基于泛频CO激光器的微量气体光声光谱仪

A CO-overtone Laser Based Photoacoustic Spectrometer for Trace Gas Detection

泛频(Δν=2)CO激光器可以输出2.8～4μm的准连续可调激光,腔内单线最大激光振荡功率可达4W。将纵向共振光声池放入双能级跃迁CO激光器光学谐振腔内,构成了高灵敏度的光声光谱仪。利用该光谱仪对低浓度的甲烷(CH4)气体作了光声测量。由于气体吸收线与CO激光器谱线有较好的重合性,以及较强的腔内激光功率,该系统对CH4气体的极限检测灵敏度达到0.1ppb(10-10)。

A COovertone (Δν=2) laser based photoacoustic spectrometer was presented.The spectrometer consists of a tunable COovertone laser with a maximum intracavity power of 4 W for single line operation in the wavelength range of 2.8～4 μm,a intracavity longitudinal resonant photoacoustic cell and a computer controlled signal detection and processing system.The spectrometer is applied to measure the concentration of methane (CH4) for demonstrating the high sensitivity of the system.A detection limit of 0.1 ppb(1×10-10) has been achieved thanks to the good spectral coincidence between laser lines and CH4 absorption lines and relatively high intracavity laser power.