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Proceedings Paper

Recent developments in the applications of mid-infrared lasers, LEDs, and other solid state sources to gas detection
Author(s): Stanley D. Smith; Harvey R. Hardaway; J. Graham Crowder
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Paper Abstract

Although mid infrared research into sources and detectors has made considerable progress in recent years, requirements for gas sensing purposes for source power and the detectivity of diode detectors - particularly in combination - remain to be convincingly demonstrated in an industrial context. Published results are often confusing in that they apply to a variety of pulse lengths and duty cycles. We suggest a standardized approach in terms of an averaged cw power output. Parameters such as radiance, drive current and electrical power are also important. We discuss the relative merits of lasers and LEDs, i.e. use of line or band absorption on gas sensing. We report recent advances in the use of immersion optics leading to detectors with D*~5x109 cmHz1/2W-1 at 5.4micrometers , LEDs with outputs improved by a factor of 5 and an LED/Diode/White cell gas sensing demonstration giving 2ppm sensitivity for NO2 with an electrical power requirement of only 0.25mW. Further consideration includes sensitivity of gas sensing, path length and volume, time constant and temperature stability. Latest results are assessed on the basis of the above and combined with some market indications.

Paper Details

Date Published: 22 May 2002
PDF: 16 pages
Proc. SPIE 4651, Novel In-Plane Semiconductor Lasers, (22 May 2002); doi: 10.1117/12.467944
Show Author Affiliations
Stanley D. Smith, Edinburgh Instruments Ltd. and Heriot-Watt Univ. (United Kingdom)
Harvey R. Hardaway, Edinburgh Instruments Ltd. (United Kingdom)
J. Graham Crowder, Heriot-Watt Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 4651:
Novel In-Plane Semiconductor Lasers
Jerry R. Meyer; Claire F. Gmachl, Editor(s)

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