Re: [ATM] How much cell induced deformation is too much?

["Stuart Hutchins" <stuart452@earthlink.net>]

Why shouldn't a mirror surface be simply specified or certified in
nanometers?  Waves come in all sizes, but the meter is an unambiguous unit,
and would give a much smaller "circle of confusion".

Just my daily contribution to heresy,

Stuart

----- Original Message ----- 
From: "Koehler, Steve" <Steve_Koehler@securecomputing.com>
To: <atm@atmlist.net>
Cc: <jcmulherin@opticalmechanics.com>
Sent: Monday, July 12, 2004 9:55 AM
Subject: RE: [ATM] How much cell induced deformation is too much?


Jim (and Mark),

> >Anybody
> >know if they reference HeNe laser (633nM) or something else?
>
> Boy, I sure hope they don't!  Another cheat like quoting surface
> aberrations without saying it, while everybody is assuming wavefront.
> It's
> certainly OK to test with lasers, but the final answer should be, if given
> as RMS, PV, or Strehl, referenced to the standard 550 nm visual
> wavelength.

OMI (Torus) has been reporting results using 633 nm.  Although they don't
mention it directly on on-line specs page for each mirror, it is clearly
stated in information they provide that explains the interferometric
results:

"The wavefront quality specification for Optical Mechanics Pro-Spec
mirrors is 0.0712l RMS at 633nm with a Strehl ratio of 0.8 or higher. The
P-V
wavefront error is not used in the specification, however it is reported in
the interferometric test report provided with each mirror and is typically
less than 0.25l. Each Torus Pro-Spec mirror must meet or exceed these
specifications before it is certified for shipment to the customer. Every
mirror is delivered with its interferometric test report and a Certificate
of
Optical Quality."

Personally, I think it would be much better to scale the results to 550 mn,
But I don't think OMI has been reporting at 633 nm to inflate the numbers.
Mulherin recently announced on the Torusmirrorgroup that he will be
switching
to reporting results at 550 nm, starting with the next batch of mirrors he
reports.  (He also mentioned that he will be changing the test photos to
include to include a null knife-edge image and a null Ronchi image with only
a few lines.)

I don't think Mulherin is currently listening on this list, so I'm Cc'ing
him
on my response, in case he would like to respond directly.

-- Steve Koehler
   steve_koehler@securecomputing.com



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