Method and Apparatus for Two-Axis, High-Speed Beam Steering

• US 20080123169A1
• Filed: 03/08/2005
• Published: 05/29/2008
• Est. Priority Date: 03/08/2004
• Status: Active Grant

• Current Assignee: Board of Regents Nevada System of Higher Education (State of Nevada)
• Original Assignee: Board of Regents of The University and Community C
• Inventors: Sutko, John L., Publicover, Nelson George
• Granted Patent: US 7,796,314 B2
• Time in Patent Office: Days
• US Class Current: 359/224
• CPC Class Codes: G02B 21/0048 scanning mirrors, e.g. rotating or galvanomirrors, MEMS mirrors

Abstract

Dual axis, beam-steering devices are disclosed. An exemplary device includes a support platform having a top surface. A reflective surface is coupled to the top surface of the support platform. First and second galvanometers are coupled via respective linkages to the support platform such that the first galvanometer rotates the support platform about a first rotational axis, and the second galvanometer rotates the support platform about a second rotational axis that is orthogonal to the first rotational axis. The support platform can be simultaneously rotated with respect to both the first rotational axis and the second rotational axis to steer a beam of electromagnetic energy (e.g. light beam) reflected by the reflective surface.

Claims

1. A two spatial axes electromagnetic radiation directing device, comprising:

a single reflective surface capable of tip-tilt movement; and

a set of closed-loop galvanometers actuators.

2. The device of claim 1, wherein the position feedback signals from said device are used to establish the position of the radiation at any time.

3. The device of claim 1, further comprising:

a support platform having a top surface and at least one side surface;

wherein the reflective surface is attached to the top surface of the support platform;

a first galvanometer attached via a first linkage to the side surface of the support platform;

a second galvanometer attached via a second linkage to the side surface of the support platform, substantially orthogonal to the first galvanometer with respect to the support platform, such that the first galvanometer rotates the support platform with respect to a first axis, and the second galvanometer rotates the support platform with respect to a second axis, the first axis orthogonal to the second axis, wherein the support platform can be simultaneously rotated with respect to both the first axis and the second axis to steer a beam of electromagnetic energy reflected by the reflective surface.

4. The device of claim 3, wherein the first galvanometer comprises a first active drive, the first active drive defining a position of the first linkage, and the second galvanometer comprises a second active drive, the second active drive defining a position of the second linkage, such that the first active drive and the second active drive together provide position information describing a position of the reflective surface with respect to the first axis and the second axis.

5. The device of claim 4, further comprising a position sensing means, the position sensing means determining a position of the reflective surface with respect to the first axis and the second axis.

6. The device of claim 5, wherein the position sensing means comprises means for reading position feedback signals received from the first and second galvanometers.

7. The device of claim 5, wherein the position sensing means comprises means for optically detecting energy reflected off a surface of the reflective surface.

8. The device of claim 5, further comprising a fixed support structure, wherein the position sensing means comprises means for making capacitive measurements between the support platform and the fixed platform.

9. The device of claim 5, wherein the position sensing means comprises a electrostatically-charged silicon means.

10. The device of claim 4, further comprising a first plurality of silicon combs for sensing a first position of the first galvanometer shaft and a second plurality of silicon combs for sensing a second position of the second galvanometer shaft, the first plurality and the second plurality together providing position information for the mirror with respect to the first axis and the second axis.

11. The device of claim 3, further comprising a first passive linkage connecting a fixed platform to the side surface of the support opposite from the first linkage'"'"'s attachment location on the side surface with respect to the support platform along the first axis.

12. The device of claim 11, further comprising a second passive linkage connecting the fixed platform to the side surface of the support opposite from the second linkage'"'"'s attachment location on the side surface with respect to the support platform along the second axis.

13. The device of claim 11, further comprising a third galvanometer attached via a third linkage to the side surface of the support platform opposite from the attachment location of the first galvanometer linkage with respect to the support platform along the first axis.

14. The device of claim 13, further comprising a fourth galvanometer attached via a fourth linkage to the side surface of the support platform opposite from the attachment location of the second galvanometer linkage with respect to the support platform along the second axis.

15. The device of claim 14, wherein the third galvanometer is wired in a first direction and the fourth galvanometer is wired in a second direction, the second direction opposite from the first direction.

16. The device of claim 3, wherein the first galvanometer is wired in a first direction and the second galvanometer is wired in a second direction, the second direction opposite from the first direction.

17. The device of claim 3, further comprising a heat sink device, the heat sink device in sufficient contact with the first galvanometer and the second galvanometer to remove heat from the first galvanometer and the second galvanometer.

18. The device of claim 3, wherein the first linkage and the second linkage each comprises a first section and a compressible means positioned between the linkage shaft and the support platform, the compressible means allowing a variable combined length of the first section and the compressible means.

19. The device of claim 3, wherein the support platform has a substantially rectangular shape defined by a first side portion, a second side portion, a third side portion, and a fourth side portion.

20. The device of claim 19, wherein the first linkage is noncompliant in rotation about the second axis and has a varying length to permit rotation of the support platform about the first axis and wherein the second linkage is noncompliant in rotation about the first axis and has a varying length to permit rotation of the support platform about the second axis.

21. The device of claim 3, wherein the first and second linkages each have a connecting interface, the connecting interface receiving an insert from the support platform and securing the insert to the interface via a pin, the pin fixed to the connecting interface and extending through the received insert, wherein the insert having a curved slot that allows the pin to engage the insert at various positions along an angular range within the curved slot.

22. The device of claim 3, wherein the support platform comprises silicon.

23. The device of claim 3, wherein the first and second linkages comprise silicon.

24. The device of claim 13, wherein the third linkage comprises silicon.

25. The device of claim 14, wherein the fourth linkage comprises silicon.

26. The device of claim 3, wherein the reflective surface comprises a dielectric coating.

27. The device of claim 3, wherein the reflective surface comprises a metal coating.

28. The device of claim 3, wherein the reflective surface can be rotated over a total mechanical angle of at least four degrees.

30. The device of claim 3, wherein the reflective surface has a minimum width of three millimeters.

29. The device of clam 3, wherein the reflective surface can be rotated at a frequency of at least 1.5 kHz.

31. A method of steering a beam of electromagnetic energy with respect to two spatial axes, the method comprising:

directing a beam of electromagnetic energy to a reflective surface; and

actuating a plurality of galvanometers to manipulate the reflective surface in a tip-tilt movement to direct the beam of electromagnetic energy.

32. The method of claim 31, wherein actuating a plurality of galvanometers comprises the first galvanometer rotating the reflective surface with respect to a first axis, a second galvanometer rotating the reflective surface with respect to a second axis, wherein the first axis is orthogonal to the second axis.

33. The method of claim 31, further comprising generating feedback signals that describe a direction of the directed beam.

34. The method of claim 33, wherein the feedback signals describe the direction of the directed beam with respect to the first axis.

35. The method of claim 33, wherein the feedback signals describe the direction of the directed beam with respect to the second axis.