Measurement system having air temperature compensation between a target and a laser tracker

• US 9,482,755 B2
• Filed: 10/09/2014
• Issued: 11/01/2016
• Est. Priority Date: 11/17/2008
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Hoffer, John M., Cramer, Peter G., Bridges, Robert E., Steffensen, Nils P., Mehler, Robert C., Steffey, Kenneth, Lasley, Daniel G.
• Primary Examiner(s): Lapage, Michael P
• Application Number:
  US14/510,259
• Publication Number:
  US 20150022826A1
• Time in Patent Office: 754 Days
• Field of Search: 359/529
• US Class Current: 1/1
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/03 by measuring coordinates of points
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01C 15/004 Reference lines, planes or sectors
• CPC Class Codes: G01C 15/06 Surveyors' staffs; Movable markers
• CPC Class Codes: G01K 7/02 using thermoelectric elements, e.g. thermocouples
• CPC Class Codes: G01K 7/22 the element being a non-linear resistance, e.g. thermistor G01K7/26 takes precedence
• 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 17/74 Systems using reradiation of electromagnetic waves other than radio waves, e.g. IFF, i.e. identification of friend or foe
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 7/48 of systems according to group G01S17/00
• CPC Class Codes: G01S 7/481 Constructional features, e.g. arrangements of optical elements
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: G02B 5/12 Reflex reflectors
• CPC Class Codes: G02B 5/122 cube corner, trihedral or triple reflector type

Abstract

A target is provided having a retroreflector. A body is provided having a spherical exterior portion, the body containing a cavity. The cavity is sized to hold the retroreflector, the cavity open to the exterior of the body and having at least one surface opposite the opening, the retroreflector at least partially disposed in the cavity, wherein the retroreflector and at least one surface define a space therebetween. A transmitter is configured to emit an electromagnetic signal. A first actuator is configured to initiate emission of the electromagnetic signal, wherein the transmitter and the first actuator are affixed to the body.

Claims

1. A system for measuring a point on a surface, comprising:

a target having a body, a retroreflector, an interface member, a transmitter, a protector, and a temperature sensor, the body having at least a portion with a spherical curvature, the portion configured to contact the point on the surface;

wherein the retroreflector is coupled to the body;

wherein the interface member is coupled to the body adjacent the retroreflector;

wherein the transmitter is coupled to the interface member and configured to emit an electromagnetic signal;

the protector is coupled to and extending from the interface member, the protector having an open end, the open end being directly exposed to an environment to be measured;

wherein the temperature sensor is configured to directly measure an air temperature through the open end and configured to send the measured air temperature to the transmitter, wherein the retroreflector, the transmitter, and the temperature sensor are coupled to the body; and

a processor configured to determine an index of refraction of air along a measurement path, the index of refraction based at least in part on a plurality of air temperatures measured by the temperature sensor at a plurality of positions between a laser tracker and the target.

2. The target of claim 1 wherein the temperature sensor is a thermistor, RTD or a thermocouple.

3. The target of claim 1 wherein the protector includes perforations.

4. The target of claim 1 further comprising an insulation member disposed between the body and the temperature sensor.

5. The target of claim 4 wherein the protector is disposed between the insulation member and the temperature sensor.