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Crystals 2019, 9(2), 96;

Construction and Optimization of Through-Hole LED Models for Use in Designing Traffic Signboards

College of Optical Sciences, University of Arizona, Tucson, AZ 85721, USA
Department of Optics and Photonics, National Central University, Taoyuan City 32001, Taiwan
Author to whom correspondence should be addressed.
Received: 30 November 2018 / Revised: 2 February 2019 / Accepted: 12 February 2019 / Published: 14 February 2019
(This article belongs to the Special Issue Advanced LED Solid-state Lighting Optics)
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A modeling procedure was proposed for the through-hole LEDs commonly used in traffic signs. The measurements from a sample batch of LEDs were performed at several midfield distances to provide a set of representative angular intensity distributions as the target pattern in the modeling process. The flat outer dimensions of the LED were accurately measured while the curvature and refractive index of the packaging dome were roughly estimated. These physical parameters were used to build a preliminary LED model in the Monte Carlo simulation software. The simulated angular intensity distribution at each distance was generated by tracing 20,000,000 rays. The normalized cross correlation (NCC) between the measured and simulated data was calculated to represent the resemblance of the model to the real LED. The roughly estimated parameters were then varied within their physical limits to optimize the NCC value. The possibilities of two parameters having interactions were also considered. The final model has all NCCs above 98.8% between the target and simulated patterns. View Full-Text
Keywords: LED; modeling; midfield; simulation; optimization; dome packaging LED; modeling; midfield; simulation; optimization; dome packaging

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Lee, T. .-T.; Chen, Y.-C. Construction and Optimization of Through-Hole LED Models for Use in Designing Traffic Signboards. Crystals 2019, 9, 96.

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