Patent ID: 6167991
Filing Date: 2001-01-02
Classification: B66B,E05F,E05Y,G01V

Abstract:
A method of detecting distance between a first plurality of emitters and a first plurality of receivers, wherein the emitters emit energy beams having an emission pattern comprising a primary beam component emitted in a narrow angle from a center of the pattern and a halo component emitted in a predetermined wide angle from the center of the pattern, the method comprising: emitting an energy beam from an emitter; sampling the halo component of the energy beam with the plurality of receivers to provide a set of energy signals indicative of intensity of the halo component energy sampled; determining, from the set of energy signals, a vertical distance from the center of the pattern to an intersection of the halo component with the first plurality of receivers; and calculating the distance between the first plurality of emitters and receivers utilizing the predetermined wide angle and the vertical distance.