[ATM] Foucault imaging fast mirrors?

[Dominic-Luc Webb <dlwebb@canit.se>]

I set up my Foucault rig (classic/generic razor blade construct). Test
subject is a 310 mm diameter F/1.55 partially polished plate glass
sphere (slumped). I thought this was going to be quick and easy, but
I encountered a couple of difficulties. First, light source had to be
changed because it was only illuminating part of the mirror, and when
that was fixed I realized my rather small Canon A-85 CCD camera
cannot get close enough to capture the fully illuminated surface with
the light source within 5 cm of COC: lens hits razor blade before
getting close enough to obtain a fully illuminated surface.

Anyone have experience with actually getting CCD image of Foucault
pattern for such fast system? Is this worthwhile test?

Dominic

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