Catoptric optical system for detecting motion of a radiant source

Abstract

A catoptric optical system enhances the ability of a radiation sensor to detect motion of a radiant source within a region of a three-dimensional space without need for a polyethylene lens array. A preferred embodiment of the system includes first and second pairs of spaced-apart concave reflector elements arranged to form a chamber having a radiation reflective interior with a rectangular opening at each of input and output ends. The reflective elements of each of the first and second pairs are positioned in opposed relationship and separated by respective first and second distances. A two-element radiation sensor having a top surface is positioned proximal to the output end of the chamber. The first and second distances separating the reflective elements of each pair and the amounts of curvature of the reflective elements of each pair cooperate to establish for detection by the radiation sensor discrete zones of sensitivity that correspond to distinct angles of incidence of radiant flux that propagates from the region of the three-dimensional space and strikes the radiation sensor. A three-dimensional fan of zones of sensitivity is created by multiple reflections from all four interior surfaces of the reflective chamber formed by the reflector elements. The three-dimensional fan of zones of sensitivity is similar to that created by an array of lenses. The radiation sensor receives the reflected incident radiant flux at a position corresponding to a zone of sensitivity where the radiant source is located.