用轨迹追踪法计算了平行和锥形毛细管内壁上的光强分布。发现管壁上的光强随距离阶跃式地快速衰减。相同聚焦透镜下，细管的光强衰减比粗管快；大锥角比小锥角衰减快。随着聚焦透镜的Ｆ数的增加，光强衰减变慢，平均光强增加 The trajectory tracking method was used to calculate the light intensity distribution on the inner walls of parallel and tapered capillary tubes. It is found that the light intensity on the tube wall attenuates rapidly with the step-by-step distance. Under the same focusing lens, the light intensity attenuation of the thin tube is faster than that of the thick tube; the large cone angle decays faster than the small cone angle. As the F-number of the focusing lens increases, the light intensity decays slowly and the average light intensity increases