Re: ATM Smoothness

[goffaxe@azstarnet.com (Bob & Valerie Goff)]

Hey, Guys and Dolls,

I love this debate about roughness and scattering,
I have just spent a year developing methods that allow me to get better than
7 to 10 angstrom roughness and the individual pieces are better than 1/30
wavefront P-V and some are better than 1/50 wavefront P-V because I have not
yet developed uniformity from piece to piece. These pieces are of Pyrex and
are strain free to the best of my ability to measure strain. 
I know that for 30 or 40 years, I have been saying that pyrex cannot be made
flatter than about 1/10 wave and that was so nebulous that I don't know
whether or not that was wavefront P-V or surface.....
I now know 94 ways of being able to not make a good elliptical diagonal.
I sit at my computer, corrected. 
The project was funded by Crazy Ed Optics and I dealt with the CEO of CEO.
As a direct result of his supporting this endeavor, he in my exclusive
distributor for these fine elliptical diagonal mirrors. You know his address.
Show me some Quartz.
Strehl ratios of 0.997 are now regarded as poor around here.
The work on the ISO standards for the quality of commercial telescopes for
sale to amateur astronomers IS COMEING ALONG WELL. Suggestions, anyone? Mel?
Burrjaw? others from even Australia as the Aussies are not represented on
ISO TC172 WG-4 (Telescopic Systems)



>
>At 16:14 98-09-25 -0700, Mel Bartels wrote:
>
>>consensus is pyrex with diluted CeO or black rouge both have 10-20
>>angstrom roughness, plate glass with either is 3-5 angstrom roughness -
>>the real question to be answered definitely is if this makes a
>>difference visually - I think it makes a very light but noticable
>>difference just looking at the unaluminized glass but at the eyepiece???
>
>Oh boy, let's start up the "sawtooth mirror" controversy again!  Tex sez,
>p. 62, 100 Å (10 nm) micro-ripple caused by HCF + other defects "do not
>seriously alter the normal diffraction image and would pass quite unnoticed
>when observing a star at the focus."  I've put a theoretical ¼-wave
>"random" mirror, with ± 1/16 wave (34 nm) surface random errors on every 1
>mm zone, through foucault.exe which said that it passed the Rayleigh
>Criterion (expected); the .8 Strehl ratio was also a pass.
>
>Bratislav will say, "But what about planetary views?"
>
>Gotta mount up my 10" RC cass with .775 Strehl ratio & PLENTY of HCF
>roughness to see if ivory tower theory pans out.
>
>       -- Jim Burrows          phone 206.244.2933, fax .0294
>       --                      mailto:burrjaw@halcyon.com
>       -- Seattle              N47.4722, W122.3661 (WGS84)
>
>