Cryogenic actuators in ground-based astronomical instrumentation

In the last few years, astronomical instruments with infrared detectors have become increasingly important. These detectors as well as the mechanical mechanisms inside the instruments are operated in high vacuum at cryogenic temperature. Since ready-for-use cryogenic actuators are often not available from stock, the Max-Planck-Institut fur Astronomie (MPIA) in Heidelberg has developed actuators for both linear and circular movement. Information about the use of materials, dry film lubricants, and components like motors, micro switches and resolvers for this temperature region is hard to find in literature. Thus, large-scale experiments and tests were made to gain experience and to qualify the actuators for their use at cryogenic temperatures.