Cassegrain secondaries (testing)
Robert Katz (bert@atlas.co.uk)
Mon, 3 Jul 95 22:31:23 BST
Any views on testing Cassegrain secondaries ? Couder's interferometric test
as described by Texereau is easy to get to the stage where both mirror and
reference differ by only a wave or so, but after that any attempt to figure
either seems to mean losing overall contact or irreducible zones, however
slowly you polish. Has anyone tried the Gaviola test ? And what views on
testing through the back of the mirror. I think ATM II mentions this as a
plausible method, but it seems fatally flawed to me...? Grateful for any
advice. I should mention that I have been making a very small (1.25") sec;
R = 14.4".