摘要
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。
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.
出处
《红外与激光工程》
EI
CSCD
北大核心
2014年第3期956-960,共5页
Infrared and Laser Engineering
基金
激光推进及其应用国家重点实验室基础研究项目
关键词
激光吸收光谱
波长调制
谐波检测
燃烧场诊断
laser absorption spectroscopy
wavelength-modulation
harmonic detection
combustion field diagnosis
