Re: (ATM) Accuracy of Foucault Test
Steve Strickland (lensnut@tpoint.net)
Fri, 18 Aug 1995 02:44:09 -0500
Years back I was part of a beginner telescope making group that Larry
Forrest hosted. We had 12 mirrors being made. Several of the old hands
participated. Larry would verify each mirror reading. He had no idea of
what the previous readings were of the random stream of 12 different
mirrors we were bringing him for analysis. In my case, and also in the
other 11 cases, Larry would repeat measurements to about a thousandth of an
inch of knife edge position (moving light source slitless tester). This was
a blind test as he had no knowledge of which mirror he was analyzing.
None of us could understand how he did it although he tried to explain.
Given enough experience, I'm utterly convinced that it is not only
possible, but it is achievable in every case, every time at any time.
To this day, I can't do it, but Larry does as a matter of routine.
--
Steve Strickland
Lensnut@tpoint.net