Trace detection in gases using phase fluctuation optical heterodyne spectroscopy
- 1 April 1980
- journal article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 36 (7) , 515-518
- https://doi.org/10.1063/1.91590
Abstract
A very sensitive technique for detecting trace molecules in the gas phase is described. Refractive index changes of a gaseous sample, which result following V→R, T relaxation of trace molecules which have been excited by a laser, are detected by optical heterodyning in a Mach-Zender interferometer. Detection sensitivities of 10 ppb for SF6 in air and 40 ppb for CH3OH in helium, have been demonstrated using CO2 TEA laser excitation and a 20-MHz detection bandwidth.Keywords
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