Design of asymmetrical total internal reflection optics with microstructures for lighting museum exhibits

Abstract

A high-quality museum lighting system should demonstrate optimal color rendering and high light source efficiency. In addition, an adequate lighting management system is required for energy saving and visual comfort. However, symmetrical total internal reflection (TIR) lenses typically applied in lighting fixtures are inadequate for providing a comfortable lighting experience for museum visitors. This paper presents a new optical lens that forms a novel asymmetrical triangular light distribution for improving the vertical illuminance uniformity of museum exhibits. Moreover, the proposed lens can reduce the reflective glare caused by the glass covering exhibits. Monte Carlo ray tracing simulation techniques were used to develop various lens structures and numerous microstructures, which enabled changing the light distribution from a traditional symmetrical to an asymmetrical triangle. Finally, an asymmetrical TIR lens with a microstructure surface was constructed and applied to exhibit lighting. According to the ray tracing results obtained using Tracepro simulation software and DIALux lighting design software, the asymmetrical lens formed an asymmetrical triangular light distribution with an LED light source and enhanced the illuminance uniformity by 29 %, improving the light quality of museum exhibits. The preliminary simulation results revealed that the proposed lens structure effectively improved the LED lighting quality in the museum.