ATM Re: Foucault Frustration

["Bennett, Thomas D" <thomas.d.bennett@lmco.com>]

Thanks everyone for relieving my frustrations. The mirror I'm testing is a
10" F6 full-thickness pyrex. When testing last week-end in the early PM, I
was able to nail repeated zonal COC readings to within a 0.01" range. Was
just surprised that temperature effects could perturb the test results so
severely - thought I was doing something wrong. The COCs just kept growing
and growing by more than 0.01" with each reading spaced just a few minutes
apart! Sounds like its better to turn off all temperature control instead of
trying to maintain a constant room temperature via  a thermostat driven
heater - will try again tonight.