The Secondary Optical Design Of Led Mini Projector Lamps

Optical design for LED source is the core technology of DLP optical engine and micro-projector. Light collection efficiency and etendue are the radical measures in improving the system’s lumen efficiency, and also the key problems in LED design. In this thesis, the theories and principles of optical design are discussed. The qualification is generalized into several aspects as collection efficiency, etendue, beam angle and uniformity. Moreover, based on mass of calculation as well as demonstration, the technique and process of optical design is introduced. Relevant soft wares are used in modeling and simulation, producing many research conclusions.Three schemes of LED based projection source are introduced. The first is CPC mode, which simplified the light path structure, obtained narrow beam collection angle, tiny etendue and uniform light spot. Then aspheric lens mode is discussed, which improved distribution uniformity and illumination efficiency. Also, TIR lens with multiple curved surfaces is introduced to reduce both the focusing length of LED source and the size of optical engine. In general, those three modes basically fulfill the design objectives.Besides, an illumination system based on LD and gradient-index lens array for micro-projector is innovatively discussed. By using theoretical calculation and simulation, the feasibility in collecting, uniforming, collimating and shaping for input laser beam is demonstrated. Then the far discussion in configuration is advanced.Moreover, a practical micro-projector engine is disassembled and tested to contract the above design schemes. The optical parameters in test results showed the advantages and disadvantages in our design work. At the end of the article, the work is summarized and the suggestions on future research are revealed.