CO作为大气中重要的污染物和煤矿、油田等环境的危险气体，CO浓度的实时监测对生产生活安全具有重要意义。筛选出CO位于2334 nm附近的R(6)吸收谱线，搭建了基于可调谐半导体激光吸收光谱技术的长光程开放光路大气CO 监测系统。采用直接吸收技术，吸收光程为700 m，借助离轴抛物面镜实现了收发同光路；低功耗、小型化的测量控制系统，在单块电路板上实现了激光器驱动、光谱信号处理等功能，单板体积为120 mm×100 mm×25 mm，功耗小于5 W。上位机对光谱数据进行多峰拟合处理，分离出CO和CH4的吸收光谱，反演CO浓度。通过分析光谱数据标准差可知，在1 s响应时间下的检测限为0.06×10-6。对大气中的CO浓度进行了连续监测，测量结果和CO点式分析仪结果一致性良好，验证了该系统仪器化的可行性。

As a kind of important pollutant in atmosphere and hazard gas in coal mine or oil field, CO has to be monitored in real-time for the safety of daily life and industrial production. The R(6) absorption line of CO near 2334 nm, without interference of H2O absorption, is screened for a tunable diode laser absorption spectroscopy (TDLAS) system, which is used to monitor the atmospheric CO by long optical path with direct absorption techniques. With the help of off-axis parabolic mirror, an optical path of 700 m is achieved by sending and receiving light on the same path. A miniaturized measuring control system of 120 mm × 100 mm × 25 mm with power consumption lower than 5 W integrating laser driver, spectral data acquisition and processing on a single board is developed. The CO and CH4 spectra are separated on host computer by means of nonlinear fitting. By analyzing the standard deviation of spectral data, it can be derived that the system has detection precision of 10-6 at 1 s respond time. A continuous atmospheric CO monitoring experiment is carried out and the results coincide well with the CO analyzer results, which proves feasibility of the instrumentation of this system.