Multi-axis magnetically actuated device

• US 6,388,789 B1
• Filed: 09/19/2000
• Issued: 05/14/2002
• Est. Priority Date: 09/19/2000
• Status: Active Grant

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: Bernstein, Jonathan
• Primary Examiner(s): Phan, James
• Application Number:
  US09/666,018
• Time in Patent Office: 602 Days
• Field of Search: 359/196-226, 359/872, 359/566, 359/900, 310/36, 310/40.R, 310/46, 310/66, 310/208, 385/16-18
• US Class Current: 359/198.1
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/058 Rotation out of a plane parallel to the substrate
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: B81C 1/00214 Processes for the simultaneaous manufacturing of a network or an array of similar microstructural devices
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/3572 Magnetic force magnetic forces controlling reflecting elements in general G02B26/085; magneto-optic devices G02F1/09
• CPC Class Codes: G02B 6/358 Latching of the moving element, i.e. maintaining or holding the moving element in place once operation has been performed; includes a mechanically bistable system
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: Y10S 359/90 Methods

Abstract

A multi-axis magnetically actuated device, an array of multi-axis magnetically actuated devices, and a method of fabrication of a multi-axis magnetically actuated device are disclosed. In addition, disclosed is an optical switch comprised of an array of multi-axis magnetically actuated devices and an array of ports adapted to receive an optical waveguide such as, for example, an optical fiber. The multi-axis magnetically actuated device of the invention is capable of rotational movement in two orthogonal directions. In one embodiment, the multi-axis magnetically actuated device comprises two nested rotational members, an inner rotational member nested within an outer rotational member that in turn is nested within a base member. The inner rotational member is mounted by two inner torsional flexures to the outer rotational member that in turn is mounted by two outer torsional flexures to the base member. The inner torsional flexures define an inner axis of rotation while the outer torsional flexures define an outer axis of rotation. The rotational motions of each rotational member arise in response to an interaction between a magnetic influence and a magnetic moment generated by a current passing through coils arranged adjacent to a surface of the inner rotational member. Bulk micromachining techniques enable the members to be formed from a monolithic silicon wafer and can produce a member with a smooth surface. The smooth surface of a member may function as a reflector. In one embodiment, the inner rotational member functions as a reflector.

Claims

1. A multi-axis magnetically actuated device comprising,

a base member,

a first rotational member mounted to the base member and for rotational movement about a first axis,

a second rotational member having first and second opposing surfaces and being mounted to the first rotational member and for rotational movement about a second axis,

a first coil pair arranged adjacent to the first surface of the second rotational member and adapted to produce a rotational movement of the first and second rotational members about the first axis in response to interaction with a first magnetic influence, and

a second coil pair arranged adjacent to the first surface of the second rotational member and adapted to produce a rotational movement of the second rotational member about the second axis in response to interaction with a second magnetic influence.

2. The device of claim 1 wherein,

the first rotational member is mounted to the base member by a first pair of torsional flexures arranged on the first rotational member and the base member to permit rotational movement of the first and second rotational members about the first axis, and

the second rotational member is mounted to the first rotational member by a second pair of torsional flexures arranged on the second rotational member and the first rotational member to permit rotational movement of the second rotational member about the second axis.

3. The device of claim 2 wherein at least one of the first pair of torsional flexures and the second pair of torsional flexures comprises a material from the group consisting of silicon, polysilicon, silicon-on-insulator, silicon nitride and silicon carbide.

4. The device of claim 2 wherein at least one of the first pair of torsional flexures and the second pair of torsional flexures comprises nickel.

5. The device of claim 2 wherein at least one of the first pair of torsional flexures and the second pair of torsional flexures further comprises a polymer coating.

6. The device of claim 1 wherein the second surface of the second rotational member is reflective.

7. The device of claim 1 further comprising a surface treatment applied to the second surface of the second rotational member.

8. The device of claim 7 wherein the surface treatment comprises a multi-layer dielectric reflector.

9. The device of claim 7 wherein the surface treatment comprises at least one metal layer.

10. The device of claim 9 wherein the at least one metal layer is further adapted for reflection.

11. The device of claim 9 wherein the at least one metal layer is selected from the group consisting of aluminum, silver, gold, and alloys thereof.

12. The device of claim 9 wherein the at least one metal layer is arranged to compensate for thermal stress-induced curvature of the second rotational member.

13. The device of claim 7 wherein the surface treatment comprises a diffraction grating.

14. The device of claim 1 further comprising an intermediate medium disposed between at least one of the first coil pair and the second coil pair and the second rotational member.

15. The device of claim 14 wherein the intermediate medium comprises an insulative layer.

16. The device of claim 14 wherein the intermediate medium comprises a silicone rubber layer.

17. The device of claim 1 further comprising,

a magnet adjacent to the second rotational member and having a first and second opposing surfaces, and

a first pole piece adjacent to the first opposing surface of the magnet, wherein the magnet and the first pole piece are arranged to produce a magnetic field gradient between the first opposing surface and the second opposing surface of the second rotational member.

18. The device of claim 17 further comprising, a second pole piece adjacent to the second opposing surface of the magnet, wherein the magnet, the first pole piece, and the second pole piece are arranged to produce a magnetic field gradient between the first opposing surface and the second opposing surface of the second rotational member.

19. The device of claim 17 wherein the first pole piece comprises an iron-base alloy containing about 45 percent to about 80 percent nickel.

20. The device of claim 1 wherein the first and second magnetic influences derive from a single magnet source.

21. A method of actuating a multi-axis magnetically actuated device, the method comprising,

applying a first electric current to a first coil pair arranged adjacent to a first surface of a second rotational member connected to a first rotational member to induce a rotational movement of the first and second rotational members about a first axis in response to interaction with a first magnetic influence, and

applying a second electric current to a second coil pair arranged adjacent to the first surface of the second rotational member to induce a rotational movement of the second rotational member about a second axis in response to interaction with a second magnetic influence.

22. The method of claim 21 comprising, applying the second electric current to the second coil pair to induce a rotational movement of the second rotational member about the second axis and substantially orthogonal to the rotational movement about the first axis.

23. The method of claim 21 further comprising the step of deflecting an optical ray in response to at least one of the rotational movement of the first and second rotational members about the first axis and the rotational movement of the second rotational member about the second axis.

24. A method of fabricating a multi-axis magnetically actuated device, the method comprising,

providing a base member,

mounting a first rotational member to the base member for rotational movement about a first axis,

mounting a second rotational member having first and second opposing surfaces to the first rotational member for rotational movement about a second axis,

arranging a first coil pair adjacent to the first surface of the second rotational member adapted to produce a rotational movement of the first and second rotational members about the first axis in response to interaction with a first magnetic influence, and

arranging a second coil pair adjacent to the first surface of the second rotational member adapted to produce a rotational movement of the second rotational member about the second axis in response to interaction with a second magnetic influence.

25. A device comprising, a plurality of multi-axis magnetically actuated devices arranged in an array, each of the multi-axis magnetically actuated devices having,

a base member,

a first rotational member mounted to the base member and for rotational movement about a first axis,

a second rotational member having first and second opposing surfaces and being mounted to the first rotational member and for rotational movement about a second axis,

a first coil pair arranged adjacent to the first surface of the second rotational member and adapted to produce a rotational movement of the first and second rotational members about the first axis in response to interaction with a first magnetic influence, and

a second coil pair arranged adjacent to the first surface of the second rotational member and adapted to produce a rotational movement of the second rotational member about the second axis in response to interaction with a second magnetic influence.

26. A device comprising, an optical switch wherein the optical switch comprises at least one multi-axis magnetically actuated device having,

a base member,

a first rotational member mounted to the base member and for rotational movement about a first axis,

a second rotational member having first and second opposing surfaces and being mounted to the first rotational member and for rotational movement about a second axis,

a first coil pair arranged adjacent to the first surface of the second rotational member and adapted to produce a rotational movement of the first and second rotational members about the first axis in response to interaction with a first magnetic influence, and

a second coil pair arranged adjacent to the first surface of the second rotational member and adapted to produce a rotational movement of the second rotational member about the second axis in response to interaction with a second magnetic influence.

27. A multi-axis magnetically actuated device comprising,

a base member,

a first rotational member,

a first mounting means for mounting the first rotational member to the base member and for permitting rotational movement about a first axis,

a second rotational member having first and second opposing surfaces,

a second mounting means for mounting the second rotational member to the first rotational member and for permitting rotational movement about a second axis,

a first magnetic moment means arranged adjacent to the first surface of the second rotational member for producing a rotational movement of the first and second rotational members about the first axis in response to interaction with a first magnetic influence, and

a second magnetic moment means arranged adjacent to the first surface of the second rotational member for producing a rotational movement of the second rotational member about the second axis in response to interaction with a second magnetic influence.