Re: [ATM] 7 inch sphereical mirror

["Richard F.L.R. Snashall" <rflrs@rcn.com>]

Sorry Dale.. (not sent to group)

Richard wrote:
> Hi Richard,
>
> Saturday, April 12, 2008, 4:49:59 PM, you wrote:
>
> RFLRS> I can't confirm that.  When focused at the 70.701% zone crossover, the
> RFLRS> Visual
> RFLRS> Strehl is about 0.92.  The RMS wavefront error is lambda/21.23 (550 nm)
> RFLRS> and P-V is lambda/6.33.  The RMS spot size, depending on what part of ZEMAX
> RFLRS> you believe is between 11.36 and 11.5 microns diameter.  The full spot
> RFLRS> diameter
> RFLRS> is greater than 27.83 microns.
>
> If your figures are correct, and a Strehl of 0.92 corresponds with an
> RMS spot size of twice the Airy disk size, then it makes a very good
> case to never use Visual Strehl as a guide to optical performance.
>
No. The Airy disk is 13.425 microns (diameter).
> RFLRS> depending on what part of ZEMAX
> RFLRS> you believe
>
> All of it. It is the premiere optical design program and in a class of
> its own.
>

The two values are from different parts of ZEMAX, pushed
to the upper sampling limit (RMS vs field and spot diagram
RMS).  The two may have different models, but if you have
to publish one, which one? (I begged the question and did
both!:-)
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