Method and apparatus for three-dimensional scanning

• US 4,622,462 A
• Filed: 03/23/1983
• Issued: 11/11/1986
• Est. Priority Date: 06/11/1981
• Status: Expired due to Fees

• Current Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Original Assignee: MTS Vektronics Corporation
• Inventors: Eaton, Homer L., Shaylor-Billings, John D.
• Primary Examiner(s): Willis, Davis L.
• Assistant Examiner(s): Gatto, James G.
• Application Number:
  US06/477,744
• Time in Patent Office: 1,329 Days
• Field of Search: 250/234, 250/235, 250/236, 250/230, 250/560, 356/376, 356/1, 350/6.4, 350/6.5
• US Class Current: 250/236
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01N 21/954 Inspecting the inner surface of hollow bodies, e.g. bores

Abstract

Three-dimensional information and a three-dimensional display of the surface of an object is provided by a scanning laser beam mounted on a high-speed rotating disc to repetitively scan across an object transported below the disc upon a moving carrier. Light reflected from the object surface back along the axis of the scanning beam is detected to indicate surface characteristics, such as reflection intensity. Positions of the projected beam in the course of its scanning rotation and of the carrier in the course of its transport motion are detected to generate signals that define the XY position of the scanning beam. Light of the projected energy beam, as reflected from the object at an angle to the beam axis, is imaged by a second lens upon a linear detector array, whereby the position of the image along the linear detector array will indicate elevation of the reflecting area along the axis of the projected beam. The signals defining the XY position of the scanning beam also define the XY positions of the elevation data from the linear array and the XY positions of the information obtained from the detector of coaxially reflected energy. Several solid-state lasers and detectors are carried by the rotating disc in one embodiment to provide measurements of different object characteristics and to improve scan speed or resolution.

Claims

1. Scanning apparatus comprising

a movably mounted support,

means for projecting an energy beam from said support along a beam axis directed to an object to be scanned,

means for effecting relative scanning motion of said support and an object to be scanned whereby said beam scans across the object in a scan pattern,

first and second mutually spaced energy receivers mounted to said support for motion therewith relative to the object to be scanned, means for moving the object relatively to the scan pattern,

said beam illuminating areas of said object in said scan pattern, one of said receivers having an energy receiving axis inclined to the beam axis and directed at said illuminated areas, and means for generating signals that define position of said illuminated areas in a plane parallel to the direction of motion of the object relative to the scan pattern.

2. Apparatus according to claim 1 wherein said one receiver includes means for generating signals representing elevations of said illuminated areas relative to said plane.

3. Scanning apparatus comprising

a movably mounted support,

means for projecting an energy beam from said support along a beam axis directed to an object to be scanned,

means for effecting relative scanning motion of said support and an object to be scanned whereby said beam scans across the object in a scan pattern,

first and second mutually spaced energy receivers mounted to said support for motion therewith relative to the object to be scanned, means for moving the object relatively to the scan pattern,

said means for effecting relative scanning motion comprising means for mounting the support for rotation about an axis perpendicular to the direction of motion of the object relative to the scan pattern, a detector, said first receiver comprising means for transmitting to said detector an image of an area of said object illuminated by said beam and reflected at an angle to said beam axis.

7. The apparatus of claim 3 wherein said second receiver has a receiving axis coaxial with said beam axis, and including a second detector positioned to receive energy of said beam reflected from said object and collected by said second receiver.

8. The apparatus of claim 3 wherein said first receiver comprises an optical slit mounted adjacent said detector, a mirror position to reflect said image toward said slit, means for mounting said mirror to said support for rotation relative to said support, means for rotatably driving said mirror to shift said image across said slit, whereby said image will pass through said slit to said detector in the course of rotation of the mirror, and means for indicating the angular position of said mirror to indicate position of said area along said beam axis.

4. Scanning apparatus comprising

a movably mounted support,

means for projecting an energy beam from said support along a beam axis directed to an object to be scanned,

means for effecting relative scanning motion of said support and an object to be scanned whereby said beam scans across the object in a scan pattern,

first and second mutually spaced energy receivers mounted to said support for motion therewith relative to the object to be scanned, means for moving the object relatively to the scan pattern, and

second means for projecting a second energy beam from said support along a second beam axis directed to said object, whereby said second energy beam scans across the object in a scan pattern, said first and second receivers each having a receiving axis directed to receive energy of respective ones of said beams as reflected from said object, whereby said object may be scanned by two beams.

5. The apparatus of claim 4 wherein at least one of said means for projecting an energy beam comprises a laser mounted on said support for motion therewith, at least one of said receivers having its receiving axis coaxial with the axis of one of said beams.

6. The apparatus of claim 4 wherein said means for effecting relative scanning motion comprises means for mounting said support for rotation about an axis parallel to said beam axis of said first mentioned beam, said second beam having an axis parallel to said first beam axis.

9. Scanning apparatus comprising

a movably mounted support,

means for projecting an energy beam from said support along a beam axis directed to an object to be scanned,

means for effecting relative scanning motion of said support and an object to be scanned whereby said beam scans across the object in a scan pattern,

first and second mutually spaced energy receivers mounted to said support for motion therewith relative to the object to be scanned, and means for moving the object relatively to the scan pattern,

said beam illuminating areas of said object in said scan pattern, and one of said receivers being offset from said projected beam axis adjacent said illuminated areas.

10. Scanning apparatus comprising

a movably mounted support,

means for projecting an energy beam from said support along a beam axis directed to an object to be scanned,

means for effecting relative scanning motion of said support and an object to be scanned whereby said beam scans across the object in a scan pattern,

first and second mutually spaced energy receivers mounted to said support for motion therewith relative to the object to be scanned, and means for moving the object relatively to the scan pattern,

said beam axis being substantially normal to the direction of motion of the object relative to the pattern, and said first receiver, having an energy receiving axis inclined to the beam axis and directed at said illuminated areas.

11. Apparatus according to claim 10 wherein said second receiver has an energy receiving axis coaxial with the beam, said last-mentioned receiving axis having a scanning motion relative to the object to be scanned, whereby said second receiver will receive energy of the beam reflected from the object through an area centered upon the projected beam axis.

12. Apparatus according to claim 10 wherein said first receiver includes a detector and a lens for focusing on said detector an image of an area illuminated by the beam, whereby the position of the image on the detector varies according to the position of the illuminated area along the beam axis.

13. A method of scanning an object comprising

projecting an energy beam at the object to cause energy of the beam to be reflected from the object,

moving the beam across the object to provide an illuminated area that traverses the object in a scan pattern,

positioning first and second reflected energy receivers to receive energy reflected along first and second receiver axes,

moving said receivers in synchronism with said beam to cause the receiver axes to scan the object in said scan pattern,

relatively moving said object and scan pattern, and

generating signals defining positions of said illuminated area in a plane parallel to the direction of motion of said object and scan pattern.

14. The method of claim 13 including the step of directing the axis of said first receiver toward said illuminated area in a direction inclined to the axis of the projected beam, and employing energy received by said first receiver to indicate position of the illuminated area along the axis of the projected beam.

15. The method of claim 13 including the step of directing both said receiver axes to intersect said energy beam.

16. A method of three dimensional scanning of an object comprising

moving a scanning energy beam in a scan pattern across the object to successively illuminate small areas of the object,

generating position signals defining position in a plane of a plurality of said illuminated areas,

moving a scanning receiver across the object in synchronism with the energy beam to receive energy reflected from said illuminated areas at an angle to a normal to said plane, and

generating, from reflected energy received by the receiver, elevation signals defining relative elevations of said illuminated areas.

17. The method of claim 16 including the step of moving a second scanning receiver across the object in synchronism with the energy beam to receive energy reflected from said illuminated areas back along the axis of said scanning energy beam, and generating, from reflected energy received by said second receiver, signals defining intensity of energy reflected from said illuminated areas.

18. Scanning apparatus comprising

a support,

means for mounting the support for rotation about a rotation axis,

means for rotatably driving the support,

means carried by the support for projecting an energy beam parallel to said axis in a scan pattern,

an object carrier mounted adjacent said support for transporting an object to be scanned across said scan pattern, whereby areas of an object carried by the carrier are successively illuminated by said energy beam,

an energy receiver mounted to said support for receiving energy reflected from said object at an angle to said axis, and

means responsive to said receiver for generating signals defining elevation of said illuminated areas in a direction parallel to said axis.

19. The scanning apparatus of claim 18 including a second energy receiver mounted to said support for receiving energy reflected from said object back along said projected beam, mans responsive to said second receiver for generating signals indicating intensity of energy reflected from said illuminated areas, and means for generating position signals defining positions of said illuminated areas in a plane normal to said axis.

20. The scanning apparatus of claim 18 wherein said first mentioned energy receiver comprises a detector array on said support and a lens on the support for focussing on the detector images of said illuminated areas.

21. The apparatus of claim 18 wherein said means for projecting an energy beam comprises a laser mounted on said support for rotation therewith, and a second energy receiver mounted to said support for receiving energy reflected from said object, both said receivers having receiving axes directed to intersect said energy beam, and means for generating signals defining positions of said illuminated areas in a plane normal to said axis.

22. Elevation scanning apparatus comprising

a support,

a mirror rotatably mounted on the support,

means for rotating the mirror,

a lens for collecting light from a point of which elevation is to be determined and for directing collected light to a surface of the mirror,

a detector for receiving light collected by the lens and reflected by the mirror,

an optical slit interposed between the detector and mirror,

peak detecting means coupled with said detector, and

means responsive to said peak detecting means for indicating angular position of the mirror upon occurrence of a peak output from the detector.

23. The elevation apparatus of claim 22 including means for rotatably mounting said support, means for rotatably driving the support, and means on the support for projecting a scanning beam at an object in a scan pattern that repetitively traverses the object, said lens being positioned on the support to collect light reflected from areas on an object illuminated by said beam.

24. The elevation apparatus of claim 23 including means for transporting an object across the scan pattern of the projected beam, and means for generating signals collectively defining positions of areas of the object successively illuminated by the projected beam.

25. The apparatus of claim 23 including receiver means on said support for collecting light reflected back along the axis of said scanning beam from said illuminated areas.