From: "Jerald F. Wright" 
To: Tom Krajci 
CC: atm{at}shore.net
Reply-To: "Jerald F. Wright" 




Tom Krajci wrote:

> From: "Jerald F. Wright" 
>
> >...I've tested one of those Astroscan primaries and it was the best
> >parabola
> >I've ever seen.  It wasn't just pretty good.  It was perfect from
> perfect >edge
> >to perfect edge....
>
> >...It was too
> >good to hang a number on.  I think it was better than 1/100 wave.
>
> Please tell us about your testing methods and equipment.  I am intrigued
> by your claim of measuring a mirror that was, in your estimation, better
> than 1/100th wave.
>
> If your results are repeatable, we can make significant progress in the
> world of amateur optics testing.
>

    I used the Focault and Ronchi tests.  I have tested mirrors better than
1/40 wave and could still see the errors with the old mark IV eyeball
without too much difficulty. On the Astroscan mirror there was no
detectable error at all. It was well beyond the sesitivity of the test. How
sensitive are the tests?  Different for different people and test rigs.
    If there ever was such a thing as a 1/100 wave mirror the Astroscan
mirror was as close as anything I will be likely to see in my lifetime. 
I'm not able to prove that it is 1/100 wave or better. But someone would
have quite a time proving it isn't.

Jerry

--- BBBS/NT v4.00 MP