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Transcripción del abstract original del autor: Tokyo Gas Co., Ltd. and Anritsu Corporation have jointly and newly developed a portable remote methane detector (PRMD). As far as the authors know, this detector is the world's first portable device that enables detection of gas leaks at a distance. The conventional method of detecting gas leaks entails lengthy inspection periods in elevated or narrow locations. Therefore, there has been a demand for remote sensing equipment to overcome these difficulties. The PRMD utilizes the infrared (IR) absorption properties of methane, the principal component of natural gas. Highly sensitive detection is accomplished by applying wavelength modulation spectroscopy (WMS), using a tunable diode laser (TDL). The device transmits a laser beam, with the wavelength set at one of the IR absorption wavelengths of methane. A detector subsequently detects a fraction of the backscatter reflected from the target. The detector thereby measures the path-integrated concentration of methane between the detector and the target. The operator of the PRMD can easily check a gas leak at a distance by hand-scanning the laser beam. When used with typical targets at distances up to 10 meters, the device has a detection limit of less than 5 ppm-m and can detect a 10 ml-min-1 gas leak from an exposed pipe. In Japan, the PRMD has already been introduced into the market by Tokyo Gas Engineering Co., Ltd. According to the operational results of Tokyo Gas, the PRMD proved to improve the operational efficiency of emergency services and quality of surveillance activities. As of 1 Jan. 2003, 39 PRMD units are in use at Tokyo Gas, other gas utilities and businesses.