| 摘要 |
The invention proposes a method for etalon suppression in a gas detection device by determining an etalon fringe period during a calibration step without gas in dependency of the DC drive current. A measuring signal which is a functio n of the gas absorption and substantially independent of an intensity modulation of an initial light signal at an initial frequency (f) is generated by determining a first pre-measuring signal when the laser source is operated at the center of the gas absorption peak, a second pre-measuring signal when the laser source is operated with a DC drive current below the gas absorption peak of the gas to be detected, and a third pre-measuring signal when the laser source is operated with a DC drive current above said gas absorption peak, with a difference between said DC drive currents which corresponds to the etalon fringe period determined in a calibration step before. The final measuring signal is determined as th e difference between the first pre-measuring signal and the arithmetic mean of the second pre-measuring signal and the third pre-measuring signal. This etalon fringe suppression allows to implement a substantial simplification of a reference channel in a gas detector, which does not require separate lock-in channels which analyse the detectorsignal either on the modulation frequency (f), or on twice the modulation frequency (2f).
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