使用量子级联激光器和多通吸收光谱技术用于CO探测

根据一氧化碳(CO)气体分子在4.7 μm处的基频吸收特性，使用中心波长为4.75 μm的量子级联激光器(QCL)和多反射气体吸收气室(MGC)设计了一种新型CO传感器。该仪器使用可在室温脉冲方式下工作并具有热电制冷功能的QCL，通过对其温度和注入电流进行调节，最终使得出射光波长定位在CO基频吸收带的一根强吸收线(2 103 cm-1)。与此同时，使用有效光程为16米的新型MGC(40 cm长，800 ml采样容积)和液氮冷却碲镉汞中红外探测器，有效提高了系统的响应灵敏度。此外，系统中配合使用了参考气室和空间滤波光学结构，有效地改善了入射光束的质量，降低了由光源的不稳定而产生的噪声，进一步提高了系统的检测灵敏度。在实验室条件下对不同浓度的CO气体进行多次重复检测，结果显示，该仪器工作稳定，按信噪比为1计算，可实现对一氧化碳气体的检测下限为5 μmol·mol-1。

Multi-Pass Absorption Spectroscopy for CO Detection Using a Quantum Cascaded Laser

According to the fundamental absorption properties of Carbon Monoxide(CO)near 4.7μm,a novel CO sensor was designed using a Quantum Cascaded Laser (QCL)whose central wavelength is 4.75μm and Multi-pass Gas Cell (MGC).This sensor uses a QCL with the thermoelectrically cooled function and can work under pulse mode and room temperature,the exiting optical wavelength was located in a strong absorption line (2 103 cm-1 )which is in the base band of CO through adjusting the in-jection current and temperature.Meanwhile,a novel MGC (40 cm long and 800 mL sampling volume)with 16 meters effective optical path length and mercury cadmium telluride mid-infrared detectors was used,thus effectively improved the sensitivity of this system.Additionally,a reference gas cell and a spatial filtering optical structure were occupied,resulting in effective im-provement of the beam quality and reduction of the noise caused by the instability of QCL,the sensitivity of this system was im-proved furtherly.It indicated that the system works stably by means of multiple measurements to the carbon monoxide gas with different concentration,a detection limit of 5μmol·mol-1 can be obtained when the signal-to-noise ratio equals 1 .