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Proceedings Paper

Circumferential and inner diameter metrology for the Advanced X-ray Astrophysics Facility optics
Author(s): Thomas E. Gordon
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Paper Abstract

The Advanced X-Ray Astrophysical Facility (AXAF) is part of NASA's Great Observatory program, and is scheduled for launch in the late 1 990's. A Wolter Type I grazing incidence telescope, it is planned to study high energy astronomical phenomena which emit in the x-ray spectrum from 0.1 -1 0 KeV (1 24 - 1 .24 A). The telescope consists of 6 nested, confocal parabola/hyperbola pairs, with the conic figure polished on the inside surfaces of cylindrical substrates. The 1 2 cylindrical elements are 1 meter in length and range in diameter from 0.5 - 1.2 meters. The specifications for the AXAF optics place strict requirements on the metrology instrumentation used to guide the fabrication process; in general, the accuracy of the measurements must be an order of magnitude better than the quality of the finished product. This is true for each of the measured parameters, which include axial figure, circumferential figure, inner diameter, and surface microroughness. Axial figure, circumferential figure, and inner diameter data are used to form maps of the inside surface of the optics, and form the basis for the subsequent fabrication cycle. Surface microroughness is used to determine the scattering performance of the system. This paper describes the facility used for the measurement of circumferential figure and inner diameter. This facility, the Circularity and Inner Diameter Station (CIDS), measures inner diameters of over 40 inches to within 70 microinches and acquires circularity data which is accurate to better than 1 microinch rms after averaging and the removal of systematic errors.

Paper Details

Date Published: 1 November 1990
PDF: 9 pages
Proc. SPIE 1333, Advanced Optical Manufacturing and Testing, (1 November 1990); doi: 10.1117/12.22808
Show Author Affiliations
Thomas E. Gordon, Hughes Danbury Optical Systems, Inc. (United States)

Published in SPIE Proceedings Vol. 1333:
Advanced Optical Manufacturing and Testing
Gregory M. Sanger; Paul B. Reid; Lionel R. Baker, Editor(s)

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