Design Of Free-form Lens Based On 'Secondary Light Source Segmentation' And Illumination Feedback

In recent years,with the increasingly serious energy problem,people's awareness of environmental protection is constantly increasing.Affected by this situation,the whole world is looking for alternative energy sources.In the field of lighting,LED has become the best alternative to traditional light sources due to its power saving,small size,long life and high luminous efficiency.With the popularity of LED light sources,the research of LED light emitting characteristics has begun to develop,the most important of which is the secondary light distribution design for LED.In general light distribution design,the LED light source is often simplified into a point light source.But in practice,the LED light source has a certain size.If such a method is used,the design tends to be biased.Therefore,we explored the secondary light distribution design metheds of LED used non-imaging optics theory in this paper.1.In this work,we proposed an analysis method for the optical design o f extended light source,which named ‘secondary light source segmentation method'.And the TIR collimating lens for extended light source was designed by this method.The conventional TIR collimating lens which designed by idealizing the light source as a point source has poor light spot uniformity at a distance of one meter away from the light source,and the energy is mainly concentrated in the area of plus or minus 9.5°,especially the slightly worse collimation effecy.Compared with the conventional TIR collimating lens at the same structure,the light spot of the lens presents approximate square shape at a distance of one meter away from the light source.In addition,the energy is mainly concentrated in the area of plus or minus 6.5°,which means it has the better collimation effect and also the better illumination uniformity.Finally,we obtained the high utilization rate of light energy that reaches 84.9%.2.A illuminance-based feedback design method is proposed to design the free-form surface.The design principle and implementation method are expounded in detail.For the optical system with clear aperture requirements,the width of the outgoing light cone on the light exit surface of the optical system can be controlled by using this method combined with the "secondary light source segmentation method".And the high light energy utilization rate can be obtained with these two metheds.3.Combining the above two methods,we designed the collimating lens group used in the projector optical engine.Based on the requirements of the system structure,the maximum utilization of light energy can be realized when the light exiting width of the collimating lens group is about 6.3° through the calculation on the optical etendue conservation theory.By establishing and simulating the model of the optomechanical engine system,the rectangular spot with uniform illuminance was obtained on the surface of the DMD chip.The uniformity reached 92%,and t he system light energy utilization rate reached 79%.Through the actual mold processing and light efficiency performance test,the overall efficiency of the projector prototype was as high as 40.2%,meeting the market requirements.