Thermal stability of lightweight graphite glass sandwich reflectors for far infrared astronomyGraphite fiber-reinforced glass matrix composites are being developed for a variety of structural applications requiring excellent thermomechanical stability. These materials are ideally suited for lightweight, high strength, thermally stable infrared mirrors because of their low density, low thermal expansion, high strength and stiffness, and their ability to be machined, replicated and figured using standard polishing techniques. These properties are particularly promising for applications such as a 3-meter balloon-borne far-infrared and submillimeter telescope mirror which must be both very lightweight and able to retain its figure accuracy when cycled between room temperature and its operating temperature of -50 C. This paper presents the results of a set of low temperature optical tests conducted to determine the figure stability of a 30-cm diameter, frit-bonded graphite/glass mirror in the +20 to -60 C temperature range using a 10.6 micron laser interferometer. The results indicate that the residual change in figure was less than 0.3 microns, rms.
Document ID
19870023745
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Bluege, J. H. (United Technologies Research Center West Palm Beach, FL, United States)
Mayor, R. A. (United Technologies Research Center West Palm Beach, FL, United States)
Hoffman, W. F. (Steward Observatory Tucson, AZ, United States)