Saiz-Lopez, in UVвЂ“Visible Differential Optical Absorption Spectroscopy (DOAS), Analytical Techniques for Atmospheric Measurement, ed. Fukuchi, Laser Remote Sensing (CRC Press, Boca Raton, 2005) Weitkamp, Lidar, Range-Resolved Optical Remote Sensing of the Atmosphere (Springer, Berlin, 2005) Experimental Techniques (Springer, Berlin, 2008)Д¬. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (2013) Midgley: IPCC, 2013: Climate Change 2013: The Physical Science Basis. Given these characteristics, this system is promising for mobile or multidirectional search and remote detection of gas leaks. The system performs measurements at high speed ~15В Hz and sufficient range (up to 45В m, ~148 feet) achieving an uncertainty of 3.1В % and normalized sensitivity of 3.3В ppmВ mВ Hz в€’1/2 for N 2O and 9.3В % and normalized sensitivity of 30В ppmВ mВ Hz в€’1/2 for CH 4 with a 0.31В mW average power QCL. Making fast time resolved observations, the system simultaneously realizes high spectral resolution and range to the target, resulting in path-averaged concentration retrieval. The measured absorption spectra are obtained using a thermal intra-pulse frequency chirped DFB quantum cascade laser at ~7.7В Вµm wavelength range with ~200В ns pulse width. It is a true standoff system and differs from other open-path systems that are deployed as point samplers or long-path transmission systems that use retroreflectors. This study presents standoff detection of CH 4 and N 2O leaks using a quantum cascade laser open-path system that retrieves path-averaged concentrations by collecting the backscattered light from a remote hard target. Moreover, they are also a security and safety concern because of possible risk of fire/explosion or toxicity. Fugitive gas emissions from agricultural or industrial plants and gas pipelines are an important environmental concern as they contribute to the global increase of greenhouse gas concentrations.

Download hard target movie for mobile