Design of aspheric lens to collimate and uniform irradiance of a light source with Lambertian angular distribution

Abstract

A design of aspheric lens is proposed to collimate a light source of Lambertian angular distribution and generate homogenous irradiance. Two numerical solutions were calculated. One used even orders of general aspheres to describe the aspheric surfaces and the performance was evaluated by commercial optical software package Tracepro. Both of high numerical aperture (NA) of 0.79 and good RMS uniformity within 95% of designed area in the second surface of lens could be obtained. The reverse of this lens would be used in focusing and the simulated point spread function (PSF) is almost diffraction-limited. The other fitted both of aspheric surface with radial spline surface and the performance was evaluated by commercial optical software package OSLO. With the radial spline surface representation, the aspheric lens has a higher NA of 0.9; meanwhile, the uniformity was still good enough and PSF is also near diffraction-limited.