Photogrammetric Distortion Measurements of Antennas in a Thermal-Vacuum Environment

摘要

The move to higher frequency communications for commercial satellites has brought about the requirement for high-accuracy thermal-distortion measurements for satellite antenna systems. In recognizing this need of the Canadian and international space industry, the Canadian Space Agency has developed, at the David Florida Laboratory in Ottawa, Canada, a photogrammetric measurement system built around a commercially available digital photogrammetry camera. To more accurately simulate the space environment, the photogrammetric tests are performed in a 7 x 10 m high-vacuum chamber with temperature cycling nominally between ―170 to + 170℃. This paper describes the current setup and methodology for the two tests on the CASA-ASAS reflector and two Ka-band transmit reflectors. The paper describes some of the challenges encountered including achieving a 50 μm accuracy on front- and back-face measurements of the two 1.5 m diameter Ka-band transmit reflectors tested simultaneously in the vacuum chamber. Future directions toward improvement of the photogrammetry system based on the experience gained from these tests are also discussed as well as other potential applications.