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Proceedings Paper

Configurable slit-mask unit of the multi-object spectrometer for infra-red exploration for the Keck telescope: integration and tests
Author(s): Peter Spanoudakis; Laurent Giriens; Simon Henein; Leszek Lisowski; Aidan O'Hare; Emmanuel Onillon; Philippe Schwab; Patrick Theurillat
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Paper Abstract

A Configurable Slit Unit (CSU) has been developed for the Multi-Object Spectrometer for Infra-Red Exploration (MOSFIRE) instrument to be installed on the Keck 1 Telescope on Mauna Kea, Hawaii. MOSFIRE will provide NIR multi-object spectroscopy over a field of view of 6.1' x 6.1'. The reconfigurable mask allows the formation of 46 optical slits in a 267 x 267 mm2 field of view. The mechanism is an evolution of a former prototype designed by CSEM and qualified for the European Space Agency (ESA) as a candidate for the slit mask on NIRSpec for the James Webb Space Telescope (JWST). The CSU is designed to simultaneously displace masking bars across the field-of-view (FOV) to mask unwanted light. A set of 46 bar pairs are used to form the MOSFIRE focal plane mask. The sides of the bars are convoluted so that light is prevented from passing between adjacent bars. The slit length is fixed (5.1 mm) but the width is variable down to 200 μm with a slit positioning accuracy of ± 18 μm. A two-bar prototype mechanism was designed, manufactured and cryogenically tested to validate the modifications from the JWST prototype. The working principle of the mechanism is based on an improved "inch-worm" stepping motion of 92 masking bars forming the optical mask. Original voice coil actuators are used to drive the various clutches. The design makes significant use of flexure structures.

Paper Details

Date Published: 18 July 2008
PDF: 12 pages
Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 70180I (18 July 2008); doi: 10.1117/12.789017
Show Author Affiliations
Peter Spanoudakis, Ctr. Suisse d'Electronique et de Microtechnique (Switzerland)
Laurent Giriens, Ctr. Suisse d'Electronique et de Microtechnique (Switzerland)
Simon Henein, Ctr. Suisse d'Electronique et de Microtechnique (Switzerland)
Leszek Lisowski, Ctr. Suisse d'Electronique et de Microtechnique (Switzerland)
Aidan O'Hare, Ctr. Suisse d'Electronique et de Microtechnique (Switzerland)
Emmanuel Onillon, Ctr. Suisse d'Electronique et de Microtechnique (Switzerland)
Philippe Schwab, Ctr. Suisse d'Electronique et de Microtechnique (Switzerland)
Patrick Theurillat, Ctr. Suisse d'Electronique et de Microtechnique (Switzerland)


Published in SPIE Proceedings Vol. 7018:
Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation
Eli Atad-Ettedgui; Dietrich Lemke, Editor(s)

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