From: "mlbrown{at}everstrive.com" 
To: atm{at}shore.net
Reply-To: "mlbrown{at}everstrive.com" 


This surface looks rougher to my naked eye than in the camera image.  I
don't have an OTA to test it with -- the idea here is my brother will make
the OTA, however I'm considering slapping one up to do a star test on it.

And I'm hoping my nephew will get it in time to see the wide open rings of
Saturn (OK, they'll only be a tiny bit narrower next year) and Jupiter
before the novelty wears off.  It was my first sight of Jupiter that
grabbed me.

=Matt

Original Message:
-----------------
From: scottythefiddler scottythefiddler{at}cogeco.ca
Date: Thu, 3 Apr 2003 06:38:58 -0500
To: mlbrown{at}everstrive.com, atm{at}shore.net
Subject: Re: ATM Am I done yet?


Congrats Matt!!!!
There have been recent messages on the list, which mentioned how surface
roughness looks worse on images than to the naked eye.  Star test it with
different size masks to determine the extant of the TDE and get it
aluminized before the glint is gone from the smiles of the little green
men....you won't want to miss being the first to observe that!

You certainly brought that mirror a long way from those edgy days early in
March.   Impressive...

sd
----- Original Message -----
From: "Matthew L. Brown" 
To: 
Sent: Thursday, April 03, 2003 12:18 AM Subject: ATM Am I done yet?


>
> Mirror: 4.25" f 9.2
>
> The readings now look decent, though I think the center could be lower.
> What I'm worried about is the roughness.  It looks worse to my naked eye,
> though there are more than the usual air currents in my testing room.
>
> Foucault Image (45kB JPEG)
> http://host67.everstrive.com/~mlbrown/ASTRONOMY/KnifeEdge2Apr.jpg
>
> Sixtests says Strehl 0.996 rms 2.7
>
> Tex says 1/19 lambda
>
> Readings (inches)
> zone 1 2 3
> 0.041 0.037 0.067
> 0.035 0.040 0.066
> 0.036 0.045 0.066
> 0.030 0.043 0.067
>
>
> TEXEREAU MIRROR TEST SHEET
>
>             Comments:    Optical diameter: 4.15
>    Readings per zone: 4
> Radius of curvature: 76.62
>                  f/D:  9.23
>     Diffraction disc: 0.000243264
>
>   1 ZONE                1          2          3
>   2 h(x)              1.1980     1.6940     2.0750
>   3 h(m)              0.5990     1.4460     1.8845
>   4 hm**2/R           0.0047     0.0273     0.0464
>   5 hm/4f             0.0039     0.0094     0.0123
>   6 D1                0.0355     0.0412     0.0665
>   7 D2                0.0355     0.0412     0.0665
>   8 D12               0.0355     0.0412     0.0665
>   9 D12 -  0.0189     0.0166     0.0224     0.0476
> 10 Lamda c           0.0119    -0.0049     0.0013
> 11 Lamda f * 1e5       4.66      -4.66       1.54
> 12 Lamda f / rho      0.192     -0.191      0.063
> 13 u * 1E6            -1.22       1.22      -0.40
> 14 Wavefront          -1.12      -0.18       0.00
> Reference parabola: y = -0.233909 * x**2 + 0
> passing through (  0.00,  0.00) and (  2.08,  0.00)
>
> Maximum wavefront error = 1 / 19.3 wave at zone 1
>
> Results for individual sets of readings:
> Reading set 1: 1 / 12.5 lamda, Max Trans Abberation=0.30
> Reading set 2: 1 / 18.8 lamda, Max Trans Abberation=0.20
> Reading set 3: 1 / 21.0 lamda, Max Trans Abberation=0.15
> Reading set 4: 1 / 36.8 lamda, Max Trans Abberation=0.11
>
>
> Do I quit while I'm ahead or try to simultaneously drop the center and
> smooth it out a bit?
> Thanks for the advice.
>
> =Matt
>
>
>
>
>




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