Patent ID: 7304742

Claim:
A photoacoustic system comprising: a photoacoustic device comprising a central hollow axial region configured to admit a gas at a first end and allow the gas to exit at a second end; a pump mounted to the second end of the central axial region, the pump adapted to pull the gas into the central axial region, through the central axial region, and out of the central axial region; at least two infrared (IR) lasers located adjacent the central axial region, the lasers irradiating the central axial region with the light traveling from the laser through the central axial region; and a microphone mounted to an inner wall in the central hollow axial region, the microphone configured to detect an acoustic signal generated by absorption of the light by the particles in the gas, the acoustic signal proportional to the optical absorption by particles in the gas at the laser wavelengths of the light, and generate an electrical signal proportional to the acoustic signal.