Laser tracker that uses a fiber-optic coupler and an achromatic launch to align and collimate two wavelengths of light

• US 9,164,173 B2
• Filed: 12/08/2014
• Issued: 10/20/2015
• Est. Priority Date: 04/15/2011
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Bridges, Robert E., Mertz, Jacob J.
• Primary Examiner(s): Ratcliffe, Luke
• Assistant Examiner(s): Abraham, Samantha K
• Application Number:
  US14/562,935
• Publication Number:
  US 20150160344A1
• Time in Patent Office: 316 Days
• US Class Current: 1/1
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• 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

Abstract

A coordinate measurement device sends a first beam of light having first and second wavelengths to a target point. The device includes a fiber-optic coupler that combines the first and second wavelengths and launches them through an achromatic optical element to produce collimated and aligned light. The device also includes first and second motors, first and second angle measuring devices, a distance meter, and a processor that determines 3D coordinates of the target point based on the measured distance and two angles.

Claims

1. A coordinate measurement device configured to send a first beam of light to a target point, the target point having a position in space, the target point returning a portion of the first beam as a second beam, the measurement device comprising:

a first light source configured to emit a first light having a first wavelength;

a second light source configured to emit a second light having a second wavelength, the second wavelength different than the first wavelength;

a fiber-optic coupler that includes at least a first port, a second port, and a third port, the first port configured to accept a first portion of the first light, the second port configured to accept a second portion of the second light, the third port configured to transmit a third light, the third light including a portion of the first portion and a portion of the second portion;

an optical system configured to transmit a portion of the third light out of the coordinate measurement device as the first beam, the optical system including an achromatic optical element configured to collimate the first beam at the first wavelength and the second wavelength;

a first motor and a second motor that together are configured to 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 first angle of rotation produced by the first motor and the second angle of rotation produced by the second motor;

a first angle measuring device configured to measure the first angle of rotation and a second angle measuring device configured to measure the second angle of rotation;

a distance meter configured to measure a first distance from the coordinate measurement device to the target point based at least in part on a third portion of the second beam received by a first optical detector; and

a processor configured to provide three-dimensional coordinates of the target point, the three-dimensional coordinates based at least in part on the first distance, the first angle of rotation, and the second angle of rotation.

2. The coordinate measurement device of claim 1, further comprising:

a position detector assembly that includes a position detector, a fourth portion of the second beam passing onto the position detector, the position detector configured to produce a first signal in response to a position of the fourth portion on the position detector; and

a control system configured to send 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 of the first beam to the position in space of the target point.

3. The coordinate measurement device of claim 1, wherein the distance meter is an absolute distance meter.

4. The coordinate measurement device of claim 1, wherein the optical system is further configured to couple the third portion of the second beam into the third port of the fiber-optic coupler.

5. The coordinate measurement device of claim 1, wherein the fiber-optic coupler further includes a fourth port.

6. The coordinate measurement device of claim 5, wherein the fourth port is attached to a low-reflection termination.

7. The coordinate measurement device of claim 1, wherein the first wavelength is between 780 nm and 850 nm.

8. The coordinate measurement device of claim 1, wherein the second wavelength is a red wavelength or a green wavelength.

9. The coordinate measurement device of claim 1, wherein the first wavelength is an infrared wavelength and the second wavelength is a visible wavelength.

10. The coordinate measurement device of claim 1, wherein the first wavelength is a visible wavelength and the second wavelength is an infrared wavelength.

11. The coordinate measurement device of claim 1, wherein the first wavelength is a visible wavelength and the second wavelength is a visible wavelength.

12. A method for measuring three-dimensional coordinates of a target point located at a position in space, the method comprising steps of:

providing a coordinate measurement device that includes a first light source that produces a first light at a first wavelength, a second light source that produces a second light at a second wavelength different than the first wavelength, a fiber-optic coupler that includes at least a first port, a second port, and a third port, an optical system that includes an optical element achromatic at the first wavelength and the second wavelength, a first motor, a second motor, a first angle measuring device, a second angle measuring device, a distance meter, and a processor;

coupling a first portion of the first light into the first port;

coupling a second portion of the second light into the second port;

transmitting a third light from the third port, the third light containing a portion of the first portion and a portion of the second portion;

transmitting a portion of the third light through the optical system out of the coordinate measurement device as a first beam of light collimated at the first wavelength and the second wavelength;

directing the first beam of light in 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 first angle of rotation produced by the first motor and the second angle of rotation produced by the second motor;

measuring the first angle of rotation with the first angle measuring device;

measuring the second angle of rotation with the second angle measuring device;

reflecting a portion of the first beam from the target point as a second beam;

measuring a first distance from the coordinate measurement device to the target point with the distance meter, the measured distance based at least in part on a third portion of the second beam of light received by a first optical detector;

determining three-dimensional coordinates of the target point based at least in part on the first distance, the first angle of rotation, and the second angle of rotation; and

storing the determined three-dimensional coordinates.

13. The method of claim 12, further comprising steps of:

providing a position detector assembly, the position detector assembly including a position detector;

sending a fourth portion of the second beam onto the position detector;

obtaining a first signal from the position detector, the first signal responsive to the position of the fourth portion on the position detector;

sending a second signal to the first motor and sending a third signal to the second motor, the second signal and the third signal based at least in part on the first signal; and

adjusting the first direction of the first beam to the position in space of the target point.

14. The method of claim 12, wherein the step of providing a coordinate measurement device further includes providing the distance meter as an absolute distance meter.

15. The method of claim 12, wherein the step of measuring a first distance from the coordinate measurement device to the target point with the distance meter further includes a step of coupling the third portion of the second beam into the third port of the fiber-optic coupler.

16. The method of claim 12, wherein the step of providing a coordinate measurement device further includes providing the fiber-optic coupler with a fourth port.

17. The method of claim 16, wherein the step of providing a coordinate measurement device further includes providing the fiber-optic coupler with the fourth port attached to a low-reflection termination.