Study On Optical Design For High-power LED Lighting

LEDs (Light Emitting Diodes) are solid-state semiconductor light sources, which areconsidered as the fourth lighting revolution after Incandescent Lamps, Fluorescent Lamps andHigh Intensity Discharge Lamps. Compared with traditional light sources, LEDs have manyadvantages such as high luminous efficiency, low energy consumption, small size,eco-friendly lighting choice, and long life, etc. Therefore they are gradually replacingtraditional light sources, more and more widely applied in all lighting fields. However,because of their own structural features, luminescent properties and so on, LEDs cannot bedirectly used for lighting. In order to meet the lighting requirements, appropriate opticaldesigns should be done to improve their luminous energy distribution. This paper is to explorethe optical design of high-power LED light sources based on the theories of nonimagingoptics and free-form surfaces.Firstly, free-form surfaces are designed for LED point light sources in this paper. A stepcalculation method without solving differential equation is utilized to design the algorithm byestablishing the energy-corresponding relationship between the light source and the targetplane. Besides, free-form lenses and reflectors which can achieve uniform distribution of theillumination on the target plane are designed, together with a design method of small-angleuniform lighting systems raised in Part4.Secondly, free-form surfaces are designed for LED extended light sources in this paper.According to the edge-ray principle of nonimaging optics, the redistribution of luminousenergy can be achieved by controlling the edge rays of the light source. This principal solvesthe design difficulties when the light source and the light distribution device are close in size.Free-form lenses which can achieve uniform distribution of illumination and luminousintensity are designed, together with a design method of reflectors for LED extended lightsources raised in Part5.Finally, simulations for all the optical models designed above are performed, using theoptical simulation software named TracePro. For LED point light sources, lenses have96.011%of utilization ratio of luminous energy and at least95%of uniformity, and thefigures for reflectors are97.554%and95%, while for small-angle lighting systems,85.428% and85%respectively. For LED extended light sources, lenses have87.348%of utilizationratio of luminous energy and at least90%of uniformity, and the figures for reflectors are87.366%and90%respectively. The simulation results demonstrate the feasibility andeffectiveness of the design methods.