Tunable diode laser absorption spectroscopy (TDLAS) is a new gas detection technique developed recently with high spectral resolution, high sensitivity and fast time response. The second-harmonic signal of wavelength modulation spectroscopy (WMS) is often used as the detection signal for gas concentration inversion. Using Simulink, a visual modeling and simulation platform, the authors simulated the WMS signal based on TDLAS, and got the second-harmonic signal by using lock-in amplifier algorithm. Digital orthogonal algorithm was studied in this paper. The relationship between second-harmonic signals and the modulation indexes was analyzed by comparing changes of second-harmonic under different modulation indexes, in order to find out the optimized parameters for second-harmonic detection.
|Number of pages||5|
|Journal||Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis|
|Publication status||Published - Apr 2013|
- Lock-in amplifier