The application discloses a
wavelength modulation-direct absorption dual-mode wide-range
gas concentration detection method with temperature self-adaptive threshold, and belongs to the technical field of tunable
diode laser absorption spectrum gas detection. The existing pure
mode switching scheme generally uses a fixed concentration threshold, and temperature change will cause the switching point to deviate from the optimal error
balance point, aiming at the problem, the application calibrates the critical peak
absorbance as a unified reference under the reference temperature, and also calculates the line intensity under different temperatures to generate a corresponding
lookup table; during work, the current line intensity is obtained by real-time temperature
lookup table, and the concentration switching threshold is dynamically updated, the
wavelength modulation mode is used in the initial detection stage, when the concentration continuously exceeds the threshold, the direct absorption mode is switched to, and when the concentration is lower than the
hysteresis threshold, it is switched back, the application uses dynamic threshold updating to make the switching point correspond to the optimal error
balance point of the two methods at all times, and the sensitivity at low concentration and the
linearity at
high concentration are considered.