Research On Circular And Square Uniform Illumination Optical System Based On White LED

At present,most industries rely on electric energy,and the lighting industry consumes most of the electric energy.In order to achieve energy conservation,environmental protection and sustainable development,it is necessary to further improve the energy efficiency of lighting and achieve green,energy-saving and high-efficiency lighting.As a new generation of green light source,LED lightemitting diode has the advantages of high luminous efficiency,low energy consumption and long service life,and is gradually applied to various lighting fields.However,since the LED light intensity exhibits a Lambertian distribution,the divergence angle is large and cannot be directly applied to a specific illumination field.Therefore,in order to meet the lighting requirements of LED light source in different occasions,it is necessary to carry out secondary optical design on the basis of the primary optical design of the LED,so as to improve the uniformity,divergence angle and utilization rate of light energy of the LED light source.This paper is devoted to the research of illumination optical system design method with high uniformity and small divergence angle.It aims to establish a lensbased secondary optical design theory and provide solutions for obtaining illumination optical systems with high uniformity and small divergence angle.In view of the problem that the divergence angle of the LED light source is too large and the uniformity is too low,two sets of uniform illumination optical system devices are designed in this paper,and finally the expected target is achieved,and a uniform spot with uniformity and divergence angle satisfying the specific application scene is obtained.This paper first proposes a design method based on near-focus aspheric lens optical illumination system.When designing a uniform illumination system,first calculate the surface parameters of the aspherical lens based on the conservation of geometric optics and optical expansion.The initial structure and evaluation function of the aspherical lens are then defined in ZEMAX in conjunction with the overall performance requirements for the illumination optics.Then,multiple rounds of optimization were performed to obtain an aspherical lens with a focal length of 76.79 mm and a diameter of 200 mm.Subsequently,the optimized aspheric lens is imported into Trace Pro for modeling and ray tracing simulation experiments,and the physical parameters are processed according to the optimal parameters obtained by the simulation results.Finally,the obtained example optical system was subjected to photometric measurement and result analysis.The experimental results show that the uniform illumination system proposed in this paper can achieve uniform illumination of divergence angle0±8.53° at 60 cm,and the spot uniformity reaches 95.82%.In view of the mutual limitation of high-order coefficients of aspherical lenses,based on the aspherical lens optical system,a uniform illumination optical system based on free-form lens is proposed.Optical system design using freeform lenses and compound parabolic mirrors.When designing the optical system,the initial structure of the free-form lens is determined according to the non-imaging optical principle and the overall performance requirements of the optical system,and then the evaluation function is constructed for optimization.Next,the optimized free-form lens is imported into Trace Pro,and the compound parabolic mirror is optimized according to the free-form lens.After several rounds of optimization,the optimal optical system model is finally obtained,and then physical processing is performed according to the model parameters.In this paper,different shapes of LED chips are used to test the uniform illumination optical system device,and square and circular uniform spots are obtained respectively.The uniformity of the spot obtained by the optical system will decrease slightly with the increase of the distance,but the divergence angle of the outgoing beam is stable.At a distance of 80 cm from the free-form surface,the uniformity of the spot is better than 97%,and the release angle is about0±2.86°.