| 摘要 |
PROBLEM TO BE SOLVED: To provide a small photoacoustic gas sensor of simple structure enhanced in absorption efficiency of an infrared ray by detection-objective gas inside a cavity irradiated by the infrared ray of a limited intensity, and enhanced in gas detection sensitivity. SOLUTION: This sensor is provided with the cavity provided with a gas flow port 20 for introducing the outside atmospheric air and an infrared ray introducing window 30, a gas diffusion filter 40 comprising a porous silicon layer provided integrally with the cavity in the gas flow port, a microphone 50 for detecting sound pressure inside the cavity by providing the first corrugated electrode 51 serving as one portion of an inner wall face of the cavity, and a light source 60 for pulse-irradiating the infrared ray into the cavity via the infrared introducing window. In particular, an infrared ray reflecting film 70 comprising Au, Al or the like is coated on an area other than the gas flow port and the infrared ray introducing port in the inner wall face of the cavity.
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