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Re: [ATM] 12.5 inches BVC advice for parabolizing
I'm very surprised.
I tought that using ronchigrams, (with one of the many free software, with offsets varying lets say from 0.3" inside ROC to 0.7 outside...) was sufficient, and that with successive testings and photo-shoots and comparisons between the ronchigrams and actual mirror images, I could make the figure look allmost exactly like the ronchigrams, then I would have a good mirror...
I also have different gratings, and I'l try to find the most precise by trying them at the different offsets.
Thanks all for your continuing input...
RML
---------- Original Message ----------------------------------
From: Dale Eason <atmpob@yahoo.com>
Date: Sun, 10 Jul 2005 21:14:22 -0700 (PDT)
>In a recent post you said you do not understand how to
>do a knife test. You will need to understand how to
>do a Foucault test or else you will not know when to
>stop or when to change stroke.
>
>How are you judging when you will be done? Ronchii
>images will not help you at that point. Suiter has
>shown in his book that for fast mirrors like yours it
>is impossible to tell a good figure from a 1/2 wave
>one using only ronchi. In general they can only tell
>you about the smoothness of the surface and edge.
>
>Dale Eason
>
>--- RM L <atm@axeinformatique.com> wrote:
>
>> Hello again,
>>
>> I'd love some advice as what approach to take when I
>> continue the work, on another day. I do not want to
>> mess up, and you may see allready a bad tendency in
>> my images... that I wouldn't see.
>>
>> I update my site with the last photos for the day.
>>
>>
>http://www.axeinformatique.com/temp/Mirror/BVC_Mirror.html
>>
>> The zoning is allmost gone now.
>>
>> I'm using standard parabolizing W stroke, going up
>> to 1,5 in of the border, with the center of mirror.
>>
>> Should I keep doing the same thing ? It's the edge
>> that scares me a little... Is it parabolizing
>> quicker than the rest ? Am I worstening the TDE ?
>>
>> I don't want to waste energy curing the TDE, but I
>> would'nt want to make it worst.
>>
>> Thanks all for your time, patience, and help.
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> ATM mailing list http://www.atmlist.net/
>>
>
>
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