Design method of diffuse transmission free-form surface combined with collimation lens array

Lighting-emitting diodes are widely applied in lighting systems, and diffusers are commonly used in systems for indirect illumination. In this paper, a design method of diffuse transmission free-form surface combined with collimation lens array is proposed. Based on the Lambertian characteristics of lighting-emitting diodes and the principle of collimation lenses, a mathematical model of diffuser with ideal diffuse transmission free-form surface is established. We propose a method of the preset collimation surface to connect the free-form surface and the collimation lens array, and derive the nonlinear algebraic equation of the diffuse transmission free-form surface according to the connection effect of the preset collimation surface. Then, solving the equation numerically by MATLAB, the profile of the diffuse transmission free-form surface is obtained. Finally, the non-sequential ray tracing software TracePro is used to simulate the irradiance distribution of the target plane. The results show better uniformity and higher efficiency comparing with the lighting system using diffuse transmission free-form surface alone and the traditional diffuse transmission lighting system.