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Proceedings Paper

Mechanical slit mask mechanism for the James Webb Space Telescope spectrometer
Author(s): Simon Henein; Peter Spanoudakis; Philippe Schwab; Laurent Giriens; Leszek Lisowski; Emmanuel Onillon; Leif I. Myklebust
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Paper Abstract

A mechanical slit mask mechanism has been designed for the Near Infrared Spectrograph of the James Webb Space Telescope. This mechanism was successfully tested at a cryogenic temperature of 30K, in vacuum. The reconfigurable mask allows to form 24 optical slits in a 137 x 137 mm2 field of view. The slit length is fixed (4.8 mm) and their width can range from 50 μm to 137 mm. The slit positioning accuracy is ± 5 μm and the slit width accuracy is ± 8 μm. The working principle of the mechanism is based on an improved "inch-worm" stepping motion of 48 masking bars forming the optical curtain. Voice coil actuators are used to drive the various clutches and the principal mobile stage. Ratchets which engage in the teeth of a rack machined on the bars allow to cancel the accumulation of motion errors as steps succeed one another. The design makes significant use flexure structures. Cryogenic performance, life and vibration tests have been performed successfully on subassemblies of the mechanism and a full-scale prototype.

Paper Details

Date Published: 12 October 2004
PDF: 12 pages
Proc. SPIE 5487, Optical, Infrared, and Millimeter Space Telescopes, (12 October 2004); doi: 10.1117/12.551106
Show Author Affiliations
Simon Henein, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)
Peter Spanoudakis, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)
Philippe Schwab, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)
Laurent Giriens, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)
Leszek Lisowski, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)
Emmanuel Onillon, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)
Leif I. Myklebust, Ctr. Suisse d'Electronique et de Microtechnique SA (Switzerland)


Published in SPIE Proceedings Vol. 5487:
Optical, Infrared, and Millimeter Space Telescopes
John C. Mather, Editor(s)

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