Design and Analysis of a Total-Internal-Reflection (TIR) Structure Based on Ray-Mapping Method for Tailored Illumination

Abstract

Tailored illumination have widespread applications such as road lighting. Most road lighting only serves the road but neglects the surroundings which are also important in illumination quality. Therefore, the background illumination is created to solve this problem, finding a balance between road and surroundings. However, optical structures in existing methods still need further processing, and details on energy efficiency are not disclosed either, resulting in a limited practicality. An improved total-internal-reflection (TIR) structure is proposed to generate a complex illumination including a pattern and a circular background. By solving a nonlinear equation which is obtained by converting the pattern problem into the boundary surface problem, the profile curves are optimized, and is then combined into a Lens by a commercial CAD software. The irradiance of the pattern is designed to be twice as much as the background, which can be adjusted by the boundary conditions. The results show that the method can generate the tailored illumination, with the uniformity of pattern and background being 95.3% and 89.3%, respectively, while the light efficiency reaches 86.8%. It can be extended to generate different patterns by modifying the boundary surface applied to road lighting, advertising, entertainment, etc.

Keywords

• Light emitting diodes
• LED lamps
• lighting
• optical design techniques
• optical devices