23 September 2011 Freeform lens design for LED illumination with high uniformity and efficiency
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Abstract
In this paper we design a freeform lens according to the LED light distribution curve so that the light rays emitted from a LED through the lens can achieve high uniformity and efficiency on the prescribed target plane. Because the model is of rotational symmetry, we consider just a 2-D lens shape and then sweep to get the 3-D result. Here a procedure based on the Snell's law and edge-ray principle for designing the freeform lens is proposed. First of all, we analyze the LED intensity distribution and subdivide it into parts. Then we calculate the zones on the target plane where the subdivided light rays should be distributed to. Finally we use an approximate analytic method to construct the freeform lens. After constructing the freeform lens, we simulate for the optical model by using the ray-tracing software LightTools®. The simulation results show that the Cree XLamp XR-E LED light source through the freeform lens can achieve up to 94.8% uniformity and 89.1% efficiency including Fresnel losses for a 1 m distance away and 1 m radius of circular illumination plane.
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Wei-Chung Chen, Hoang Yan Lin, "Freeform lens design for LED illumination with high uniformity and efficiency", Proc. SPIE 8123, Eleventh International Conference on Solid State Lighting, 81230K (23 September 2011); doi: 10.1117/12.893489; https://doi.org/10.1117/12.893489
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