基于三次样条的双自由曲面LED匀光透镜设计

Design of Double Freeform Surface Lens for LED Uniform Illumination Based on Cubic Splines

对发光二极管(LED)光源进行均匀照明配光时,内曲面为半球面等特定面型的透镜无法满足对照明均匀度的要求,同时光源适用性也不广泛,提出了一种可按需要建立并修改内曲面的双自由曲面透镜设计。通过分析LED光源数据,设置拟合点,构建三次样条曲线作为透镜内曲面母线,再运用传统的边缘光线理论、光通量网格划分及Snell定律等计算外自由曲面母线,旋转母线得到透镜模型,最后对透镜进行优化,提高照明均匀度。将透镜模型在Trace Pro中进行模拟,结果表明在距高比为4时,基于单个朗伯光源及非类朗伯光源下设计出的透镜实现的照明均匀度分别为90%和85%,光能利用率分别约为86%和80%。说明此设计适用于不同光源,还可用在近场均匀照明等方面。

For realizing uniform illumination of different laser emitting diodes （LEDs） with different fight intensity distributions, the hemisphere inner surface lens and other formed inner surface lens cannot play the total role of uniform illumination optimizer and are not suitable for all kinds of LEDs, so a design of double free-form surface lens with modifiable inner surface is put forward. By analyzing the LED light source, the inner surface can be decided from the interpolated points, and it is based on a cubic interpolation of the values at neighboring grid points. The outer surface is deduced on the edge-ray theory, energy mapping method and Shell＇s law and so on. The lens is optimized to improve uniformity of illumination, and the model is simulated in TracePro. The results show that at a distance- height ratio equals 4, the values of illumination uniformity under the condition of Lambertian source and non- Lambertian source are 90% and 85%, respectively; the values of efficiency are about 86% and 80%. That is to say, the design can be applied to different kinds of sources, and is suitable for near-field uniform illumination lens.