A rotary indexing mechanism for use in a cryogenic and vacuum environment has been designed and deployed in several spaceborne instruments. In the course of space qualification, this mechanism was subjected to severe environmental testing, including thermal cycling (40-800K), vibration (10.6 g's RMS), and acoustics (147 dB RMS). A typical mechanism positions sets of spectral and neutral-density filters in the optical path of a cryogenic radiometer. The filter sets operate independently, with stepper motors providing the indexing feature to each set. Gear-driven resolvers provide feedback to the motors to ensure accurate angular positioning. The sequence and timing of filter combinations is controlled by an on-board microprocessor which commands filter selection routines. This paper describes the overall mechanical architecture, specific design details, and command and control sequences for a typical mechanism. In addition, design tips are given to show how several operational problems were solved.

Date Published: 27 April 1988
PDF: 8 pages
Proc. SPIE 0973, Cryogenic Optical Systems and Instruments III, (27 April 1988); doi: 10.1117/12.948389

Published in SPIE Proceedings Vol. 0973:
Cryogenic Optical Systems and Instruments III
Ramsey K. Melugin; Warren G. Pierce, Editor(s)