6 September 1995 Gimbal mechanism for cryogenic alignment of 1-meter diameter optics
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Abstract
A two axis optical gimbal mechanism for aligning 1 meter diameter telescope primaries and test flat mirrors at temperatures from 300 to 4.2 K was constructed for use in the SIRTF Telescope Test Facility (STTF). This mechanism consists of an aluminum frame, pivoting on a monoball bearing, and driven in tip and tilt by tungsten di-sulfide lubricated lead screws with external drive motors. Flexures decouple the optical support frame from stresses generated by differential rates of cooling. A second set of flexures decouples the mirror mechanically and thermally from distortion in the gimbal mechanism. The mechanism provides sub arc-second resolution in either axis, while limiting the heat leak to less than 100 mW at 4.2 K. Linear variable differential tranformers are used at temperatures from 300 to 4.2 K to measure a home position. The STTF and gimbal are presently operational, and have been used in two separate interferometric measurements of a 0.5 meter, f 4.0 beryllium spherical mirror at 6 K. The gimbal will be used in the interferometric testing of a beryllium telescope primary mirror from the Infrared Technology Testbed, for the Space Infrared Telescope Facility at JPL.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Robert G. Chave, Alfred Edward Nash, James Hardy, "Gimbal mechanism for cryogenic alignment of 1-meter diameter optics", Proc. SPIE 2542, Optomechanical and Precision Instrument Design, (6 September 1995); doi: 10.1117/12.218669; https://doi.org/10.1117/12.218669
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