An acoustically resonant CO<sub>2</sub> laser photoacoustic (PA) spectrometer for remote or <i>in situ</i> monitoring of air pollutants has been designed. The salient features of this PA system, along with the optimization tests of various operating parameters that affect the PA signal (buffer-gas pressure, type of buffer gas, laser power, gas concentration, and acoustic modes), are described. The system has been applied for the detection of pollutants emitted from the exhaust of a car located at a remote distance. Also, an alarm system based on the PA detection technique has been built for leak detection of toxic gases at industrial complexes. The minimum detectable concentration of C<sub>2</sub> H<sub>4</sub> and SO<sub>2</sub> with this system is 50 parts in 10<sup>12</sup> by volume and 50 parts in 10<sup>9</sup> by volume, respectively.
© 1997 Optical Society of America
M. A. Gondal, "Laser photoacoustic spectrometer for remote monitoring of atmospheric pollutants," Appl. Opt. 36, 3195-3201 (1997)