Investigation On The LED Lighting Design Based On Freeform Lens

As the fourth generation light source,LED has the characteristics of long life,low power consumption,strong structure and close to point light source.Compared with the traditional light source,LED light source is the real green lighting.Therefore,it is widely used in various lighting fields.However,different lighting areas have different lighting requirements,and different lighting design of LED light source is required according to the requirements.The freeform lens design based on nonimaging optics has high degree of freedom,and can effectively control the beam and complete the lighting requirements.It has a broad application prospect in the field of LED lighting design.The existing methods to design freeform lens was summarized in this paper,then the corresponding design is carried out on this basis.With the nonimaging optics as the theoretical basis,the mathematical expression of freeform lens is deduced.Based on the law of energy conservation and lighting requirements,the initial and the topological relation of energy were given.The data of freeform surface is calculated by MATLAB software.The 3D model of this surface is build by SolidWorks software.Simulation analysis is carried out by LightTools software of optical design.The simulation results show that the design method of the freeform surface can achieve the uniform light spot of circular and annular,and reach the preset lighting requirements.However,the light spot of rectangular does not have clear outline and uniform light distribution.There is a certain gap with the preset result.There are two reasons: one is that there are algorithm errors in the numerical solution,the other is that the 3D modeling software also has some errors in the process of solid modeling.The latter is the main reason.A new method for design of freeform surface with uniform illumination based on new LED collimation system was proposed in this paper.The collimator is rotationally symmetric around a central axis.The light collecting angle of the collimating system is about 236° and its illumination half-angle is less than 0.2°.The freeform surface is designed on the exit plane of the collimating system in order to achieve the goal of different lighting.Similarly,with the nonimaging optics as the theoretical basis,the mathematical expression of freeform lens is deduced.It is simpler than the above method.Based on the law of energy conservation,the ‘many-to-one' topological relation of energy between the exit plane of the collimating system and target surface are presented in detail.It is more detailed than the above method.Similarly,the freeform surface is obtained by programming equations and 3D modeling.It is better continuity and less error than the above method.Then combine the collimation system with freeform surface.Simulation analysis is carried out by LightTools software of optical design.The simulation results show that the design method of the freeform surface can achieve uniform light spot of circular,annular and rectangle,and meet the design requirements.