<title>Spatial heterodyne spectroscopy: laboratory tests of field-widened, multiple-order, and vacuum ultraviolet systems</title>

Abstract

We describe a new instrumental technique for interference spectroscopy, Spatial Heterodyne Spectroscopy (SHS), which promises to extend into the far-ultraviolet (FIJV; 1200 A - 2000 A) spectral region the large throughput advantage at high spectral resolution usually associated with Fabry-Perot and Michelson interferometers. In addition, SHS systems are compact in size, can be field widened to increase their throughp it advantage even further, and have no moving parts. SHS appears to be well suited for high resolution, space-based spectroscopy of faint interstellar emission lines in the far-ultraviolet. This has significant implications for the study of the dynamics and distribution of hot gas within the Galactic disk and halo. SHS systems built and tested in the laboratory at visible and UV wavelengths have verified the basic concepts and performance characteristics of the technique. lit this paper we review the first proof-of-concept laboratory demonstrations of a field widened SHS configuration and a multiple order SHS system, which extends the spectral range of the basic device and present new results of sus performance in the vacuum ultraviolet (1850A). The design of an SHS system capable of obtaining velocity resolved spectra of the CIV )t155O doublet from the interstellar medium is also discussed.