System for distinguishing true target reflections from ghost target

Abstract

A system for distinguishing real target reflections from ghost target reflections for use in adjusting the orientation of a plane defined by a rotating laser beam from a laser transmitter is provided. One or more retroreflective targets are positioned in desired locations along a rotational arc to define the desired plane through which the laser beam is rotated. The laser beam rotates back and forth scanning for targets positioned along the rotational arc. The laser beam is reflected from the targets to the laser transmitter for processing. A plurality of detection zones are established within the rotational arc. The detection zones are associated with a direction of rotation of the laser beam so that the laser beam traverses a target prior to traversing a potential shiny surface which could cause a ghost target reflection. As the laser beam scans a target prior to a shiny surface, reflections received after a target reflection are ignored as being potentially invalid reflections. Once a true target reflection is received, the orientation of the laser beam is adjusted until the laser beam traverses the center of the target.