Gas concentration detection method based on nonlinear fitting of second harmonic signal

The invention discloses a non-linear fitting gas concentration detection method of a second harmonic signal, which comprises the following steps: 1, constructing a Voigt linear function of the second harmonic signal, 2, calculating an initial fitting value, carrying out non-linear fitting on the collected second harmonic signal of a reference channel and a measurement channel to obtain an optimal fitting parameter, and 3, calculating according to the optimal fitting parameter to obtain a fitted standard second harmonic signal and a second harmonic signal peak value, and performing concentration inversion by using the peak value. On the basis of not adding a hardware structure, the problem that the measurement accuracy is influenced by signal baseline drift and signal deformation is solved through a nonlinear fitting method of the second harmonic signal, so that the detection accuracy can be improved, and the stability of a detection system can be ensured. 本发明公开了一种二次谐波信号的非线性拟合的气体浓度检测方法，包括：1、构建二次谐波信号的Voigt线型函数，