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Proceedings Paper

Review Of Progress In Remote Sensing By Tunable Diode Laser Heterodyne Spectroscopy
Author(s): David A Glenar
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Paper Abstract

Heterodyne spectroscopy at infrared wavelengths is a unique approach to the study of atmospheric species and astrophysical objects. It's coherent detection properties ma4 it 7 the only optical technique to combine ultra-high frequency resolving power (v/A = 106- 107) with diffraction-limited spatial resolution. The use of lead-salt tunable diode lasers (TDL's) as local oscillators in a heterodyne instrument offers the additional advantage of continuous tunability, permitting operation over the entire nominal tuning range of the device. Previous investigators have obtained high signal-to-noise TDL heterodyne spectra of terrestrial atmospheric features in solar absorption and molecular features in sunspots. Until recently, however, the noisy character and low output power of TDL's have precluded their use for heterodyne detection of objects much fainter than the sun. Attempts to observe planets and astrophysical infrared sources have produced only a handful of weak continuum detections. The major categories of TDL excess noise are now fairly well understood, and new device fabrication techniques have produced dramatic improvements in noise reduction, power output, single mode tunability and operation at long wavelengths (X > 10 microns). These next generation devices should result in ground-based instrument performance which rivals the CO2 laser heterodyne technique throughout the 8 to 13 micron atmospheric window.

Paper Details

Date Published: 26 November 1983
PDF: 12 pages
Proc. SPIE 0438, Tunable Diode Laser Development and Spectroscopy Applications, (26 November 1983); doi: 10.1117/12.937447
Show Author Affiliations
David A Glenar, Colgate University (United States)

Published in SPIE Proceedings Vol. 0438:
Tunable Diode Laser Development and Spectroscopy Applications
Chiwoei Wayne Lo, Editor(s)

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