研究了以大功率发光二极管(LED)作为光源的聚合物光纤束(POFB)透镜耦合器的原理和设计方法,基于能量补偿和坐标迭代法设计了一种能量均匀分布自由曲面透镜耦合器。透镜耦合器由两个折射曲面和两个反射曲面以及一个环形柱透镜面组成,折射曲面将修正的朗伯型大功率LED光束中发散角度较小的光线均匀分配在POFB端面上;反射曲面将LED光束中发散角度较大的光线作为补偿光线进行能量重新分配以提高目标面的照度均匀性,并以光纤束端面的照度均匀性和有效光利用率为优化目标对透镜耦合器结构进行优化设计。光学仿真结果表明,当采用3535规格的LED作为光源时,设计的耦合器可使直径为0.5 mm的20×20根POFB端面照度均匀性达到92%,有效光利用率达到71%。

The principle and design method of polymer optical fiber bundle (POFB) lens coupler with high-power light emitting diode (LED) as light source is studied. Based on energy compensation and coordinate iteration method, a free-form lens coupler with uniform energy distribution is designed. The lens coupler consists of two refraction free-form surfaces, two reflection free-form surfaces and a circular cylindrical lens surface. The small divergence angle of the modified Lambertian high-power LED beam is quasi-uniformly distributed on the end face of POFB through refractive free-form surface. The reflection free-form surface reallocates the energy of large divergence angle of LED beam as compensation to improve the target surface illumination uniformity. Lens coupler is designed and optimized for illumination uniformity and effective light utilization of the end face of the fiber bundle. The results of optical simulation show that when the 3535 LED is used as the light source, the designed coupler can make the illumination uniformity of the 20×20 polymer fiber bundle with the diameter of 0.5 mm reach 92% and effective light utilization reach 71%.