The Study Of Optical Design For Limited Shape Lighting

With the rapid development of the COB packaging integration technology, high power COB-LED are widely used in commercial lighting, such as street light, automobile headlamps, searchlight and so on. COB-LED have advantages of high brightness, low light failure and high photosynthetic efficiency. To improve the actual efficiency and reduce light-pollution, it is important to design optical systems to reach limited light shapes with high uniform and high efficiency. This topic will study for reflective and transmissive type optical system.For realizing uniform illumination with large surface LED by compact double surface lens, we propose a method that lens can be calculated directly based on the finite element theory and edge light theory. According to the theory of edge light, internal surface adopt spherical, which make angle of surface source edge light shrinkage. According to illumination distribution, the Mathematical model of the lens can be directly computed based on the theory of differential geometry, Snell’s law and finite element method. Meanwhile, using optical software to analysis lens, and we can find that uniformity and efficiency are all above 91.00% when lens compactness is between 1:1.25 and 1:2.5.For unsymmetrical illumination with reflector optical system, two kinds of surface types are proposed. One is a parabola type, source are inputted under reflector. In TracePro secondary development environment, we can use macro language to optimize. We can obtain a compound parabolic reflector to realized square uniform illumination distribution. We can obtain a reflector to meet near field illumination by optimization. Then we fit curve of near field illumination. Using the fitting function optimization and calculating best configuration interval value to design plate lamp, and uniformity and efficiency above 90.50% and 95.00%. For free-form surface, we propose a free-form reflector design method. The surface source is located at the top of the reflector, whose luminous surface back faces the target plane. Surface source is divided to micro surfaces by finite element method, so that it can be treated as point sources. According to rectangular illumination distribution, the energy relationship between surface source and target plane is established. Meanwhile, the mathematical model of the reflector can be directly computed, Numerical solution of free-form reflector can be calculated by Matlab software without feedback optimizing. Finally, for the petals lighting reflector optical system. Establishing the energy relationship between surface source and target plane according to characteristics of petal shaped light distribution. Petals lighting reflector can be designed by above design method of free reflector surface. Because petal leaves have sizes, we can change them by importing contract parameters. We can achieve the relationship between illumination distribution and source according to any lighting shape. So, we can achieve any limited shape lighting.This methods are universal usability.