Re: ATM Am I done yet?

[Douglas Braun <doug@dougbraun.com>]

If you actually looked at the entire mirror with the tester, you would probably
agree with my decision.  The outer 30% had a sort of "piecewise linear"
appearance.  I think each opening on the mask fell was roughly centered on
one of the linear sections, so the discontinuities beteween them were hidden
from the Foucault test.

If I set the tester to grey out the zone right over one of the "steps", I found
that I could move the knife-edge sideways about .005" and still see a bit
of shadow from the edge of the step.  This seems like an awful lot
of transverse abberation!

The star test seemed to show more scattered light (sort of a diffuse glow
surrounding the star), and Saturn was less sharp and contrasty compared to an
earlier star test, where I had an obvious TDE, but a smoother surface.  

Doug


At 09:48 AM 9/18/02 +0200, Galogaza wrote:

>Douglas,
>>So despite the good looking numbers (which tended to change significantly
>if I re-tested with the mirror
>in a different orientation), I decided to smooth out the mirror and
>re-figure it.
>
>
>I will reconsider decision to smooth out the mirror
>which is 0.99 Strehl.
>First I will check measuring system and try to get reproducibility out of
>it. Then, and only then,  will
>I touch the mirror. If you do not believe
>the test apparatus and its results then what's left?
>
>Regards
>Vladimir.