Retroreflector covered by window

• US 20050185182A1
• Filed: 02/17/2005
• Published: 08/25/2005
• Est. Priority Date: 02/24/2004
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Brown, Lawrence B., Raab, Simon, Bridges, Robert E.
• Granted Patent: US 7,388,654 B2
• Time in Patent Office: Days
• US Class Current: 356/399
• 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 7/497 Means for monitoring or calibrating
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 5/122 cube corner, trihedral or triple reflector type

Abstract

Embodiments may comprise methods, apparatuses, systems, and one or more computer-readable media having computer-readable instructions thereon for adjusting a laser retroreflector to compensate for passing laser light through a window of the retroreflector comprising: determining an adjustment factor to compensate for propagation errors due to passing laser light through the window of the retroreflector; and adjusting a location of a reflection point of the retroreflector to minimize the propagation errors based on the adjustment factor.

Claims

1. A method for adjusting a laser retroreflector to compensate for passing laser light through a window of the retroreflector comprising:

determining an adjustment factor to compensate for propagation errors due to passing laser light through the window of the retroreflector; and

adjusting a location of a reflection point of the retroreflector to minimize the propagation errors based on the adjustment factor.

2. The method of claim 1 wherein the adjusting the location of the reflection point comprises:

optimizing a depth location of the reflection point of the retroreflector based on the adjustment factor.

3. The method of claim 2 wherein the optimizing comprises:

determining the depth location according the following formula;

d=T(1−

1/n)k

where T is the thickness of the window, n is the index of refraction of the window, and k is the adjustment factor.

4. The method of claim 3 wherein the optimizing further comprises:

determining the adjustment factor k wherein k is chosen to result in a minimum transverse error and a minimum radial error of the laser light in relation to the reflection point.

5. The method of claim 3 wherein T=1 mm, n=1.51509, k=1.0908, and d=0.3708 mm.

6. A laser retroflector apparatus comprising:

a window for passing laser light to the retroreflector;

a reflection point located on the retroreflector for reflecting the laser light after the laser light has passed through the window;

wherein the reflection point is located at a selected location to minimize propagation errors of the laser light due to the laser light passing through the window.

7. The laser retroflector apparatus of claim 6 wherein:

the selected location is an optimized depth location of the reflection point of the retroreflector based on an adjustment factor to reduce the propagation errors.

8. The laser retroflector apparatus of claim 7 wherein:

the selected location is structurally located according the following formula;

d=T(1−

1/n)k

where T is the thickness of the window, n is the index of refraction of the window, and k is the adjustment factor.

9. The laser retroflector apparatus of claim 8 wherein:

wherein k is chosen to structurally result in a minimum transverse error and a minimum radial error of the laser light in relation to the reflection point.

17. The laser retroflector apparatus of claim 6 wherein the retroflector comprises:

a cube-corner retroreflector formed of three mutually perpendicular reflective faces.

10. A system for adjusting a laser retroreflector to compensate for passing laser light through a window of the retroreflector comprising:

means for determining an adjustment factor to compensate for propagation errors due to passing laser light through the window of the retroreflector; and

means for adjusting a location of a reflection point of the retroreflector to minimize the propagation errors based on the adjustment factor.

11. The system of claim 10 wherein the means adjusting the location of the reflection point comprises:

means for optimizing a depth location of the reflection point of the retroreflector based on the adjustment factor.

12. The system of claim 11 wherein the means for optimizing comprises:

means for determining the depth location according the following formula;

d=T(1−

1/n)k

where T is the thickness of the window, n is the index of refraction of the window, and k is the adjustment factor.

13. The system of claim 12 wherein the means for optimizing further comprises:

means for determining the adjustment factor k wherein k is chosen to result in a minimum transverse error and a minimum radial error of the laser light in relation to the reflection point.

18. The system of claim 10 wherein the retroflector comprises:

a cube-corner retroreflector formed of three mutually perpendicular reflective faces.

14. One or more computer-readable media having computer-readable instructions thereon which, when executed by a computer, cause the computer to:

determine an adjustment factor to compensate for propagation errors due to passing laser light through a window of a retroreflector; and

determine a location of a reflection point of the retroreflector to minimize the propagation errors based on the adjustment factor.

15. The one or more computer-readable media having computer-readable instructions thereon of claim 14 which, when executed by a computer, cause the computer to:

optimize a depth location of the reflection point of the retroreflector based on the adjustment factor.

16. The one or more computer-readable media having computer-readable instructions thereon of claim 15 which, when executed by a computer, cause the computer to:

determine the depth location according the following formula;

d=T(1−

1/n)k

where T is the thickness of the window, n is the index of refraction of the window, and k is the adjustment factor.