Subject: Re: APO 3.5m User's committee meeting minutes, 5/14/01

From: jeg@astro.Princeton.EDU

Submitted: Thu, 24 May 2001 09:56:44 -0400 (EDT)

Message number: 502 (previous: 501, next: 504 up: Index)

The continuing confusion about where the UV hit in DIS is taking place
is confusing to me. The problem is with the dielectric reflective coatings
in the schmidt camera and on the prism. I built a system with a uv
diode, filters, and a mercury lamp which compared 3650/63 with 4046 and 
4358. In the camera block the antireflection coatings were measured
by shining a beam through the block and out the hole, meeting no
reflective surfaces. The antireflection coatings so tested, those
on the collimator, and those on the schmidt corrector plate, were all
as specified. (These tests also dispel any doubts about the cements
in the camera). The reflective coatings, however, were not, and showed
very small reflectance at 3650; the losses in the camera (2 reflections)
were approximately the square of the losses in the prism (1 45 degree
reflection). I no longer have those records, they being at least two
disk crashes removed, but they were reported, I believe, on this forum.
It WAS a long time ago.

--jim


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