Patent ID: 8830469

Claim:
A method for detecting at least one target gas by laser spectroscopy using one of a laser and a laser diode having a monochromic emission wavelength and which is tuneable by varying one of an operating temperature and operating current, the method comprising: first tuning of the one of the laser and the laser diode over a first broad tuning width in a wavelength range of one band of the at least one target gas, at least two absorption lines of a reference gas and at least one absorption line of the at least one target gas being included in the first tuning width, for calibration of a wavelength scale of the one of the laser and the laser diode relative to one of a varied operating temperature and a varied operating current; second tuning of the one of the laser and the laser diode over a second, narrow tuning width in the wavelength range of the one band of the at least one target gas, the second, narrow tuning width at which the second tuning is performed being narrower than the first broad tuning width, at least one of the at least one absorption line of the at least one target gas being included in the second tuning width, for detection of the at least one target gas; detecting the at least one gas by laser spectroscopy using the one of the laser and the laser diode; and measuring a concentration of the at least one target gas; wherein the target gas and reference gas are different gases.