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Proceedings Paper

A mid-IR ICL-based sensor for field measurements of ambient CH4
Author(s): D. Sonnenfroh; R. Varner; M. Silva; M. Allen
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Paper Abstract

We are developing a mid-IR ICL-based sensor for field measurements of ambient CH4. We describe some of the design considerations for this sensor. Our sensor uses a Type II Quantum Cascade Laser (or Interband Cascade Laser, ICL) operating near 3.3 μm to monitor a well-isolated line in the υ3 fundamental band of CH4. The ICL operates in cw mode at cryogenic temperature. The sensor consists of two major components, an optical breadboard containing the laser, transfer optics, sample cell, and detectors, and an instrumentation module containing power supplies and system control computer. Light from the laser is collimated using a reflective microscope objective and transported to a multipass cell via a simple optics train. The multipass cell provides an optical path of ~7 meters in an 0.25 m base path. The spectrometer uses TE-cooled InAs detectors along with our Balanced Ratiometric Detection. Our measured precision for CH4 is 15 ppbv for a 60 sec integration time. We report on additional sensor characterization and data from recent field trials at two facilities maintained by the University of New Hampshire.

Paper Details

Date Published: 17 October 2006
PDF: 7 pages
Proc. SPIE 6386, Optical Methods in the Life Sciences, 63860Q (17 October 2006); doi: 10.1117/12.692861
Show Author Affiliations
D. Sonnenfroh, Physical Sciences Inc. (United States)
R. Varner, Univ. of New Hampshire (United States)
M. Silva, Physical Sciences Inc. (United States)
M. Allen, Physical Sciences Inc. (United States)

Published in SPIE Proceedings Vol. 6386:
Optical Methods in the Life Sciences
Alexey A. Belyanin; Mostafa Analoui; Rebekah Anna Drezek; Claire F. Gmachl, Editor(s)

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