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Proceedings Paper

Optical design of Lyman/FUSE
Author(s): David A. Content; Pamela S. Davila; John F. Osantowski; Timo T. Saha; Mark E. Wilson; Scott D. Friedman
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Paper Abstract

Lyman/FUSE, the Far Ultraviolet Spectroscopic Explorer, is a proposed low earth orbit mission to explore the 1OO-16OGi spectra of diverse astronomical sources. The simultaneous design goals of high spectral resolution, high sensitivity, high signal to noise ratio, limited slit imaging capability, wide spectral coverage, compactness, and high stability were a formidable challenge. In the design, a Wolter type II glancing incidence telescope (70 cm aperture, f/1O) feeds two spectroscopic channels. A boresighted fme error sensor is used to point the instrument. In the 4oo-16oc1i range, a 1.84m Rowland circle spectrograph uses five near normal incidence gratings with a common MAMA detector. To achieve acceptable resolving power and limited imaging with a fast telescope, the grating aberrations must be significantly reduced below those obtained with toroidal or ellipsoidal gratings. A modified ellipsoidal grating is used to achieve resolving powers of 30000 in the three high resolution bands covering 91O-125Q. A separate EUV channel will explore the 1OO-35O range with lower spectral and spatial resolution. The throughput in this range is improved by more than an order of magnitude over the Extreme Ultraviolet Explorer (EUVE), when EUVE is operating in its spectroscopic mode. The optical design and results of ray tracing studies are presented, as well as the expected effective area in each channel.

Paper Details

Date Published: 1 July 1990
PDF: 10 pages
Proc. SPIE 1235, Instrumentation in Astronomy VII, (1 July 1990); doi: 10.1117/12.19157
Show Author Affiliations
David A. Content, NASA/Goddard Space Flight Ctr. (United States)
Pamela S. Davila, NASA/Goddard Space Flight Ctr. (United States)
John F. Osantowski, NASA/Goddard Space Flight Ctr. (United States)
Timo T. Saha, NASA/Goddard Space Flight Ctr. (United States)
Mark E. Wilson, NASA/Goddard Space Flight Ctr. (United States)
Scott D. Friedman, Johns Hopkins Univ. (United States)

Published in SPIE Proceedings Vol. 1235:
Instrumentation in Astronomy VII
David L. Crawford, Editor(s)

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