BEAM STEERING FOR LASER RADAR AND OTHER USES

• US 20130241761A1
• Filed: 03/15/2013
• Published: 09/19/2013
• Est. Priority Date: 03/16/2012
• Status: Abandoned Application

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Cooper, Alexander, Smith, Daniel G., Novak, W. Thomas
• Application Number:
  US13/840,093
• Publication Number:
  US 20130241761A1
• Time in Patent Office: Days
• US Class Current: 342/54
• CPC Class Codes: G01S 13/865 Combination of radar systems with lidar systems
• 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
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 26/108 having one or more prisms as scanning elements
• CPC Class Codes: G02B 5/122 cube corner, trihedral or triple reflector type
• CPC Class Codes: G06F 30/00 Computer-aided design [CAD]

Abstract

Optical systems suitable for use as or in laser radar systems and other uses include a beam-forming unit, a beam-scan unit, and a controller. The beam-forming unit includes a first optical element, and the beam-scan unit includes a second optical element. The first optical element is movable to shape and direct a substantially collimated optical beam along a nominal propagation axis to a target, and the second optical element includes at least one movable beam deflector that moves the optical beam in a scanning manner relative to the nominal propagation axis. The controller is coupled to the beam-forming unit and beam-scan unit, and is configured to induce movement of the first optical element required for shaping and directing the optical beam along the nominal propagation axis and to induce independent motion of the beam deflector of the second optical element as required to scan the optical beam relative to the nominal propagation axis. The beam deflector can be refractive or reflective.

Claims

1. An optical system, comprising:

a beam-forming unit comprising a first optical element;

a beam-scan unit comprising a second optical element; and

a controller coupled to the beam-forming unit and beam-scan unit;

wherein the first optical element is movable to shape and direct an optical beam out along a nominal propagation axis, and the second optical element comprises at least one movable beam deflector that moves the optical beam in a scanning manner relative to the nominal propagation axis; and

the controller is configured to induce movement of the first optical element as required for shaping and directing the optical beam along the nominal propagation axis and to induce motion of the beam deflector of the second optical element as required to scan the optical beam relative to the nominal propagation axis.

2. The system of claim 1, wherein:

the second optical element comprises a rotatable or tiltable actuator coupled to the controller and to which the second optical element is coupled; and

the controller is configured to actuate the actuator as required to produce scanning motion of the optical beam.

3. The system of claim 1, further comprising a transmit/receive system coupled to the controller and configured to send the optical beam to the target and to receive at least a portion of the optical beam as reflected from the target.

4. The system of claim 3, wherein:

the transmit/receive system further comprises a source of the optical beam; and

the source comprises a laser that produces the optical beam.

5. The system of claim 1, wherein the second optical element is movable independently of movement of the first optical element.

6. The system of claim 1, wherein the first optical element is adjustable to vary at least one of focus of the optical beam as incident on the target, width of the optical beam as incident on the target, shape of the optical beam as incident on the target, and direction of the nominal propagation axis relative to the beam-shaping optical system.

7. The system of claim 1, wherein the first optical element is a reflective optical element.

8. The system of claim 7, wherein:

the reflective optical element is a corner cube situated to receive the optical beam from a light source; and

the second optical element is situated to receive the optical beam from the corner cube and configured to return the optical beam to the corner cube as the second optical element is being moved relative to the corner cube.

9. The system of claim 1, wherein:

the beam-forming unit further comprises a focus-adjust device;

the beam-scan unit further comprises a rotation-adjust device;

the focus-adjust device is coupled to the first optical element and to the controller to move the first optical element as required to focus the optical beam on the target; and

the rotation-adjust device is coupled to the second optical element and to the controller to adjust at least one parameter associated with movement of the beam deflector.

10. The system of claim 9, wherein:

the beam-forming unit further comprises a reflective optical element; and

the focus-adjust device adjusts a linear position of the reflective optical element as required to focus the optical beam on the target.

30. The optical system of claim 1, configured as a laser radar system.

11. An optical system, comprising:

a beam-shaping optical system producing an optical beam;

a movable beam deflector directing the optical beam to a target; and

a beam-scan controller operably coupled to the beam deflector to produce an optical-beam scan angle, relative to a nominal propagation axis, based on an orientation of at least a portion of the beam-shaping optical system and a setting of the movable beam deflector.

12. The system of claim 11, wherein the optical beam is received from the beam-shaping optical system.

13. The system of claim 11, configured as a laser radar system, wherein the optical beam is an interrogation beam.

14. The system of claim 11, wherein the beam-scan controller is configured to establish a plurality of repeating scan angles.

15. The system of claim 11, wherein:

the beam-scan controller is configured to direct the optical beam in a pointing direction based on an orientation of at least a portion of the beam-shaping optical system; and

a movement axis of the beam deflector is parallel to the optical-beam pointing direction.

16. The system of claim 11, wherein the beam deflector comprises at least one rotatable optical element.

17. The system of claim 16, wherein the optical element comprises a mirror.

18. The system of claim 16, wherein the optical element comprises a wedge prism.

19. The system of claim 18, wherein the wedge prism is situated so that the optical beam produced by the beam-shaping optical system is incident at an angle to the wedge prism corresponding to a minimum deviation by the wedge prism.

20. The system of claim 16, wherein:

the beam deflector comprises a rotation stage; and

the optical element is coupled to the rotation stage.

21. The system of claim 16, wherein the beam deflector comprises a first rotatable wedge prism having a first wedge angle and a second rotatable wedge prism having a second wedge angle.

22. The system of claim 21, further comprising first and second rotation stages coupled to the first and second rotatable wedge prisms, respectively.

23. The system of claim 11, further comprising an optical detection system configured to receive at least a portion of interrogation optical beam from the target and to produce a target assessment based on the received portion.

24. The system of claim 23, wherein the target assessment is associated with a target distance or a target shape.

25. The system of claim 24, wherein:

the beam scan controller is configured to establish an interrogation optical beam pointing direction based on an orientation of at least a portion of the beam-shaping optical system and rotate the scan angle about the pointing direction so as to define a scan path; and

the target assessment produced by the optical detection system is at least one of a target dimension or a target surface profile.

26. The system of claim 25, wherein the target assessment is based on at least a magnitude of the received portion and the scan angle.

27. The system of claim 11, further comprising an optical detection system configured to receive at least a portions of the interrogation optical beam from the target and to produce a target assessment based on the received portions and the associated scan angles.

28. The system of claim 27, wherein:

the beam scan controller is configured to establish an interrogation optical beam pointing direction based on an orientation of at least a portion of the beam shaping optical system and to rotate the scan angle about the orientation so as to define a scan path; and

the target assessment produced by the optical detection system is at least one of a target feature dimension or target feature location.

29. The optical system of claim 11, configured as a laser radar system.

31. A method, comprising:

establishing a beam orientation of an optical beam along a nominal propagation axis using a beam-shaping optical system;

scanning the optical beam about the nominal propagation axis using a movable beam deflector;

delivering the scanned beam to a target;

receiving at least a portion of the beam back from the target; and

determining a characteristic of the target based on the received portion.

32. The method of claim 31, wherein the beam is scanned along a circular path relative to the nominal propagation axis.

33. The method of claim 31, further comprising:

adjusting the optical beam orientation based on the determined target characteristic; and

re-determining the target characteristic.

34. The method of claim 31, wherein:

the optical beam orientation is established with respect to a selected target feature; and

using the beam deflector, the optical beam is scanned about the selected target feature.

35. The method of claim 31, wherein the beam deflector comprises at least one refractive optical element.

36. The method of claim 35, wherein:

the refractive optical element comprises a wedge prism; and

scanning of the optical beam is produced by deviating the optical beam by transmission through the wedge prism as the wedge prism moves.

37. The method of claim 36, wherein the wedge prism is situated at an angle associated with a minimum optical beam deviation.

38. The method of claim 31, wherein:

the beam deflector comprises a reflective optical element; and

scanning of the optical beam is produced by deviating the optical beam by reflection from the reflective optical element as the reflective optical element moves.

39. An optical apparatus, comprising:

a beam-forming optical system configured to produce an optical beam;

a primary beam scanner situated and configured to produce a primary scan of the optical beam, using the beam-forming optical system;

a secondary beam scanner situated and configured to receive the optical beam from the primary beam scanner and produce a secondary scan, such that the scanning optical beam is directed along a scan path defined by the primary and secondary beam scanners; and

an optical detection system configured to estimate target distances associated with at least a portion of the scan path based on portions of the optical beam received from the target.

40. The apparatus of claim 39, further comprising a scan controller configured to establish the primary scan based on an at least one target distance produced by the optical detection system.

41. The apparatus of claim 39, wherein the secondary beam scanner includes at least one refractive optical element situated to receive the optical beam from the primary beam scanner and transmit the received optical beam along the scan path.

42. The apparatus of claim 41, wherein:

the at least one refractive optical element includes at least a first wedge prism and a second wedge prism;

the first wedge prism is situated and configured to receive the optical beam from the primary beam scanner and to transmit the received optical beam to the second wedge prism; and

the second wedge prism is situated and configured to transmit the optical beam from the first wedge prism along the scan path.

43. The apparatus of claim 39, wherein the secondary beam scanner includes at least one reflective optical element situated to receive the optical beam from the primary beam scanner and reflect the received optical beam along the scan path.

44. A laser radar apparatus, comprising:

an optical fiber situated to emit an optical beam along an axis;

a corner cube situated along the axis so as to receive the emitted optical beam;

a displacement stage coupled to the corner cube and configured to displace the corner cube along the axis;

a return reflector situated along the axis to receive the emitted optical beam from the corner cube and reflect the emitted optical beam as a returned beam to the corner cube;

a beam-forming lens situated along the axis to receive the returned beam from the corner cube and produce an interrogation beam;

a focus controller coupled to the displacement stage and configured to adjust a separation of the corner cube and the beam forming lens so as to focus the interrogation beam at a selected target distance;

a primary beam scanner configured to direct the axis toward a selected target location; and

a secondary beam scanner coupled to produce scan-inducing movement of an optical element so as to produce an angular deviation of the interrogation beam with respect to the axis so as to define a scan path.

45. The laser radar of claim 44, further comprising:

an optical receiver system configured detect at least portions of the interrogation optical beam returned from a target; and

a processor coupled to the optical receiver systems and configured to determine a target characteristic for at least a portion of the target based on the detected portions of the interrogation optical signal and the scan path.

46. The laser radar of claim 44, wherein the optical element of the secondary beam scanner comprises at least one refractive optical element, wherein the secondary beam scanner is coupled to produce a scan-inducing motion of the refractive optical element.

47. The laser radar of claim 46, wherein the refractive optical element comprises a wedge prism.

48. The laser radar of claim 44, wherein the optical element of the secondary beam scanner comprises at least one reflective optical element, wherein the secondary beam scanner is coupled to produce a scan-inducing motion of the reflective optical element.

49. The laser radar of claim 44, further comprising a rotatable reflective surface, wherein the secondary beam scanner is coupled to produce a rotation of the rotatable reflective surface.

50. A manufacturing system, comprising:

a design system including a data storage device;

a profile-shaping system coupled to the design system and configured to form a profile on a workpiece according to design data provided by the design system;

a profile-measurement system configured to measure the profile formed by the profile-shaping system, the profile-measurement system comprising a laser radar as recited in claim 44; and

an inspection system coupled to the profile-measurement system and to the data storage device, and configured to compare profile data from the profile-measurement system with design data from the design system.

51. The manufacturing system of claim 50, further comprising a repair system configured to, whenever the inspection system detects a significant error in the profile data from the profile-measurement system relative to the design data, perform a repair on a corresponding region of the workpiece.

52. A manufacturing system, comprising:

a design system including a data storage device;

a profile-shaping system coupled to the design system and configured to form a profile on a workpiece according to design data provided by the design system;

a profile-measurement system configured to measure the profile formed by the profile-shaping system, the profile-measurement system comprising an optical apparatus as recited in claim 44; and

an inspection system coupled to the profile-measurement system and to the data storage device, and configured to compare profile data from the profile-measurement system with design data from the design system.