Multiple channel optical flying spot triangulation ranger system

• US 4,900,146 A
• Filed: 03/18/1988
• Issued: 02/13/1990
• Est. Priority Date: 03/18/1988
• Status: Expired due to Fees

• Current Assignee: Lincoln Electric Company (Lincoln Electric Holdings Incorporated)
• Original Assignee: General Electric Company
• Inventors: Penney, Carl M., Irwin, Nancy H., Corby, Nelson R. Jr.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US07/169,707
• Time in Patent Office: 697 Days
• Field of Search: 356/1, 356/141, 356/152, 356/376
• US Class Current: 356/3.01
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves

Abstract

Multiple light detection channels are introduced into a flying spot optical triangulation ranging system to increase the speed of acquiring range values. A laser beam is rapidly swept across a surface by a beam deflector. Each fiber optic channel can receive light only from a different point along a line at the intersection of the swept beam with the surface. The receiver channels are duplicated and separate detectors generate signal pulses at times that are a function of range to the surface. These are processed in parallel to calculate N range values per beam sweep, where N is the number of channels.

Claims

1. An improved swept aperture flying spot triangulation ranger system comprising:

means for providing a narrow spot of light beam and rapidly sweeping said beam across a surface in a given direction;

multiple adjacent linearly arrayed light detection channels optically coupled to separate detectors, one detector per channel, each of said channels having a rectangular entry face, lens means for focusing images of a light spot onto said detection channels entry faces, which respectively receive light scattered from the surface at different rectangular sensitive zones along a line that forms the intersection of said light beam with said surface, and aperture stop means disposed between said lens means and said detection channels having a rectangular slit;

said detectors each generating a signal pulse at a time that is a function of range to the surface so that for every sweep of said light beam a plurality of range points are measured equal to the number of said detection channels; and

means for parallel processing said signal pulses and calculating multiple range values.

2. The ranger system of claim 1 wherein said light detection channels are comprised of separate noncoherent fiber optic bundles.

3. The range system of claim 1 wherein said light detection channels are separated by opaque barriers and are solid glass.

4. The ranger system of claim 1 wherein the number of said light detection channels is about ten to twenty.

5. The ranger system of claim 1 wherein said detectors are photomultipliers.

6. The ranger system of claim 1 further comprising mirror means for scanning said light beam in a direction orthogonal to said given direction following every beam sweep and successively measuring other sets of range points, and calculating range values on a strip of said surface.

7. A multiple channel swept aperture flying spot triangulation ranger system comprising:

a narrow spot of laser beam source and means for deflecting and sweeping said beam across a surface in an X direction;

multiple adjacent linearly arrayed fiber optic light detection channels, each of said channels having a rectangular entry face and receiving light only from a different rectangular sensitive zone along a line that forms the intersection of said laser beam with said surface, and an aperture stop plate disposed between said receiving lens and said fiber optic channels having a rectangular slit to limit passage of light and increase depth of focus;

a receiving lens to focus light scattered from the surface onto entrance faces of said detection channels;

separate detectors, one detector per channel, sensing the light delivered by said fiber optic channels and generating signal pulses at times related to range to the surface; and

means for processing said signal pulses in parallel and calculating multiple range values equal to the number of said detection channels.

8. The ranger system of claim 7 wherein the number of said fiber optic channels is about ten to twenty.

9. The ranger system of claim 8 further comprising polygonal mirror means to scan said laser beam in the Y-direction in coordination with the X direction sweep.

10. The ranger system of claim 7 wherein said means for deflecting said laser beam is an acousto-optic deflector.

11. The ranger system of claim 7 wherein said detectors are photomultipliers.