Design of Freeform LED Lens with Large Light Deflection Angle for Road Lighting Application

The deflection of light of a single optical surface is limited by the Fresnel reflection loss and it is usually not enough to meet the requirements in large road width, tilt lighting LED lens design. This paper presents a method which greatly increases the light deflection angle of LED lens by combining a tilting aspherical surface with a freeform surface. Using this design method, a road lighting LED lens for length L= 30m, road width W= 12m and tilt angle theta= 15 degrees is designed and manufactured. The experimental results show that the overall road luminance uniformity is as high as 0.7. This design method greatly expand the light distributing capacity of the free-form surface LED lens, and it can be widely used in the design of LED road lighting lens and other illumination applications where large light deflection angle is needed.