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Optical Engineering

Spatial heterodyne spectroscopy for long-wave infrared: first measurements of broadband spectra
Author(s): Christoph R. Englert; David D. Babcock; John M. Harlander
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Paper Abstract

We describe the design and implementation of a long-wave infrared (LWIR) spectrometer based on the spatial heterodyne spectroscopy (SHS) technique, and present the first measurements of broadband LWIR spectra taken with an SHS instrument. This work represents the first successful application of SHS to the field of LWIR spectroscopy, which is currently dominated by Fourier transform spectrometers, grating spectrometers, and Fabry-Perot interferometers. A unique combination of properties makes SHS a valuable addition to the existing types of LWIR spectrometers. Most notable are the interferometric throughput (no slit), lack of moving parts, and that the measured spectra are not contaminated by a changing scene, which makes SHS particularly suitable for applications in rugged environments and on moving platforms. The instrument discussed here is called the Spatial Heterodyne Imager for Chemicals and Atmospheric Detection (SHIMCAD), and is designed to cover the wavelength range between about 8.4 μm (1190 cm-1) and 11.2 μm (890 cm-1) with a spectral resolution of about 4 cm-1. First, laboratory SHS transmission spectra of methanol and polyimide (Kapton®) are presented. The instrument is built to be mobile, so that ultimately field measurements can be conducted.

Paper Details

Date Published: 1 October 2009
PDF: 9 pages
Opt. Eng. 48(10) 105602 doi: 10.1117/1.3250194
Published in: Optical Engineering Volume 48, Issue 10
Show Author Affiliations
Christoph R. Englert, U.S. Naval Research Lab. (United States)
David D. Babcock, Artep, Inc. (United States)
John M. Harlander, St. Cloud State Univ (United States)

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