Non-blind area PAL system design based on dichroic filter

Opt Express. 2016 Mar 7;24(5):4913-4923. doi: 10.1364/OE.24.004913.

Abstract

An inevitable problem of Panoramic Annular Lens (PAL) System is the blind area in the central part of image plane, which vastly reduces the pixel efficiency of detector. Here we present a design of PAL system based on dichroic filter, which can combine two channels of rays in different bands and image them on the same detector. The dichroic filter in this paper is designed to make ultraviolet rays reflect and visible rays transmit, and the ultraviolet rays are imaged on the PAL imaging area while the visible rays are imaged on the blind area of conventional PAL image plane. In order to image both bands of rays on the same plane, we add a correcting lens group in front of PAL system. As a result, the FOV of ultraviolet channel is ranging from 30°~90° and the one of visible channel is ranging from 0°~10°.