Hi Joe,
I´ve found the link. Maybe you are interested in this prototype. ;-)
It has a really beautiful design, hasn´t it? Thank you for your
coments, I love everything related to lenses.
http://www.geocities.com/maitani_fan/camera_technologies.html
Cheers,
Dave
----- Original Message -----
From: "Joe Gwinn" <joegwinn@xxxxxxxxxxx>
To: <olympus@xxxxxxxxxx>
Sent: Tuesday, April 13, 2004 3:13 PM
Subject: [OM] GRIN glass in 85/1.2 prototype?
> At 3:28 AM +0200 4/13/04, Listar wrote:
> >From: "David Irisarri" <div2000@xxxxxxxxxxxxxxxxx>
> >Subject: [OM] Re: Please help - I want to buy E-1 system
> >Date: Mon, 12 Apr 2004 23:11:53 +0200
> >
> >
> >Fixed focal lenses shoud be at least f2 for the new E-system!
> >
> >And I would like to see a new 85/1,2 lens. (42.5/1,2) I think
> >Olympus made a prototype many years ago of one 85/1.2 using
> >special glass, called "grin glass" or something like that!
>
> It's "GRIN glass". GRIN stands for GRadient Index of Refraction.
>
> A GRIN lens is typically a flat piece of special glass that nonetheless
can focus light into images, because (unlike standard optical glass) this
special glass has a refractive index that varies with distance from the
optical axis. The variation is parabolic, with the higher refractive index
in the center.
>
> Multimode optical fibers are in fact elongated GRIN lenses made of fused
silica glass. Typically, the germanium-doped core is 50 or 62 microns in
diameter, and the overall fiber (including the pure silica cladding glass)
is 125 microns (1/8 of a millimeter) in diameter.
>
> Small (a few millimeters in diameter) GRIN lenses are widely used in fiber
optics, and in xerox machines. I've never seen a GRIN lens big enough for a
camera lens. The chemical process that makes the carefully varying
refractive index profile is a bit tricky, and works best with small
diameters.
>
> My guess is that it turned out to be too expensive to make GRIN lenses
both large enough and accurate enough for a 35mm camera lens.
>
> Joe Gwinn
>
>
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