Patent ID: 8322191

Claim:
A photoacoustic gas sensor comprising: an electromagnetic radiation source configured to emit electromagnetic radiation; a photoacoustic cell configured to receive a gas sample to be detected, wherein the photoacoustic cell includes an optical element adjacent the photoacoustic cell and configured to transmit at least part of the electromagnetic radiation into the photoacoustic cell, wherein the photoacoustic cell includes a front wall, a reflective back wall, and reflective side walls extending between the front wall and the back wall to collectively define an optical cavity, wherein the optical element is positioned adjacent the front wall and opposite the back wall, wherein the cross-sectional area defined by the side walls increases from the front wall toward the back wall, and wherein the electromagnetic radiation transmitted into the photoacoustic cell first reflects off the reflective back wall of the photoacoustic cell; and an acoustical detector acoustically coupled to the photoacoustic cell, the acoustical detector configured to detect an acoustic signal that is related to absorption of the electromagnetic radiation by the gas sample in the photoacoustic cell.