iOPTRON - Astronomy Technology Today

A HOT TOPIC - ACTIVE COOLING OF A PRIMARY TELESCOPE MIRROR
Figure 3: 60 minutes of cooling with a beginning temperature of ambient-air
and 36-inch mirror of 20°C and ending ambient of 5°C; primary
cooled with fans; mirror temperatures measured at thicknesses of 30
mm, 45 mm and 65 mm; temperature Delta of 5.5°C, 7.5°C and 8.5°C.
mocouples on various thicknesses of or the
36-inch primary mirror by which I can easily
measure and document the cooling dynamics
of the mirror, and confirmed, to a
first order, that Houdart’s calculator is, to a
useful degree, accurate. Having modeling
software program that allowed me to play
with certain variables within my control was
Figure 4: 60 minutes of cooling with a beginning temperature of ambientair
and 36-inch mirror of 20°C and ending ambient of 10°C; primary
cooled with fans; mirror temperatures measured at thicknesses of 30
mm, 45 mm and 65 mm; temperature Delta of 3.5°C, 4.5°C and 5.5°C.
very helpful. Figures 3-5 model the primary’s
cooling dynamics across three typical
scenarios.
The bottom line for the weight-re-
54 Astronomy TECHNOLOGY TODAY