Free-form surface generation in a double pole coordinate system for off-axis illumination application

We apply the previously proposed double pole ray mapping technique to design a non-symmetrical optical surface for generating an off-axis rectangular illumination pattern, which is aimed for road luminaire. This paper explores the methods to determine the edges of an unsymmetrical collection solid angle in the source space for different target requirements as well as the mechanical structures of optical surfaces. By sampling source grids within the defined region in a double pole coordinate system, we achieve nearly perfect mapping between source and target with a high uniformity for the off-axis rectangular illumination pattern. The testing result of the prototyped free-form lens also shows good illumination performance, which is consistent with our simulation result. Besides, the tolerance analysis of the luminaire system is performed to understand the sensitivity of the LED's position on illumination performance.