| Benefit from the rapid development of high-power LED light source and micro-display chip industries, micro-projection step into people's lives. Micro-projection optical engines can be divided into two categories—"embedded" and "stand-alone". Embedded optical engine can be embedded into mobile phones, laptops, PSP, digital cameras and other electronic devices. Stand-alone optical engine can be used independently. Its volume is smaller than traditional projector and more professional than the embedded one.Projection optical system consists of two parts:illumination and imaging. The rays emitted from the light source are redistributed by the illumination system and form a prescribed illuminance distribution on the micro-display chip. The properties of illumination system (energy efficiency, uniformity of illumination, etc) play a key role in the performance of optical engine.An illumination system which consists of two aspheric PC lenses is designed based on etendue which is an important concept of non-image optics and front part of Kohler illumination. Simulation results of TracePro show that an energy efficiency of 64.2% is achieved under an ANSI uniformity of 94% for 1mm×1mm LED. In addition, corresponding four pieces projection lens is designed in Code_Ⅴ. Above work completely design the CF-LCoS projection optical engine which has advantages of simple structure, good uniformity, high energy efficiency and so on.Stray light exists in a variety of optical systems. For the purpose of suppressing stray light, the opto-mechanical model of CF-LCoS optical engine has been established in TracePro. Stray light is analyzed using Monte-Carlo method. By simulation and experiments, it can be found that the edges of PBS prism and imaging lenses, the inner surfaces of cone and spacer are the key positions which will generate stray light. In order to suppress the stray light, not only baffles are used, but key surfaces are also blackened. Furthermore, extinction paint is smeared on the edges of the imaging lenses and inner surfaces of the spacer. Simulation and experimental results both prove that above methods can suppress the stray light greatly and effectively. Reduction of stray light removes the industrial barrier of high-quality optical engine.When using high-power LED as light source, a good thermal design has become the key factor to ensure its optical performance in normal play. In this master's paper, numerical simulation and experiments are performed to study the thermal characteristics of 1W and 20W high-power LEDs respectively. At first, an active cooling thermal module is designed for mobile phones embedded optical engine. The thermal module includes heat sink and thermal slices. The thermal slices transfer heat to the mobile phone outer cover and reduce the heat gathered around the optical engine. Then two fan cooling thermal modules are designed for stand-alone optical engine, including heat pipe solution and aluminum heat sink solution. Heat pipe solution is compact and the final actual result is desirable, but with high cost. Aluminum heat sink solution is bulky, its effect is a bit weak relative to heat pipe solution, but much cheaper. In addition, a summary of commonly used LED junction temperature test methods is given. Forward voltage method is more accurate and thermal resistance method is easy to operate. These thermal designs ensure the stable operation of optical engine.Finally, we build a micro-projection optical engine test equipment which can measure the flux, uniformity, contrast and other related items. The factory standard of optical engine has been established based on those testing methods. |
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