RE: [ATM] Another Astigmatism question, but at the sphere stage

[Royston_Jeremy@emc.com]

Hello Jarvis,
	The knife edge to mirror distance should be kept constant to better
than your measurement accuracy while rotating it - say 0.001" or 25 micron.
This isn't a trivial mechanical problem. The ball bearing test described in
Texereau isn't quantitative, but very sensitive. Perhaps on of the more
mathematically inclined members could supply a simulation rather like
Diffraction

Best wishes, Jerry

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Jarvis Krumbein
Sent: Sonntag, 28. August 2005 20:35
To: wa4guu@verizon.net
Cc: atm@atmlist.net
Subject: Re: [ATM] Another Astigmatism question, but at the sphere stage

Instead of going to the trouble of rotating the mirror why not rotate the
knife edge/slit to achieve the same end.  It would be much easier to
compare readings taken across different diameters and would give instant
answers.

Jarvis Krumbein

On Sun, 28 Aug 2005 13:09:41 -0400 "Jerry" <wa4guu@verizon.net> writes:
> I did not reply because I don't know if Jay's test method is valid or 
> not. I
> think it is flawed but since I know little about Sixtests, the order 
> and
> timing of his 3 sets of readings on 2 diameters and how he chooses 
> those
> diameters I think it is too difficult to offer help by email. So not 
> knowing
> I thought I should stay out of it.
> 
> But.....
> 

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