Re: [ATM] ronchi accuracy

[Jan Bentz <jbentz@inreach.com>]

For teaching purposes with a group of people nothing works better than 
the ronchi test using a perforated flat.  No math, no looking for 
fringes, and if all have the same mirror, alignment is easy.

Jan Bentz

Michael Peck wrote:

>At 13:23 12/10/05, Mel Bartels wrote:
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>>I've been using the Ronchi test for 25 years.  I make better mirrors using
>>the Ronchi test compared to using other tests.
>>
>>
>>Not only do I need to test for all the above, but I also need a test that is
>>reliable, consistent, accurate, inexpensive, easy and fast to use.
>>Particularly in mirror making classes, the bottleneck is testing, when
>>students line up, waiting for their mirror to be tested and analyzed.
>>
>>There's an amazing variety of tests to select from.  Some are easier to use,
>>some are more predictable, some are more accurate, and some are more
>>expensive.  Many tests use math.  Most Americans are mathematically
>>illiterate.  To recommend a math intensive test is to tell many that mirror
>>making is beyond them.
>>
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>
>Have you considered building an interferometer for class use? If not, why not?
>
>Just one comment for now. Any optical test involves mathematics. 
>Generating theoretical ronchi patterns for comparison is a highly 
>mathematical  and computationally intensive exercise, especially if 
>you do it right. So it seems to me regardless of the test the 
>mathematically illiterate have to rely on the work of the 
>mathematically literate. Since the mathematically literate have 
>produced free software for the analysis of just about any optical 
>test you can think of mathematical illiteracy shouldn't be an 
>obstacle to the use of better tests.
>
>Mike
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>_________________
>
>Michael Peck
>email mpeck1@ix.netcom.com
>Wildlife photoblog http://wildlife-pix.com
>Amateur telescope making http://home.earthlink.net/~mlpeck54/astro/astro.html 
>
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