Research On Second Optical Design Of LED Light Source Based On Free Form Surface

LED light source as the fourth generation of green light source, compared with the traditional light source with high luminous efficiency, low power consumption, long life, small size, environmental protection and other advantages, has been widely used in various fields.However, due to the divergence of the LED light source is too large and uneven distribution of light energy, it can not be directly applied to lighting and other aspects, the need for second optical design, re-distribution of light energy to meet the actual needs. The application of non-imaging optics, edge-light principle and free form theory, the second optical design of the LED light source,such as collimation and smoothing, based on DLP technology projection, is studied.In this paper, the collimation and smoothing of LED light source are studied, and the collimation effect of compound parabolic concentrator (CPC) is analyzed, results show that the optical angle is 9 degrees, the minimum divergence angle, half-angle of divergence is 2.823 degrees. Because of the shortcomings of CPC, such as the length and diameter are relatively large, and the structure is not compact, a new method based on free form design is proposed.Through the application of parallel relationship between light vector, establishing mathematical model of freeform lens collimation, calculating the coordinates of discrete points by iterative method using Matlab programming, 3D models of free-form surface lens is established in Solidworks. Optical simulation using Tracepro software, respectively researched 0.01mm,0.1mm, 0.5mm, 1mm square chip out of the light. The results show that the collimation of the 0.01mm chip is better, the minimum angle of divergence is 1.502 degrees, the light energy utilization rate of 90.67%.The uniformity of illumination after light collimation is researched, by using the compound eye lens with TIR lens above design, composed of optical system collimation and uniform light, mainly on the near field (100mm) and the far field (lm) when the illumination uniformity. The results show the illumination uniformity of the spot area is above 90%.In order to be able to uniform the light source, this paper presents a method of uniform design based on free surface, which is consistent with the modeling method of collimation.Through simulation analysis, when the beam angle is 60 degrees, the best illumination uniformity, uniformity is 96.97%, the light spot size is a circular range of r=1.732m. At 120 degrees, the highest utilization rate of light energy is 85.79%, the illumination uniformity is 94.39%, and the light spot size is r=5.196m.Finally, the LED light source array is studied, mainly for the LED light source linear array and planar array. By using Laws of spyro, the maximum flatness condition is obtained under various conditions, and the light uniformity is obtained by optical simulation.