采用自由曲面透镜作为分束器以生成具有任意能量比的离散光斑阵列。根据能量守恒定律,将入射光束划分为一系列与光斑阵列对应的子区域。对于每个子区域,采用分离变量法计算子区域与相应光斑之间的光线映射关系,并采用最小二乘法构造遵循该映射关系的自由曲面。提供两个设计实例以检验自由曲面分束器的可行性:第一个设计可生成具有相同能量比例的高斯光斑阵列,第二个设计可产生具有预设不均匀能量比例的矩形平顶光斑阵列。仿真结果表明,考虑菲涅耳损耗后,两个设计实例的光输出比均高于89%。

Freeform lenses are used as freeform surface beam splitters to generate discrete spot arrays with arbitrary energy proportions. According to the law of conservation of energy, the incident beam is divided into a series of subregions corresponding to the spot array. For each subarea, variable separation is used to acquire the ray map between the input beam within the subarea and the corresponding spot. Further, a least squares method is used to construct the freeform surface following the ray map. Two design examples are provided to demonstrate the capabilities of freeform beam splitters: one could generate a Gaussian spot array with an equal energy proportion and the other could generate a square top-hat spot array with a predefined non-uniform energy proportion. Both freeform beam splitters exhibit light output ratios of over 89% considering Fresnel losses.