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Mirror Quality

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Posted by Robert May on September 30, 2002 19:03:11 UTC

The mirrors are listed as diffraction limited. This generally is understood as being 1/4 wave surface error or less.
As with any optical surface, you do really need to test it yourself to insure that it does meet your spec as the whole technique of making surfaces, especially surfaces other than a spherical one, are pretty much hand done and evaluated by humans so there can be a fair bit of a variance as to what is good.
Having a good set of test results for a particular mirror can make the exchange for a better mirror very easy although the cost of shipping is often left up to you, negating the nice prices.
I'd buy a mirror if I needed a moderate quality one and didn't want to spend the time making it. I will note that I don't consider a mirror done until it's within 1/10th wave on the wavefront.

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