Abstract

Optimization of road lighting towards more sustainable and efficient sources is of major importance. We therefore pursue developing a LED roadway lighting design methodology, from luminance optimization towards the design of the freeform optics, enabling to optimize the illumination power distribution on the street to minimize the required optical output power and power consumption while still fulfilling the CIE 140 - 2000 standard. First, an artificial source is designed featuring an optimized illumination pattern towards the CIE standards while minimizing the required optical output power. Following, the design and optimization of the freeform optic is tackled, enabling the beam shaping of the LED emission pattern towards the optimized illumination pattern. Successful optimization of the freeform optic was achieved, starting from sequential mode calculations using an ideal point source, followed by an iterative optimization using backward raytracing of the requested illumination pattern and extended source simulations. The optimized freeform illumination lens comprises 2 biconic Zernike surfaces, and outperforms the state-of-the-art with respect to the average luminance, and the overall and longitudinal uniformity of the luminance. As a result, we believe our design methodology offers a promising procedure for efficient road lighting design, while having the potential to contribute to more eco-friendly lighting.

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