A typical light distribution design in the high efficient LED street lamp

On the basis of space Brewster law, combining with light distribution curve and iterative algorithm at the same time, this paper realizes correspondence between emergent ray and specific spot on the road. Two freeform surface lens has been designed with one-way iterative algorithm and two-way iterative algorithm respectively. One is used on the road which the width is 20m, interval between lamps and height of lamp are 40m and 8m respectively and the other is used on the road which width is 20m, interval between lamps and height of lamp are 20m and 5m respectively. After analyzing its effect using TracePro, we find the light efficiency is 84% and light uniformity has reached 77% with two-way iterative algorithm, which has the same light efficiency as with one-way iterative algorithm, meanwhile, dark regions on the road corners are eliminated efficiently and light uniformity has been improved greatly.