Stark-effect-modulated phase-fluctuation optical heterodyne interferometer for trace-gas analysis.
A narrow-bandwidth (cw) phase-fluctuation laser-heterodyne interferometer for trace-gas detection is described. Performance was evaluated using both Stark-effect modulation and conventional beam chopping. Sensitivities of 10(-8) cm(-1) were obtained in both cases. However, when Stark-effect modulation was employed, the usual background signal caused by interfering absorbing species and windows could be subtracted from the overall signal. In this mode, a detection limit of 5 parts in 10(9) (ppb) NH(3) in air was obtained.
Campillo
A J
AJ
Lin
H B
HB
Dodge
C J
CJ
Davis
C C
CC