From: "Ulhas Deshpande" 
To: "ATM" 
Reply-To: "Ulhas Deshpande" 


Hello All
Last night I sat down and compiled my last three days  KE readings. Three
sets of four reading per Zone for six zones. I averaged ( meaned ?) the
readings and then medianed. Entered these values in SixTests and the result
gave S=0.901 RMS 14.2 for Mean Values and S=0.865 and RMS = 16.7 for 
Median values. Both SixTest files are below. Test Mean of 225 225R 225RR
203.0 60.0 Mirror, obstruction diameters (mm) Foucault
0.0 Source distance (0=moving source) y, mm X, mm
   24.6  0
   43.1  -0.60537
   56.8  0.236008
   71.6  -0.13335
   84.1  0.735542
   95.8  1.09855
*
0.000 2504.870 Conic targets:  b, R (mm) 0.2065 Measurement std deviation,
mm 2520.0 Longitudinal reading bias, mm

Test Median of 225 225R 225RR
203.0 60.0 Mirror, obstruction diameters (mm) Foucault
0.0 Source distance (0=moving source) y, mm X, mm
   24.6  0
   43.1  -0.60537
   56.8  0.0381
   71.6  -0.13335
   84.1  0.508
   95.8  0.9906
*
0.000 2520.000 Conic targets:  b, R (mm) 0.2065 Measurement std deviation,
mm 2520.0 Longitudinal reading bias, mm

Looking at the results I realised that most of the error was in the area
below radius 30 which will be the central hole in the Cass Primary after
the core is removed. Using an obstruction of 60 in the setup the results
improved dramatically to give S=0.942 for the median and S=0.940 for mean.
It appears that the boundary between the core piece,which is fixed with POP
in the hole, and the main glass is either causing an error in the reading
or has prevented the core piece from conforming to the overall curve. So,
since I have good value for the main portion of the mirror and I do not
want to take the risk of now spoiling the figure with further work, I shall
accept the mirror as finished and now think of Star Testing for
confirmation.
Cheers
Ulhas

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