Remote methane sensor using Tunable Diode Laser Spectroscopy (TDLS) via a 1W Raman So

We report a long-range near-IR methane sensor for inspection of natural gas collection, storage sites and pipeline networks. The principle is that a laser carrier beam is directed at the target surface across a test path and the backscatter from the surface is collected via a large Fresnel lens onto the photoreceiver. A Raman amplifier has been designed to amplify the TDLS optical signal generated by a 1650.95nm DFB laser diode to over 1W CW. Combining the high power output of the Raman amplifier and the highly sensitive TDLS technique, we may report 100ppm.m sensitivity at more than 100m by extrapolation