Re: [ATM] Day and Night Foucault

[Anthony Stillman <atmer@flash.net>]

  Arjan,


First, going exclusively by the numbers you report, whether from the evening or the afternoon, the mirror in question has an RMS of done.000, a strehl of done.000, and a peak to valley of done.000.
    
But just to be sure, I took the numbers from the two charts you posted and plugged them into Sixtests, the defacto standard as you can be sure its right (thank you Jim for all the work you?ve put into it).  From the results I divine that the reduction software you are using is the problem.  The numbers Sixtests reports are somewhat better than what the posted charts show and the results are more consistent.  Specifically ?fta3? has a strehl of 0.994 and an RMS of 3.5nm, ?fta2? has a strehl of 1.000 and an RMS of 0.1nm.


      Let me add, I seriously doubt that even a skilled observer under ideal conditions averging a inordinate number of readings can measure a mirror to much better than 1/20 of a wave.  Maybe measuring the caustic, but even then, only with great care.

Also, that's a really good mirror you've made.
  
      Anthony


  est modus in rebus 
Literally: There is a proper measure of things.  
Meaning: Choose the middle ground.




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