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Electro-optical contour measuring system

  • US 4,226,536 A
  • Filed: 02/23/1979
  • Issued: 10/07/1980
  • Est. Priority Date: 02/23/1979
  • Status: Expired due to Term
First Claim
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1. A system for accurately and rapidly measuring the surface contour of a shaped object, said system comprising:

  • A. a fixture for stably supporting said object with respect to a reference axis extending in a given direction;

    B. a carriage movable in said direction on a track in a straight line path parallel to said reference axis, said carriage having a structural beam which extends at right angles to said axis and faces the surface of the object to be measured;

    C. a triangulation rangefinder assembly borne by said carriage beam and constituted by a pivotally-mounted light beam illuminator and a pivotally-mounted automatic tracker, said illuminator and said tracker being rotatable about spaced pivot points on said carriage beam, the line extending between said pivot points representing a triangulation baseline having a known value;

    D. motor means to advance said carriage in incremental steps along said track from one end of said object to the other;

    said carriage in the course of its movement along said track being subject to displacements which slightly distort the orientation of the rangefinder relative to the surface of the shaped object being measured;

    E. means to render said assembly operative at each step position of said carriage to cause said illuminator to swing through a sector wherein said light beam impinges on said surface to produce a luminous spot thereon that scans in a path normal to said reference axis from one edge of the object to the other and to cause said tracker in response to the light reflected from said surface to follow said scanning spot;

    F. means operatively associated with said illuminator and tracker to determine the changing angular values assumed by the illuminator and by the tracker in the course of each tracked scan to produce values representative thereof;

    G. calibration means intercepted by said scanning spot and mechanically independent of the carriage for sensing said distortions in the range finder assembly orientation relative to the surface being measured resulting from stepping of said carriage along said track to product correction values therefor; and

    H. a computer having said known baseline value stored therein and responsive to said changing angular values and to said correction values to compute by triangulation the changing position of said spot on said surface in the course of a tracked scan and to thereby provide a contour reading of each scan, whereby the contour of the entire surface is determined upon the completion of carriage advance from one end of the object to the other.

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