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波长调制谱技术(WMS)在慢扫描信号基础上叠加上高频的调制电流,并加到半导体激光器的驱动电流上,于是激光频率在线性扫描的同时受交流调制。频率调制的激光束在通过吸收气体以后,其吸收线的强度也受到相同频率调制。采用谐波小波方法作为数据解调的手段,对WMS技术产生的信号进行处理并实现了2f信号的提取。采用这种方法对波数为7185.6cm-1的水蒸气谱线进行测量实验,调制频率达到180kHz,对数据进行谐波小波处理后获得了高质量的2f信号,该2f信号的峰值中心辨识度高,其数据光滑度、信号的抗干扰能力方面均优于数字锁相方法。
Wavelength modulation spectroscopy (WMS) superimposes a high-frequency modulation current on a slow-scan signal and adds it to the drive current of the semiconductor laser so that the laser frequency is AC-modulated while linearly scanning. After the frequency modulated laser beam passes through the absorbed gas, the intensity of its absorption line is also modulated by the same frequency. Using the method of harmonic wavelet as a means of data demodulation, the signal generated by WMS technology is processed and the 2f signal is extracted. This method was used to measure the water vapor spectrum with a wave number of 7185.6cm-1, the modulation frequency reached 180kHz, and the high-quality 2f signal was obtained after harmonic wavelet processing. The peak center identification of the 2f signal was high , Its data smoothness, anti-interference ability of signals are better than digital phase-locked method.