A laser gas detector for the search of leaks from underground gas mains

A highly sensitive high-speed He-Ne laser-based absorption hydrocarbon gas detector is described. The measured concentration range is 3-1000 ppm, relative error in a range of 3-10 ppm does not exceed 20%, and in a range of 10-1000 ppm does not exceed 10%. Settling-up time of the readings does not exceed 2 s, the overall dimensions are 600 x 240 x 135 mm, and the weight is 13 kg. The desined characteristics are achieved by using a two-channel optical system with a double-mirror multipass cell, a two-channel synchronous detection, and digital signal processing. The device can be used for the search of leaks from underground gas mains and in ecological studies of the atmosphere and soils, as well as in oil and gas geological survey.