T3D Re: The largest Fresnel lens.

[Peter Homer <P.J.Homer@xxxxxxxxxxxxx>]

Prof Lunazzi wrote

>The single lens stereoscope remind me of a large Fresnel lens I saw in
>1992 at San JosČ when visiting California.
>
>It was used for watching a TV viewer, enlarged.  (TV viewer = TV
>apparatous)
>
>Now I am very interesting in knowing where to buy the largest Fresnel
>lenses, and where to buy the better Fresnel lenses.  If both conditions
>belongs to the same address, the better would be.
>
>The Fresnel lens is a very didactical example on how a common lens works
>(Marion, Physics for Biologist's book): starting from a pinhole camera,
>you add prisms around to get more luminousity, then you rediscover the
>Fresnel lens.  At the same time, you loose focusing depth.

I have seen these advertised for sale in mail order catalogues overhere in
the UK but I am not shure how good they are .Also ones with legs atatched
for placing over clse up work or worn round the neck with a cord. There
other smaller ones which are fitted to the back window of a car to provide
a wider view for parking. These have a coarser structure so that the prisms
can easily be seen . I have also seen large ones with fine structure for
the back windows of buses and coaches . If I have one of these catalogues
at the moment I could send you the address if I will probably recieve one
soon. The largest Fresnel lens I can think which also shows their structure
well are the ones used to focus the light in light houses but I dont know
where you could get one of those!   P.J.homer




>--
>Prof. Jose' J. Lunazzi
>Universidade Estadual de Campinas - UNICAMP - Instituto de Fi'sica
>Campinas - SP - Brazil
><lunazzi@xxxxxxxxxxxx> (eternal FREE address sponsored by
>http://www.Netforward.com)
><http://www.digicron.com/lunazzi>




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End of TECH-3D Digest 309
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