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**Running List** ATM Group thoughts on Mirror Figuring and Testing: Data Input/Analysis CHECK LIST, pointers.]
Just repairing a couple BAD typos - like "please do ( ) send HTML! : )
- forgot to put the NOT in!
By the way - we can get a section on this list started with out stuff -
and then come back through and edit it later and resend.
There may be a few folks working simultaneously - in that case - we just
need to modify them by splices as required - and discarding old lists as
new versions arrive.
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** ATM CHECK LIST for MIRROR FIGURING and **
** FOCAULT, RONCHI, and STAR - TEST INTERPRETATIONS. **
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Hi All! This is a running list - please do not edit any one else's ideas
- but PLEASE DO! : ) Add your ideas and valued mirror making knowledge
to the bottom of this list! No criticisms necessary - everyone's own
findings are highly valued!
NOTE:
If you are using this information to help you figure your mirror - pleas
know that these ideas are only suggestions and no one making a
contribution here can be liable for the use of their opinions.
The topic is anything that can help in figuring a mirror successfully -
tricks tips - laps - polishing techniques - whatever - there are no
rules to speak of - just a collaboration to help us all out.
We can get our own ideas section on this list started -
and then come back through and edit/add to it later and resend.
There may be a few folks working/sending simultaneously - in that case
- we just need to modify them by splices as required - discarding old
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ATM List member contributions: Mirror Figuring
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Bobs Prabowo: List
Here's my check list:
1. Test the mirror with Ronchi test, memorize the image of the bands (or
draw the bands) and what the image means, i.e, undercorrected or
overcorrected, has a TDE etc.
2. Foucault test and see how the shadow looks like. Does it match the
Ronchi
test or not.
3. Put on the Couder mask and align it carefully.
4. Take the zonal measurements
5.Input the reading to Tex, make sure that:
a. the radius of zones opening you input is the measured radius of
zones.
That means, you measured the zones opening and input these numbers to
Tex.
b.Select the right Unit of measurement (inches, cm or mm), do it each
time
you run the program.
c. Determine the type of tester whether it uses moving light source or
fixed
light source.
d. While inputing the readings don't forget to put decimal mark (if
necessary), forgetting to do so will cause you lots of pain :-)
e. Check if the graph matches the Ronchi test result and the Foucalut
shadowgram.
That's my check list, others with more experience may have longer check
list, or maybe with their experiences they don't need one :-)
Good luck,
Bob
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Bill Gillespie:
Bills "total new guy" mirror figuring considerations:
These ideas have come to me from the experienced members of this fine
ATM list.
(Please take everything I say with some element of caution! : )
1a)Dont be afraid to apply some pressure while polishing.
1b)Before figuring attempts - the sole objective is to get the the
mirror to a sphere - as indicated when focault testing by a sudden shift
or "flip" in lighting on the mirrors surface when crossing the null
point right at radius of curvature.
2) Any thing that looks like a "Doughnut" in the tester - is just some
other conic section - don't freak out.
3) Keep on polishing! Polish some more!
4) Once the mirror is Fully Polished out (Water Clear) - all you can see
on the surface under a strong light - is dust. Then get ready to do some
testing.
5) Don't worry about testing to much - until you are fully and surely
polished out.
6) Read up on mirror making from books available at Willmann-Bell. There
are several.
7) Wearing insulated gloves may keep the heat from your hands from
creating variations in the mirror while figuring
8) Play with the tester - make sure you take good measurements and know
where you are when viewing the results of your tests.
9) The basic tests I know of that are commonly used are the:
** The Ronchi Grating TEST **
(with the screen (grating) covering - at the same time - both the
light source and the viewing area (peep hole for my tester): the test
bands for a sphere are STRAIGHT - at any view inside or out of ROC
(radius of curvature)
** The Focault TEST **
(the tester is easy to make - look in the web)
and the;
** The Star TEST **
this test is simply looking at the mirror figure by
focusing on a stationary star - Polaris is used for us with no mount
drive in the N. Hemisphere. It will require an "telescope assembly"
either temporary or 'real' for the mirror to be placed in - I plan to
finish my scope mount and OTA - so that I can do star tests while doing
my mirrors figuring.
10)Dont be afraid to fail. A perfect mirror is the objective result -
but I'm having fun just trying to get some place remotely close - (which
may be a lot better than most "store bought" mirrors by the way!)
11)Mirror making seems to be an art - and one that requires learning,
patience and careful consideration for "what variables are effecting
what" so to speak - and the sharing of knowledge from those that have
been exactly were we now are! So ask - and look into the ATM archives
http://www.system.missouri.edu/atm/for help. This is a great list of
fine collaborative humans in general.
12)As Mel Bartels says - Keep on smiling! - your making a very fine
quality optical surface that is literally within millionths of an inch
of tolerance - with your own two hands! : )
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This space dedicated to the ..
next fine collaborative humans opinions! : )