US Patent 7765871 System and method for gas analysis using photoacoustic spectroscopy

A system and method for analyzing a target analyte gas concentration using a photoacoustic spectroscopy cell comprising:i) a modulatable light source which provides optical radiation at an absorption wavelength of a target analyte;ii) a resonant acoustic chamber for containing said analyte;iii) a microphone positioned within said chamber whereby the acoustic reactance of the microphone is a substantial factor in determining the acoustic resonant frequency of the acoustic chamber and where the magnitude of the acoustic reactance of the microphone is at least two times the acoustic resistance of the microphone.