GIMBAL INSTRUMENT HAVING A PREALIGNED AND REPLACEABLE OPTICS BENCH

• US 20120262698A1
• Filed: 04/13/2012
• Published: 10/18/2012
• Est. Priority Date: 04/15/2011
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Brown, Lawrence B., West, James K., Day, Jonathan Robert
• Granted Patent: US 8,681,320 B2
• Time in Patent Office: Days
• US Class Current: 356/4.01
• CPC Class Codes: G01B 11/03 by measuring coordinates of points
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4808 Evaluating distance, position or velocity data
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G01S 7/491 Details of non-pulse systems
• CPC Class Codes: G06F 17/40 Data acquisition and logging for input to computer G06F3/00
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A method includes providing: an optics assembly including a housing, a beam splitter, and a position detector; and an alignment fixture; placing the assembly on the fixture which makes contact with the assembly on the first region; projecting the third beam of light onto a first surface; rotating the assembly about the sixth axis on the fixture; sensing a change in a position of the third beam of light in response to rotation of the assembly about the sixth axis; adjusting the first path to align the third beam of light to the sixth axis; attaching the assembly to a dimensional measurement device; directing the third beam of light to a retroreflector target; reflecting a portion of the third beam from the target as a fourth beam of light; and sending a third portion of the fourth beam from the beam splitter to the position detector.

Claims

1. A dimensional measurement device that sends a first beam of light to a remote retroreflector target, the retroreflector target having a position in space, the retroreflector target returning a portion of the first beam as a second beam, the measurement device comprising:

a first motor and a second motor that together direct the first beam of light to a first direction, the first direction determined by a first angle of rotation about a first axis and a second angle of rotation about a second axis, the second axis substantially perpendicular to the first axis, the first axis and the second axis intersecting substantially at a gimbal point, the first angle of rotation produced by the first motor and the second angle of rotation produced by the second motor;

an optics assembly including a housing, a light element, a lens, a first beam splitter, and a position detector, wherein the light element, the lens, the first beam splitter, and the position detector are fixedly attached to the housing, the housing having a substantially cylindrical shape over at least a first region of an outer surface of the housing, the cylindrical shape having a third axis passing through a center line of the cylindrical shape, distances from the third axis to points on the first region being a substantially constant value, the light element being either a source of light or an optical fiber component attached to the source of light, the light element configured to emit a first light, the first beam being a portion of the first light emitted from the optics assembly, the optics assembly configured to send the first beam of light along a fourth axis, the third axis and the fourth axis substantially coincident and substantially in line with the gimbal point and substantially in a plane containing the first axis and perpendicular to the second axis, the first beam splitter configured to send a second portion of the second beam of light to the position detector, the position detector configured to produce a first signal in response to a position of the second portion on the position detector; and

a control system that sends a second signal to the first motor and a third signal to the second motor, the second signal and the third signal based at least in part on the first signal, the control system configured to adjust the first direction to the position in space of the retroreflector target.

2. The dimensional measurement device of claim 1, wherein the optical assembly is configured to direct the first beam along the third axis.

3. The dimensional measurement device of claim 1, wherein the first region is metallic.

4. The dimensional measurement device of claim 1, wherein the optical fiber component is a ferrule.

5. The dimensional measurement device of claim 1, wherein the source of light is a diode laser.

6. The dimensional measurement device of claim 1, wherein the lens is configured to collimate the first light.

7. The dimensional measurement device of claim 1, wherein the optics assembly includes a second beam splitter, the first beam splitter and the second beam splitter being a beam-splitter set.

8. The dimensional measurement device of claim 7, wherein the optics assembly is configured to align the first light entering the beam-splitter set and the first light exiting the beam-splitter set along the fourth axis.

9. The dimensional measurement device of claim 1, further including a distance meter that measures a first distance from the gimbal point to the retroreflector target based at least in part on a first portion of the second beam received by a first optical detector.

10. The dimensional measurement device of claim 1, further including a first angle measuring device that measures the first angle of rotation and a second angle measuring device that measures the second angle of rotation.

11. The dimensional measurement device of claim 8, further including a first angle measuring device that measures the first angle of rotation and a second angle measuring device that measures the second angle of rotation.

12. A method of pre-aligning an optics assembly, installing the optics assembly in a dimensional measurement device, and using the dimensional measurement device to measure a remote retroreflector target, the method comprising steps of:

providing a first motor and a second motor that together align a fifth axis to a first direction, the first direction determined by a first angle of rotation about a first axis and a second angle of rotation about a second axis, the second axis substantially perpendicular to the first axis, the first axis, the second axis, and the fifth axis intersecting substantially at a gimbal point, the first angle of rotation produced by the first motor and the second angle of rotation produced by the second motor;

providing an optics assembly including a housing, a light element, a lens, a first beam splitter, and a position detector, wherein the light element, the lens, the first beam splitter, and the position detector are fixedly attached to the housing, the housing having a substantially cylindrical shape over at least a first region of an outer surface of the housing, the cylindrical shape having a sixth axis passing through a center line of the cylindrical shape, distances from the sixth axis to points on the first region having a substantially constant value, the light element being either a source of light or an optical fiber component attached to the source of light, the light element configured to emit a first light, a third beam of light being a portion of the first light, the third beam of light having a first path in relation to the optics assembly, the optics assembly configured to enable adjustment of the first path;

providing an alignment fixture, the alignment fixture configured to support the optics assembly on the first region and to constrain rotation of the optics assembly about the sixth axis;

placing the optics assembly on the alignment fixture in such a manner that the alignment fixture makes contact with the optics assembly at points of contact on the first region;

projecting the third beam of light onto a first surface, the first surface at a first distance from the optics assembly;

rotating the optics assembly about the sixth axis on the alignment fixture;

sensing a change in a position of the third beam of light on the first surface in response to the rotation of the optics assembly about the sixth axis;

adjusting the first path to align the third beam of light to the sixth axis, the adjustment based at least in part on the observed change in the position of the third beam of light on the first surface;

attaching the optics assembly to the dimensional measurement device, wherein the attaching aligns the third beam of light with the fifth axis;

directing the third beam of light to a remote retroreflector target;

reflecting a portion of the third beam of light from the retroreflector target as a fourth beam of light; and

sending a third portion of the fourth beam of light from the beam splitter to the position detector.

13. The method of claim 12, wherein the step of sensing a change in a position of the third beam of light on the first surface in response to the rotation of the optics assembly about the sixth axis further includes measuring a first runout diameter at the first surface.

14. The method of claim 13, further including steps of:

projecting the third beam of light onto a second surface, the second surface at a second distance from the optics assembly; and

adjusting the first path to align the third beam of light to the sixth axis, the adjustment based at least in part on the observed change in the position of the third beam of light on the second surface.

15. The method of claim 14, wherein the step of adjusting the first path to align the third beam of light to the sixth axis further includes measuring a second runout diameter at the second surface.

16. The method of claim 12, wherein, in the step of sensing a change in a position of the third beam of light on the first surface, the first surface is a surface of an optical detector.

17. The method of claim 12, wherein, in the step of providing an optics assembly, the first region is metallic.

18. The method of claim 12, wherein, in the step of providing an optics assembly, the optical fiber component is a ferrule.

19. The method of claim 12, wherein, in the step of providing an optics assembly, the source of light is a diode laser.

20. The method of claim 12, wherein the step of providing an optics assembly further includes providing the lens configured to collimate the first light.

21. The method of claim 12, further comprising:

providing a distance meter that measures a third distance from the gimbal point to the retroreflector target based at least in part on a first portion of the second beam received by a first optical detector; and

measuring the third distance.

22. The method of claim 12, further comprising:

providing a first angle measuring device that measures the first angle of rotation and a second angle measuring device that measures the second angle of rotation; and

measuring the first angle of rotation and the second angle of rotation.

23. The method of claim 21, further comprising providing a first angle measuring device that measures the first angle of rotation and a second angle measuring device that measures the second angle of rotation.

24. The method of claim 12, further including steps of:

providing the position detector configured to produce a first signal in response to a position of the third portion on the position detector;

providing a control system, the control system configured to sends a second signal to the first motor and a third signal to the second motor, the second signal and the third signal based at least in part on the first signal, the control system configured to adjust the first direction to the position in space of the retroreflector target; and

adjusting the first direction.