二氧化碳作为大气中重要的温室气体, 与气候变化和人类活动密切相关, 因此对其浓度的探测具有重要意义。 利用近红外可调谐二极管激光器结合自主设计的便携式小型化柱面镜光学多通吸收池, 实现了二氧化碳气体的高灵敏探测。 通过Matlab编写光线传输矩阵, 优化设计了基于柱面镜的光学多通吸收池, 相比于传统Herriott型多通池, 具有腔镜利用面积高、 在相同体积内可实现有效光程长等特点, 在物理基长为15 cm的情况下, 实现了14 m的有效光程。 实验中使用中心波长为1.57 μm的DFB二极管激光器, 采用直接吸收光谱方法对CO2气体进行了探测研究, 并用Allan方差对系统性能进行了分析。 结果表明, 在平均时间为5 s时, 系统的探测灵敏度为33.1 μL·L-1, 平均时间为235 s时, 系统的探测灵敏度可达到5.3 μL·L-1。 此外, 利用该系统实现了大气中CO2的探测, 得到大气中的CO2浓度为383.4 μL·L-1。 基于柱面镜多通池搭建的可调谐激光吸收光谱(TDLAS)系统, 结合了柱面镜多通池可在小体积内实现长光程和可调谐激光吸收光谱技术高灵敏度、 高分辨率、 快速响应的优点, 大大减小了系统体积, 提高了系统探测灵敏度, 在气体探测领域有广泛的应用。

Carbon dioxide is one of the most important greenhouse gases playing an important role in climate change and human activities, so the detection of carbon dioxide concentration has an important significance. Highly sensitive detection of carbon dioxide gas was achieved by using near infrared tunable diode laser absorption spectroscopy combined with self-designed portable miniaturized cylindrical mirror multi-pass absorption cell. The cylindrical mirrors multi-pass absorption cell was optimized and designed by using a light transmission matrix programmed with Matlab software, compared with traditional Herriott multipass cell, which has the advantages of high mirror utilization and longer optical path length in the same volume. An effective optical path length of 14 m was achieved with 15 cm physical length. In present work, a DFB diode laser emission at 1.57 μm was used as a light source. Direct absorption spectroscopy method was used to detect the CO2, and the Allan variance was used to analyze the system performance. The results showed that the detection sensitivity of the system can be achieved 5.3 μL·L-1 with the average time of 5 s, and a detection sensitivity of 33.1 μL·L-1 can be achieved by averaging in 235 s. In addition, CO2 in the atmosphere was measured by the developed CO2 sensor, the measured results showed that the concentration of CO2 in the atmosphere is about 383.4 μL·L-1. The tunable diode laser absorption spectroscopy (TDLAS) system based on cylindrical mirrors multi-pass absorption cell, combined with the cylindrical mirrors multi-pass cell can achieve long optical path in a small volume and tunable diode laser absorption spectroscopy technology has the advantages of high sensitivity, high resolution and fast response, greatly reduces volume and improves detection sensitivity of the system, which has a broad application in the field of gas detection.