Optimisation of photoacoustic resonant cells with commercial microphones for diode laser gas detection.
The theoretical and experimental study of the differential Helmholtz resonant (DHR) cell sensitivity under variation of the total gas pressure is made for various commercial microphones. Near-infrared lasers (room-temperature diode lasers) were used to measure the response of DHR cell versus pressure of the absorbing gas and frequency of the laser radiation modulation. Several molecular absorbers like H2O, CH4, mixed with molecular buffer gases were used to investigate the behavior of the photoacoustic (PA) signal characteristics with a DHR cell. The experimental data are compared with the results of computer simulation. The minimal detectable concentrations of gases were determined for the DHR cell for each commercial microphone.
D008697:Methane / Q000032:analysis; D011312:Pressure; D013055:Spectrophotometry, Infrared / Q000295:instrumentation*; D014867:Water / Q000032:analysis
D014867:Water; D008697:Methane