Precise optical model of multi-chip white LEDs

A single-chip white light LED is commonly modeled by considering the phosphor coating as a homogeneous Lambertian light source. However, this approach leads to an incorrect optical simulation of phosphor-coated multi-chip LEDs due to the presence of a previously unreported spatial distribution of em...

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Bibliographic Details
Published inOptics express Vol. 15; no. 12; pp. 7572 - 7577
Main Authors Chien, Wei-Ting, Sun, Ching-Cherng, Moreno, Ivan
Format Journal Article
LanguageEnglish
Published United States 11.06.2007
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Summary:A single-chip white light LED is commonly modeled by considering the phosphor coating as a homogeneous Lambertian light source. However, this approach leads to an incorrect optical simulation of phosphor-coated multi-chip LEDs due to the presence of a previously unreported spatial distribution of emission spots across the phosphor layer. We introduce "weighting" factors based on position-dependent light strength across the phosphor surface in order to improve the model accuracy. Following the modeling algorithm in the mid-field region, we have built up a precise and practical optical model by using Monte Carlo ray tracing and weighting factors. We measure the LED radiation distribution at several representative distances to test the model performance. In all cases, the accuracy is higher than 99.5% in normalized cross correlation between the simulated pattern and experimental measurement.
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ISSN:1094-4087
1094-4087
DOI:10.1364/oe.15.007572