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Unique design for use of closed cycle refrigerators for astronomical observations

The use of closed cycle cryogenic refrigerators in astronomical applications has been limited due to vibration problems. A closed cycle cooler system to cool instruments to about 50 K and the detectors below 20 K has been designed. The design uses two cold heads diametrically opposed to cancel vibration input to both the telescope and the instrument optical system. The use of vibration damping material to isolate the cold heads results in a nominally vibration free system. A reduction in low frequency vibration amplitude approaching three orders of magnitude was witnessed. This has been demonstrated both in the laboratory and while the system was operating on a telescope.