可调谐激光光谱的理论及实验研究

Theoretical and Experimental Studies on Tunable Laser Spectroscopy

为了准确快速地检测气体浓度,对可调谐激光光谱技术及其主要噪声来源进行了分析。理论分析可知,偶次谐波分量在谐振位置有最大值,且幅度逐次下降,因此采用二次谐波检测的方法来获取气体浓度。剩余幅度调制和干涉信号是系统的两大影响因素,通过数学推导,得到了二者谐波分量的表达式,并给出了相应的抑制方法。

In order to measure the gas concentration quickly and exactly, the paper analyzes the tunable diode laser absorption spectroscopy and the source of its noise. From the theoretical studies, it shows that the even harmonics will reach the maximum value in the resonant location and its amplitude will go down successively. So the concentration of gas can be gotten with the second harmonic detection method. The two affecting factors are residual amplitude modulation and interferometric signal in the system. The harmonic expression of the two affecting factors can be gotten by mathematical derivation, and to give the corresponding restraint method.