Six degree-of-freedom laser tracker that cooperates with a remote sensor

• US 10,302,413 B2
• Filed: 10/14/2016
• Issued: 05/28/2019
• Est. Priority Date: 04/15/2011
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Bridges, Robert E.
• Primary Examiner(s): Murphy, Daniel L
• Application Number:
  US15/293,494
• Publication Number:
  US 20170030705A1
• Time in Patent Office: 956 Days
• Field of Search: 356 401
• 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 coordinate measuring device includes: a light source operable to emit a first light, the first light being visible light having a first wavelength; a fiber launch operable to receive the first light through a first optical fiber, to launch the first light into free space, and to collimate the launched first light into a first beam of light having a diameter_defined by the fiber launch, the first beam of light operable to leave the coordinate measuring device absent an intervening beam expander, the fiber launch being further coupled through the first optical fiber to a distance meter operable to measure a first distance to a retroreflector illuminated by the first beam of light; a first motor and a second motor operable 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 operable to measure the first angle of rotation and a second angle measuring device operable to measure the second angle of rotation; and, a processor operable to determine three-dimensional (3D) coordinates of the target based at least in part on the measured first angle of rotation, the measured second angle of rotation, and the measured first distance.

Claims

1. A coordinate measuring device comprising:

a light source operable to emit a first light, the first light being visible light having a first wavelength;

a fiber launch operable to receive the first light through a first optical fiber, to launch the first light into free space, and to collimate the launched first light into a first beam of light having a diameter defined by the fiber launch, the first beam of light operable to leave the coordinate measuring device absent an intervening beam expander, the fiber launch being further coupled through the first optical fiber to a distance meter operable to measure a first distance to a retroreflector illuminated by the first beam of light;

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

a processor operable to determine three-dimensional (3D) coordinates of the target based at least in part on the measured first angle of rotation, the measured second angle of rotation, and the measured first distance.

2. The coordinate measuring device of claim 1 wherein the first light is red light.

3. The coordinate measuring device of claim 1 wherein the light source is selected from the group consisting of:

a diode laser, a vertical cavity surface emitting laser (VCSEL), and a superluminescent diode.

4. The coordinate measuring device of claim 1 further comprising a first beam splitter operable to receive returned first light from the retroreflector, to send a first portion of the returned first light to the fiber launch, and to send a second portion of the returned first light to a position detector.

5. The coordinate measuring device of claim 4 further comprising a control system, the control system operable to adjust the first angle of rotation produced by the first motor and the second angle of rotation produced by the second motor to keep the first beam centered on the retroreflector, the adjusting of the first angle and the second angle based at least in part on a position of the second portion of the returned first light on the position detector.

6. The coordinate measuring device of claim 5 wherein the position detector is selected from the group consisting of:

a lateral-effect detector, a quadrant detector, a complementary metal-oxide-semiconductor (CMOS) array, and a charge-coupled device (CCD) array.

7. The coordinate measuring device of claim 1 wherein the distance meter is an absolute distance meter.

8. The system of claim 1 further comprising a Faraday isolator operable to pass the first light traveling in a forward direction away from the light source but to block the first light traveling in the reverse direction toward the light source, the Faraday isolator including an input optical fiber coupled to the first optical fiber, the Faraday isolator further including an output optical fiber, the output optical fiber being a single-mode optical fiber.