Trace Gas Sensor Based on Quartz-Enhanced Photo Acoustic Spectroscopy

Abstract

Photo acoustic spectroscopy (PAS) is a widely used method for trace gas sensing. It is based on photo acoustic effect which was discovered by Bell in 1880’s. When the laser power is absorbed by the medium, the absorbed energy can be transformed into heat energy by non-radiative processes. If the laser is modulated, the heat and the pressure wave generated by the heat will also be modulated. This process will produce acoustic wave. Microphone based PAS detection is employed for many years for gas sensing.