An LED Collimator Lens for Uniform Illumination

• Main Author: 劉凱翔
• Other Authors: 陳金嘉
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/17282650013439010656

碩士 === 國立彰化師範大學 === 電機工程學系 === 99 === This thesis proposes a novel light-emitting diode (LED) collimator lens whose function can force the light rays emitted from an LED light source to uniformly illuminate the target plane. Thus, it can be used to form a lighting modular for general projection lighting. The outer layer of the lens is a freeform total internally reflective (TIR) surface that LED light rays with a larger angle to the axis will be totally reflected by the freeform surface firstly and then be refracted outwardly by the multi-spherical surfaces in the front of the lens. However, LED light rays closing the axis will firstly be refracted to parallel to the axis by the rear convex surface of the lens, and then be refracted outwardly by the central and concave optical surface, which is located at the front end of the lens. Through the above arrangement, light rays emitted from the LED can be redistributed to produce uniform illumination. In addition, a cylindrical surface is dag out on the rear side of the lens so that the lens volume can be reduced and the TIR condition can be achieved. Finally, the lens can be constructed with the assistance of a three-dimensional CAD program and optical software. From the computer simulation result, if the dimension of the luminance surface of the LED is , then the measured optical efficiency of 94% and illumination uniformity of 0.8 on a detecting surface of 2.5-m diameter and 10-m away can be achieved, which has satisfied the condition for general projection lighting.