To: atm{at}shore.net
From: "Matthew L. Brown" 
Reply-To: "Matthew L. Brown" 


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

--- BBBS/NT v4.00 MP