Spherically mounted light source with angle measuring device, tracking system, and method for determining coordinates

• US 20030227616A1
• Filed: 02/24/2003
• Published: 12/11/2003
• Est. Priority Date: 02/22/2002
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Laser Trackers, LLC (Faro Technologies Incorporated)
• Inventors: Bridges, Robert E.
• Granted Patent: US 7,248,374 B2
• Time in Patent Office: Days
• US Class Current: 356/139.06
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/005 coordinate measuring machines
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves

Abstract

A device for use in conjunction with a coordinate measuring device, a three-dimensional coordinate measuring system and a method of measuring three-dimensional coordinates are described. The device includes a light source mounted substantially within the center of a spherical member having a spherical surface configured such that the distance from the light source to the outer contact surface of the sphere is substantially equal to the radius of the sphere regardless of sphere orientation. The three-dimensional coordinate measuring system further includes a coordinate-measuring device, the coordinate-measuring device configured to track the movement of the light source and to measure either azithmuth angles and zenith angles, or to spherically encode tracking information related to relevant positions of the light source. The present method includes emitting light at a target with a light source, wherein the light source is mounted substantially within the center of a spherical member having a spherical surface configured such that the distance from the light source to the outer contact surface of the sphere is substantially equal to the radius of the sphere regardless of sphere orientation, moving the surface of the spherical member across a device to be measured, tracking said light source with a tracking device, and measuring information related to the relative position of the light source using either angular or spherical encoders.

Claims

1. A three-dimensional coordinate measuring system, comprising:

a light source mounted substantially within the center of a spherical member having a spherical surface configured such that the distance from the light source to the outer contact surface of the sphere is substantially equal to the radius of the sphere regardless of sphere orientation; and

a coordinate-measuring device, the coordinate-measuring device configured to track the movement of the light source and to measure either azithmuth angles and zenith angles, or to spherically encode tracking information related to relevant positions of the light source.

2. The system in accordance with claim 1, wherein two coordinate-measuring devices are configured to simultaneously measure azithmuth and elevation angles of the light source positioned within the center of the spherical surface.

3. The system in accordance with claim 1, wherein the outer surface of spherical member comprises a metal material.

4. The system in accordance with claim 1, wherein the spherical member is generally shaped as a hemisphere.

5. The system in accordance with claim 1, wherein the spherical member has a lip extending along open edges of the spherical surface, wherein the lip is configured to increase the spherical surface area.

6. The system in accordance with claim 1, wherein the spherical member comprises a metal ball generally shaped as a hemisphere and including a lip around the edge of the hemisphere.

7. The system in accordance with claim 1, further including a kinematic nest, wherein the kinematic nest, the light source and the spherical member are configured such that the light source returns to substantially the same place each time the spherical member is removed and replaced within the kinematic nest.

8. The system in accordance with claim 1, further including a tooling ball, wherein the tooling ball, the light source and the spherical member are configured such that movement of the spherical member around the tooling ball substantially moves the light source equidistantly around the center of the tooling ball sphere.

9. The system in accordance with claim 1, wherein the light source is a point light source.

10. The system in accordance with claim 9, wherein the point light source generally has a hemispherical emission pattern.

11. The system in accordance with claim 1, further comprising an afocal beam-reducer assembly.

12. The system in accordance with claim 1, further comprising a position detector assembly.

13. The system in accordance with claim 12, wherein the position detector assembly is one of a lateral-effect cell, a photosensitive array, or a quadrant detector.

14. The system in accordance with claim 1, wherein the coordinate-measuring device is configured to spherically encode tracking information related to relevant positions of the light source using a spherical encoder, and further wherein the spherical encoder is absolute or incremental, reflective or transmissive, and imaging or defracting.

15. The system in accordance with claim 14, wherein the spherical encoder comprises an encoder sphere, a beam-illumination assembly, and a beam-imaging assembly.

16. A device for use in conjunction with a coordinate measuring device, comprising:

a light source mounted substantially within the center of a spherical member having a spherical surface configured such that the distance from the light source to the outer contact surface of the sphere is substantially equal to the radius of the sphere regardless of sphere orientation.

17. The device in accordance with claim 16, wherein the light source is a point light source.

18. The device in accordance with claim 17, wherein the point light source generally has a hemispherical emission pattern.

19. The device in accordance with claim 16, wherein the outer surface of spherical member comprises a metal material.

20. The device in accordance with claim 16, wherein the spherical member is generally shaped as a hemisphere.

21. The device in accordance with claim 16, wherein the spherical member has a lip extending along open edges of the spherical surface, wherein the lip is configured to increase the spherical surface area.

22. The device in accordance with claim 16, wherein the spherical member comprises a metal ball generally shaped as a hemisphere and including a lip around the edge of the hemisphere.

23. A method of measuring three-dimensional coordinates, comprising:

emitting light at a target with a light source, wherein the light source is mounted substantially within the center of a spherical member having a spherical surface configured such that the distance from the light source to the outer contact surface of the sphere is substantially equal to the radius of the sphere regardless of sphere orientation;

moving the surface of the spherical member across a device to be measured;

tracking said light source with a tracking device; and

measuring information related to the relative position of the light source using either angular or spherical encoders.