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Proceedings Paper

Design for the COBE far-infrared absolute spectrophotometer (FIRAS)
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Paper Abstract

The Far InfraRed Absolute Spectrophotometer (FIRAS) was built to measure the spectrum of diffuse emission from 1 to 100 cm-1, with particular attention to possible differences between the spectrum of the cosmic microwave background radiation (CMBR) and a blackbody spectrum as small as 0.1% of the peak of the CMBR spectrum. The FIRAS has differential inputs and outputs, a full beam external calibrator, a controllable reference blackbody, and a polarizing Michelson interferometer with bolometer detectors. It is operated at a temperature of 1.5 K inside a liquid helium cryostat to suppress instrument emission and improve detector sensitivities. It has an intrinsic frequency resolution of the order of 0.7%, maximum path lengths of 1.2 and 5.9 cm, and a beamwidth of 7 degree(s), and achieved its goals for accuracy and rms sensitivity for νIν, which are better than 10-9 W/cm2sr over the frequency range from 2 to 20 cm-1.

Paper Details

Date Published: 1 October 1993
PDF: 12 pages
Proc. SPIE 2019, Infrared Spaceborne Remote Sensing, (1 October 1993); doi: 10.1117/12.157823
Show Author Affiliations
John C. Mather, NASA Goddard Space Flight Ctr. (United States)
Dale J. Fixsen, NASA Goddard Space Flight Ctr. (United States)
Richard A. Shafer, NASA Goddard Space Flight Ctr. (United States)


Published in SPIE Proceedings Vol. 2019:
Infrared Spaceborne Remote Sensing
Marija S. Scholl, Editor(s)

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