基于三基色发光二极管(light emitting diode, LED)与方棒的投影照明系统具有色域宽、体积小的优点, 但三基色LED和方棒配合使用时, 存在投影亮度不高的问题。首先基于光学扩展量匹配原则选择了LED光源, 然后设计了一组自由曲面的准直透镜和收集透镜。仿真结果表明: 准直透镜出射光线集中在±7.5°内, 方棒出射端±30°内的能量利用率为51.7%。实际加工并测试了设计的自由曲面准直透镜和收集透镜。测试结果表明: 采用本文设计的没有镀减反增透膜的透镜组, 投影机出射亮度比原使用镀了增透减反膜的透镜的系统高1.6%。预计设计的透镜镀减反增透膜后投影机出射亮度有望提升9.8%。

The illumination system with 3-primary-color light emitting diodes (LEDs) and light rod has the advantages of wide color gamut and small volume. However, there is a problem of low brightness when combining the 3-primary-color LEDs with the light rod. Firstly, the LED light source was selected based on the etendue theory, and then a set of free-form collimating lenses and collecting lenses were designed. The simulation results show that the light emitted by the collimator lens is concentrated within ±7.5°, and the energy utilization rate within the ±30°at the exit of the light rod is about 51.7%. Moreover,the designed lenses were manufactured and tested. The practical results show that the projection illuminance of the designed lenses set without the anti-reflection film can be improved by 1.6% than the original system with the anti-reflection film. It is expected that a 9.8% improvement of the projection illuminance can be achieved after the designed lenses are coated with the anti-reflection film.