Design Of LED Lighting System Based On Freeform Surface

As a new type of green light source in twenty-first Century,LED has a wide range of applications in lamp,interior lighting and plant tissue culture because of its advantages of low power consumption,high efficiency,high brightness.However,the LED light source has a large luminous angle and can not be directly used for lighting.Therefore,it is necessary to design suitable optical systems in combination with actual lighting occasions.The LED's Lambert luminescence properties provide the theoretical basis for lighting optical design.In lighting optical design,the free surface method because of its more flexible spatial structure and higher degree of freedom of design,which has been widely studied and applied.Therefore,it is both of theoretical and practical value to study the design method and application scene of free-form surface.This paper focuses on the free-form surface geometry method and partial differential equation method,combined with the application scenarios of collimated illumination and uniform illumination,the corresponding mathematical formulas were derived respectivel,using Matlab to calculate the discrete points of the freeform surface,using Solidworks to construct the corresponding physical model,and finally to verify the feasibility of the model through the optical software Lighttools.The specific contents are as follows:1?In uniform illumination,according to Snell's law,the geometrical mapping relationship between the incident light,freeform surface and the target surface is established,and the energy mapping relationship is obtained by using the law of conservation of energy.A set of partial differential equations is deduced and used to reduce the calculation difficulty.Numerical solution to solving partial differential equations.In collimating lighting,the free-form surface designed by geometry can make all the light parallel to the light axis.Define the incident angle,calculate the cut angle and slope of the point on the freeform surface according to the geometric principle of light,after iterative operation,you can find all the coordinates of the free surface;2?A reflector,which can be used in classrooms,offices,etc.,is designed.The reflector reflects light with a divergence angle of 120° to the ground at 3.5 meters and forms a rectangular uniform light spot of 3 meters in width.By LightTools software simulation:the uniformity can reach 87%,the energy utilization rate is 84%.Designed rectangular uniform illumination lens for plant tissue culture lighting.According to the arrangement of 2 ? 12,rectangular uniform illumination can be achieved in the 1200 mm ? 500 mm region of 300 mm.By LightTools software simulation: the uniformity can reach 86.3%,the energy utilization rate reaches 81%.3?Design a new type of LED collimating lens that can collimate LED light with a light emitting angle of 180°.The total reflection surface of the lens is changed from a rotating paraboloid to a rotating conical surface,so that the number of lens surfaces is reduced from 3 to 2,which can reduce certain difficulties in processing.By the simulation of the LightTools: 1.4 m ? 1.4 m on the target plane can receive 90.56% of the energy emitting angle of about 3 ° in the 1500 mm distance;when the light source size is not more than 1.4 mm,the utilization rate of light energy reaches 50%,the illumination distance exceeds 7 m.