34th Solar Physics Division Meeting, June 2003
Session 20 Instrumentation
Poster, Wednesday, June 18, 2003, 3:30-5:00pm, Mezzanine

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[20.08] Solar Imaging UV/EUV Spectrometers Using TVLS Gratings

R. J. Thomas (NASA/GSFC)

It is a particular challenge to develop a stigmatic spectrograph for UV/EUV wavelengths since the very low normal-incidence reflectance of standard materials most often requires that the design be restricted to a single optical element which must simultaneously provide both re-imaging and spectral dispersion. This problem has been solved in the past by the use of toroidal gratings with uniform line-spaced rulings (TULS). A number of solar EUV spectrometers have been based on such designs, including SOHO/CDS, Solar-B/EIS, and the sounding rockets SERTS and EUNIS. More recently, Kita, Harada, and collaborators have developed the theory of spherical gratings with varied line-space rulings (SVLS) operated at unity magnification, which have been flown on several astronomical satellite missions. We now combine these ideas into a spectrometer concept that puts varied-line space rulings onto toroidal gratings. Such TVLS designs are found to provide excellent imaging even at very large spectrograph magnifications and beam-speeds, permitting extremely high-quality performance in remarkably compact instrument packages. Optical characteristics of three new solar spectrometers based on this concept are described: SUMI and RAISE, two sounding rocket payloads, and NEXUS, currently being proposed as a Small-Explorer (SMEX) mission.

The author(s) of this abstract have provided an email address for comments about the abstract: Roger.J.Thomas@nasa.gov

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.