免标定波长调制光谱在气体温度和浓度测量中的应用

可调谐二极管激光吸收光谱在诸多领域有广泛的应用，但因为基线获取的困难，在高压、强干扰条件下的测量存在困难。波长调制光谱的理论显示，一次谐波信号（1f）和二次谐波信号（2f）包含了初始光强和光电探测器增益两个公共项。通过一次谐波信号归一化的二次谐波（2f/1f）信号，消除了信号强度与光强的相关性，可得到吸收光谱的绝对强度及温度等信息。通过测量激光调制参数，结合已知光谱参数可通过数值仿真得到理论的2f/1f 信号。利用数值锁相算法，可以实现频分复用的免标定波长调制光谱测量，实验显示，当恒温池设定温度为600 K、700 K 和800 K 时，光谱测量温度与热电偶测量值偏差小于2%，该方法具有可靠性和更强适应性。

Application of calibration-free wavelength-modulation spectroscopy in measurements of gas temperature and concentration

Tunable diode laser absorption spectroscopy is widely used in many applications，with difficulty of abstracting baseline，it is hard to be used in high-pressure and high-disturbing conditions. It's indicated in theory of wavelength-modulation spectroscopy that the first and second order harmonic signals contain tow common terms: incident intensity and gain of detector. By normalizing 2f signal with 1f signal (2f/1f), dependency of 2f/1f signal on incident intensity was eliminated, absolute strength of a spectra can be obtained subsequently. With measured laser parameter and known spectral parameters, theoretical 2f/1f signal was simulated by numerical calculation. Calibration-free wavelength-modulation spectroscopy was built based on frequency demultiplexing method, by numeric lock-in code. When a temperature stabilized cell was set at 600 K, 700 K, 800 K, precision of 2% is achieved compared with thermocouple measurement, which indicates that the method is much more reliable and adaptable.