Locator camera arrangement having multiple light sources

• US 9,631,922 B2
• Filed: 11/16/2015
• Issued: 04/25/2017
• Est. Priority Date: 04/05/1999
• Status: Expired due to Term

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Bridges, Robert E., Brown, Lawrence B., West, James K., Ackerson, D. Scott
• Primary Examiner(s): LEE, HWA S
• Application Number:
  US14/942,683
• Publication Number:
  US 20160069665A1
• Time in Patent Office: 526 Days
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/02 for measuring length, width or thickness G01B11/08 takes precedence
• CPC Class Codes: G01B 11/026 by measuring distance between sensor and object G01B11/0608 takes precedence
• CPC Class Codes: G01B 11/03 by measuring coordinates of points
• CPC Class Codes: G01B 9/02012 using temporal intensity variation
• 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 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49

Abstract

A method for measuring a distance includes modulating the light beam at a first frequency, receiving a second beam by the optical detector to produce a first electrical signal having the first frequency and a first phase; modulating the light beam at a second frequency different than the first frequency; receiving the second beam by the optical detector to produce a second electrical signal having the second frequency and a second. After these steps, the retroreflector is moved while modulating the light beam continuously at the second frequency; and a first distance to the retroreflector is determined based at least in part on a the first and second frequencies and phases.

Claims

1. A laser based coordinate measuring device, comprising:

a distance meter that measures distance based at least in part on the speed of light;

a structure that is rotatable by a first angle and a second angle about two substantially orthogonal axes, the structure launching a beam from the distance meter;

a first encoder for measuring the first angle;

a second encoder for measuring the second angle;

a retroreflector target disposed remote from the rotatable structure;

a locator camera, which comprises an optical system having a lens, a photosensitive array, and a plurality of light sources, disposed on the rotatable structure for determining an approximate location of the target, wherein;

the plurality of light sources emits a cone of light for illuminating the retroreflector target;

wherein a first ray of light emitted by one of the plurality of light sources travels to the retroreflector target in a straight line, a second ray of light reflected by the retroreflector target travels to the lens in a straight line and forms a pattern of light on the photosensitive array;

an electronics system that analyzes the pattern of light on the photosensitive array to determine the approximate angular direction to the retroreflector target; and

an actuator system to orient the rotatable structure in accordance with the location determined by the locator camera.

2. The device of claim 1, wherein the distance meter is coupled to the structure by an optical fiber.

3. The device of claim 1, wherein a plurality of identical light sources are disposed in a ring surrounding the lens.

4. The device of claim 2, wherein a plurality of identical light sources are disposed in a ring surrounding the lens.