Freeform Lens Design of Beam Shaping With User-Defined Rotation-Symmetric Profile by Using Numerical Method

A freeform lens construction is proposed to form a specific rotation symmetric beam profile with collimation in this paper. In the proposed approach, two freeform surfaces are constructed segment-by-segment using a numerical method based on Snell's law to produce an output beam profile which has both good irradiance uniformity and high collimation. It is shown that as the number of segments used to construct the freeform surfaces increases, the output beam profile approaches the specific profile. A sparse design point freeform surface construction method is additionally proposed which allows the beam profile to approach the desirable distribution with a fewer number of segments. The proposed method is used to construct freeform lenses for producing output beams with two user-defined irradiance patterns, i.e., annular and triangular distributions. The simulation results show that either demonstrated irradiance distribution is close to the specific distribution. Overall, the present results show that the proposed method provides a versatile and efficient approach for designing freeform lenses with a specific distribution of the output beam profile and good collimation.