1 February 1985 Temperature Control Of Silica Mirrors For Cryogenically-Cooled Telescopes In Space
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Abstract
Since silica mirrors have been shown to have significantly less distortion due to cryogenic cooldown, a silica primary mirror of approximately 1 meter diameter is being considered for the Space Infrared Telescope Facility (SIRTF). This is a departure from the technology of the Infrared Astronomical Satellite (IRAS) Optical Subsystem, which was built mostly of beryllium and had a primary mirror of 0.62 meter diameter. Using a thermal and cryogenic transient analysis program developed previously, we have modeled the SIRTF Optical Subsystem, including the primary mirror, using lumped-parameter techniques. The mirror thermal response to variations in aperture heat load and in heat sink temperature have been explored. Calculations have been made of system noise components from primary mirror spatial and temporal temperature variations. We demonstrate that in spite of the relatively low thermal conductivity and diffusivity of glass as compared to beryllium, that noise sources arising from the thermal response of the primary mirror are sufficiently small to maintain background-limited infrared observations at wavelengths out to 200 micrometers. Mirror thermal performance with and without copper wires for cooling is also considered.
© (1985) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ramsey K. Melugin, Ramsey K. Melugin, Jeffrey H. Lee, Jeffrey H. Lee, Walter F. Brooks, Walter F. Brooks, } "Temperature Control Of Silica Mirrors For Cryogenically-Cooled Telescopes In Space", Proc. SPIE 0509, Cryogenic Optical Systems and Instruments I, (1 February 1985); doi: 10.1117/12.944990; https://doi.org/10.1117/12.944990
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