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#79290 - 08/31/02 01:25 PM Fresnel lens  
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wwh Offline
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Fresnel, Augustin Jean (1788-1827), French physicist, an adherent of the wave theory of light. Born in Broglie, Eure-et-Loir, and educated at Caen and at the École Polytechnique in Paris, he made numerous experiments in the interference of light. Fresnel was the first to demonstrate that two beams of light polarized in different planes do not exhibit interference effects. From this experiment he correctly deduced that the wave motion of light is transverse, rather than longitudinal (like that of sound) as had been previously believed. Fresnel was the first to produce circularly polarized light. He also worked out a number of basic optical formulas, including those for reflection, refraction, double refraction, and the polarization of light reflected from a transparent substance. Fresnel's work on optical effects caused by the motion of objects was important in the later development of the theory of relativity. In the field of applied optics, Fresnel designed the type of compound lens, often called a Fresnel lens, that is used to produce parallel beams of light from lighthouses and in a type of spotlight frequently used in theatrical lighting. Fresnel's scientific work was known only to a small group of scientists during his lifetime, and some of his papers were not published until after his death. He was a member of the French Academy of Sciences and of the Royal Society of London.

You can buy a Fresnel lense from Edmund Scientific. In early days of television they were sold to
enlarge image on TV screen. I still have one.



"Fresnel, Augustin Jean," Microsoft(R) Encarta(R) 98 Encyclopedia. (c) 1993-1997 Microsoft Corporation. All rights reserved.


#79291 - 10/18/02 09:31 PM Re: Fresnel lens  
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Vermont
I have many fond memories of hanging and aiming "fresnels" in my college theatre days... and the lekos and scoops...



formerly known as etaoin...
#79292 - 10/18/02 10:07 PM Re: Fresnel lens  
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of troy Offline
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i too, have large (12 inch square-- 30 cm or so) fresnel lens. it is very flat, and useful. it's also a wonderful toy, that family children love. its plastic, so its safe for children to use with care.


#79293 - 10/18/02 10:26 PM Re: Fresnel lens  
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wwh Offline
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Jackie sent me a URL where you can buy a clear plastic Fresnel magnier for about ten bucks.
Said to be very helpful for reading fine print. I plan to get one.
http://www.vikingop.com/shop/catalog/sku.asp?SKS=6&ID=SP304&LEVEL=SK&PR=Q10&



#79294 - 10/19/02 01:00 AM Re: Fresnel lens  
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Piedmont Region of Virginia, U...
And Fresnel only lived till he was about 39 years old, if my math's right.

The ASp is my checker. She'll let me know whether I missed it by a decade or not...


#79295 - 10/31/02 06:26 PM Re: Fresnel lens  
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Occasional Idiot Offline
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Alliance Tool and Die Corp. had a Fresnel Optics division in Rochester, NY. They used to cut the metal dies and mold the plastic lenses mainly for overhead projectors. I remember seeing a 3-4 ft diameter die being continuously cut over a period of a few days. The copper "hair" spun off like cotton candy into huge piles.


#79296 - 10/31/02 06:57 PM Re: Fresnel lens  
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wwh Offline
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If you use Netscape 4.7, you will see that Netscape has a far advanced Fresnel lens
that can make a beam of light bend into an arc. Quite revolutionary.
Dear Occasional Idiot. Welcome to the laughing academy.




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