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Proceedings Paper

Optical modeling activities for NASA's James Webb Space Telescope (JWST): III. Wavefront aberrations due to alignment and figure compensation
Author(s): Joseph M. Howard
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Paper Abstract

This paper is part three of a series describing the ongoing optical modeling activities for the James Webb Space Telescope (JWST). The first two papers discussed modeling JWST on-orbit performance using wavefront sensitivities to predict line of sight motion induced blur, and stability during thermal transients [1-2]. The work here investigates the aberrations resulting from alignment and figure compensation of the controllable degrees of freedom (i.e. the primary and secondary mirrors), which may be encountered during ground alignment and on-orbit commissioning of the observatory. The optical design of the telescope is a three-mirror anastigmat, with an active fold mirror at the exit pupil for fine guiding. The primary mirror is over 6.5 meters in diameter, and is composed of 18 hexagonal segments that can individually positioned on hexapods, as well as compensated for radius of curvature. This architecture effectively gives both alignment and figure control of the primary mirror. The secondary mirror can be moved in rigid body only, and the tertiary mirror is fixed. Simulations are performed of various combinations of alignment and figure errors corrected by the primary and secondary mirrors. Single field point knowledge is assumed in the corrections, and aberrations over the field are reported for the varying cases.

Paper Details

Date Published: 14 September 2007
PDF: 11 pages
Proc. SPIE 6675, Optical Modeling and Performance Predictions III, 667503 (14 September 2007); doi: 10.1117/12.735069
Show Author Affiliations
Joseph M. Howard, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 6675:
Optical Modeling and Performance Predictions III
Mark A. Kahan, Editor(s)

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