Abstract

The design and calculated performance is described for a spectrometer included on the Extreme Ultraviolet Explorer (EUVE) astronomical satellite. The instrument is novel in design, consisting of three plane reflection gratings mounted in the converging beam behind a grazing incidence telescope. This configuration is based on new varied line-space (VLS) gratings which have recently been proposed. A sample EUVE grating has been mechanically ruled and experimentally characterized. It recovered over 80% of the theoretical efficiency of perfectly formed grooves, reaching 38% absolute at a wavelength of 114 Å. The grating was used to construct a laboratory spectrographic version of the EUVE spectrometer and recorded the spectrum of helium from 228 to 320 Å. The spectral resolution was λ/Δλ ∼ 2000 and the image heights were ∼10 sec of arc. Individual spots were ∼25 × 50 μm, which is a significant improvement over existing grazing incidence spectrographs. A line profile measurement at 1 Å away from first order 304 Å showed <1.5%/ Å of grating stray light and a rapid decline toward the wings. In visible light, no grating stray or ghost light could be seen. Three flight spectrometer channels in combination span the 70–760-Å band with an effective collecting area of 0.3–1 cm2 over the 80–600-Å region. The spectrometer has an inherent resolution of λ/Δλ ∼ 300, but if combined with a worst-case satellite performance will yield a spectral resolution of λ/Δλ = 110–240 and a spatial resolution of 1–2 min of arc. For a 40,000-sec observation, the average 3σ sensitivity to continuum flux is ∼2 × 10−27 erg/cm2/sec/Hz. This is a factor of 100 dimmer than a bright known EUV source and is comparable to the sensitivity of the all-sky survey which will be carried out on the EUVE. At a 5σ detection threshold, the spectrometer sensitivity to individual spectral lines is 1–4 × 10−3 photons/cm2/sec, which is a factor of 50 better than available with the EUVE wide bandpass telescopes. Simulated observations of two known classes of extrasolar EUV sources reveal rich spectra. During a six-month spectroscopic phase, target selection will be conducted by guest investigators chosen by NASA.

© 1985 Optical Society of America

Full Article  |  PDF Article
OSA Recommended Articles
Extreme Ultraviolet Spectrometer for Space Research

Shailendra Kumar, Francesco Paresce, Stuart Bowyer, and Michael Lampton
Appl. Opt. 13(3) 575-580 (1974)

A 30-cm objective grating for far-UV astronomy: theoretical study and laboratory tests

Renée Prangé, Michel Duban, Alfred Vidal-Madjar, Jürgen Barnstedt, D. Parisot, M. Decaudin, J. P. Crussaire, C. Laurent, A. Labèque, G. Ancourt, J. Flamand, M. Grewing, R. Hoekstra, A. Thévenon, G. Bargot, M. Barthélémy, F. Canovas, J. Charra, C. Hallier, H. Lagardère, G. Levanti, G. Michaud, and H. Poncet
Appl. Opt. 28(3) 496-509 (1989)

X-ray optics. 2: A technique for high resolution spectroscopy

Webster C. Cash
Appl. Opt. 30(13) 1749-1759 (1991)

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Figures (23)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Tables (2)

You do not have subscription access to this journal. Article tables are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Equations (44)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Metrics

You do not have subscription access to this journal. Article level metrics are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription