Methane detection on the sub-ppm level with a near-infrared diode laser photoacoustic sensor

Abstract The Groupe de Spectrometrie Moleculaire et Atmospherique (Reims, France) and the Institute of Atmospheric Optics (Tomsk, Russia) have developed a photoacoustic (PA) system based on differential Helmholtz resonance for infrared gas detection. We demonstrate with this PA cell used in conjunction with a near-infrared diode laser emitting at 1.65 μm the possibility to detect methane in air flow at atmospheric or reduced pressure. The achieved ultimate sensitivity of the PA cell is 2.4 × 10 −10 W cm −1 with 1 s integration time. With a diode laser in the 1.65 μm region, this PA cell makes it possible to detect 0.3 ppm of methane in air.

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