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Proceedings Paper

NIRCam Long Wavelength Channel grisms as the Dispersed Fringe Sensor for JWST segment mirror coarse phasing
Author(s): Fang Shi; Brian M. King; Norbert Sigrist; Scott A. Basinger
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Paper Abstract

The baseline wavefront sensing and control for James Webb Space Telescope (JWST) includes the Dispersed Hartmann Sensors (DHS) for segment mirror coarse phasing. The two DHS devices, residing on the pupil wheel of the JWST's Near Infrared Camera (NIRCam) Short Wavelength Channel (SWC), can sense the JWST segment mirror pistons by measuring the heights of 20 inter-segment edges from the dispersed fringes. JWST also incorporates two identical grisms in the NIRCam's Long Wavelength Channel (LWC). The two grisms, designed as the Dispersed Fringe Sensor (DFS), are used as the backup sensor for JWST segment mirror coarse phasing. The versatility of DFS enables a very flexible JWST segment coarse phasing process and the DFS is designed to have larger piston capture range than that of DHS, making the coarse phasing more robust. The DFS can also be a useful tool during JWST ground integration and test (I&T). In this paper we describe the DFS design details and use the JWST optical model to demonstrate the DFS coarse phasing process during flight and ground I&T.

Paper Details

Date Published: 12 July 2008
PDF: 14 pages
Proc. SPIE 7010, Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter, 70102E (12 July 2008); doi: 10.1117/12.789641
Show Author Affiliations
Fang Shi, Jet Propulsion Lab. (United States)
Brian M. King, Jet Propulsion Lab. (United States)
Norbert Sigrist, Jet Propulsion Lab. (United States)
Scott A. Basinger, Jet Propulsion Lab. (United States)


Published in SPIE Proceedings Vol. 7010:
Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter
Jacobus M. Oschmann; Mattheus W. M. de Graauw; Howard A. MacEwen, Editor(s)

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