Tunable laser spectrometer uses reflections from ordinary objects. Topographic target (ordinary feature of surroundings) returns enough energy to receiver so absorption by trace gases detected. Chopping laser beam allows return to be compared with original signal. Amplifier locks in on chopping frequency or laser modulation frequency. In laboratory simulations, spectrometer detected nitrogen dioxide in concentrations of only few parts per million.
Monitoring Trace Gases in the Atmosphere
NASA Tech Briefs ; 9 , 2
1985-10-01
Miscellaneous
No indication
English
NTRS | 2005
|British Library Conference Proceedings | 1997
|Density measurements of trace gases
NTRS | 1977
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