Nonimaging Optical Irradiance Optimization for Enhanced ROI of Mobile Robot LiDAR

In this paper, the design method of illumination optics for solid-state AMCW (Amplitude Modulated Continuous Wave) LiDAR (Light Detection And Ranging) is suggested. To satisfy the horizontally long and vertically narrow atypical ROI (Region of Interest) of LiDAR, the concept of etendue is applied. For light sources placed in a rectangle shape, the short side of the source corresponds to the slow axis and the long side corresponds to the fast axis. In order to cover a light source placed in a rectangle, a translational design in which the cross section of the lens is extended in the axial direction is adopted. The refractive surface of the lens is modeled with two parametric curves, and parameters are adjusted to satisfy the given radiance criteria. In the design example, the design of a primary lens composed of one circular arc and a secondary lens formed by connecting circular arcs was derived. The designed optical system showed an efficiency of about 65% and a uniformity of 12%.