SITE 2K bow

[Richard Stover]

Hello all,

As we go to faster and faster cameras the CCD shape is becoming ever
more important.  In addition, the very tight constraints on overall
flatness of our large CCD mosaics requires us to know the shape of our
CCDs to rather high accuracy.  Therefore at Lick Observatory we have
been developing a system to measure CCD surface shape.  The concept behind
the system is similar to a Hartmann test.  We bounce a laser off the CCD
surface and measure where the reflected beam goes.  The system will
allow us to measure the shape of the CCD in a dewar under cryogenic
conditions.  We have so far looked at a number of Loral 2kx2k CCDs.  We're
using the system to help us develop better methods for CCD packaging.
We also measured a SITe 2Kx2K CCD at room temperature.  Unfortunately we
have not measured the same one cold yet.

We are expecting delivery of a new SITe 2kx2K any day now, and we will
be measuring that device both warm and cold.  We should have accurate
measurements of this device before the end of January.  I'll report
back to this forum on our results.

Our surface measuring system is undergoing significant modifications
to make it automated.  Once this is done it should be relatively
easy and quick for us to measure CCD shapes.  At that point we may
make the facility available to others.  Is there much interest in
having such a facility available?

Richard Stover
UCO/Lick Observatory
University of California
Santa Cruz, CA 95064
408-459-2139