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Proceedings Paper

Image processing for alignment of aspheric optics without fiducials
Author(s): Babak N. Saif; Perry E. Greenfield; Warren Hack; Ritva A. Keski-Kuha; Lee D. Feinberg; David Chaney
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Paper Abstract

James Webb Space Telescope (JWST) has a segmented Primary Mirror (PM). PM is made of 18 beryllium hexagonal shaped segments. Flat-to-flat dimension of a segment is 1.315 meters. The PM is an ellipsoid of~ 6.5 meters in diameter with a conic constant of -0.99666 and a radius of curvature ~16 meters. After the PM, telescope are assembled and instruments are installed the observatory will go through environmental testing. The environmental test consist of acoustic and vibration test. The objective is to measure the change in the surface astigmatism of the Primary mirror segments at center of curvature before and after vibration and acoustic test. At the final stage of assembly the inner segments of the PM have no external fiducials. The challenge is to separate the alignment astigmatism from surface astigmatism without any external fiducials. This paper describes an alignment method that uses the print-through in the mirror segments as fiducials to separate the two astigmatisms.

Paper Details

Date Published: 4 May 2010
PDF: 7 pages
Proc. SPIE 7723, Optics, Photonics, and Digital Technologies for Multimedia Applications, 772309 (4 May 2010); doi: 10.1117/12.853992
Show Author Affiliations
Babak N. Saif, Space Telescope Science Institute (United States)
Perry E. Greenfield, Space Telescope Science Institute (United States)
Warren Hack, Space Telescope Science Institute (United States)
Ritva A. Keski-Kuha, NASA Goddard Space Flight Ctr. (United States)
Lee D. Feinberg, NASA Goddard Space Flight Ctr. (United States)
David Chaney, Ball Aerospace & Technologies Corp. (United States)

Published in SPIE Proceedings Vol. 7723:
Optics, Photonics, and Digital Technologies for Multimedia Applications
Peter Schelkens; Touradj Ebrahimi; Gabriel Cristóbal; Frédéric Truchetet; Pasi Saarikko, Editor(s)

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