Wide field of view two-axis laser locator

Abstract

A remote laser locator system for viewing a wide field of view and detecting the angular position of a remote laser. A laser beam directed toward the sensor from any position within a 90 degree circular field-of-view can be detected to a positional accuracy of less than 0.1 degree in a two-axis coordinate system. The system utilizes an inline or coaxial optical sensor having field-of-view (FOV) optics that compress the field-of-view. The compressed output from the FOV optics is directed through a polarizer and filter to a phase shifter. The phase shifter, a pair of birefringent crystals, encodes the angle of incidence of the laser beam as a phase shift between the two components of the polarized input beam. Subsequently, an analyzer such as a Wollaston prism decomposes the beam into two linear component beams. These component beams are processed through a second phase shifter and an analyzer pair which are rotated axially with respect to the first pair to provide four distinct component beams. These components are condensed through a reimager lens and coupled to an array of intensity detectors. The array detector outputs are then combined to provide two normalized signal proportional to a trigonometric function of the two components of the angle of incidence of the laser beam, indicative of its position in space.