Biography
Biography: Seoyong Shin
Abstract
A uniform light diffuser for a light-emitting diode (LED) light source is an essential device widely used in lighting engineering. We present a linear Fresnel lens design for LED uniform illumination applications. The LED source is an array of LED. An array of collimating lens is applied to collimate output from the LED array. Two linear Fresnel lenses are used to redistribute the collimated beam along two dimensions in the illumination area. Collimating lens and linear Fresnel lens surfaces are calculated by geometrical optics and non-imaging optics. A collimating lens has the simple structure of a plano-convex lens. The linear Fresnel lens is constructed by many grooves. The collimated beam output from the collimating lens array is divided into many fragments corresponding to the number of Fresnel lens grooves. Each fragment is refracted by a groove and distributed over the illumination area, so that total beam can be distributed to the illumination target uniformly. The designed system was modeled and simulated with LightTools software to explore the optical performance. The simulation results indicate that 82% optical efficiency was achieved at a uniformity of 76.9% for the proposed system. The simulation of the performance of our design for practical purposes, such as indoor and street lighting, and the comparison with a conventional light source were conducted. The simulation results show that this design has a compact structure, a high optical efficiency, and a good uniform distribution. Some consideration on the energy saving and optical performance are discussed by comparison with other typical light sources. The results show that our proposed LED lighting system is a strong candidate for low cost, energy saving for indoor and outdoor lighting applications.