基于光腔衰荡光谱技术的压力计校准方法

压强是工业生产过程中的一个重要参数，其准确测量是过程控制的关键。气体分子光谱线型和线宽取决于分子间相互作用和温度、气压等因素，利用窄线宽气体吸收光谱的压力展宽效应，可通过高分辨地测量气体吸收谱线得到压强信息，实现压力计校准。提出了一种基于光腔衰荡光谱技术和气体吸收谱线压力展宽效应的压力计校准方法。采用5.2 μm可调谐量子级联激光器，基于连续光腔衰荡光谱技术建立了压力计校准实验装置。室温下，测量水汽在1 877 cm-1附近的一吸收谱线，线宽为0.084 21 cm-1，重复性测量误差小于1.53×10-4 cm-1，对应的压强大小为98.12 kPa，检测灵敏度优于0.18 kPa，与高精度压力计读数98.14 kPa一致。利用测试谱线线宽与压强的关系得到压力展宽系数(0.087 12±0.000 965) cm-1·atm-1，与HITARN数据库参考值0.087 1 cm-1·atm-1一致。实验校准了一小量程压力计。结果表明基于光腔衰荡光谱的高分辨吸收谱线测量在压强检测和压力计校准领域具有很好的应用前景。

Calibration Method of Pressure Gauges Based on Cavity Ring-Down Spectroscopy Technique

The accurate measurement of pressure is of great importance to industry process control. In absorption spectroscopy, the spectral line profile and line-width of gas depend on the molecular interactions, temperature, pressure and other factors. The pressure induced line- broadening effect of narrow-band absorption lines of gases can be used for pressure measurement and calibration. A novel pressure gauge calibration method based on cavity ring-down spectroscopy (CRDS) and pressure induced line-broadening effect is presented and experimentally demonstrated at room temperature with a CRDS setup employing a 5.2 μm tunable quantum cascade laser and an absorption line of trace moisture in air near 1 877 cm-1 wavenumber. The measured line-width is 0.084 21 cm-1, and the corresponding pressure is 98.12 kPa, which is in good agreement with a high-precision pressure gauge reading 98.14 kPa. A pressure measurement limit of 0.18 kPa is achieved, estimated from the line-width measurement uncertainty. In addition, the measured pressure broadening coefficient is (0.087 12±0.000 965) cm-1·atm-1, which is in good agreement with the reference value 0.087 1 cm-1·atm-1 given by HITARN database at the same temperature. The proposed method is applied to calibrate a small-scale pressure gauge with sufficient accuracy. The results indicate that high-resolution measurement of absorption line based on CRDS has the potential for high-accuracy pressure measurement and calibration.