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Proceedings Paper

WaFIRS: a waveguide far-IR spectrometer enabling spectroscopy of high-z galaxies in the far-IR and submillimeter
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Paper Abstract

The discovery of galaxies beyond z~1 which emit the bulk of their luminosity at long wavelengths has demonstrated the need for high-sensitivity, broad-band spectroscopy in the far-IR/submm/mm bands. Because many of these sources are not detectable in the optical, long-wavelength spectroscopy is key to measuring their redshifts and ISM conditions. The continuum source list will increase in the coming decade with new ground-based instruments (SCUBA2, Bolocam, MAMBO), and the surveys of HSO and SIRTF. Yet the planned spectroscopic capabilities lag behind, in part due to the difficulty in scaling existing IR spectrograph designs to longer wavelengths. To overcome these limitations, we are developing WaFIRS, a novel concept for long-wavelength spectroscopy which utilizes a parallel-plate waveguide and a curved diffraction grating. WaFIRS provides the large (~60%) instantaneous bandwidth and high throughput of a conventional grating system, but offers a dramatic reduction in volume and mass. WaFIRS requires no space overheads for extra optical elements beyond the diffraction grating itself, and is two-dimensional because the propagation is confined between two parallel plates. Thus several modules could be stacked to multiplex either spatially or in different frequency bands. The size and mass savings provide opportunities for spectroscopy from space-borne observatories which would be impractical with traditional spectrographs. With background-limited detectors and a cooled 3.5 m telescope, the line sensitivity would be comparable to that of ALMA, with instantaneous broad-band coverage. We present the spectrometer concept, performance verification with a mm-wave prototype, and our progress toward a cryogenic astronomical instrument

Paper Details

Date Published: 5 March 2003
PDF: 12 pages
Proc. SPIE 4850, IR Space Telescopes and Instruments, (5 March 2003); doi: 10.1117/12.461572
Show Author Affiliations
Charles M. Bradford, California Institute of Technology (United States)
Bret J. Naylor, California Institute of Technology (United States)
Jonas Zmuidzinas, California Institute of Technology (United States)
James J. Bock, Jet Propulsion Lab. (United States)
California Institute of Technology (United States)
J. Gromke, California Institute of Technology (United States)
Hien Nguyen, Jet Propulsion Lab. (United States)
Mark Dragovan, Jet Propulsion Lab. (United States)
Minhee Yun, Jet Propulsion Lab. (United States)
Lieko Earle, Univ. of Colorado/Boulder (United States)
Jason Glenn, Univ. of Colorado/Boulder (United States)
Hideo Matsuhara, Institute of Space and Astronautical Science (Japan)
Peter A. R. Ade, Cardiff Univ. (United Kingdom)
Lionel Duband, CEA Grenoble (France)


Published in SPIE Proceedings Vol. 4850:
IR Space Telescopes and Instruments
John C. Mather, Editor(s)

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