可调谐二极管激光吸收光谱分析技术(TDLAS)是近年来兴起的一种痕量气体分析方法。 因其高分辨率、 高分析速度、 非接触测量、 可实时在线监测等优点, 受到人们广泛青睐, 已经广泛应于科研和工业自动化等领域的气体检测中。 为了满足分析仪器测量灵敏度和精度的要求, 对于很低浓度和信噪比较小的痕量气体浓度测量, 往往需要较长的吸收光程和复杂的数据处理算法, 这增加了分析仪器的软硬件成本。 本文提出利用高压气体射流产生的减压作用, 在不改变TDLAS分析仪器软硬件设置的条件下提高TDLAS的分析能力。 对于安装于样气压力为0.3～0.5 MPa和排气压力为219.3 kPa的TDLAS分析系统, 实验结果表明, 通过射流强化的方法, 可以使信噪比提高24倍, 探测灵敏度提高一个数量级, 测量精度提高6.3倍。

Tunable diode laser absorption spectroscopy is a new trace gas detection technique provided with high precision in current. As the absorption of spectrum is popular for the advantages of high resolution, high analysis speed, non-contact detection and on-line monitoring, it has been widely applied in scientific research, industrial automation and other fields for gas monitoring techniques. In order to satisfy the requirements of accuracy and sensitivity with low concentration and the small signal noise ratio (SNR) of the trace gases for the instrument, it usually needs longer absorption optical path and complicated data processing algorithm which will surely increase the hardware and software costs of the analysis instrument. In this article, we propose an approach which utilizes the cooling and decompression effects of the high pressure gas when it is injected. With the detecting system hardware and software unchanged, we optimized the detecting system analysis capacity. For the installation of TDLAS detecting system where the sample gas inlet pressure is 0.3~0.5 MPa and exhaust pressure is 219.3 kPa, experimental results show that by using the jet vacuum enhanced method, we improved the signal SNR nearly 24 times, optimized the detection sensitivity almost to an order of magnitude and the precision increased 6.3 times.