利用一个波长为3.291 μm的室温连续、带间级联激光器和一个有效光程长为54.6 m的多通池, 研究了用于中红外甲烷检测的压强测量及补偿技术。通过对测得的甲烷直接吸收光谱信号进行洛伦兹吸收线型拟合, 测量了吸收池内气体压强并补偿了压强变化对甲烷浓度的影响。利用浓度为2.1×10-6的甲烷气体样品, 在1.33×104~10.64×104 Pa的范围内进行了压强标定; 对压强为9.31×104 Pa、浓度为2.1×10-6甲烷气体样品的压强测量结果进行阿仑方差分析, 结果表明, 当积分时间为2.2 s时, 压强的测量精度约为219.5 Pa。在1.33×104、3.99×104和6.65 ×104 Pa三种不同压强条件下, 对浓度分别为1.0×10-6、1.2×10-6、1.4×10-6、1.6×10-6、2.1×10-6甲烷气体样品的浓度和压强做了15组测量, 验证了所给出的压强测量和补偿技术的可行性。

A pressure measurement and compensation technique was studied by employing a 3.291 μm Continuous Wave (CW) Interband Cascade Laser (ICL) and a dense-patterned Multipass Gas Cell (MPGC) with an effective optical path length of 54.6 m. The pressure inside the MPGC was measured based on direct Lorentzian absorption line fitting on the measured absorption spectral signal of CH4, and then pressure compensation was made on the masured CH4 concentration. Pressure calibration was performed from 1.33×104 Pa to 10.64×104 Pa using a 2.1×10-6 CH4 sample. An Allan deviation analysis of the measured pressure of a 2.1×10-6 CH4 at 9.31×104 Pa pressure indicates a measurement precision of ~219.5 Pa with a 2.2 s averaging time. Fiveteen groups of pressure/concentration measurements of 1.0×10-6, 1.2×10-6, 1.4×10-6, 1.6×10-6 and 2.1×10-6 CH4 samples at different pressures of 1.33×104, 3.99×104 and 6.65×104 Pa were performed, and the results proved the feasibility of the proposed pressure measurement and compensation technique.