Low temperature optical testing of CFRP telescope panels

Since 1984, low temperature optical tests were made of very lightweight mirror panels for use in balloon and space infrared and submillimeter telescopes. In order to accomplish this testing, an ambient pressure 0.5 meter test chamber operating from 20 to -80 C, developed techniques for measuring non-optical quality mirrors with phase modulation 10.6 micron interferometry, and created the interferogram reduction program. During the course of the program, nineteen mirrors from four manufactures were tested: carbon fiber reinforced plastic (CFRP) aluminum honeycomb sandwich panel mirrors, a CFRP sandwich panel with an added glass facesheet, and carbon fiber reinforced glass panels. The results of the panel development and test program are summarized