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Proceedings Paper

Evaluation of simulation alternatives for the brute-force ray-tracing approach used in backlight design
Author(s): Karel Desnijder; Peter Hanselaer; Youri Meuret
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Paper Abstract

A key requirement to obtain a uniform luminance for a side-lit LED backlight is the optimised spatial pattern of structures on the light guide that extract the light. The generation of such a scatter pattern is usually performed by applying an iterative approach. In each iteration, the luminance distribution of the backlight with a particular scatter pattern is analysed. This is typically performed with a brute-force ray-tracing algorithm, although this approach results in a time-consuming optimisation process. In this study, the Adding-Doubling method is explored as an alternative way for evaluating the luminance of a backlight. Due to the similarities between light propagating in a backlight with extraction structures and light scattering in a cloud of light scatterers, the Adding-Doubling method which is used to model the latter could also be used to model the light distribution in a backlight. The backlight problem is translated to a form upon which the Adding-Doubling method is directly applicable. The calculated luminance for a simple uniform extraction pattern with the Adding-Doubling method matches the luminance generated by a commercial raytracer very well. Although successful, no clear computational advantage over ray tracers is realised. However, the dynamics of light propagation in a light guide as used the Adding-Doubling method, also allow to enhance the efficiency of brute-force ray-tracing algorithms. The performance of this enhanced ray-tracing approach for the simulation of backlights is also evaluated against a typical brute-force ray-tracing approach.

Paper Details

Date Published: 27 April 2016
PDF: 9 pages
Proc. SPIE 9889, Optical Modelling and Design IV, 98890O (27 April 2016); doi: 10.1117/12.2227655
Show Author Affiliations
Karel Desnijder, KU Leuven (Belgium)
Peter Hanselaer, KU Leuven (Belgium)
Youri Meuret, KU Leuven (Belgium)

Published in SPIE Proceedings Vol. 9889:
Optical Modelling and Design IV
Frank Wyrowski; John T. Sheridan; Youri Meuret, Editor(s)

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