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Here is an 8" f/4.5 mirror I recently refigured. The owner said it was Foucault tested at no better than 1/2 wave by another mirror maker. The null test setup shows the edge and center errors as I received the mirror and what I eventually ended up with. These were made using a 100 lpi grating. The star test showed almost no error - so it may be better than 1/4 wave (whatever that is <g>). I'm kidding of course and have absolutely no justification for making any type of wavefront judgment pertaining to numerical quality. I used Photoshop to adjust the scans as the originals were of poor contrast. I have lots of videos of tests but doubt that that's a very Web friendly method to present data. :)
Mirror as received above. As finished is below.
