LED道路照明中实现任意照度分布的自由曲面光学设计

Freeform Lens Design with Arbitrary Illuminance Distribution in LED Road Lighting

摘要:

提出了一种新型的LED道路照明中实现任意照度分布的自由光学曲面设计方法。旨在实现单盏路灯在路面长度和宽度方向上的照度分布均呈特定分布，以满足道路照明对路面照度、亮度均匀性以及环境比的要求。采用分离变量与最小能量块迭代结合的方法对光源以及接收面进行网格划分，保证光源和接收面的对应单元内具有相同的能量大小。最后根据边缘光线理论、斯涅耳定律以及误差控制方法构建透镜表面。同时考虑路灯安放位置以及倾斜角的问题，透镜对应路面宽度方向上非对称。以给定路面长度方向照度呈余弦分布、宽度方向照度呈梯形分布为例，采用此种方法设计出聚碳酸酯非连续自由曲面路灯透镜。结果表明，路面长度方向上照度接近余弦分布，误差小于6%，路面总照度均匀度达到0.93，道路环境比达0.55。

Abstract:

A new freeform lens design method is proposed to realize arbitrary illuminance distribution in LED road lighting. The purpose is to achieve specific illuminance distribution in both longitudinal and transverse directions on the road surface for a single luminaire, so as to meet the demands of illuminance and luminance uniformity and surrounding ratio on the road surface. Grid divisions of energy both on the light source and the receiver are taken with the combination of variable separation mapping method and iterative minimum energy block method, so as to make sure the equal energy be received in corresponding cells of the source and the receiver. Freeform lens surface is constructed based on edge ray principle, Snells law and error control. Meanwhile, considering the position and tilt angle of the luminaires, the lens is asymmetric in the transverse direction. Take it for example that the illuminance distribution in longitudinal direction on the road surface is cosine, while in transverse direction trapezoidal, a polycarbonate discontinuous freeform lens was designed according to this method. The simulated illumiance distribution in longitudinal direction on the road surface is similar to cosine, with the error less than 6%. The overall illuminance uniformity reaches 0.93, and the surrounding ratio is 0.55.