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Proceedings Paper

Quick-scanning TDL spectrometry for atmospheric trace gas monitoring with antiscintillation performance
Author(s): Ryuji Koga; Osami Wada; Ming Wang; Naoki Kagawa
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Paper Abstract

Infrared laser beam as suffer from absorption form various gas species not to say of water vapor or carbon dioxide. If the tunable diode laser is employed as source, we can obtain more information from the fluctuating absorption signal than ever by virtue of TDL's spectral purity and its quick tunability. By scanning an absorption spectrum around an absorption line, not sticking to the center of a line, spectral interference from an adjacent line or scintillation can be eliminated with a real-time digital signal processing. Based on the actual data about temporal sequence of transmittance for TDL beam through open atmosphere, it is found that the scintillation is frozen if the spectral scanning is done within 0.1 second, and the more the less. In order to facilitate this principle, received electronic signal is treated by a high speed digital signal processing system. A special integrated circuit device, DSP, is exploited of its high performance in numerical calculation speed. Elimination of spectral interference is performed with a personal computer based on an algorithm named as 'adjoint spectrum' invented by the authors. This is also implemented by DSP. Function of the test equipment the authors have built is shown.

Paper Details

Date Published: 21 October 1996
PDF: 6 pages
Proc. SPIE 2834, Application of Tunable Diode and Other Infrared Sources for Atmospheric Studies and Industrial Process Monitoring, (21 October 1996); doi: 10.1117/12.255320
Show Author Affiliations
Ryuji Koga, Okayama Univ. (Japan)
Osami Wada, Okayama Univ. (Japan)
Ming Wang, Okayama Univ. (Japan)
Naoki Kagawa, Fukuyama Univ. (Japan)

Published in SPIE Proceedings Vol. 2834:
Application of Tunable Diode and Other Infrared Sources for Atmospheric Studies and Industrial Process Monitoring
Alan Fried, Editor(s)

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