Remote Sensing of Hydrogen Concentration by Low Power Laser

Abstract

An eye-safe Raman lidar for remote measurement of hydrogen gas concentration was constructed. The lidar used a low power diode-pumped solid state laser of wavelength 349nm and pulse energy 120μJ. Detection was possible for H₂ gas concentration in the gas cell of more than 4% at a distance of 5m from the lidar. The concentration of hydrogen gas leaked into the open air at a distance of 10m from the lidar was successfully measured in outdoor conditions. From these experimental results, the detection sensitivity of the receiver was evaluated by calculated using a biaxial lidar model. As a result, it was confirmed that H₂ gas concentration of 1% up to a distance of 10m was able to detect using a Fresnel lens of aperture 305mm. This result showed that the eye-safe Raman lidar could be used for hydrogen gas leakage detection.