In lighting design, freefrom optical element plays a key role due to its considerable degree of freedom. In spite of many methods to design freefrom optical system, the prototype of the system is still important, for describing freefom optics with mathematical equations or optimizing in optical design software. In this paper, we analyze several illumination systems in order to verify that different forms of lens could achieve similar light distribution curves (LDCs). In section 3, an approach to realize IESNA Type I lighting with the help of optimization in Zemax is proposed based on calculating reference LDC. The result shows that the efficiency of the system is 84.27% and the optimized LDC is very near to the desired one.
A freeform LED lamp that meets the requirement of street light distribution is presented. The illumination system shows high uniformity and low glare. The prototype of this freeform is simple based on 3D modeling in LightTools. The lens is mounted on a chip-on-board (COB) LED as the luminaire with inclination to meet the requirement of CIE standard for different types of road lighting arrangement: one-sided arrangement below (one-sided arrangement above), double-sided mirrored arrangement and double-sided staggered arrangement. Also, the sensitivity analysis is performed for considering real installation.