探测大气CO₂浓度对气候环境的研究具有重要意义。采用相干探测较非相干探测具有更高的信噪比。目前1．5μm波长由于在人眼安全、系统设计简单廉价等方面存在一定优势，使1．5 μm可能成为未来探测大气分子或气溶胶激光雷达的主流波长。阐述了激光雷达相干探测大气CO₂的原理，设计了1．5 μm相干探测激光雷达系统，并对系统的信噪比进行了估算，得出结论：1．5 μm相干探测CO₂是可行的，经过3 min的脉冲积累，在3 km处仍具有高于10的信噪比值。该激光雷达相干探测系统也可用于大气风场探测。

Detection of the concentration of CO₂ is much significant to research on climate and environment. Coherent detection has the advantage of bigger SNR(signal-to-noise ratio)than incoherent detection. Now 1.5 μm laser has better performance in eye safety and low cost system design etc.,so 1.5 μm is the popular wavelength for the future molecule and aerosol lidar. The principle of detecting CO₂ with coherent lidar is described and the coherent lidar system with 1.5 μm is designed,whose SNR is also estimated. Some conclusions can be drawn that coherent detection of concentration of CO₂ with 1.5 μm is feasible and the SNR at 6 km distance is bigger than 10 after 3 minutes pulse accumulation. This coherent lidar system can also be applied to measure wind fields of atmosphere.