Quick scanning TDL spectrometry for atmospheric trace gas monitoring with anti-scintillation performance
- Okayama Univ., Tsushima, Okayama (Japan). Dept. of Electrical and Electronic Engineering
- Fukuyama Univ. (Japan). Dept. of Electronic and Electrical Engineering
Infrared laser beams suffer from absorption from various gas species not to say of water vapor or carbon dioxide. If the tunable diode laser is employed as source, the authors 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.
- OSTI ID:
- 500941
- Report Number(s):
- CONF-960848--; ISBN 0-8194-2222-3
- Country of Publication:
- United States
- Language:
- English
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