreflang="pl" data-title="Soczewka Fresnela" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Lente_de_Fresnel" title="Lente de Fresnel – Portuguese" lang="pt" hreflang="pt" data-title="Lente de Fresnel" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9B%D0%B8%D0%BD%D0%B7%D0%B0_%D0%A4%D1%80%D0%B5%D0%BD%D0%B5%D0%BB%D1%8F" title="Линза Френеля – Russian" lang="ru" hreflang="ru" data-title="Линза Френеля" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Fresnel_lens" title="Fresnel lens – Simple English" lang="en-simple" hreflang="en-simple" data-title="Fresnel lens" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Fresnelova_%C5%A1o%C5%A1ovka" title="Fresnelova šošovka – Slovak" lang="sk" hreflang="sk" data-title="Fresnelova šošovka" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Fresnelova_le%C4%8Da" title="Fresnelova leča – Slovenian" lang="sl" hreflang="sl" data-title="Fresnelova leča" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%A4%D1%80%D0%B5%D1%81%D0%BD%D0%B5%D0%BB%D0%BE%D0%B2%D0%B0_%D1%81%D0%BE%D1%87%D0%B8%D0%B2%D0%B0" title="Фреснелова сочива – Serbian" lang="sr" hreflang="sr" data-title="Фреснелова сочива" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Fresnel-linssi" title="Fresnel-linssi – Finnish" lang="fi" hreflang="fi" data-title="Fresnel-linssi" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Fresnel-lins" title="Fresnel-lins – Swedish" lang="sv" hreflang="sv" data-title="Fresnel-lins" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%AA%E0%AE%BF%E0%AE%B0%E0%AF%86%E0%AE%A9%E0%AF%86%E0%AE%B2%E0%AF%8D_%E0%AE%B5%E0%AE%BF%E0%AE%B2%E0%AF%8D%E0%AE%B2%E0%AF%88" title="பிரெனெல் வில்லை – Tamil" lang="ta" hreflang="ta" data-title="பிரெனெல் வில்லை" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B9%80%E0%B8%A5%E0%B8%99%E0%B8%AA%E0%B9%8C%E0%B9%81%E0%B8%9F%E0%B8%A3%E0%B9%81%E0%B8%99%E0%B8%A5" title="เลนส์แฟรแนล – Thai" lang="th" hreflang="th" data-title="เลนส์แฟรแนล" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Fresnel_lens" title="Fresnel lens – Turkish" lang="tr" hreflang="tr" data-title="Fresnel lens" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9B%D1%96%D0%BD%D0%B7%D0%B0_%D0%A4%D1%80%D0%B5%D0%BD%D0%B5%D0%BB%D1%8F" title="Лінза Френеля – Ukrainian" lang="uk" hreflang="uk" data-title="Лінза Френеля" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Th%E1%BA%A5u_k%C3%ADnh_Fresnel" title="Thấu kính Fresnel – Vietnamese" lang="vi" hreflang="vi" data-title="Thấu kính Fresnel" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-war mw-list-item"><a href="https://war.wikipedia.org/wiki/Lente_Fresnel" title="Lente Fresnel – Waray" lang="war" hreflang="war" data-title="Lente Fresnel" data-language-autonym="Winaray" data-language-local-name="Waray" class="interlanguage-link-target"><span>Winaray</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E8%8F%B2%E6%B6%85%E7%88%BE%E9%80%8F%E9%8F%A1" title="菲涅爾透鏡 – Cantonese" lang="yue" hreflang="yue" data-title="菲涅爾透鏡" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E8%8F%B2%E6%B6%85%E8%80%B3%E9%80%8F%E9%8F%A1" title="菲涅耳透鏡 – Chinese" lang="zh" hreflang="zh" data-title="菲涅耳透鏡" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet 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<div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Compact composite lens</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:MuseeMarine-phareFresnel-p1000466.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/68/MuseeMarine-phareFresnel-p1000466.jpg/220px-MuseeMarine-phareFresnel-p1000466.jpg" decoding="async" width="220" height="293" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/68/MuseeMarine-phareFresnel-p1000466.jpg/330px-MuseeMarine-phareFresnel-p1000466.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/68/MuseeMarine-phareFresnel-p1000466.jpg/440px-MuseeMarine-phareFresnel-p1000466.jpg 2x" data-file-width="1920" data-file-height="2560" /></a><figcaption>First-order rotating catadioptric Fresnel lens, dated 1870, displayed at the <i><a href="/wiki/Mus%C3%A9e_national_de_la_Marine" title="Musée national de la Marine">Musée national de la Marine</a></i>, Paris. In this case the dioptric prisms (inside the bronze rings) and catadioptric prisms (outside) are arranged to concentrate the light from the central lamp into four revolving beams, seen by sailors as four flashes per revolution. The assembly stands 2.54 metres (8.3 ft) tall and weighs about 1.5 tonnes (3,300 lb).</figcaption></figure> <p>A <b>Fresnel lens</b> (<span class="rt-commentedText nowrap"><span class="IPA nopopups noexcerpt" lang="en-fonipa"><a href="/wiki/Help:IPA/English" title="Help:IPA/English">/<span style="border-bottom:1px dotted"><span title="/ˈ/: primary stress follows">ˈ</span><span title="'f' in 'find'">f</span><span title="'r' in 'rye'">r</span><span title="/eɪ/: 'a' in 'face'">eɪ</span><span title="'n' in 'nigh'">n</span><span title="/ɛ/: 'e' in 'dress'">ɛ</span><span title="'l' in 'lie'">l</span></span>,<span class="wrap"> </span>-<span style="border-bottom:1px dotted"><span title="'n' in 'nigh'">n</span><span title="/əl/: 'le' in 'bottle'">əl</span></span>/</a></span></span> <a href="/wiki/Help:Pronunciation_respelling_key" title="Help:Pronunciation respelling key"><i title="English pronunciation respelling"><span style="font-size:90%">FRAY</span>-nel, -⁠nəl</i></a>; <span class="rt-commentedText nowrap"><span class="IPA nopopups noexcerpt" lang="en-fonipa"><a href="/wiki/Help:IPA/English" title="Help:IPA/English">/<span style="border-bottom:1px dotted"><span title="/ˈ/: primary stress follows">ˈ</span><span title="'f' in 'find'">f</span><span title="'r' in 'rye'">r</span><span title="/ɛ/: 'e' in 'dress'">ɛ</span><span title="'n' in 'nigh'">n</span><span title="/ɛ/: 'e' in 'dress'">ɛ</span><span title="'l' in 'lie'">l</span></span>,<span class="wrap"> </span>-<span style="border-bottom:1px dotted"><span title="/əl/: 'le' in 'bottle'">əl</span></span>/</a></span></span> <a href="/wiki/Help:Pronunciation_respelling_key" title="Help:Pronunciation respelling key"><i title="English pronunciation respelling"><span style="font-size:90%">FREN</span>-el, -⁠əl</i></a>; or <span class="rt-commentedText nowrap"><span class="IPA nopopups noexcerpt" lang="en-fonipa"><a href="/wiki/Help:IPA/English" title="Help:IPA/English">/<span style="border-bottom:1px dotted"><span title="'f' in 'find'">f</span><span title="'r' in 'rye'">r</span><span title="/eɪ/: 'a' in 'face'">eɪ</span><span title="/ˈ/: primary stress follows">ˈ</span><span title="'n' in 'nigh'">n</span><span title="/ɛ/: 'e' in 'dress'">ɛ</span><span title="'l' in 'lie'">l</span></span>/</a></span></span> <a href="/wiki/Help:Pronunciation_respelling_key" title="Help:Pronunciation respelling key"><i title="English pronunciation respelling">fray-<span style="font-size:90%">NEL</span></i></a><sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>) is a type of composite compact <a href="/wiki/Lens_(optics)" class="mw-redirect" title="Lens (optics)">lens</a> which reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections. </p><p>The simpler <a href="/wiki/Dioptrics" title="Dioptrics">dioptric</a> (purely <a href="/wiki/Refraction" title="Refraction">refractive</a>) form of the lens was first proposed by <a href="/wiki/Georges-Louis_Leclerc,_Comte_de_Buffon" title="Georges-Louis Leclerc, Comte de Buffon">Georges-Louis Leclerc, Comte de Buffon</a><sup id="cite_ref-chisholm-1911-lighthouse_2-0" class="reference"><a href="#cite_note-chisholm-1911-lighthouse-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>, and independently reinvented by the French physicist <a href="/wiki/Augustin-Jean_Fresnel" title="Augustin-Jean Fresnel">Augustin-Jean Fresnel</a> (1788–1827) for use in <a href="/wiki/Lighthouse" title="Lighthouse">lighthouses</a>.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Catadioptric_system" title="Catadioptric system">catadioptric</a> (combining refraction and reflection) form of the lens, entirely invented by Fresnel, has outer <a href="/wiki/Prism_(optics)" title="Prism (optics)">prismatic</a> elements that use <a href="/wiki/Total_internal_reflection" title="Total internal reflection">total internal reflection</a> as well as refraction to capture more oblique light from the light source and add it to the beam, making it visible at greater distances. </p><p>The design allows the construction of lenses of large <a href="/wiki/Aperture" title="Aperture">aperture</a> and short <a href="/wiki/Focal_length" title="Focal length">focal length</a> without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. </p><p>Because of its use in lighthouses, it has been called "the invention that saved a million ships".<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Forerunners">Forerunners</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=2" title="Edit section: Forerunners"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The first person to focus a lighthouse beam using a lens was apparently the London glass-cutter Thomas Rogers, who proposed the idea to <a href="/wiki/Trinity_House" title="Trinity House">Trinity House</a> in 1788.<sup id="cite_ref-tag-prior_6-0" class="reference"><a href="#cite_note-tag-prior-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The first Rogers lenses, 53<span class="nowrap"> </span>cm in diameter and 14<span class="nowrap"> </span>cm thick at the center, were installed at the <a href="/wiki/Old_Lower_Lighthouse" title="Old Lower Lighthouse">Old Lower Lighthouse</a> at <a href="/wiki/Portland_Bill" title="Portland Bill">Portland Bill</a> in 1789. Behind each lamp was a back-coated spherical glass mirror, which reflected rear radiation back through the lamp and into the lens. Further samples were installed at <a href="/wiki/Baily_Lighthouse" title="Baily Lighthouse">Howth Baily</a>, <a href="/wiki/North_Foreland" title="North Foreland">North Foreland</a>, and at least four other locations by 1804. But much of the light was wasted by absorption in the glass.<sup id="cite_ref-tag-prior_6-1" class="reference"><a href="#cite_note-tag-prior-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>In 1748, <a href="/wiki/Georges-Louis_Leclerc,_Comte_de_Buffon" title="Georges-Louis Leclerc, Comte de Buffon">Georges-Louis Leclerc, Comte de Buffon</a> was the first to replace a convex lens with a series of concentric <a href="/wiki/Annulus_(mathematics)" title="Annulus (mathematics)">annular</a> prisms, ground as steps in a single piece of glass,<sup id="cite_ref-chisholm-1911-lighthouse_2-1" class="reference"><a href="#cite_note-chisholm-1911-lighthouse-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>to reduce weight and absorption. In 1790<sup id="cite_ref-condorcet-1790_8-0" class="reference"><a href="#cite_note-condorcet-1790-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> (although secondary sources give the date as 1773<sup id="cite_ref-appleton-1861_9-0" class="reference"><a href="#cite_note-appleton-1861-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 609">: 609 </span></sup> or 1788<sup id="cite_ref-tag-2017_10-0" class="reference"><a href="#cite_note-tag-2017-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup>), the <a href="/wiki/Marquis_de_Condorcet" title="Marquis de Condorcet">Marquis de Condorcet</a> suggested that it would be easier to make the annular sections separately and assemble them on a frame; but even that was impractical at the time.<sup id="cite_ref-tag-fres_11-0" class="reference"><a href="#cite_note-tag-fres-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-levitt-p71_12-0" class="reference"><a href="#cite_note-levitt-p71-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> These designs were intended not for lighthouses,<sup id="cite_ref-chisholm-1911-lighthouse_2-2" class="reference"><a href="#cite_note-chisholm-1911-lighthouse-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> but for <a href="/wiki/Burning_glass" title="Burning glass">burning glasses</a>.<sup id="cite_ref-appleton-1861_9-1" class="reference"><a href="#cite_note-appleton-1861-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 609">: 609 </span></sup> <a href="/wiki/David_Brewster" title="David Brewster">David Brewster</a>, however, proposed a system similar to Condorcet's in 1811,<sup id="cite_ref-chisholm-1911-lighthouse_2-3" class="reference"><a href="#cite_note-chisholm-1911-lighthouse-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-tag-2017_10-1" class="reference"><a href="#cite_note-tag-2017-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ripley-dana-1879_13-0" class="reference"><a href="#cite_note-ripley-dana-1879-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> and by 1820 was advocating its use in British lighthouses.<sup id="cite_ref-chisholm-1911-brewster_14-0" class="reference"><a href="#cite_note-chisholm-1911-brewster-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Publication_and_refinement">Publication and refinement</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=3" title="Edit section: Publication and refinement"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Fresnel_lighthouse_lens_diagram.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/ab/Fresnel_lighthouse_lens_diagram.png/220px-Fresnel_lighthouse_lens_diagram.png" decoding="async" width="220" height="258" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/ab/Fresnel_lighthouse_lens_diagram.png/330px-Fresnel_lighthouse_lens_diagram.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/ab/Fresnel_lighthouse_lens_diagram.png/440px-Fresnel_lighthouse_lens_diagram.png 2x" data-file-width="492" data-file-height="578" /></a><figcaption>Cross-section of a first-generation Fresnel lighthouse lens, with sloping mirrors <i>m, n</i> above and below the refractive panel <i>RC</i> (with central segment <i>A</i>). The design was later improved by replacing the mirrors with reflective prisms to reduce losses. If the cross-section in every vertical plane through the lamp <i>L</i> is the same (cylindrical symmetry), the light is spread evenly around the horizon.</figcaption></figure> <p>The French <a href="/w/index.php?title=Commission_des_Phares&action=edit&redlink=1" class="new" title="Commission des Phares (page does not exist)">Commission des Phares</a><span class="noprint" style="font-size:85%; font-style: normal;"> [<a href="https://fr.wikipedia.org/wiki/Commission_des_phares_(France)" class="extiw" title="fr:Commission des phares (France)">FR</a>]</span> (Commission of Lighthouses) was established by Napoleon in 1811, and placed under the authority of French physicist <a href="/wiki/Augustin-Jean_Fresnel" title="Augustin-Jean Fresnel">Augustin-Jean Fresnel</a>'s employer, the Corps of Bridges and Roads. As the members of the commission were otherwise occupied, it achieved little in its early years.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> However, on 21 June 1819—three months after winning the physics <span title="French-language text"><i lang="fr">Grand Prix</i></span> of the Academy of Sciences for his celebrated memoir on <a href="/wiki/Diffraction" title="Diffraction">diffraction</a>—Fresnel was "temporarily" seconded to the commission on the recommendation of <a href="/wiki/Fran%C3%A7ois_Arago" title="François Arago">François Arago</a> (a member since 1813), to review possible improvements in lighthouse illumination.<sup id="cite_ref-tag-fres_11-1" class="reference"><a href="#cite_note-tag-fres-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p><p>By the end of August 1819, unaware of the Buffon-Condorcet-Brewster proposal,<sup id="cite_ref-tag-fres_11-2" class="reference"><a href="#cite_note-tag-fres-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ripley-dana-1879_13-1" class="reference"><a href="#cite_note-ripley-dana-1879-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> Fresnel made his first presentation to the commission,<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> recommending what he called <span title="French-language text"><i lang="fr">lentilles à échelons</i></span> ('lenses by steps') to replace the reflectors then in use, which reflected only about half of the incident light.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> Another report by Fresnel, dated 29 August 1819 (Fresnel, 1866–70, vol. 3, pp. 15–21), concerns tests on reflectors, and does not mention stepped lenses except in an unrelated sketch on the last page of the manuscript. The minutes of the meetings of the Commission go back only to 1824, when Fresnel himself took over as Secretary.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> Thus the exact date on which Fresnel formally recommended <span title="French-language text"><i lang="fr">lentilles à échelons</i></span> is unknown.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2023)">citation needed</span></a></i>]</sup> Much to Fresnel's embarrassment, one of the assembled commissioners, <a href="/wiki/Jacques_Charles" title="Jacques Charles">Jacques Charles</a>, recalled Buffon's suggestion.<sup id="cite_ref-levitt-p59_20-0" class="reference"><a href="#cite_note-levitt-p59-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> However, whereas Buffon's version was <a href="/wiki/Lens_(optics)#Types_of_simple_lenses" class="mw-redirect" title="Lens (optics)">biconvex</a> and in one piece,<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> Fresnel's was <a href="/wiki/Lens_(optics)#Types_of_simple_lenses" class="mw-redirect" title="Lens (optics)">plano-convex</a> and made of multiple prisms for easier construction. </p><p>With an official budget of 500 francs, Fresnel approached three manufacturers. The third, François Soleil, found a way to remove defects by reheating and remolding the glass. Arago assisted Fresnel with the design of a modified <a href="/wiki/Argand_lamp" title="Argand lamp">Argand lamp</a> with concentric wicks (a concept that Fresnel attributed to <a href="/wiki/Benjamin_Thompson" title="Benjamin Thompson">Count Rumford</a><sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup>), and accidentally discovered that <a href="/wiki/Fish_glue" class="mw-redirect" title="Fish glue">fish glue</a> was heat-resistant, making it suitable for use in the lens. The prototype, finished in March 1820, had a square lens panel 55<span class="nowrap"> </span>cm on a side, containing 97 polygonal (not annular) prisms—and so impressed the Commission that Fresnel was asked for a full eight-panel version. This model, completed a year later in spite of insufficient funding, had panels 76<span class="nowrap"> </span>cm square. In a public spectacle on the evening of 13 April 1821, it was demonstrated by comparison with the most recent reflectors, which it suddenly rendered obsolete.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p><p>Soon after this demonstration, Fresnel published the idea that light, including apparently <a href="/wiki/Polarization_(waves)" title="Polarization (waves)">unpolarized</a> light, consists exclusively of <a href="/wiki/Transverse_wave" title="Transverse wave">transverse waves</a>, and went on to consider the implications for <a href="/wiki/Birefringence" title="Birefringence">double refraction</a> and partial reflection.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </p><p>Fresnel acknowledged the British lenses and Buffon's invention in a memoir read on 29 July 1822 and printed in the same year.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> The date of that memoir may be the source of the claim that Fresnel's lighthouse advocacy began two years later than Brewster's;<sup id="cite_ref-chisholm-1911-brewster_14-1" class="reference"><a href="#cite_note-chisholm-1911-brewster-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> but the text makes it clear that Fresnel's involvement began no later than 1819.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> </p><p>Fresnel's next lens was a rotating apparatus with eight "bull's-eye" panels, made in annular arcs by <a href="/wiki/Saint-Gobain" title="Saint-Gobain">Saint-Gobain</a>,<sup id="cite_ref-levitt-p71_12-1" class="reference"><a href="#cite_note-levitt-p71-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> giving eight rotating beams—to be seen by mariners as a periodic flash. Above and behind each main panel was a smaller, sloping bull's-eye panel of trapezoidal outline with trapezoidal elements.<sup id="cite_ref-gombert-2017_27-0" class="reference"><a href="#cite_note-gombert-2017-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> This refracted the light to a sloping plane mirror, which then reflected it horizontally, 7 degrees ahead of the main beam, increasing the duration of the flash.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> Below the main panels were 128 small mirrors arranged in four rings, stacked like the slats of a <a href="/wiki/Louver" title="Louver">louver</a> or <a href="/wiki/Venetian_blind" class="mw-redirect" title="Venetian blind">Venetian blind</a>. Each ring, shaped like a <a href="/wiki/Frustum" title="Frustum">frustum</a> of a <a href="/wiki/Cone" title="Cone">cone</a>, reflected the light to the horizon, giving a fainter steady light between the flashes. The official test, conducted on the unfinished <span title="French-language text"><span lang="fr" style="font-style: normal;"><a href="/wiki/Arc_de_Triomphe" title="Arc de Triomphe">Arc de Triomphe</a></span></span> on 20 August 1822, was witnessed by the Commission—and by <a href="/wiki/Louis_XVIII" title="Louis XVIII">Louis XVIII</a> and his entourage—from 32 kilometres (20 mi) away. The apparatus was stored at <a href="/wiki/Bordeaux" title="Bordeaux">Bordeaux</a> for the winter, and then reassembled at <a href="/wiki/Cordouan_Lighthouse" title="Cordouan Lighthouse">Cordouan Lighthouse</a> under Fresnel's supervision—in part by Fresnel's own hands. On 25 July 1823, the world's first lighthouse Fresnel lens was lit.<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> As expected, the light was visible to the horizon, more than 32 kilometres (20 mi) out.<sup id="cite_ref-watson-1999_30-0" class="reference"><a href="#cite_note-watson-1999-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p><p>The day before the test of the Cordouan lens in Paris, a committee of the Academy of Sciences reported on Fresnel's memoir and supplements on double refraction—which, although less well known to modern readers than his earlier work on diffraction, struck a more decisive blow for the wave theory of light.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> Between the test and the reassembly at Cordouan, Fresnel submitted his papers on <a href="/wiki/Photoelasticity" title="Photoelasticity">photoelasticity</a> (16 September 1822), <a href="/wiki/Elliptical_polarization" title="Elliptical polarization">elliptical</a> and <a href="/wiki/Circular_polarization" title="Circular polarization">circular polarization</a> and <a href="/wiki/Optical_rotation" title="Optical rotation">optical rotation</a> (9 December), and partial reflection and <a href="/wiki/Total_internal_reflection" title="Total internal reflection">total internal reflection</a> (7 January 1823),<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> essentially completing his reconstruction of <a href="/wiki/Physical_optics" title="Physical optics">physical optics</a> on the <a href="/wiki/Transverse_wave" title="Transverse wave">transverse wave</a> hypothesis. Shortly after the Cordouan lens was lit, Fresnel started coughing up blood.<sup id="cite_ref-levitt-p97_33-0" class="reference"><a href="#cite_note-levitt-p97-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> </p><p>In May 1824,<sup id="cite_ref-ripley-dana-1879_13-2" class="reference"><a href="#cite_note-ripley-dana-1879-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> Fresnel was promoted to Secretary of the <span title="French-language text"><i lang="fr">Commission des Phares</i></span>, becoming the first member of that body to draw a salary,<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> albeit in the concurrent role of Engineer-in-Chief.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> Late that year, being increasingly ill, he curtailed his fundamental research and resigned his seasonal job as an examiner at the <span title="French-language text"><span lang="fr" style="font-style: normal;"><a href="/wiki/%C3%89cole_Polytechnique" class="mw-redirect" title="École Polytechnique">École Polytechnique</a></span></span>, in order to save his remaining time and energy for his lighthouse work.<sup id="cite_ref-brock-1909_36-0" class="reference"><a href="#cite_note-brock-1909-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> </p><p>In the same year he designed the first <i>fixed</i> lens—for spreading light evenly around the horizon while minimizing waste above or below.<sup id="cite_ref-tag-fres_11-3" class="reference"><a href="#cite_note-tag-fres-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Ideally the curved refracting surfaces would be segments of <a href="/wiki/Toroid" title="Toroid">toroids</a> about a common vertical axis, so that the dioptric panel would look like a cylindrical drum. If this was supplemented by reflecting (<a href="/wiki/Catoptrics" title="Catoptrics">catoptric</a>) rings above and below the refracting (dioptric) parts, the entire apparatus would look like a beehive.<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> The second Fresnel lens to enter service was indeed a fixed lens, of third order, installed at Dunkirk by 1 February 1825.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> However, due to the difficulty of fabricating large toroidal prisms, this apparatus had a 16-sided polygonal plan.<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> </p><p>In 1825 Fresnel extended his fixed-lens design by adding a rotating array outside the fixed array. Each panel of the rotating array was to refract part of the fixed light from a horizontal fan into a narrow beam.<sup id="cite_ref-tag-fres_11-4" class="reference"><a href="#cite_note-tag-fres-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> </p><p>Also in 1825, Fresnel unveiled the <span title="French-language text"><i lang="fr">Carte des Phares</i></span> ('lighthouse map'), calling for a system of 51 lighthouses plus smaller harbor lights, in a hierarchy of lens sizes called "orders" (the first being the largest), with different characteristics to facilitate recognition: a constant light (from a fixed lens), one flash per minute (from a rotating lens with eight panels), and two per minute (16 panels).<sup id="cite_ref-42" class="reference"><a href="#cite_note-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> </p><p>In late 1825,<sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup> to reduce the loss of light in the reflecting elements, Fresnel proposed to replace each mirror with a catadioptric prism, through which the light would travel by refraction through the first surface, then <a href="/wiki/Total_internal_reflection" title="Total internal reflection">total internal reflection</a> off the second surface, then refraction through the third surface.<sup id="cite_ref-44" class="reference"><a href="#cite_note-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> The result was the lighthouse lens as we now know it. In 1826 he assembled a small model for use on the <span title="French-language text"><span lang="fr" style="font-style: normal;"><a href="/wiki/Canal_Saint-Martin" title="Canal Saint-Martin">Canal Saint-Martin</a></span></span>,<sup id="cite_ref-musee_45-0" class="reference"><a href="#cite_note-musee-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> but he did not live to see a full-sized version: he died on 14 July 1827, at the age of 39. </p> <div class="mw-heading mw-heading3"><h3 id="After_Fresnel">After Fresnel</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=4" title="Edit section: After Fresnel"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The first stage of the development of lighthouse lenses after the death of Augustin Fresnel consisted in the implementation of his designs. This was driven in part by his younger brother Léonor—who, like Augustin, was trained as a civil engineer but, unlike Augustin, had a strong aptitude for management. Léonor entered the service of the Lighthouse Commission in 1825, and went on to succeed Augustin as Secretary.<sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup> </p><p>The first fixed lens to be constructed with toroidal prisms was a first-order apparatus designed by the Scottish engineer <a href="/wiki/Alan_Stevenson" title="Alan Stevenson">Alan Stevenson</a> under the guidance of Léonor Fresnel, and fabricated by Isaac Cookson & Co. using French glass; it entered service at the <a href="/wiki/Isle_of_May" title="Isle of May">Isle of May</a>, Scotland, on 22 September 1836.<sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> The first large catadioptric lenses were made in 1842 for the lighthouses at Gravelines and <a href="/wiki/%C3%8Ele_Vierge" title="Île Vierge">Île Vierge</a>, France; these were fixed third-order lenses whose catadioptric rings (made in segments) were one metre in diameter. Stevenson's first-order <a href="/wiki/Skerryvore" title="Skerryvore">Skerryvore</a> lens, lit in 1844, was only partly catadioptric; it was similar to the Cordouan lens except that the lower slats were replaced by French-made catadioptric prisms, while mirrors were retained at the top. The first <i>fully</i> catadioptric first-order lens, installed at Pointe d'Ailly in 1852, also gave eight rotating beams plus a fixed light at the bottom; but its top section had eight catadioptric panels focusing the light about 4 degrees ahead of the main beams, in order to lengthen the flashes. The first fully catadioptric lens with <i>purely revolving</i> beams—also of first order—was installed at <a href="/wiki/Saint-Cl%C3%A9ment-des-Baleines" title="Saint-Clément-des-Baleines">Saint-Clément-des-Baleines</a> in 1854, and marked the completion of Augustin Fresnel's original <i>Carte des Phares</i>.<sup id="cite_ref-48" class="reference"><a href="#cite_note-48"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup> </p><p><a href="/wiki/Thomas_Stevenson" title="Thomas Stevenson">Thomas Stevenson</a> (younger brother of Alan) went a step beyond Fresnel with his "holophotal" lens, which focused the light radiated by the lamp in nearly all directions, forward or backward, into a single beam.<sup id="cite_ref-49" class="reference"><a href="#cite_note-49"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> The first version, described in 1849, consisted of a standard Fresnel bull's-eye lens, a paraboloidal reflector, and a rear hemispherical reflector (functionally equivalent to the Rogers mirror of 60 years earlier, except that it subtended a whole hemisphere). Light radiated into the forward hemisphere but missing the bull's-eye lens was deflected by the paraboloid into a parallel beam surrounding the bull's-eye lens, while light radiated into the backward hemisphere was reflected back through the lamp by the spherical reflector (as in Rogers' arrangement), to be collected by the forward components. The first unit was installed at North Harbour, <a href="/wiki/Peterhead" title="Peterhead">Peterhead</a>, in August 1849. Stevenson called this version a "catadioptric holophote", although each of its elements was either purely reflective or purely refractive. In the second version of the holophote concept, the bull's-eye lens and paraboloidal reflector were replaced by a catadioptric Fresnel lens—as conceived by Fresnel, but expanded to cover the whole forward hemisphere. The third version, which Stevenson confusingly called a "dioptric holophote", was more innovative: it retained the catadioptric Fresnel lens for the front hemisphere, but replaced the rear hemispherical reflector with a hemispherical array of annular prisms, each of which used <i>two</i> total internal reflections to turn light diverging from the center of the hemisphere back toward the center. The result was an all-glass holophote, with no losses from metallic reflections.<sup id="cite_ref-50" class="reference"><a href="#cite_note-50"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> </p><p><a href="/wiki/James_Timmins_Chance" title="James Timmins Chance">James Timmins Chance</a> modified Thomas Stevenson's all-glass holophotal design by arranging the double-reflecting prisms about a vertical axis. The prototype was shown at the <a href="/wiki/1862_International_Exhibition" title="1862 International Exhibition">1862 International Exhibition</a> in London. Later, to ease manufacturing, Chance divided the prisms into segments, and arranged them in a cylindrical form while retaining the property of reflecting light from a single point back to that point. Reflectors of this form, paradoxically called "dioptric mirrors", proved particularly useful for returning light from the landward side of the lamp to the seaward side.<sup id="cite_ref-51" class="reference"><a href="#cite_note-51"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Fresnel_Lens_at_Point_Arena_Lighthouse_Museum.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/37/Fresnel_Lens_at_Point_Arena_Lighthouse_Museum.jpg/220px-Fresnel_Lens_at_Point_Arena_Lighthouse_Museum.jpg" decoding="async" width="220" height="318" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/37/Fresnel_Lens_at_Point_Arena_Lighthouse_Museum.jpg/330px-Fresnel_Lens_at_Point_Arena_Lighthouse_Museum.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/37/Fresnel_Lens_at_Point_Arena_Lighthouse_Museum.jpg/440px-Fresnel_Lens_at_Point_Arena_Lighthouse_Museum.jpg 2x" data-file-width="2563" data-file-height="3709" /></a><figcaption>First-order group-flashing Fresnel lens, on display at the Point Arena Lighthouse Museum, <a href="/wiki/Point_Arena_Light" title="Point Arena Light">Point Arena Lighthouse</a>, <a href="/wiki/Mendocino_County,_California" title="Mendocino County, California">Mendocino County, California</a>. The three dioptric panels (inside the brass rings) and three catadioptric panels (outside) are partly split in two, giving three double-flashes per rotation.</figcaption></figure> <p>As lighthouses proliferated, they became harder to distinguish from each other, leading to the use of colored filters, which wasted light. In 1884, <a href="/wiki/John_Hopkinson" title="John Hopkinson">John Hopkinson</a> eliminated the need for filters by inventing the "group-flashing" lens, in which the dioptric and/or the catadioptric panels were split so as to give multiple flashes—allowing lighthouses to be identified not only by frequency of flashes, but also by multiplicity of flashes. Double-flashing lenses were installed at Tampico (Mexico) and <a href="/wiki/Little_Basses_Reef_Lighthouse" title="Little Basses Reef Lighthouse">Little Basses</a> (Sri Lanka) in 1875, and a triple-flashing lens at <a href="/wiki/Casquets_lighthouses" title="Casquets lighthouses">Casquets Lighthouse</a> (<a href="/wiki/Channel_Islands" title="Channel Islands">Channel Islands</a>) in 1876.<sup id="cite_ref-52" class="reference"><a href="#cite_note-52"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> The example shown (right) is the double-flashing lens of the <a href="/wiki/Point_Arena_Light" title="Point Arena Light">Point Arena Light</a>, which was in service from 1908 to 1977.<sup id="cite_ref-53" class="reference"><a href="#cite_note-53"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup> </p><p>The development of hyper-radial lenses was driven in part by the need for larger light sources, such as gas lights with multiple jets, which required a longer focal length for a given beam-width, hence a larger lens to collect a given fraction of the generated light. The first hyper-radial lens was built for the Stevensons in 1885 by <a href="/wiki/Barbier,_Benard,_et_Turenne" title="Barbier, Benard, et Turenne">F. Barbier & Cie</a> of France, and tested at <a href="/wiki/South_Foreland_Lighthouse" class="mw-redirect" title="South Foreland Lighthouse">South Foreland Lighthouse</a> with various light sources. <a href="/wiki/Chance_Brothers" title="Chance Brothers">Chance Brothers</a> (Hopkinson's employers) then began constructing hyper-radials, installing their first at <a href="/wiki/Bishop_Rock,_Isles_of_Scilly" class="mw-redirect" title="Bishop Rock, Isles of Scilly">Bishop Rock</a> Lighthouse in 1887.<sup id="cite_ref-54" class="reference"><a href="#cite_note-54"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> In the same year, Barbier installed a hyper-radial at <a href="/wiki/Tory_Island" title="Tory Island">Tory Island</a>. But only about 30 hyper-radials went into service<sup id="cite_ref-tag-hyper_55-0" class="reference"><a href="#cite_note-tag-hyper-55"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup> before the development of more compact bright lamps rendered such large optics unnecessary (see <i><a href="/wiki/Hyperradiant_Fresnel_lens" title="Hyperradiant Fresnel lens">Hyperradiant Fresnel lens</a></i>). </p><p>Production of one-piece stepped dioptric lenses—roughly as envisaged by Buffon—became feasible in 1852, when John L. Gilliland of the <a href="/wiki/Corning_Inc." title="Corning Inc.">Brooklyn Flint-Glass Company</a> patented a method of making lenses from pressed and molded glass. The company made small bull's-eye lenses for use on railroads, steamboats, and docks;<sup id="cite_ref-tag-us_56-0" class="reference"><a href="#cite_note-tag-us-56"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> such lenses were common in the United States by the 1870s.<sup id="cite_ref-ripley-dana-1879_13-3" class="reference"><a href="#cite_note-ripley-dana-1879-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 488">: 488 </span></sup> In 1858 the company produced "a very small number of pressed flint-glass sixth-order lenses" for use in lighthouses—the first Fresnel lighthouse lenses made in America.<sup id="cite_ref-tag-us_56-1" class="reference"><a href="#cite_note-tag-us-56"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> By the 1950s, the substitution of plastic for glass made it economic to use Fresnel lenses as condensers in overhead projectors.<sup id="cite_ref-57" class="reference"><a href="#cite_note-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Design">Design</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=5" title="Edit section: Design"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Fresnel_lens.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Fresnel_lens.svg/170px-Fresnel_lens.svg.png" decoding="async" width="170" height="254" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Fresnel_lens.svg/255px-Fresnel_lens.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Fresnel_lens.svg/340px-Fresnel_lens.svg.png 2x" data-file-width="535" data-file-height="800" /></a><figcaption>1: Cross-section of Buffon/Fresnel lens. 2: Cross-section of conventional <a href="/wiki/Lens_(optics)#Types_of_simple_lenses" class="mw-redirect" title="Lens (optics)">plano-convex lens</a> of equivalent power. (Buffon's version was <a href="/wiki/Lens_(optics)#Types_of_simple_lenses" class="mw-redirect" title="Lens (optics)">biconvex</a>.<sup id="cite_ref-levitt-p59_20-1" class="reference"><a href="#cite_note-levitt-p59-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup>)</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Flat_flexible_plastic_sheet_lens.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Flat_flexible_plastic_sheet_lens.JPG/220px-Flat_flexible_plastic_sheet_lens.JPG" decoding="async" width="220" height="138" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Flat_flexible_plastic_sheet_lens.JPG/330px-Flat_flexible_plastic_sheet_lens.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Flat_flexible_plastic_sheet_lens.JPG/440px-Flat_flexible_plastic_sheet_lens.JPG 2x" data-file-width="2292" data-file-height="1441" /></a><figcaption>Close-up view of a flat Fresnel lens shows concentric circles on the surface</figcaption></figure> <p>The Fresnel lens reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections. An ideal Fresnel lens would have an infinite number of sections. In each section, the overall thickness is decreased compared to an equivalent simple lens. This effectively divides the continuous surface of a standard lens into a set of surfaces of the same curvature, with stepwise discontinuities between them. </p><p>In some lenses, the curved surfaces are replaced with flat surfaces, with a different angle in each section. Such a lens can be regarded as an array of prisms arranged in a circular fashion with steeper prisms on the edges and a flat or slightly convex center. In the first (and largest) Fresnel lenses, each section was actually a separate prism. 'Single-piece' Fresnel lenses were later produced, being used for automobile headlamps, brake, parking, and turn signal lenses, and so on. In modern times, <a href="/wiki/CNC" class="mw-redirect" title="CNC">computer-controlled milling equipment (CNC)</a> or <a href="/wiki/3-D_printing" class="mw-redirect" title="3-D printing">3-D printers</a> might be used to manufacture more complex lenses.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2023)">citation needed</span></a></i>]</sup> </p><p>Fresnel lens design allows a substantial reduction in thickness (and thus mass and volume of material) at the expense of reducing the imaging quality of the lens, which is why precise imaging applications such as photography usually still use larger conventional lenses. </p><p>Fresnel lenses are usually made of glass or plastic; their size varies from large (old historical lighthouses, meter size) to medium (book-reading aids, OHP viewgraph projectors) to small (<a href="/wiki/Twin-lens_reflex_camera" title="Twin-lens reflex camera">TLR</a>/<a href="/wiki/Single-lens_reflex_camera" title="Single-lens reflex camera">SLR</a> camera screens, micro-optics). In many cases they are very thin and flat, almost flexible, with thicknesses in the <style data-mw-deduplicate="TemplateStyles:r1154941027">.mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}</style>1 to 5 mm (<span class="frac"><span class="num">1</span>⁄<span class="den">32</span></span> to <span class="frac"><span class="num">3</span>⁄<span class="den">16</span></span> in) range.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2023)">citation needed</span></a></i>]</sup> </p><p>Most modern Fresnel lenses consist only of refractive elements. Lighthouse lenses, however, tend to include both refracting and reflecting elements, the latter being <i>outside</i> the metal rings seen in the photographs. While the inner elements are sections of refractive lenses, the outer elements are reflecting prisms, each of which performs two refractions and one <a href="/wiki/Total_internal_reflection" title="Total internal reflection">total internal reflection</a>, avoiding the light loss that occurs in reflection from a silvered mirror. </p> <div class="mw-heading mw-heading2"><h2 id="Lighthouse_lens_sizes">Lighthouse lens sizes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=6" title="Edit section: Lighthouse lens sizes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><span class="anchor" id="Sizes_of_lighthouse_lenses"></span> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Block_Island_Southeast_Light,_Spring_Street_and_Mohegan_Trail_at_Mohegan_Bluffs,_New_Shoreham,_Washington_County,_RI_HAER_RI,5-NESH,1-_(sheet_8_of_12).png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Block_Island_Southeast_Light%2C_Spring_Street_and_Mohegan_Trail_at_Mohegan_Bluffs%2C_New_Shoreham%2C_Washington_County%2C_RI_HAER_RI%2C5-NESH%2C1-_%28sheet_8_of_12%29.png/170px-Block_Island_Southeast_Light%2C_Spring_Street_and_Mohegan_Trail_at_Mohegan_Bluffs%2C_New_Shoreham%2C_Washington_County%2C_RI_HAER_RI%2C5-NESH%2C1-_%28sheet_8_of_12%29.png" decoding="async" width="170" height="255" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Block_Island_Southeast_Light%2C_Spring_Street_and_Mohegan_Trail_at_Mohegan_Bluffs%2C_New_Shoreham%2C_Washington_County%2C_RI_HAER_RI%2C5-NESH%2C1-_%28sheet_8_of_12%29.png/255px-Block_Island_Southeast_Light%2C_Spring_Street_and_Mohegan_Trail_at_Mohegan_Bluffs%2C_New_Shoreham%2C_Washington_County%2C_RI_HAER_RI%2C5-NESH%2C1-_%28sheet_8_of_12%29.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/20/Block_Island_Southeast_Light%2C_Spring_Street_and_Mohegan_Trail_at_Mohegan_Bluffs%2C_New_Shoreham%2C_Washington_County%2C_RI_HAER_RI%2C5-NESH%2C1-_%28sheet_8_of_12%29.png/340px-Block_Island_Southeast_Light%2C_Spring_Street_and_Mohegan_Trail_at_Mohegan_Bluffs%2C_New_Shoreham%2C_Washington_County%2C_RI_HAER_RI%2C5-NESH%2C1-_%28sheet_8_of_12%29.png 2x" data-file-width="9632" data-file-height="14442" /></a><figcaption>Description of lens orders, from <a href="/wiki/Block_Island_Southeast_Light" title="Block Island Southeast Light">Block Island Southeast Light</a>, Rhode Island.</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Makapuu_point_light.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Makapuu_point_light.JPG/170px-Makapuu_point_light.JPG" decoding="async" width="170" height="215" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Makapuu_point_light.JPG/255px-Makapuu_point_light.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Makapuu_point_light.JPG/340px-Makapuu_point_light.JPG 2x" data-file-width="361" data-file-height="457" /></a><figcaption><a href="/wiki/Makapuu_Point_Light" class="mw-redirect" title="Makapuu Point Light">Makapuu Point Light</a></figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><span><video id="mwe_player_0" poster="//upload.wikimedia.org/wikipedia/commons/thumb/9/94/Fresnel_lens_-_Chiba_-_2021_5_23.webm/220px--Fresnel_lens_-_Chiba_-_2021_5_23.webm.jpg" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="220" height="124" data-durationhint="16" data-mwtitle="Fresnel_lens_-_Chiba_-_2021_5_23.webm" data-mwprovider="wikimediacommons" resource="/wiki/File:Fresnel_lens_-_Chiba_-_2021_5_23.webm"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/9/94/Fresnel_lens_-_Chiba_-_2021_5_23.webm/Fresnel_lens_-_Chiba_-_2021_5_23.webm.480p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="480p.vp9.webm" data-width="854" data-height="480" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/9/94/Fresnel_lens_-_Chiba_-_2021_5_23.webm/Fresnel_lens_-_Chiba_-_2021_5_23.webm.720p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="720p.vp9.webm" data-width="1280" data-height="720" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/9/94/Fresnel_lens_-_Chiba_-_2021_5_23.webm/Fresnel_lens_-_Chiba_-_2021_5_23.webm.1080p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="1080p.vp9.webm" data-width="1920" data-height="1080" /><source src="//upload.wikimedia.org/wikipedia/commons/9/94/Fresnel_lens_-_Chiba_-_2021_5_23.webm" type="video/webm; codecs="vp8"" data-width="3840" data-height="2160" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/9/94/Fresnel_lens_-_Chiba_-_2021_5_23.webm/Fresnel_lens_-_Chiba_-_2021_5_23.webm.144p.mjpeg.mov" type="video/quicktime" data-transcodekey="144p.mjpeg.mov" data-width="256" data-height="144" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/9/94/Fresnel_lens_-_Chiba_-_2021_5_23.webm/Fresnel_lens_-_Chiba_-_2021_5_23.webm.240p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="240p.vp9.webm" data-width="426" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/9/94/Fresnel_lens_-_Chiba_-_2021_5_23.webm/Fresnel_lens_-_Chiba_-_2021_5_23.webm.360p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="360p.vp9.webm" data-width="640" data-height="360" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/9/94/Fresnel_lens_-_Chiba_-_2021_5_23.webm/Fresnel_lens_-_Chiba_-_2021_5_23.webm.360p.webm" type="video/webm; codecs="vp8, vorbis"" data-transcodekey="360p.webm" data-width="640" data-height="360" /></video></span><figcaption>Walking around a fresnel lens on display in <a href="/wiki/Chiba_Prefecture" title="Chiba Prefecture">Chiba</a>, <a href="/wiki/Japan" title="Japan">Japan</a>.</figcaption></figure> <p>Fresnel designed six sizes of lighthouse lenses, divided into four <i>orders</i> based on their size and focal length.<sup id="cite_ref-Baiges_58-0" class="reference"><a href="#cite_note-Baiges-58"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> The 3rd and 4th orders were sub-divided into "large" and "small". In modern use, the orders are classified as first through sixth order. An intermediate size between third and fourth order was added later, as well as sizes above first order and below sixth. </p><p>A first-order lens has a focal length of <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1154941027">920 mm (<span class="frac">36<span class="sr-only">+</span><span class="num">1</span>⁄<span class="den">4</span></span> in) and stands about 2.59 m (8 ft 6 in) high, and 1.8 m (6 ft) wide. The smallest (sixth) order has a focal length of 150 mm (6 in) and a height of <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1154941027">433 mm (<span class="frac">17<span class="sr-only">+</span><span class="num">1</span>⁄<span class="den">16</span></span> in).<sup id="cite_ref-Baiges_58-1" class="reference"><a href="#cite_note-Baiges-58"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-59" class="reference"><a href="#cite_note-59"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-60" class="reference"><a href="#cite_note-60"><span class="cite-bracket">[</span>60<span class="cite-bracket">]</span></a></sup> </p><p>The largest Fresnel lenses are called <a href="/wiki/Hyperradiant_Fresnel_lens" title="Hyperradiant Fresnel lens">hyperradiant</a> (or hyper-radial). One such lens was on hand when it was decided to build and outfit the <a href="/wiki/Makapuu_Point_Light" class="mw-redirect" title="Makapuu Point Light">Makapuu Point Light</a> in Hawaii. Rather than order a new lens, the huge optic construction, 3.7 metres (12 ft) tall and with over a thousand prisms, was used there.<sup id="cite_ref-LHF_61-0" class="reference"><a href="#cite_note-LHF-61"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable plainrowheaders"> <caption>Lighthouse lens orders<sup id="cite_ref-62" class="reference"><a href="#cite_note-62"><span class="cite-bracket">[</span>62<span class="cite-bracket">]</span></a></sup> </caption> <tbody><tr> <th scope="col">Modern order </th> <th scope="col">Fresnel order </th> <th scope="col">Focal length (mm) </th> <th scope="col">Height (m) </th> <th scope="col">First installed </th> <th scope="col">Application </th></tr> <tr> <th scope="row">Hyper-radial </th> <td> </td> <td>1330 </td> <td>3.76 </td> <td>1887 </td> <td>Major "landfall" lighthouses </td></tr> <tr> <th scope="row">Mesoradial </th> <td> </td> <td>1125 </td> <td>3.20 </td> <td>1909 </td> <td>Two Brazilian lighthouses </td></tr> <tr> <th scope="row">1st </th> <td>1st </td> <td>920 </td> <td>2.59 </td> <td>1823 </td> <td>Large seacoast lights </td></tr> <tr> <th scope="row">2nd </th> <td>2nd </td> <td>700–750 </td> <td>2.07 </td> <td> </td> <td><a href="/wiki/Great_Lakes" title="Great Lakes">Great Lakes</a> lighthouses, seacoasts, islands, sounds </td></tr> <tr> <th scope="row">3rd </th> <td>3rd (large) </td> <td>500 </td> <td>1.58 </td> <td>1825 </td> <td>Seacoast sounds, river entry, bays, channels, range lights </td></tr> <tr> <th scope="row"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1154941027"><span class="frac">3<span class="sr-only">+</span><span class="num">1</span>⁄<span class="den">2</span></span> </th> <td> </td> <td>375 </td> <td>1.09 </td> <td> </td></tr> <tr> <th scope="row">4th </th> <td>3rd (small) </td> <td>250 </td> <td>0.722 </td> <td> </td> <td>Shoals, reefs, harbor lights, islands in rivers and harbors </td></tr> <tr> <th scope="row">5th </th> <td>4th (large) </td> <td>187.5 </td> <td>0.541 </td> <td> </td> <td>Breakwaters, river and channel lights, Small islands in sounds </td></tr> <tr> <th scope="row">6th </th> <td>4th (small) </td> <td>150 </td> <td>0.433 </td> <td> </td> <td>Pier and breakwater lights in harbors </td></tr> <tr> <th scope="row">7th </th> <td> </td> <td>100–140 </td> <td>0.165 </td> <td> </td> <td>Used in Scotland and Canada </td></tr> <tr> <th scope="row">8th </th> <td> </td> <td>70–75 </td> <td>0.0826 </td> <td> </td> <td>Used in Scotland and Canada </td></tr></tbody></table> <ul class="gallery mw-gallery-traditional"> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:1st_order_Fresnel_lighthouse_lens.jpg" class="mw-file-description" title="First-order lens."><img alt="First-order lens." src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0f/1st_order_Fresnel_lighthouse_lens.jpg/80px-1st_order_Fresnel_lighthouse_lens.jpg" decoding="async" width="80" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0f/1st_order_Fresnel_lighthouse_lens.jpg/120px-1st_order_Fresnel_lighthouse_lens.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0f/1st_order_Fresnel_lighthouse_lens.jpg/160px-1st_order_Fresnel_lighthouse_lens.jpg 2x" data-file-width="2000" data-file-height="3000" /></a></span></div> <div class="gallerytext">First-order lens.</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Cape_Meares_Lighthouse_lens_-_Oregon.jpg" class="mw-file-description" title="First-order lens (Cape Meares Lighthouse)"><img alt="First-order lens (Cape Meares Lighthouse)" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Cape_Meares_Lighthouse_lens_-_Oregon.jpg/94px-Cape_Meares_Lighthouse_lens_-_Oregon.jpg" decoding="async" width="94" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Cape_Meares_Lighthouse_lens_-_Oregon.jpg/141px-Cape_Meares_Lighthouse_lens_-_Oregon.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Cape_Meares_Lighthouse_lens_-_Oregon.jpg/188px-Cape_Meares_Lighthouse_lens_-_Oregon.jpg 2x" data-file-width="400" data-file-height="510" /></a></span></div> <div class="gallerytext">First-order lens (<a href="/wiki/Cape_Meares_Lighthouse" class="mw-redirect" title="Cape Meares Lighthouse">Cape Meares Lighthouse</a>)</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:First-order_lens_from_Destruction_Island_WA.jpg" class="mw-file-description" title="First-order lens from Destruction Island WA, built in France 1888. Currently at Westport Maritime Museum."><img alt="First-order lens from Destruction Island WA, built in France 1888. Currently at Westport Maritime Museum." src="//upload.wikimedia.org/wikipedia/commons/thumb/e/ee/First-order_lens_from_Destruction_Island_WA.jpg/90px-First-order_lens_from_Destruction_Island_WA.jpg" decoding="async" width="90" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/ee/First-order_lens_from_Destruction_Island_WA.jpg/135px-First-order_lens_from_Destruction_Island_WA.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/ee/First-order_lens_from_Destruction_Island_WA.jpg/180px-First-order_lens_from_Destruction_Island_WA.jpg 2x" data-file-width="3000" data-file-height="4000" /></a></span></div> <div class="gallerytext">First-order lens from Destruction Island WA, built in France 1888. Currently at Westport Maritime Museum.</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Cape_Willoughby_Lighthouse_Fresnel_lens.jpg" class="mw-file-description" title="Close-up of a second-order lens."><img alt="Close-up of a second-order lens." src="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Cape_Willoughby_Lighthouse_Fresnel_lens.jpg/120px-Cape_Willoughby_Lighthouse_Fresnel_lens.jpg" decoding="async" width="120" height="84" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Cape_Willoughby_Lighthouse_Fresnel_lens.jpg/180px-Cape_Willoughby_Lighthouse_Fresnel_lens.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/51/Cape_Willoughby_Lighthouse_Fresnel_lens.jpg/240px-Cape_Willoughby_Lighthouse_Fresnel_lens.jpg 2x" data-file-width="1136" data-file-height="793" /></a></span></div> <div class="gallerytext">Close-up of a second-order lens.</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:St._Simons_Lighthouse,_close-up_of_top,_Georgia,_USA.JPG" class="mw-file-description" title="Third-order lens (St. Simons Island Light)."><img alt="Third-order lens (St. Simons Island Light)." src="//upload.wikimedia.org/wikipedia/commons/thumb/a/af/St._Simons_Lighthouse%2C_close-up_of_top%2C_Georgia%2C_USA.JPG/80px-St._Simons_Lighthouse%2C_close-up_of_top%2C_Georgia%2C_USA.JPG" decoding="async" width="80" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/af/St._Simons_Lighthouse%2C_close-up_of_top%2C_Georgia%2C_USA.JPG/120px-St._Simons_Lighthouse%2C_close-up_of_top%2C_Georgia%2C_USA.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/af/St._Simons_Lighthouse%2C_close-up_of_top%2C_Georgia%2C_USA.JPG/160px-St._Simons_Lighthouse%2C_close-up_of_top%2C_Georgia%2C_USA.JPG 2x" data-file-width="4000" data-file-height="6000" /></a></span></div> <div class="gallerytext">Third-order lens (<a href="/wiki/St._Simons_Island_Light" title="St. Simons Island Light">St. Simons Island Light</a>).</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Oita_sekizaki_lighthouse_old_lense.jpg" class="mw-file-description" title="Fourth-order lens (Sekizaki Lighthouse, Oita, Japan)."><img alt="Fourth-order lens (Sekizaki Lighthouse, Oita, Japan)." src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Oita_sekizaki_lighthouse_old_lense.jpg/90px-Oita_sekizaki_lighthouse_old_lense.jpg" decoding="async" width="90" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Oita_sekizaki_lighthouse_old_lense.jpg/135px-Oita_sekizaki_lighthouse_old_lense.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Oita_sekizaki_lighthouse_old_lense.jpg/180px-Oita_sekizaki_lighthouse_old_lense.jpg 2x" data-file-width="1200" data-file-height="1600" /></a></span></div> <div class="gallerytext">Fourth-order lens (Sekizaki Lighthouse, <a href="/wiki/%C5%8Cita,_%C5%8Cita" class="mw-redirect" title="Ōita, Ōita">Oita</a>, Japan).</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Fourth_order_Fresnel_Lens_originally_from_Cape_Arago_Lighthouse_OR.jpg" class="mw-file-description" title="Fourth order lens from Cape Arago Lighthouse. Currently at Coos History Museum."><img alt="Fourth order lens from Cape Arago Lighthouse. Currently at Coos History Museum." src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Fourth_order_Fresnel_Lens_originally_from_Cape_Arago_Lighthouse_OR.jpg/58px-Fourth_order_Fresnel_Lens_originally_from_Cape_Arago_Lighthouse_OR.jpg" decoding="async" width="58" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Fourth_order_Fresnel_Lens_originally_from_Cape_Arago_Lighthouse_OR.jpg/87px-Fourth_order_Fresnel_Lens_originally_from_Cape_Arago_Lighthouse_OR.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Fourth_order_Fresnel_Lens_originally_from_Cape_Arago_Lighthouse_OR.jpg/116px-Fourth_order_Fresnel_Lens_originally_from_Cape_Arago_Lighthouse_OR.jpg 2x" data-file-width="1960" data-file-height="4032" /></a></span></div> <div class="gallerytext">Fourth order lens from Cape Arago Lighthouse. Currently at Coos History Museum.</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Fifth-order_Fresnel_lens,_lighthouse_at_Key_West,_FL,_US.jpg" class="mw-file-description" title="Fifth-order lens, at Key West Lighthouse"><img alt="Fifth-order lens, at Key West Lighthouse" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Fifth-order_Fresnel_lens%2C_lighthouse_at_Key_West%2C_FL%2C_US.jpg/76px-Fifth-order_Fresnel_lens%2C_lighthouse_at_Key_West%2C_FL%2C_US.jpg" decoding="async" width="76" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Fifth-order_Fresnel_lens%2C_lighthouse_at_Key_West%2C_FL%2C_US.jpg/114px-Fifth-order_Fresnel_lens%2C_lighthouse_at_Key_West%2C_FL%2C_US.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Fifth-order_Fresnel_lens%2C_lighthouse_at_Key_West%2C_FL%2C_US.jpg/152px-Fifth-order_Fresnel_lens%2C_lighthouse_at_Key_West%2C_FL%2C_US.jpg 2x" data-file-width="3336" data-file-height="5253" /></a></span></div> <div class="gallerytext">Fifth-order lens, at <a href="/wiki/Key_West_Lighthouse" title="Key West Lighthouse">Key West Lighthouse</a></div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Ponce_de_Leon_Inlet_Lighthouse_Lens_Museum_-_Replica_6th_Order_Lens_-_March_2016_(25919436890).jpg" class="mw-file-description" title="Sixth-order lens (Ponce de Leon Inlet Light)"><img alt="Sixth-order lens (Ponce de Leon Inlet Light)" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6a/Ponce_de_Leon_Inlet_Lighthouse_Lens_Museum_-_Replica_6th_Order_Lens_-_March_2016_%2825919436890%29.jpg/79px-Ponce_de_Leon_Inlet_Lighthouse_Lens_Museum_-_Replica_6th_Order_Lens_-_March_2016_%2825919436890%29.jpg" decoding="async" width="79" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6a/Ponce_de_Leon_Inlet_Lighthouse_Lens_Museum_-_Replica_6th_Order_Lens_-_March_2016_%2825919436890%29.jpg/119px-Ponce_de_Leon_Inlet_Lighthouse_Lens_Museum_-_Replica_6th_Order_Lens_-_March_2016_%2825919436890%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6a/Ponce_de_Leon_Inlet_Lighthouse_Lens_Museum_-_Replica_6th_Order_Lens_-_March_2016_%2825919436890%29.jpg/159px-Ponce_de_Leon_Inlet_Lighthouse_Lens_Museum_-_Replica_6th_Order_Lens_-_March_2016_%2825919436890%29.jpg 2x" data-file-width="2945" data-file-height="4446" /></a></span></div> <div class="gallerytext">Sixth-order lens (<a href="/wiki/Ponce_de_Leon_Inlet_Light" title="Ponce de Leon Inlet Light">Ponce de Leon Inlet Light</a>)</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:First-_and_fourth-order_Fresnel_lenses,_Key_West,_FL,_US.jpg" class="mw-file-description" title="Comparison of first- and fourth-order lenses (Key West Lighthouse)"><img alt="Comparison of first- and fourth-order lenses (Key West Lighthouse)" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e4/First-_and_fourth-order_Fresnel_lenses%2C_Key_West%2C_FL%2C_US.jpg/108px-First-_and_fourth-order_Fresnel_lenses%2C_Key_West%2C_FL%2C_US.jpg" decoding="async" width="108" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e4/First-_and_fourth-order_Fresnel_lenses%2C_Key_West%2C_FL%2C_US.jpg/162px-First-_and_fourth-order_Fresnel_lenses%2C_Key_West%2C_FL%2C_US.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e4/First-_and_fourth-order_Fresnel_lenses%2C_Key_West%2C_FL%2C_US.jpg/216px-First-_and_fourth-order_Fresnel_lenses%2C_Key_West%2C_FL%2C_US.jpg 2x" data-file-width="4016" data-file-height="4465" /></a></span></div> <div class="gallerytext">Comparison of first- and fourth-order lenses (Key West Lighthouse)</div> </li> </ul> <div class="mw-heading mw-heading2"><h2 id="Types">Types</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=7" title="Edit section: Types"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>There are two main types of Fresnel lens: <i>imaging</i> and <i>non-imaging</i>. Imaging Fresnel lenses use segments with curved cross-sections and produce sharp images, while non-imaging lenses have segments with flat cross-sections, and do not produce sharp images.<sup id="cite_ref-63" class="reference"><a href="#cite_note-63"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup> As the number of segments increases, the two types of lens become more similar to each other. In the abstract case of an infinite number of segments, the difference between curved and flat segments disappears. </p><p>Imaging lenses can be classified as: </p> <dl><dt>Spherical</dt> <dd>A spherical Fresnel lens is equivalent to a <a href="/wiki/Simple_lens" title="Simple lens">simple</a> <a href="/wiki/Spherical_lens" class="mw-redirect" title="Spherical lens">spherical lens</a>, using ring-shaped segments that are each a portion of a sphere, that all focus light on a single point. This type of lens produces a sharp image, although not quite as clear as the equivalent simple spherical lens due to diffraction at the edges of the ridges. This type is sometimes called a <a href="/wiki/Kinoform" title="Kinoform">kinoform</a> when the ridges are microscopic, at the wavelength scale.</dd> <dt>Cylindrical</dt> <dd>A cylindrical Fresnel lens is equivalent to a simple <a href="/wiki/Cylindrical_lens" title="Cylindrical lens">cylindrical lens</a>, using straight segments with circular cross-section, focusing light on a single line. This type produces a sharp image, although not quite as clear as the equivalent simple cylindrical lens due to diffraction at the edges of the ridges.</dd></dl> <p>Non-imaging lenses can be classified as: </p> <dl><dt>Spot</dt> <dd>A non-imaging spot Fresnel lens uses ring-shaped segments with cross sections that are straight lines rather than circular arcs. Such a lens can focus light on a small spot, but does not produce a sharp image. These lenses have application in solar power, such as focusing sunlight on a solar panel. Fresnel lenses may be used as components of <a href="/wiki/K%C3%B6hler_illumination" title="Köhler illumination">Köhler illumination</a> optics resulting in very effective <a href="/wiki/Nonimaging_optics" title="Nonimaging optics">nonimaging optics</a> Fresnel-Köhler (FK) solar concentrators.<sup id="cite_ref-IntroNio2e_64-0" class="reference"><a href="#cite_note-IntroNio2e-64"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup></dd> <dt>Linear</dt> <dd>A non-imaging linear Fresnel lens uses straight segments whose cross sections are straight lines rather than arcs. These lenses focus light into a narrow band. They do not produce a sharp image, but can be used in solar power, such as for focusing sunlight on a pipe, to heat the water within.<sup id="cite_ref-65" class="reference"><a href="#cite_note-65"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup></dd></dl> <div class="mw-heading mw-heading2"><h2 id="Uses">Uses</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=8" title="Edit section: Uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Illumination">Illumination</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=9" title="Edit section: Illumination"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Inchkeith_lighthouse_Fresnel_lens.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2a/Inchkeith_lighthouse_Fresnel_lens.JPG/70px-Inchkeith_lighthouse_Fresnel_lens.JPG" decoding="async" width="70" height="202" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/2a/Inchkeith_lighthouse_Fresnel_lens.JPG/105px-Inchkeith_lighthouse_Fresnel_lens.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/2a/Inchkeith_lighthouse_Fresnel_lens.JPG/140px-Inchkeith_lighthouse_Fresnel_lens.JPG 2x" data-file-width="1648" data-file-height="4761" /></a><figcaption><a href="/wiki/Inchkeith" title="Inchkeith">Inchkeith</a> lighthouse lens and drive mechanism at the <a href="/wiki/National_Museum_of_Scotland" title="National Museum of Scotland">National Museum of Scotland</a></figcaption></figure> <p>High-quality glass Fresnel lenses were used in lighthouses, where they were considered state of the art in the late 19th and through the middle of the 20th centuries; most lighthouses have now retired glass Fresnel lenses from service and replaced them with much less expensive and more durable <a href="/wiki/Aerobeacon" title="Aerobeacon">aerobeacons</a>, which themselves often contain plastic Fresnel lenses.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (September 2020)">citation needed</span></a></i>]</sup> Lighthouse Fresnel lens systems typically include extra annular <a href="/wiki/Prism_(optics)" title="Prism (optics)">prismatic</a> elements, arrayed in faceted domes above and below the central planar Fresnel, in order to catch all light emitted from the light source. The light path through these elements can include an <a href="/wiki/Internal_reflection" class="mw-redirect" title="Internal reflection">internal reflection</a>, rather than the simple <a href="/wiki/Refraction" title="Refraction">refraction</a> in the planar Fresnel element. These lenses conferred many practical benefits upon the designers, builders, and users of lighthouses and their illumination. Among other things, smaller lenses could fit into more compact spaces. Greater light transmission over longer distances, and varied patterns, made it possible to triangulate a position.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (September 2020)">citation needed</span></a></i>]</sup> </p><p>Perhaps the most widespread use of Fresnel lenses, for a time, occurred in <a href="/wiki/Automobile" class="mw-redirect" title="Automobile">automobile</a> <a href="/wiki/Headlamp" title="Headlamp">headlamps</a>, where they can shape the roughly parallel beam from the parabolic reflector to meet requirements for dipped and main-beam patterns, often both in the same headlamp unit (such as the European <a href="/wiki/H4_lamp" class="mw-redirect" title="H4 lamp">H4</a> design). For reasons of economy, weight, and impact resistance, newer cars have dispensed with glass Fresnel lenses, using <a href="/wiki/Multifaceted_reflector" title="Multifaceted reflector">multifaceted reflectors</a> with plain <a href="/wiki/Polycarbonate" title="Polycarbonate">polycarbonate</a> lenses. However, Fresnel lenses continue in wide use in automobile tail, marker, and reversing lights. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Colortran_Fresnel.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Colortran_Fresnel.JPG/220px-Colortran_Fresnel.JPG" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/Colortran_Fresnel.JPG/330px-Colortran_Fresnel.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/49/Colortran_Fresnel.JPG/440px-Colortran_Fresnel.JPG 2x" data-file-width="1280" data-file-height="960" /></a><figcaption>A Fresnel lantern with the lens open to show the ridges</figcaption></figure> <p>Glass Fresnel lenses also are used in lighting instruments for <a href="/wiki/Theatre" title="Theatre">theatre</a> and <a href="/wiki/Motion_pictures" class="mw-redirect" title="Motion pictures">motion pictures</a> (see <a href="/wiki/Fresnel_lantern" title="Fresnel lantern">Fresnel lantern</a>); such instruments are often called simply <i>Fresnels</i>. The entire instrument consists of a metal housing, a reflector, a lamp assembly, and a Fresnel lens. Many Fresnel instruments allow the lamp to be moved relative to the lens' <a href="/wiki/Focus_(optics)" title="Focus (optics)">focal point</a>, to increase or decrease the size of the light beam. As a result, they are very flexible, and can often produce a beam as narrow as 7° or as wide as 70°.<sup id="cite_ref-66" class="reference"><a href="#cite_note-66"><span class="cite-bracket">[</span>66<span class="cite-bracket">]</span></a></sup> The Fresnel lens produces a very soft-edged beam, so is often used as a wash light. A holder in front of the lens can hold a colored plastic film (<i>gel</i>) to tint the light or wire screens or frosted plastic to diffuse it. The Fresnel lens is useful in the making of motion pictures not only because of its ability to focus the beam brighter than a typical lens, but also because the light is a relatively consistent intensity across the entire width of the beam of light. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Optical_Landing_System,_night,_aboard_USS_Dwight_D._Eisenhower_(CVN-69).jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/05/Optical_Landing_System%2C_night%2C_aboard_USS_Dwight_D._Eisenhower_%28CVN-69%29.jpg/220px-Optical_Landing_System%2C_night%2C_aboard_USS_Dwight_D._Eisenhower_%28CVN-69%29.jpg" decoding="async" width="220" height="138" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/05/Optical_Landing_System%2C_night%2C_aboard_USS_Dwight_D._Eisenhower_%28CVN-69%29.jpg/330px-Optical_Landing_System%2C_night%2C_aboard_USS_Dwight_D._Eisenhower_%28CVN-69%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/05/Optical_Landing_System%2C_night%2C_aboard_USS_Dwight_D._Eisenhower_%28CVN-69%29.jpg/440px-Optical_Landing_System%2C_night%2C_aboard_USS_Dwight_D._Eisenhower_%28CVN-69%29.jpg 2x" data-file-width="1900" data-file-height="1196" /></a><figcaption><a href="/wiki/Optical_landing_system" title="Optical landing system">Optical landing system</a> on US Navy aircraft carrier <a href="/wiki/USS_Dwight_D._Eisenhower" title="USS Dwight D. Eisenhower">USS <i>Dwight D. Eisenhower</i></a></figcaption></figure> <p><a href="/wiki/Aircraft_carrier" title="Aircraft carrier">Aircraft carriers</a> and naval air stations typically use Fresnel lenses in their <a href="/wiki/Optical_landing_system" title="Optical landing system">optical landing systems</a>. The "meatball" light aids the pilot in maintaining proper glide slope for the landing. In the center are amber and red lights composed of Fresnel lenses. Although the lights are always on, the angle of the lens from the pilot's point of view determines the color and position of the visible light. If the lights appear above the green horizontal bar, the pilot is too high. If it is below, the pilot is too low, and if the lights are red, the pilot is very low.<sup id="cite_ref-67" class="reference"><a href="#cite_note-67"><span class="cite-bracket">[</span>67<span class="cite-bracket">]</span></a></sup> </p><p>Fresnel lenses are also commonly used in <a href="/wiki/Searchlight" title="Searchlight">searchlights</a>, <a href="/wiki/Spotlight_(theatre_lighting)" title="Spotlight (theatre lighting)">spotlights</a>, and <a href="/wiki/Flashlight" title="Flashlight">flashlights</a>. </p> <div class="mw-heading mw-heading3"><h3 id="Imaging">Imaging</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=10" title="Edit section: Imaging"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Magnifying-fresnel-lens.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Magnifying-fresnel-lens.jpg/220px-Magnifying-fresnel-lens.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Magnifying-fresnel-lens.jpg/330px-Magnifying-fresnel-lens.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Magnifying-fresnel-lens.jpg/440px-Magnifying-fresnel-lens.jpg 2x" data-file-width="1536" data-file-height="1152" /></a><figcaption>A plastic Fresnel lens sold as a TV-screen enlarging device</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:SinclairFTV1fresnellens1.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/SinclairFTV1fresnellens1.JPG/220px-SinclairFTV1fresnellens1.JPG" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/SinclairFTV1fresnellens1.JPG/330px-SinclairFTV1fresnellens1.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/16/SinclairFTV1fresnellens1.JPG/440px-SinclairFTV1fresnellens1.JPG 2x" data-file-width="3648" data-file-height="2736" /></a><figcaption>The Fresnel lens used in the <a href="/wiki/TV80" title="TV80">Sinclair FTV1</a> portable CRT TV, which enlarges the vertical aspect of the display only</figcaption></figure> <p>Fresnel lenses are used as simple hand-held <a href="/wiki/Magnifying_glass" title="Magnifying glass">magnifiers</a>. They are also used to correct several visual disorders, including ocular-motility disorders such as <a href="/wiki/Strabismus" title="Strabismus">strabismus</a>.<sup id="cite_ref-68" class="reference"><a href="#cite_note-68"><span class="cite-bracket">[</span>68<span class="cite-bracket">]</span></a></sup> Fresnel lenses have been used to increase the visual size of <a href="/wiki/CRT_display" class="mw-redirect" title="CRT display">CRT displays</a> in pocket <a href="/wiki/Television" title="Television">televisions</a>, notably the <a href="/wiki/Sinclair_Research_Ltd." class="mw-redirect" title="Sinclair Research Ltd.">Sinclair</a> <a href="/wiki/TV80" title="TV80">TV80</a>. They are also used in <a href="/wiki/Traffic_light" title="Traffic light">traffic lights</a>. </p><p>Fresnel lenses are used in left-hand-drive European <a href="/wiki/Lorry" class="mw-redirect" title="Lorry">lorries</a> entering the UK and Republic of Ireland (and vice versa, right-hand-drive Irish and British trucks entering mainland Europe) to overcome the blind spots caused by the driver operating the lorry while sitting on the wrong side of the cab relative to the side of the road the car is on. They attach to the passenger-side window.<sup id="cite_ref-69" class="reference"><a href="#cite_note-69"><span class="cite-bracket">[</span>69<span class="cite-bracket">]</span></a></sup> </p><p>Another automobile application of a Fresnel lens is a rear view enhancer, as the <a href="/wiki/Wide-angle_lens" title="Wide-angle lens">wide view angle</a> of a lens attached to the rear window permits examining the scene behind a vehicle, particularly a tall or bluff-tailed one, more effectively than a <a href="/wiki/Rear-view_mirror" title="Rear-view mirror">rear-view mirror</a> alone. Fresnel lenses have been used on rangefinding equipment and <a href="/wiki/Moving_map_display" title="Moving map display">projected map display</a> screens.<sup id="cite_ref-70" class="reference"><a href="#cite_note-70"><span class="cite-bracket">[</span>70<span class="cite-bracket">]</span></a></sup> </p><p>Fresnel lenses have also been used in the field of popular entertainment. The British rock artist <a href="/wiki/Peter_Gabriel" title="Peter Gabriel">Peter Gabriel</a> made use of them in his early solo live performances to magnify the size of his head, in contrast to the rest of his body, for dramatic and comic effect. In the <a href="/wiki/Terry_Gilliam" title="Terry Gilliam">Terry Gilliam</a> film <i><a href="/wiki/Brazil_(1985_film)" title="Brazil (1985 film)">Brazil</a></i>, plastic Fresnel screens appear ostensibly as magnifiers for the small CRT monitors used throughout the offices of the Ministry of Information. However, they occasionally appear between the actors and the camera, distorting the scale and composition of the scene to humorous effect. The <a href="/wiki/Pixar" title="Pixar">Pixar</a> movie <a href="/wiki/Wall-E" class="mw-redirect" title="Wall-E">Wall-E</a> features a Fresnel lens in the scenes where the protagonist watches the musical <a href="/wiki/Hello,_Dolly!_(film)" title="Hello, Dolly! (film)"><i>Hello, Dolly!</i></a> magnified on an <a href="/wiki/IPod" title="IPod">iPod</a>. </p><p><a href="/wiki/Virtual_reality" title="Virtual reality">Virtual reality</a> headsets, such as the <a href="/wiki/Meta_Quest_2" class="mw-redirect" title="Meta Quest 2">Meta Quest 2</a> and the <a href="/wiki/HTC_Vive" title="HTC Vive">HTC Vive Pro</a> use Fresnel lenses,<sup id="cite_ref-71" class="reference"><a href="#cite_note-71"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup> as they allow a thinner and lighter form factor than regular lenses.<sup id="cite_ref-72" class="reference"><a href="#cite_note-72"><span class="cite-bracket">[</span>72<span class="cite-bracket">]</span></a></sup> Newer devices, such as the <a href="/wiki/Meta_Quest_Pro" title="Meta Quest Pro">Meta Quest Pro</a>, have switched to a <a href="/wiki/Pancake_lens" title="Pancake lens">pancake lens</a> design<sup id="cite_ref-73" class="reference"><a href="#cite_note-73"><span class="cite-bracket">[</span>73<span class="cite-bracket">]</span></a></sup> due to its smaller form factor and less <a href="/wiki/Chromatic_aberration" title="Chromatic aberration">chromatic aberration</a> than Fresnel lenses.<sup id="cite_ref-74" class="reference"><a href="#cite_note-74"><span class="cite-bracket">[</span>74<span class="cite-bracket">]</span></a></sup> </p><p>Multi-focal Fresnel lenses are also used as a part of <a href="/wiki/Retinal_scan" title="Retinal scan">retina identification</a> cameras, where they provide multiple in- and out-of-focus images of a fixation target inside the camera. For virtually all users, at least one of the images will be in focus, thus allowing correct eye alignment. </p><p><a href="/wiki/Canon_Inc." title="Canon Inc.">Canon</a> and <a href="/wiki/Nikon" title="Nikon">Nikon</a> have used Fresnel lenses to reduce the size of telephoto lenses. Photographic lenses that include Fresnel elements can be much shorter than corresponding conventional lens design. Nikon calls the technology <i>Phase Fresnel</i>.<sup id="cite_ref-75" class="reference"><a href="#cite_note-75"><span class="cite-bracket">[</span>75<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-76" class="reference"><a href="#cite_note-76"><span class="cite-bracket">[</span>76<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Polaroid_SX-70" title="Polaroid SX-70">Polaroid SX-70</a> camera used a Fresnel reflector as part of its viewing system. <a href="/wiki/View_camera" title="View camera">View</a> and <a href="/wiki/Large_format" title="Large format">large format</a> cameras can utilize a Fresnel lens in conjunction with the <a href="/wiki/Ground_glass" title="Ground glass">ground glass</a>, to increase the perceived brightness of the image projected by a lens onto the ground glass, thus aiding in adjusting focus and composition. </p> <div class="mw-heading mw-heading3"><h3 id="Projection">Projection</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=11" title="Edit section: Projection"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The use of Fresnel lenses for image projection reduces image quality, so they tend to occur only where quality is not critical or where the bulk of a solid lens would be prohibitive. Cheap Fresnel lenses can be stamped or molded of transparent plastic and are used in <a href="/wiki/Overhead_projector" title="Overhead projector">overhead projectors</a> and <a href="/wiki/Projection_television" class="mw-redirect" title="Projection television">projection televisions</a>. </p><p>Fresnel lenses of different focal lengths (one <a href="/wiki/Collimator" title="Collimator">collimator</a>, and one collector) are used in commercial and <a href="/wiki/DIY" class="mw-redirect" title="DIY">DIY</a> projection. The collimator lens has the lower focal length and is placed closer to the light source, and the collector lens, which focuses the light into the triplet lens, is placed after the projection image (an <a href="/wiki/Active_matrix_LCD" class="mw-redirect" title="Active matrix LCD">active matrix LCD</a> panel in <a href="/wiki/LCD_projector" title="LCD projector">LCD projectors</a>). Fresnel lenses are also used as collimators in <a href="/wiki/Overhead_projector" title="Overhead projector">overhead projectors</a>. </p> <div class="mw-heading mw-heading3"><h3 id="Solar_power">Solar power</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=12" title="Edit section: Solar power"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Since plastic Fresnel lenses can be made larger than glass lenses, as well as being much cheaper and lighter, they are used to concentrate sunlight for heating in <a href="/wiki/Solar_cooker" title="Solar cooker">solar cookers</a>, in solar forges, and in <a href="/wiki/Solar_thermal_collector" title="Solar thermal collector">solar collectors</a> used to heat water for domestic use. They can also be used to generate steam or to power a <a href="/wiki/Stirling_engine" title="Stirling engine">Stirling engine</a>. </p><p>Fresnel lenses can concentrate sunlight onto <a href="/wiki/Solar_cell" title="Solar cell">solar cells</a> with a ratio of almost 500:1.<sup id="cite_ref-77" class="reference"><a href="#cite_note-77"><span class="cite-bracket">[</span>77<span class="cite-bracket">]</span></a></sup> This allows the active solar-cell surface to be reduced, lowering cost and allowing the use of more efficient cells that would otherwise be too expensive.<sup id="cite_ref-78" class="reference"><a href="#cite_note-78"><span class="cite-bracket">[</span>78<span class="cite-bracket">]</span></a></sup> In the early 21st century, Fresnel reflectors began to be used in <a href="/wiki/Concentrating_solar_power" class="mw-redirect" title="Concentrating solar power">concentrating solar power</a> (CSP) plants to concentrate solar energy. One application was to preheat water at the coal-fired <a href="/wiki/Liddell_Power_Station" title="Liddell Power Station">Liddell Power Station</a>, in Hunter Valley Australia. </p><p>Fresnel lenses can be used to <a href="/wiki/Sintering" title="Sintering">sinter</a> sand, allowing <a href="/wiki/3D_printing" title="3D printing">3D printing</a> in glass.<sup id="cite_ref-79" class="reference"><a href="#cite_note-79"><span class="cite-bracket">[</span>79<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=13" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Fresnel_imager" title="Fresnel imager">Fresnel imager</a></li> <li><a href="/wiki/Fresnel_zone_plate" class="mw-redirect" title="Fresnel zone plate">Fresnel zone plate</a></li> <li><a href="/wiki/Lenticular_lens" title="Lenticular lens">Lenticular lens</a></li> <li><a href="/wiki/Linear_Fresnel_reflector" class="mw-redirect" title="Linear Fresnel reflector">Linear Fresnel reflector</a></li> <li><a href="/wiki/Prism_lighting" title="Prism lighting">Prism lighting</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=14" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFJ._Wells2008" class="citation book cs2"><a href="/wiki/John_C._Wells" title="John C. 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(1911), <span class="cs1-ws-icon" title="s:1911 Encyclopædia Britannica/Lighthouse"><a class="external text" href="https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Lighthouse">"Lighthouse" </a></span>, <i><a href="/wiki/Encyclop%C3%A6dia_Britannica_Eleventh_Edition" title="Encyclopædia Britannica Eleventh Edition">Encyclopædia Britannica</a></i>, vol. 16 (11th ed.), Cambridge University Press, pp. 627–651</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Lighthouse&rft.btitle=Encyclop%C3%A6dia+Britannica&rft.pages=627-651&rft.edition=11th&rft.pub=Cambridge+University+Press&rft.date=1911&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFresnel+lens" class="Z3988"></span>.</span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation encyclopaedia cs2"><a rel="nofollow" class="external text" href="http://www.merriam-webster.com/dictionary/fresnel%20lens">"Fresnel lens"</a>, <i><a href="/wiki/Merriam-Webster" title="Merriam-Webster">Merriam-Webster</a></i>, <a rel="nofollow" class="external text" href="https://web.archive.org/web/20131217120005/http://www.merriam-webster.com/dictionary/fresnel%20lens">archived</a> from the original on 17 December 2013<span class="reference-accessdate">, retrieved <span class="nowrap">19 March</span> 2013</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Fresnel+lens&rft.btitle=Merriam-Webster&rft_id=http%3A%2F%2Fwww.merriam-webster.com%2Fdictionary%2Ffresnel%2520lens&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFresnel+lens" class="Z3988"></span>.</span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWells2008" class="citation book cs2"><a href="/wiki/John_C._Wells" title="John C. 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Tag, <a rel="nofollow" class="external text" href="http://uslhs.org/chronology-lighthouse-events">"Chronology of Lighthouse Events"</a>, U.S. Lighthouse Society, accessed 22 August 2017; <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170408105558/http://uslhs.org/chronology-lighthouse-events">archived</a> 8 April 2017.</span> </li> <li id="cite_note-tag-fres-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-tag-fres_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-tag-fres_11-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-tag-fres_11-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-tag-fres_11-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-tag-fres_11-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text">T. Tag, <a rel="nofollow" class="external text" href="http://uslhs.org/fresnel-lens">"The Fresnel lens"</a>, U.S. Lighthouse Society, accessed 12 August 2017; <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160722002916/http://uslhs.org/fresnel-lens">archived</a> 22 July 2017.</span> </li> <li id="cite_note-levitt-p71-12"><span class="mw-cite-backlink">^ <a href="#cite_ref-levitt-p71_12-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-levitt-p71_12-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Levitt, 2013, p.<span class="nowrap"> </span>71.</span> </li> <li id="cite_note-ripley-dana-1879-13"><span class="mw-cite-backlink">^ <a href="#cite_ref-ripley-dana-1879_13-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ripley-dana-1879_13-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-ripley-dana-1879_13-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-ripley-dana-1879_13-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text">G. Ripley and C.A. Dana (eds.), <a rel="nofollow" class="external text" href="https://archive.org/stream/americancyclopae07ripluoft#page/486/mode/2up">"Fresnel, Augustin Jean"</a>, <i>American Cyclopædia</i>, 1879, vol. 7, pp. 486–489.</span> </li> <li id="cite_note-chisholm-1911-brewster-14"><span class="mw-cite-backlink">^ <a href="#cite_ref-chisholm-1911-brewster_14-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-chisholm-1911-brewster_14-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChisholm1911" class="citation encyclopaedia cs2"><a href="/wiki/Hugh_Chisholm" title="Hugh Chisholm">Chisholm, Hugh</a>, ed. (1911), <span class="cs1-ws-icon" title="s:1911 Encyclopædia Britannica/Brewster, Sir David"><a class="external text" href="https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Brewster,_Sir_David">"Brewster, Sir David" </a></span>, <i><a href="/wiki/Encyclop%C3%A6dia_Britannica_Eleventh_Edition" title="Encyclopædia Britannica Eleventh Edition">Encyclopædia Britannica</a></i>, vol. 4 (11th ed.), Cambridge University Press, pp. 513–514</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Brewster%2C+Sir+David&rft.btitle=Encyclop%C3%A6dia+Britannica&rft.pages=513-514&rft.edition=11th&rft.pub=Cambridge+University+Press&rft.date=1911&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFresnel+lens" class="Z3988"></span>.</span> </li> <li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text">Levitt, 2013, pp. 49–50.</span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text">Levitt, 2013, pp. 51, 53; Elton, 2009, p.<span class="nowrap"> </span>190; Fresnel, 1866–70, vol. 1, p.<span class="nowrap"> </span>xcvii, and vol. 3, p.<span class="nowrap"> </span>xxiv. ("July 21" in Levitt, 2013, p.<span class="nowrap"> </span>240, is a transcription error, inconsistent with the primary source cited.)</span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text">Fresnel, 1866–70, vol. 3, pp. 5–14; on the date, see p.<span class="nowrap"> </span>6n. Levitt (2013, p.<span class="nowrap"> </span>58) gives the date only as August 1819.</span> </li> <li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text">Levitt, 2013, pp. 56, 58.</span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text">Fresnel, 1866–70, vol. 3, p.<span class="nowrap"> </span>6n.</span> </li> <li id="cite_note-levitt-p59-20"><span class="mw-cite-backlink">^ <a href="#cite_ref-levitt-p59_20-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-levitt-p59_20-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Levitt, 2013, p.<span class="nowrap"> </span>59.</span> </li> <li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text">Levitt, 2013, p.<span class="nowrap"> </span>59. The biconvex shape may be inferred from Buffon's description, quoted in Fresnel, 1822, tr. Tag, at p.<span class="nowrap"> </span>4.</span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text">Fresnel, 1822, tr. Tag, p.<span class="nowrap"> </span>11.</span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text">Levitt, 2013, pp. 59–66. Levitt gives the size of the eight-panel version as <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1154941027">720 mm (<span class="frac">28<span class="sr-only">+</span><span class="num">1</span>⁄<span class="den">3</span></span> in). Elton (2009, p.<span class="nowrap"> </span>193) gives it as 76<span class="nowrap"> </span>cm and indicates that the first panel was tested on 31 October 1820; cf. Fresnel, 1866–70, vol. 3, pp. xxxii & xxxiv, and Fresnel, 1822, tr. Tag, p.<span class="nowrap"> </span>7.</span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text">A. Fresnel, "Note sur le calcul des teintes que la polarisation développe dans les lames cristallisées" et seq., <i>Annales de Chimie et de Physique</i>, Ser.<span class="nowrap"> </span>2, vol. 17, pp. 102–111 (May 1821), 167–196 (June 1821), 312–315 ("Postscript", July 1821); reprinted in Fresnel, 1866–1870, vol. 1, pp. 609–648; translated as "On the calculation of the tints that polarization develops in crystalline plates, & postscript", <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/Zenodo" title="Zenodo">Zenodo</a>: <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://zenodo.org/record/4058004">4058004</a></span> / <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.5281%2Fzenodo.4058004">10.5281/zenodo.4058004</a>, 2021.</span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text">Fresnel, 1822, tr. Tag, pp. 2–4.</span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text">Fresnel, 1822, tr. Tag, p.<span class="nowrap"> </span>1.</span> </li> <li id="cite_note-gombert-2017-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-gombert-2017_27-0">^</a></b></span> <span class="reference-text">D. Gombert, photograph of the <a rel="nofollow" class="external text" href="https://www.flickr.com/photos/gebete29/32970312394/in/photostream/"><i>Optique de Cordouan</i></a> in the collection of the <i>Musée des Phares et Balises</i>, <a href="/wiki/Ushant" title="Ushant">Ouessant</a>, France, 23 March 2017.</span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text">Fresnel, 1822, tr. Tag, pp. 13, 25.</span> </li> <li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text">Elton, 2009, p.<span class="nowrap"> </span>195; Levitt, 2013, pp. 72–76.</span> </li> <li id="cite_note-watson-1999-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-watson-1999_30-0">^</a></b></span> <span class="reference-text">B. Watson, <a rel="nofollow" class="external text" href="https://www.smithsonianmag.com/science-nature/science-makes-a-better-lighthouse-lens-170677431/">"Science Makes a Better Lighthouse Lens"</a>, <i>Smithsonian</i>, vol. 30 no.<span class="nowrap"> </span>5 (August 1999), pp 30–31.</span> </li> <li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text">Buchwald, 1989, pp. 260, 288–290, 297; cf. Born & Wolf, 1999, p.<span class="nowrap"> </span>xxviii.</span> </li> <li id="cite_note-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-32">^</a></b></span> <span class="reference-text">Fresnel, 1866–1870, vol. 1, pp. 713–718, 731–751, 767–799.</span> </li> <li id="cite_note-levitt-p97-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-levitt-p97_33-0">^</a></b></span> <span class="reference-text">Levitt, 2013, p.<span class="nowrap"> </span>97.</span> </li> <li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text">Levitt, 2013, p.<span class="nowrap"> </span>82.</span> </li> <li id="cite_note-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-35">^</a></b></span> <span class="reference-text">Elton, 2009, p.<span class="nowrap"> </span>190.</span> </li> <li id="cite_note-brock-1909-36"><span class="mw-cite-backlink"><b><a href="#cite_ref-brock-1909_36-0">^</a></b></span> <span class="reference-text">H.M. Brock, <a href="https://en.wikisource.org/wiki/Catholic_Encyclopedia_(1913)/Augustin-Jean_Fresnel" class="extiw" title="s:Catholic Encyclopedia (1913)/Augustin-Jean Fresnel">"Fresnel, Augustin-Jean"</a>, <i>Catholic Encyclopedia</i>, 1907–12, vol. 6 (1909).</span> </li> <li id="cite_note-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-37">^</a></b></span> <span class="reference-text">Young, 1855, p.<span class="nowrap"> </span>399; Boutry, 1948, pp. 601–602.</span> </li> <li id="cite_note-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-38">^</a></b></span> <span class="reference-text">Cf. Elton, 2009, p.<span class="nowrap"> </span>198, Figure 12.</span> </li> <li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text">Levitt, 2013, p.<span class="nowrap"> </span>84.</span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text">Elton, 2009, pp. 197–198.</span> </li> <li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text">Elton, 2009, pp. 198–199.</span> </li> <li id="cite_note-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-42">^</a></b></span> <span class="reference-text">Levitt, 2013, pp. 82–84.</span> </li> <li id="cite_note-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-43">^</a></b></span> <span class="reference-text">Elton, 2009, p.<span class="nowrap"> </span>200.</span> </li> <li id="cite_note-44"><span class="mw-cite-backlink"><b><a href="#cite_ref-44">^</a></b></span> <span class="reference-text">Levitt, 2013, pp. 79–80.</span> </li> <li id="cite_note-musee-45"><span class="mw-cite-backlink"><b><a href="#cite_ref-musee_45-0">^</a></b></span> <span class="reference-text">Musée national de la Marine, <a rel="nofollow" class="external text" href="http://mnm.webmuseo.com/ws/musee-national-marine/app/collection/record/9067">"Appareil catadioptrique, Appareil du canal Saint-Martin"</a>, accessed 26 August 2017; <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170826030358/http://mnm.webmuseo.com/ws/musee-national-marine/app/collection/record/9067">archived</a> 26 August 2017.</span> </li> <li id="cite_note-46"><span class="mw-cite-backlink"><b><a href="#cite_ref-46">^</a></b></span> <span class="reference-text">Levitt, 2013, pp. 28, 72, 99.</span> </li> <li id="cite_note-47"><span class="mw-cite-backlink"><b><a href="#cite_ref-47">^</a></b></span> <span class="reference-text">Elton, 2009, pp. 199, 200, 202; Levitt, 2013, pp. 104–105.</span> </li> <li id="cite_note-48"><span class="mw-cite-backlink"><b><a href="#cite_ref-48">^</a></b></span> <span class="reference-text">Levitt, 2013, pp. 108–110, 113–116, 122–123. Elton (2009, p.<span class="nowrap"> </span>208) notes that although the Skerryvore lens was lit on 1 February 1844, the catadioptric portion was yet to be added.</span> </li> <li id="cite_note-49"><span class="mw-cite-backlink"><b><a href="#cite_ref-49">^</a></b></span> <span class="reference-text">Elton, 2009, pp. 209–210, 238.</span> </li> <li id="cite_note-50"><span class="mw-cite-backlink"><b><a href="#cite_ref-50">^</a></b></span> <span class="reference-text">Elton, 2009, pp. 210–213.</span> </li> <li id="cite_note-51"><span class="mw-cite-backlink"><b><a href="#cite_ref-51">^</a></b></span> <span class="reference-text">Elton, 2009, pp. 221–223.</span> </li> <li id="cite_note-52"><span class="mw-cite-backlink"><b><a href="#cite_ref-52">^</a></b></span> <span class="reference-text">Elton, 2009, pp. 227–230; Levitt, 2013, p.<span class="nowrap"> </span>219.</span> </li> <li id="cite_note-53"><span class="mw-cite-backlink"><b><a href="#cite_ref-53">^</a></b></span> <span class="reference-text">Point Arena Lighthouse Keepers, Inc., <a rel="nofollow" class="external text" href="https://www.pointarenalighthouse.com/about/lighthouse-history/">"Lighthouse History"</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210119171021/https://www.pointarenalighthouse.com/about/lighthouse-history/">Archived</a> 19 January 2021 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>, accessed 1 March 2021.</span> </li> <li id="cite_note-54"><span class="mw-cite-backlink"><b><a href="#cite_ref-54">^</a></b></span> <span class="reference-text">Elton, 2009, p.<span class="nowrap"> </span>233; Levitt, 2013, pp. 222–224.</span> </li> <li id="cite_note-tag-hyper-55"><span class="mw-cite-backlink"><b><a href="#cite_ref-tag-hyper_55-0">^</a></b></span> <span class="reference-text">T. Tag, <a rel="nofollow" class="external text" href="http://uslhs.org/hyper-radial-lenses">"Hyper-Radial Lenses"</a>, U.S. Lighthouse Society, accessed 28 February 2021; <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210211202401/https://uslhs.org/hyper-radial-lenses">archived</a> 11 February 2021.</span> </li> <li id="cite_note-tag-us-56"><span class="mw-cite-backlink">^ <a href="#cite_ref-tag-us_56-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-tag-us_56-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">T. 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Margolin (24 August 2016), <a rel="nofollow" class="external text" href="https://motherboard.vice.com/en_us/article/this-3d-printer-runs-on-sand-and-sun">"This 3D printer runs on sand and sun"</a>, <i>Vice</i>, <a rel="nofollow" class="external text" href="https://web.archive.org/web/20171201182205/https://motherboard.vice.com/en_us/article/wnxpe9/this-3d-printer-runs-on-sand-and-sun">archived</a> from the original on 1 December 2017<span class="reference-accessdate">, retrieved <span class="nowrap">27 February</span> 2021</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Vice&rft.atitle=This+3D+printer+runs+on+sand+and+sun&rft.date=2016-08-24&rft.au=M.+Margolin&rft_id=https%3A%2F%2Fmotherboard.vice.com%2Fen_us%2Farticle%2Fthis-3d-printer-runs-on-sand-and-sun&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFresnel+lens" class="Z3988"></span>.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="Bibliography">Bibliography</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=15" title="Edit section: Bibliography"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>M. Born and E. Wolf, <i>Principles of Optics</i>, 7th Ed., Cambridge, 1999.</li> <li>G.-A. Boutry, 1948, "Augustin Fresnel: His time, life and work, 1788–1827", <i>Science Progress</i>, vol. 36, no. 144 (October 1948), pp. 587–604; <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/43413515">jstor.org/stable/43413515</a>.</li> <li>J. Z. Buchwald, 1989, <i><a rel="nofollow" class="external text" href="https://archive.org/details/riseofwavetheory0000buch">The Rise of the Wave Theory of Light: Optical Theory and Experiment in the Early Nineteenth Century</a></i>, University of Chicago Press, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-226-07886-1" title="Special:BookSources/978-0-226-07886-1">978-0-226-07886-1</a>.</li> <li>J. Elton, 2009, "A Light to Lighten our Darkness: Lighthouse Optics and the Later Development of Fresnel's Revolutionary Refracting Lens 1780–1900", <i>International Journal for the History of Engineering & Technology</i>, vol. 79, no. 2 (July 2009), pp. 183–244; <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1179%2F175812109X449612">10.1179/175812109X449612</a>.</li> <li>A. Fresnel, 1822, "Mémoire sur un nouveau système d'éclairage des phares", read 29 July 1822; reprinted in Fresnel, 1866–1870, vol. 3, <a rel="nofollow" class="external text" href="https://archive.org/details/oeuvrescompltes01fresgoog/page/n182">pp. 97–126</a>; translated by T. Tag as <a rel="nofollow" class="external text" href="http://uslhs.org/sites/default/files/attached-files/Fresnel%27s%20Memoire%20-%20Translation.pdf">"Memoir upon a new system of lighthouse illumination"</a>, U.S. Lighthouse Society, accessed 26 August 2017; <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160819111647/http://uslhs.org/sites/default/files/attached-files/Fresnel's%20Memoire%20-%20Translation.pdf">archived</a> 19 August 2016. (Cited page numbers refer to the translation.)</li> <li>A. Fresnel (ed. H. de Sénarmont, E. Verdet, and L. Fresnel), 1866–1870, <i>Oeuvres complètes d'Augustin Fresnel</i> (3 vols.), Paris: Imprimerie Impériale; <a rel="nofollow" class="external text" href="https://books.google.com/books?id=1l0_AAAAcAAJ">vol. 1 (1866)</a>, <a rel="nofollow" class="external text" href="https://books.google.com/books?id=g6tzUG7JmoQC">vol. 2 (1868)</a>, <a rel="nofollow" class="external text" href="https://archive.org/details/oeuvrescompltes01fresgoog">vol. 3 (1870)</a>.</li> <li>T. H. Levitt, 2013, <i>A Short Bright Flash: Augustin Fresnel and the Birth of the Modern Lighthouse</i>, New York: W.W. Norton, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-393-35089-0" title="Special:BookSources/978-0-393-35089-0">978-0-393-35089-0</a>.</li> <li>T. Young (ed. G. Peacock), 1855, <i>Miscellaneous Works of the late Thomas Young</i>, London: J. Murray, <a rel="nofollow" class="external text" href="https://books.google.com/books?id=GyzPAAAAMAAJ">vol. 1</a>.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=16" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>"The Fresnel Lens", <i>The Keeper's Log</i>, Winter 1985, pp. 12–14.</li> <li><a href="/wiki/United_States_Coast_Guard" title="United States Coast Guard">U.S. Coast Guard</a>, <i>Aids to Navigation</i>, Washington, DC: <a href="/wiki/U.S._Government_Printing_Office" class="mw-redirect" title="U.S. Government Printing Office">U.S. Government Printing Office</a>, 1945.</li> <li>U.S. Coast Guard, <a rel="nofollow" class="external text" href="https://media.defense.gov/2017/Jul/03/2001772523/-1/-1/0/ATON_LIGHTHOUSEBIB2007.PDF"><i>Lighthouses, Lenses, Illuminants, Engineering, & Augustin Fresnel: A Historical Bibliography on Works Published Through 2007</i></a>.</li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Fresnel_lens&action=edit&section=17" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png" decoding="async" width="30" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/45px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/59px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></span></span></div> <div class="side-box-text plainlist">Wikimedia Commons has media related to <span style="font-weight: bold; font-style: italic;"><a href="https://commons.wikimedia.org/wiki/Category:Fresnel_lenses" class="extiw" title="commons:Category:Fresnel lenses">Fresnel lenses</a></span>.</div></div> </div> <ul><li><a rel="nofollow" class="external text" href="https://uslhs.org/">United States Lighthouse Society</a>, especially "<a rel="nofollow" class="external text" href="https://uslhs.org/history/fresnel-lenses">Fresnel Lenses</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210302174800/https://uslhs.org/history/fresnel-lenses">Archived</a> 2 March 2021 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>".</li> <li>W. A. Britten, <a rel="nofollow" class="external text" href="http://lighthousegetaway.com/lights/fresnel.html">"The Fresnel lens"</a> (with photographs).</li> <li>J. Francis, <a rel="nofollow" class="external text" href="https://web.archive.org/web/20090520054046/http://www.digitalartform.com/archives/2009/04/fresnel_lens_-.html">"Fresnel Lens - Maxwell Simulation"</a>, 13 April 2009.</li> <li>J. Hare, <a rel="nofollow" class="external text" href="http://vega.org.uk/video/programme/226">"How the Fresnel lens works"</a> (5-minute video), Vega Science Trust, 2008.</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFT._Pepper" class="citation web cs2">T. Pepper, <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080130074143/http://www.terrypepper.com/lights/index.htm">"Seeing the Light: Lighthouses on the western Great Lakes"</a>, archived from <a rel="nofollow" class="external text" href="http://www.terrypepper.com/lights/index.htm">the original</a> on 30 January 2008</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Seeing+the+Light%3A+Lighthouses+on+the+western+Great+Lakes&rft.au=T.+Pepper&rft_id=http%3A%2F%2Fwww.terrypepper.com%2Flights%2Findex.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFresnel+lens" class="Z3988"></span>.</li> <li><a rel="nofollow" class="external text" href="https://www.youtube.com/watch?v=fQufI-QJLZg">The Fresnel Lens: the Invention That Saved 1000 Ships</a></li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output 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.navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Lighthouses" title="Template:Lighthouses"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Lighthouses" title="Template talk:Lighthouses"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Lighthouses" title="Special:EditPage/Template:Lighthouses"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Lighthouses" style="font-size:114%;margin:0 4em"><a href="/wiki/Lighthouse" title="Lighthouse">Lighthouses</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="3"><div> <ul><li><a href="/wiki/History_of_lighthouses" title="History of lighthouses">History of lighthouses</a></li> <li><a href="/wiki/Conservation_and_restoration_of_lighthouses" title="Conservation and restoration of lighthouses">Conservation of lighthouses</a></li> <li><a href="/wiki/Lighthouse_museum" title="Lighthouse museum">Museums</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Types</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Construction</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Aerial_lighthouse" class="mw-redirect" title="Aerial lighthouse">Aerial</a></li> <li><a href="/wiki/Caisson_lighthouse" title="Caisson lighthouse">Caisson</a></li> <li><a href="/wiki/Crib_lighthouse" title="Crib lighthouse">Crib</a></li> <li><a href="/wiki/Integral_lighthouse" title="Integral lighthouse">Integral</a></li> <li><a href="/wiki/Pile_lighthouse" title="Pile lighthouse">Pile</a></li> <li><a href="/wiki/Screw-pile_lighthouse" title="Screw-pile lighthouse">Screw-pile</a></li> <li><a href="/wiki/Skeletal_tower" title="Skeletal tower">Skeletal tower</a></li> <li><a href="/wiki/Lightvessel" class="mw-redirect" title="Lightvessel">Vessel</a> (acting)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Navigational purpose</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Daymark" title="Daymark">Daymark</a></li> <li><a href="/wiki/Leading_lights" title="Leading lights">Leading lights</a></li> <li><a href="/wiki/Sea_mark" title="Sea mark">Sea mark</a></li> <li><a href="/wiki/Sector_light" title="Sector light">Sector light</a></li></ul> </div></td></tr></tbody></table><div></div></td><td class="noviewer navbox-image" rowspan="6" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"><a href="/wiki/File:Brier_Island_Lighthouse_(3)_-_cropped.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Brier_Island_Lighthouse_%283%29_-_cropped.jpg/70px-Brier_Island_Lighthouse_%283%29_-_cropped.jpg" decoding="async" width="70" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Brier_Island_Lighthouse_%283%29_-_cropped.jpg/105px-Brier_Island_Lighthouse_%283%29_-_cropped.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Brier_Island_Lighthouse_%283%29_-_cropped.jpg/140px-Brier_Island_Lighthouse_%283%29_-_cropped.jpg 2x" data-file-width="205" data-file-height="431" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Fixtures</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Aerobeacon" title="Aerobeacon">Aerobeacon</a></li> <li><a href="/wiki/Argand_lamp" title="Argand lamp">Argand lamp</a></li> <li><a href="/wiki/Automatic_lamp_changer" title="Automatic lamp changer">Automatic lamp changer</a></li> <li><a href="/wiki/Bird-cage_lantern" title="Bird-cage lantern">Bird-cage lantern</a></li> <li><a href="/wiki/Carcel_lamp" title="Carcel lamp">Carcel lamp</a></li> <li><a href="/wiki/Dal%C3%A9n_light" title="Dalén light">Dalén light</a></li> <li><a href="/wiki/Foghorn" title="Foghorn">Foghorn</a></li> <li><a class="mw-selflink selflink">Fresnel lens</a></li> <li><a href="/wiki/Lens_lantern" title="Lens lantern">Lens lantern</a></li> <li><a href="/wiki/Lewis_lamp" title="Lewis lamp">Lewis lamp</a></li> <li><a href="/wiki/Light_characteristic" title="Light characteristic">Light characteristic</a></li> <li><a href="/wiki/VRB-25" title="VRB-25">VRB-25</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Maintenance</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Lighthouse_keeper" title="Lighthouse keeper">Keepers</a></li> <li><a href="/wiki/Light_dues" title="Light dues">Light dues</a></li> <li><a href="/wiki/Pharology" title="Pharology">Pharologists</a></li> <li><a href="/wiki/Lighthouse_tender" title="Lighthouse tender">Tender</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Locations</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Lists_of_lighthouses#Africa" title="Lists of lighthouses">Africa</a></li> <li><a href="/wiki/Lists_of_lighthouses#Antarctica" title="Lists of lighthouses">Antarctica</a></li> <li><a href="/wiki/Lists_of_lighthouses#Asia" title="Lists of lighthouses">Asia</a></li> <li><a href="/wiki/Lists_of_lighthouses#Europe" title="Lists of lighthouses">Europe</a></li> <li><a href="/wiki/Lists_of_lighthouses#North_America" title="Lists of lighthouses">North America</a></li> <li><a href="/wiki/Lists_of_lighthouses#Oceania" title="Lists of lighthouses">Oceania</a></li> <li><a href="/wiki/Lists_of_lighthouses#South_America" title="Lists of lighthouses">South America</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Categories</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Category:Lighthouse_builders" title="Category:Lighthouse builders">Lighthouse builders</a></li> <li><a href="/wiki/Category:Lighthouses_by_heritage_register" title="Category:Lighthouses by heritage register">Lighthouses by heritage register</a></li> <li><a href="/wiki/Category:Lighthouses_by_century_of_completion" title="Category:Lighthouses by century of completion">Lighthouses by century of completion</a></li> <li><a href="/wiki/Category:Lighthouses_by_year_of_completion" title="Category:Lighthouses by year of completion">Lighthouses by year of completion</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Global<br />organizations</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/General_lighthouse_authority" title="General lighthouse authority">General lighthouse authority</a></li> <li><a href="/wiki/International_Association_of_Marine_Aids_to_Navigation_and_Lighthouse_Authorities" title="International Association of Marine Aids to Navigation and Lighthouse Authorities">International Association of Lighthouse Authorities</a></li> <li><a href="/w/index.php?title=Amateur_Radio_Lighthouse_Society&action=edit&redlink=1" class="new" title="Amateur Radio Lighthouse Society (page does not exist)">Amateur Radio Lighthouse Society</a></li> <li><a href="/wiki/International_Lighthouse_and_Lightship_Weekend" title="International Lighthouse and Lightship Weekend">International Lighthouse and Lightship Weekend</a></li> <li><i><a href="/wiki/Lighthouse_Digest" title="Lighthouse Digest">Lighthouse Digest</a></i></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="3" style="font-weight:bold;"><div> <ul><li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Lighthouses" title="Category:Lighthouses">Category</a></li> <li><span class="noviewer" typeof="mw:File"><span title="Commons page"><img alt="" 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