Study On Optical Design Methods For High Power LED Extended Sources

The use of solid-state lighting sources, especially light-emitting diode (LED) as a light source for lighting system design not only can greatly save energy, reduce environmental pollution, but also reduce the light volume, extended system life. However, due to the difference of structural and optical properties between LED and traditional light sources, existing lighting design based on optical imaging methods can not be directly applied to LED. Large flexible space layout and design freedom of freeform surface simplify the structure of the optical system especially in the illumination optical design, optical freeform surface can control LED light intensity and control the angle of light emitted at the same time point, it is very suitable for LED-based lighting system design, The current widely used method of free surface design method is differential structure, this method is widely used in the field of secondary lens of LED light source and more satisfactory results can be obtained by this method. But it does not apply to secondary optical design for LED packaging and LED integrated light source lens. Therefore, the research on the optical design method for LED extended sources not only has theoretical value but also actual meaning. The main subject of innovation of our study is the use of non-imaging optical edged-ray theory and the feedback correction algorithm theory method to construct optical free-form surface for high-power LED extended sources to achieve high energy efficiency and uniform illumination optical system.Design problems of lens axis of rotation symmetry:As we know the size of LED extended source, and its radiation spectrum, based on the conditions of conservation of the brightness of the LED light source, equation can be build between the light illumination and brightness target plane by edged-ray theory, determine the initial curve of the free surface and Numerical iteration to get data of the cut line, then rotationally symmetric optical model can be established by 3D modeling software.Road lighting Lens design problem of LED extended source:As we know the size of LED extended source, and its radiation spectrum, the point data of the free-form surface can be achieved based on the edged-ray theory and grid method,then the light source is replaced by extended light source in the optical simulation and the difference between expected Illumination and simulation illumination is compared, optimization coefficients are calculated and bring it into point source model calculation and the ideal optical model can be obtained by multiple amendments.The subject then use the above design theory to design rotation axis symmetric optical system road lighting system, the design models are ssimulated by Optical simulation software, the optical design methods are proved to be right and effective.