Design Of Illuminating Optic For Projection Based On Non-imaging Optics

Due to green energy saving promption,Led light sources with great advantages gradually replace traditional light sources and find applications in various illumination systems.Because of light emitting characteristics,design of the Led light irradiance is needed to meet the specific application requirements.Usually freeform optical elements are designed to meet the requirements of illumination and display based on non-imaging optics theory.Non-imaging optics theory is essential for Led illumination design and the research on Led illumination design also promotes the rapid development of non-imaging optics.Researchers have proposed various methods for the design of Led freeform surface optical elements,such as numerical optimization method,tailoring method,partial differential equation method,mesh division method and simultaneous multiple surface method etc.Optical projection is an important application field of Led illumination,and has great potential for further development.High brightness and miniaturization is the trend of modem projection system.Illumination system plays an important role in the optical projection system.Considering the characteristics of Led light sources,designs of the traditional square rod and compound eye illumination system is investigated to obtain the effects of uniform irradiance and rectangular shaping.However,there are many components in these two systems and the optical total length is too large to meet the needs of the development of projection system.In this paper,a freeform optical element is designed to obtain the uniform illumination by using the mesh division method.A rectangular spot of 60mmx80mm is formed on the target plane of 50mm far from the lens and the illumination uniformity reaches 85%.In this paper the non-imaging method is used to design the freeform optical element to form the spot pattern with rotationally-symmetry.Firstly,freeform optical elements are designed to generate annular spot for Led collimation light source and point light source,respectively.Then,the relationship between the off-axis amount of light source and the distance of spot deviation is studied.Finally,the Olympic five-ring pattern is generated in the form of lens array.The TracePro simulation shows that an Olympic five-ring pattern with the size of 1400mm x 600mm is formed on the target plane of 2000mm far from the optical element.The optical efficiency is 79.1%and 85.7%,and the uniformity is 75%and 80%,respectively.A freeform optical element has been designed and fabricated using 3D printing method for LED point source.The freeform optical element has been evaluated and experimental results with five-ring Olympic logo patterns have been obtained,which shows that the experimental results are consistent with the theoretical design.