研究了气流环境下碳纤维/环氧树脂复合材料激光烧蚀羽烟对透射率的影响。由射流理论得到光学路径长度关系式，由碳纤维/环氧树脂复合材料的激光烧蚀模拟得到羽烟密度及速度关系式，进而利用Lambert-Beer 定律得到了羽烟透射率的计算模型。利用模型计算了激光辐照过程中的羽烟透射率，并与实验结果进行比较，验证了模型的合理性。进一步计算了外部参数对激光透射率的影响，计算结果表明，激光辐照开始后，热解区域在表面，烟气易于逸出，透射率快速下降到最低值，随后热解区域内移，由于材料渗透率较低，烟气逸出困难，透射率逐渐回升；激光功率密度越大，最小透射率越低，辐照期间的平均透射率越低；气流速度较大时，整个辐照期间的透射率都较高；总功率一定时，光斑半径越大，最小透射率越高，辐照期间的平均透射率越低。

The influence of plume on transmittivity during laser irradiating c-epoxy composites in gas flow is researched. A calculated model for transmittivity of plume is given by using Lambert- Beer theory. In the model, the length of optical paths is calculated by jet theory, density and velocity of plume can be got from the simulation of laser ablating carbon/epoxy composites. The plume transmittivity during laser irradiating is computed by the model. The result is compared with the experiment, and it is confirmed that the model is reasonable. The influence of extrinsic parameters on laser transmittivity is calculated. The results indicate that when laser irradiation begins, thermal decomposition zone is on the material surface and it is easy for plume escaping from the zone, and transmittivity decreases to minimum value quickly. Then thermal decomposition zone moves to the interior and it is difficult for plume escaping from the zone because of low permeability, and transmittivity increases slowly. Higher laser intense decreases the minimum transmittivity and average transmittivity of the whole irradiation time; higher flow velocity can increase the transmittivity of the whole irradiation time; when total laser power is constant, bigger spot size can increase the minimum transmittivity and decrease average transmittivity of the whole irradiation time.