File:Fresnel lighthouse lens diagram.png
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Fresnel_lighthouse_lens_diagram.png (492 × 578 pixels, file size: 88 KB, MIME type: image/png)
Summary
| Description |
English: Section diagram showing how a Fresnel lens (A) in a lighthouse works to collimate light from an oil lamp (L) into a parallel beam. The Fresnel lens, invented in 1822 by Augustin-Jean Fresnel, increased the light projecting power of lighthouses greatly without the weight of a conventional lens of its size. Also shown are mirror strips (m,n) mounted above and below the lens that most lighthouses had, to gather more of the lamp's light. Alterations: removed caption, erased blots in white areas, changed brightness levels to get rid of noise in white areas, sharpened light path lines. |
| Date | |
| Source | Downloaded from Adolphe Ganot (1872) Natural Philosophy for General Readers and Young Persons, D. Appleton & Co., New York, p.328, fig.257 (translated with permission from Ganot's Cours Élémentaire de Physique by Edmund Atkinson) |
| Author | Adolphe Ganot |
| Permission (Reusing this file) |
Public domain - Ganot died in 1887; published in USA before 1923 |
Licensing
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This is a faithful photographic reproduction of a two-dimensional, public domain work of art. The work of art itself is in the public domain for the following reason:
The official position taken by the Wikimedia Foundation is that "faithful reproductions of two-dimensional public domain works of art are public domain".
This photographic reproduction is therefore also considered to be in the public domain in the United States. In other jurisdictions, re-use of this content may be restricted; see Reuse of PD-Art photographs for details. | ||||
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This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.
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This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See Wikipedia:Public domain and Wikipedia:Copyrights for more details.
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File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 12:03, 17 December 2007 | | 492 × 578 (88 KB) | wikimediacommons>Chetvorno | {{Information |Description=Diagram of how a Fresnel lens in a lighthouse works. |Source=Downloaded from [http://books.google.com/books?id=sKELAAAAYAAJ&pg=PA328 Adolphe Ganot (1872) ''Natural Philosophy for General Readers and Young Persons'', D. Appleton |
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