Design of a dual-channel panoramic annular lens for imaging and time-of-flight based on freeform surface prisms.

We propose a dual-channel panoramic annular lens (PAL) utilizing freeform surface prisms, enabling visible light imaging and time-of-flight (TOF) dot matrix detection through a single lens, which solves the problems of relative position calibration and time consistency between TOF and the imaging lens. Based on freeform surface prisms, inspired by off-axis three mirror lenses and AR prisms, we replaced the relay lens group of PAL with two freeform surface prisms to achieve dual channel PAL with a large field of view (FoV) and small distortion. The imaging and TOF channels have the same FoV of 360° × (40° - 100°). The F-numbers of the imaging and TOF channels are 2.8 and 2.97, and the  -  distortion of all channels is less than 3.6%. The imaging channel's modulation transfer function (MTF) at 144 lp/mm is greater than 0.285, and the MTF of the TOF channel at 50 lp/mm is greater than 0.462. The structure of the above system provides what we believe to be a new idea for achieving a compact multi-channel imaging and TOF co-system optical system. It offers a promising approach for detecting positions in a large FoV.