Re: [ATM] fringe testing a convex and concave surface together.

[Mike Lockwood <melockwo@uiuc.edu>]

Mark,

Mark Holm wrote:
> Where does one get a high f-ratio Fresnel lens of moderately large size
> and sufficient quality?

By using the central part of a larger Fresnel from a big screen TV, or 
a Fresnel that was intended for a solar cooker.

> Here is a mildly crazy idea.  Could you use a
> fairly fast Fresnel lens with a negative lens to make it a telephoto or
> Barlow sort of setup?

I don't know.  It might work.

> No need for achromatism since you will be wanting
> monochromatic light anyhow.  Distortion would seem like the main
> abberation one would want to avoid.

Seems like a large lens could be made from plate glass fairly easily, 
since the quality would probably be better than a flexible Fresnel. 
Again, the light is monochromatic, so a simple convex lens is fine.

Another option is to simply get really far away and view the fringes 
with a small telescope.

	Mike Lockwood

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