Laser microphotoacoustic sensor of ammonia traces in the atmosphere

A microphotoacoustic highly selective sensor of ammonia is built. Main attention is paid to the operation mechanism of the acoustic sensor based on a quartz tuning fork. The optimal dimensions and configuration of the acoustic resonator are determined, which made it possible to increase the sensor sensitivity by two-three times compared to the sensitivity of the existing devices. The detector sensitivity for ammonia was 60 ppb (0.05 mg m(-3)) for the measurement time of 10 s and a 25-mW, 1.53-mu m laser beam in the acoustic resonator.