Abstract
A portable remote gas-leak detector using a 1.65μm InGaAsP DFB laser is developed. It is designed as a manportable long-path absorption methane lidar using a topographical target with a distance of several meters. An operator can search for gas leaks by hand scanning of the laser light. High sensitivity is accomplished by means of second-harmonic detection using wavelength-modulation spectroscopy. The experimental methane detection limit with a diffusive target of magnesium oxide (distance: 8 m, incidence: 60 deg) is 2.2 ppm·m with a time constant of 0.1 s. Measurement with a realistic target shows that the detector can findsmall gas leaks of 10 ml/min within the distance of several meters.
