提出一种多向平行分光透镜的自由曲面组合设计方法，可适用于广义朗伯分布的发光二极管（LED）光源，实现任意多向的平行分光。设计了应用于雨量传感器的透镜，在不增加光源的前提下，增加出射的光线路径数量，透镜体积小、光效利用率高，增大了传感器的光学探测区域，可为相关的光电器件的设计与优化提供便利。理论计算和建模仿真进一步证明了此方案的可行性和有效性。

A combination design method of freeform surface of multidirectional parallel beam splitting lens is proposed, which can be applied to the light emitting diode (LED) light source of generalized Lambertian distribution to realize any multidirectional parallel beam splitting. A lens is designed for the rainfall sensor, which can increase the number of outgoing ray paths without adding the light source. The designed lens has such advantages as small volume and high luminous efficiency, which can help to increase the optical detection of the sensor area and provide convenience to the design and optimization of related photoelectricity devices. Theoretical calculation and modeling simulation further verify the feasibility and validity of this plan.