LASER METROLOGY SYSTEM AND METHOD

• US 20080309949A1
• Filed: 06/13/2008
• Published: 12/18/2008
• Est. Priority Date: 06/13/2007
• Status: Active Grant

• Current Assignee: Nikon Metrology NV (Nikon Corporation)
• Original Assignee: Metris Canada Inc.
• Inventors: Rueb, Kurt D.
• Granted Patent: US 7,876,457 B2
• Time in Patent Office: Days
• US Class Current: 356/614
• 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 7/4812 transmitted and received beams following a coaxial path

Abstract

A laser metrology system for determining a location of a target utilizes a laser projector having a laser source for projecting a laser beam. A rotating head directs the laser beam in a lateral direction. A sensor associated with the laser projector is capable of sensing the laser beam. A reflective target is configured to reflect the laser beam projector from the laser source toward the sensor in a manner indicative of the angle of the rotating head and the pulse of the laser beam to determine location of the target.

Claims

1. A laser metrology system for determining a location of a target, comprising:

a laser projector having a laser source for projecting a laser beam and a rotating head directing the laser beam in a lateral direction,

a sensor associated with said laser projector and being capable sensing the laser beam;

a reflective target configured to reflect the laser beam projected from said laser source toward said sensor in a manner indicative of an angle of said rotating head and pulse of said laser beam thereby determining the location of the target.

2. The laser metrology system set forth in claim 1, wherein said laser projector houses said sensor.

3. The laser metrology system set forth in claim 1, wherein said sensor communicates with a computer programmed to determine the location of the target from a signal received from said sensor.

4. The laser metrology system set forth in claim 1, wherein said laser projector includes a cylindrical lens for generating a fan shaped laser beam capable of generating a reflective signal off said reflective target indicative of a three dimensional location of said reflective target.

5. The laser metrology system set forth in claim 1, wherein said laser projector includes two cylindrical lenses for generating two fan shaped laser beams oriented at about 90 degrees and being capable of producing two a reflective signals off said reflective target indicative of a three dimensional location of said reflective target.

6. The laser metrology system set forth in claim 1, wherein said reflective target is a retro-reflective sphere.

7. The laser metrology system set forth in claim 1, wherein said laser projector includes a stationary mount disposed at a known location.

8. The laser metrology system set forth in claim 1, wherein said laser projector includes a collimator and a mirror for directing the laser beam through a lens thereby generating the fan shaped laser beam.

9. The laser metrology system set forth in claim 7, wherein said mirror and said lens rotates through 360 degrees at a substantially constant speed.

10. The laser metrology system set forth in claim 1, wherein said laser source projects said laser beam along a vertical axis through a collimator to a rotating mirror thereby redirecting said laser beam in a direction lateral to said vertical axis.

11. The laser metrology system set forth in claim 1, wherein said projector includes a beam splitter for redirecting a signal received from said reflective target toward said sensor.

12. A method of determining a position of a target, comprising the steps of:

providing a source of a projected laser beam, a sensor and head for directing said laser beam;

generating a projected laser beam from said source;

directing said laser beam through said head in a lateral direction toward a target; and

said target reflecting a reflected laser beam toward said sensor in a manner indicative of at least one of an elevational, horizontal angular orientation and other geometric constraint of said target relative to said sensor;

said sensor signaling a computer the angular orientation of said target relative to said sensor and said computer determining the location of said target from said angular orientation of said target relative to said sensor.

13. The method set forth in claim 12, wherein said step of providing a head is further defined by providing a cylindrical lens with said head thereby modifying said projected laser beam into a fan shaped pattern.

14. The method set forth in claim 12, wherein said step of providing a head is further defined by providing cooperating cylindrical lenses with said head thereby modifying said projected laser beam into a pair of fan shaped patterns oriented a predetermined angle of about forty five degrees.

15. The method set forth in claim 12, further including the step of rotating said head thereby projecting said projected laser beam along a 360°

lateral direction.

16. The method set forth in claim 12, wherein said step of generating said projected laser beam is further defined by generating said projected laser beam in a substantially vertical direction.

17. The method set forth in claim 12, wherein said step of reflecting said laser beam toward said sensor is further defined by directing said projected laser beam through said head in a reverse direction from source of said laser beam to said sensor.

18. The method set forth in claim 17, further including the step of splitting reflected laser beam from said projected laser beam toward said sensor.

19. A laser metrology system for determining the position of a target, comprising:

a laser projector including a laser source, sensor and rotating head directing a transmitted laser beam laterally and a lens generating a transmitted laser beam; and

a retro-reflective target reflecting said transmitted laser beam to said sensor indicative of the head angle and the pulse generated by said rotating head.

20. The laser metrology system as defined in claim 19, wherein said head includes two angularly related lenses generating two fan-shaped laser beams and said sensor determining the horizontal and elevational angle from the projector to said target based on the relative timing of the received pulses from said targets.

21. The laser metrology system as defined in claim 19, wherein said retro-reflective target is a retro-reflective sphere.

22. The laser metrology system as defined in claim 19, wherein said laser projector includes a stationary base at a predetermined known location including said laser, collimator and sensor, and a rotating head including a mirror and said lens which rotates through 360 degrees at a substantially constant speed.

23. The laser metrology system as defined in claim 19, wherein said laser projects a transmitted laser beam upwardly in a vertical axis through said collimator to a rotating mirror and said mirror reflects said laser beam generally horizontally.

24. The laser metrology system as defined in claim 19, wherein said rotating head includes two cylindrical lenses offset in said rotating head at an angle of about 90 degrees.

25. The laser metrology system as defined in claim 19, wherein said lens is a cylindrical lens generating a planar fan-shaped laser beam.

26. A method of determining a position of a target, comprising:

generating a transmitted laser beam;

directing said transmitted laser beam through lenses generating a rotating transmitted laser beam onto a retro-reflective target; and

said retro-reflective target reflecting said angular laser light through said lens to a sensor connected to a computer, said computer determining at least one of a horizontal, elevation angle, and other geometric constraint from the transmitter to the target based on the relative timing of the received pulses from the targets indicative of an horizontal and an elevation angle.

27. The method as defined in claim 26, including the step of mounting said lens in a rotating head.

28. The method as defined in claim 26, including the step of generating said transmitted laser beam upwardly in a vertical axis.

29. The method as defined in claim 26, including the step of deflecting said laser beam laterally with a rotating mirror through said lens.

30. The method as defined in claim 26, including the step of directing said laser beam through cylindrical lenses generating two angularly related planar fan-shaped rotating laser beams.