基于光谱吸收法的瓦斯实时监测系统的核心器件是开放式光学吸收池,根据矩阵传输理论和q参数的ABCD法则,设计了由2 个相对的C-Lens 组成的光学吸收池结构,并在ZEMAX 的物理光学模式下实现仿真与优化.由理论分析得到结构的初步参数并在ZEMAX 中进行优化,并使用合适的优化操作数对像差进行校正,经过逐步优化得到工作距离为100.39 mm 的吸收池结构参数.高斯光束从一端光纤输出的束腰半经为5.2 ?m,经C-Lens 聚焦和准直后,耦合到另一端光纤的束腰半经为5.48 ?m,该光学吸收池对甲烷近红外激光的耦合效率达到92%.通过实验验证了该光学吸收池的稳定性和高耦合效率,适用于甲烷气体的开放式光学气体传感和在线监测.

The core device of gas absorption spectroscopy real-time monitoring system is open optical absorption cell.According to the transmission matrix theory and ABCD rule of q parameter,optical absorption cell structure composed of two opposing C-Lensis designed,and its simulation and optimization is realized under ZEMAX physical optics model.Preliminary parameters obtained from the theoretical analysis of the structure are optimized in ZEMAX,and the suitable optimization function is used for correcting aberration and to get parameters of absorption cell structure with a working distance of100.39cmafter gradually optimization.Gaussian beam waist radius from one end of the fiber output as 5.2 ?m,after C-Lens focusing and collimating,is coupled to the other end of the fiber output with waistradius of 5.48?m,and the coupling efficiency of optical absorption cell for methane near-infrared laser is up to 92%.Experiments show the stability of the optical absorption cell and a high coupling efficiency,which is suitable for methane gas open optical gas sensing and online monitoring applications.