Design, Analysis and Fabrication of Light Guiding System with Natural and Artificial Light Sources for Illumination

• Main Authors: Yi-Yung Chen, 陳怡永
• Other Authors: Allen Jong-Woei Whang
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/70110027374416557370

博士 === 國立臺灣科技大學 === 電子工程系 === 96 === The light guiding system with sunlight can be separated into collecting, guiding, and illumination parts. The collecting part has dynamic and static systems. Many dynamic system use parabolic concentrator with sun tracking system for high efficiency. However, exposure to UV in sunlight has been proved to be hazardous to humans, and the heat content of IR degrades illumination quality. In order to solve the two problems, we develop an innovative cassegrain solar concentrator system utilizing the theory of chromatic aberration by a chromatic lens to filter out UV completely and reduce IR by half. Further, collected light is almost equal to sunlight that the two appear equal to the human eye. However, using a concentrator with sun tracking system consumes electric power and needs frequent maintenance. We design an optical component to collect sunlight for indoor illumination that includes a collecting part and a guiding part without a sun tracking system. In this design, we use a CPC structure utilizing the edge-ray principle to design the collecting part to gather sunlight at many different angles. For the maximum efficiency, we define two conditions to evaluate the static concentrator is total energy saving in the visible range. Because the efficiency of the guiding depends on the number of times the rays are reflected, we build a math model to calculate the number of reflections in a circular lightpipe. For improve the efficiency of the static collecting part, we present another static concentrator system made up of refractional units for changing slanted sunlight to vertical light. The capability can improve the efficiency of the optical structure under it. Based on the vignetting effect and the loss of sunlight, we discuss the configurations of refractional units and compare their performances. For evaluating the performances, we define a parameter to evaluate the refracting capability. And then, we design optical structure to be used as tiles on the outsides of buildings to collect the sunlight from the static concentrator. To cover an entire building, we have designed optical units to be used together that can compress light. We have used saw-toothed surface and curved surface with two different principles, the Co-focus and Parallel-plate, to design four kinds of optical units. Finally, we analyze the efficiency and the beam divergence angle to compare these optical structures. According to the reversibility of light, the illumination part of light guiding system can be designed with the reverse engineering of guiding part. We focus on artificial light source, LED, for auxiliary illumination system. First, we design a RGB LED illumination system that can use color sequential to replace color wheel and also can mix color to get the color you want. Optical element tapered lightpipe is also used in this structure, and we investigate to understand the mechanism of irradiance distribution, it assists in the design of lightpipe for different applications. The efficiency is above 80% and the uniformity is better than 60%. LED array is the general method if using whit LED to be auxiliary light source. We present a theory and design method by systemic concepts and focuses on the study of optical properties. We can design, efficiently, a LED lighting module and achieve a satisfactory uniformity by this theory and method, the design of a uniform LED illumination system. By this method, we not only obtain the maximally flat illumination distribution but also the emitting angle of the system can be designed at will. For a wide application area, LEDs are always with secondary optic elements for a specific characteristic. However, the secondary optic element has two serious phenomena, die-imaging and yellow hue to reduce the quality of illumination. We study the two phenomena on the relationship between the phenomena and the imaging power of TIR lens. Finally, we adopt the MacAdam ellipsis system to define the reasonable color gamut.