34th Solar Physics Division Meeting, June 2003
Session 24 Beyond SDO
Oral, Thursday, June 19, 2003, 1:30-3:30pm, Auditorium

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[24.05] Normal-incidence EXtreme-Ultraviolet imaging Spectrometer - NEXUS

K. P. Dere (Naval Research Laboratory)

NEXUS is the result of a breakthrough optical design that incorporates new technologies to achieve high optical throughput at high spatial (1 arcsec) and spectral (1-2 km s-1) resolution over a wide field of view in an optimal extreme-ultraviolet spectral band. This achievement was made possible primarily by two technical developments. First, a coating of boron-carbide deposited onto a layer of iridium provided a greatly enhanced reflectivity at EUV wavelengths that would enable NEXUS to observe the Sun over a wide temperature range at high cadence. The reflectivity of these coatings have been measured and demonstrated in the laboratory.

The second key development was the use of a variable-line-spaced toroidal grating spectrometer. The spectrometer design allowed the Sun to be imaged at high spatial and spectral resolution along a 1 solar radius-long slit and over a wavelength range from 450 to 800 Å, nearly an entire spectral order. Because the spectrograph provided a magnification of about a factor of 6, only 2 optical elements are required to achieved the desired imaging performance. Throughput was enhanced by the use of only 2 reflections. The could all be accomodated within a total instrument length of 1.5m.

We would like to acknowledge support from ONR

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