Mechanical sensors of electromagnetic fields

• US 6,835,926 B2
• Filed: 04/12/2002
• Issued: 12/28/2004
• Est. Priority Date: 04/12/2001
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Weitekamp, Daniel P., Lambert, Bruce
• Primary Examiner(s): Luu, Thanh X.
• Application Number:
  US10/123,084
• Publication Number:
  US 20020162947A1
• Time in Patent Office: 991 Days
• Field of Search: 324/529, 731/04, 731/05, 250/225, 250/306, 250/307, 250/308, 250/309, 250/310, 250/311, 250/234
• US Class Current: 250/234
• CPC Class Codes: G01R 29/0885 using optical probes, e.g. electro-optical, luminescent, glow discharge, or optical interferometers
• CPC Class Codes: G01R 29/12 Measuring electrostatic fields or voltage-potential

Abstract

Sensing devices and techniques based on motion of a mechanical oscillator caused by electromagnetic interaction, such as a magnetic polarization with a magnetic field or an electric polarization with an electric field.

Claims

1. A device, comprising:

a micro mechanical oscillator exhibiting an electromagnetic polarization, wherein said electromagnetic polarization includes a static magnetic dipole moment;

a circuit unit located adjacent to said micro oscillator to produce a temporally-changing electromagnetic signal in the space where said micro mechanical oscillator is located, wherein said electromagnetic polarization interacts with said electromagnetic signal to cause said micro mechanical oscillator to move; and

a motion detection module to measure motion of said micro mechanical oscillator to produce a motion signal indicating a property of said electromagnetic signal.

2. The device as in claim 1, wherein said micro mechanical oscillator includes a ferromagnetic material which exhibits said static magnetic dipole moment.

3. The device as in claim 1, further comprising a plurality of additional micro mechanical oscillators each substantially identical to said micro mechanical oscillator to form an oscillator array that includes said micro mechanical oscillator and said plurality of additional micro mechanical oscillators, wherein said oscillator array interacts with said evanescent field to cause light transmitted through said fiber to have information on said property of said electromagnetic signal.

4. The device as in claim 1, further comprising a substrate, wherein said micro mechanical oscillator comprises:

two support units spaced from each other and formed on said substrate, and

a mechanical suspension comprising one end engaged to one of said two support units and another end engaged to another support unit, said mechanical suspension operable to oscillate around an axis.

5. A device, comprising:

a micro mechanical oscillator exhibiting an electromagnetic polarization, wherein said electromagnetic polarization includes a static electric dipole moment;

a circuit unit located adjacent to said micro oscillator to produce a temporally-changing electromagnetic signal in the space where said micro mechanical oscillator is located, wherein said electromagnetic polarization interacts with said electromagnetic signal to cause said micro mechanical oscillator to move; and

a motion detection module to measure motion of said micro mechanical oscillator to produce a motion signal indicating a property of said electromagnetic signal.

6. The device as in claim 5, wherein said micro mechanical oscillator includes a ferroelectric material which exhibits said static electric dipole moment.

7. The device as in claim 5, further comprising a plurality of additional micro mechanical oscillators each substantially identical to said micro mechanical oscillator to form an oscillator array that includes said micro mechanical oscillator and said plurality of additional micro mechanical oscillators, wherein said oscillator array interacts with said evanescent field to cause light transmitted through said fiber to have information on said property of said electromagnetic signal.

8. The device as in claim 5, further comprising a substrate, wherein said micro mechanical oscillator comprises:

two support unite spaced from each other and formed on said substrate, and

a mechanical suspension comprising one end engaged to one of said two support units and another end engaged to another support unit, said mechanical suspension operable to oscillate around an axis.

9. The device as in claim 5, wherein said motion detection module comprises:

a light source to produce an optical beam that illuminates at least a part of said micro mechanical oscillator; and

an optical detector located to receive light reflected or scattered from said micro mechanical oscillator to produce a defector signal as said motion signal.

10. The device as in claim 9, further comprising:

an optical waveguide to direct the optical beam from said light source to said micro mechanical oscillator and to guide at least a part of said light reflected or scattered from said micro mechanical oscillator to said optical detector.

11. A device, comprising:

a micro mechanical oscillator exhibiting an electromagnetic polarization,

a circuit unit located adjacent to said micro oscillator to produce a temporally-changing electromagnetic signal in the space where said micro mechanical oscillator is located, wherein said electromagnetic polarization interacts with said electromagnetic signal to cause said micro mechanical oscillator to move; and

a motion detection module to measure motion of said micro mechanical oscillator to produce a motion signal indicating a property of said electromagnetic signal, wherein said motion detection module comprises a light source to produce an optical beam that illuminates at least a part of said micro mechanical oscillator, and an optical detector located to receive light reflected or scattered from said micro mechanical oscillator to produce a detector signal as said motion signal,

wherein said motion detection module further includes a fiber that receives said optical beam and directs said optical beam to said optical detector,

wherein said fiber has a portion of fiber cladding removed to form an optical surface within an evanescent field of light guided in said fiber, and

wherein said micro mechanical oscillator is located relative to said optical surface to interact with said evanescent field to cause light transmitted through said fiber to have information on motion of said micro mechanical oscillator.

12. The device as in claim 11, wherein said circuit unit includes two electrodes spaced from each other and wherein said micro mechanical oscillator is located between said two electrodes.

13. The device as in claim 11, wherein said micro mechanical oscillator is a torsional oscillator that rotates around a rotational axis in response to a torque produced by an interaction between said electromagnetic polarization and said electromagnetic signal.

14. The device as in claim 11, further comprising a plurality of additional micro mechanical oscillators each substantially identical to said micro mechanical oscillator to form an oscillator array that includes said micro mechanical oscillator and said plurality of additional micro mechanical oscillators, wherein said oscillator array interacts with said evanescent field to cause light transmitted through said fiber to have information on said property of said electromagnetic signal.

15. The device as in claim 11, further comprising a plurality of additional micro mechanical oscillators each substantially identical to said micro mechanical oscillator to form an oscillator array that includes said micro mechanical oscillator and said plurality of additional micro mechanical oscillators, wherein said oscillator array are located to be illuminated by said optical beam to produce a scattered optical signal received by said optical detector.

16. The device as in claim 15, wherein said oscillator array is a linear array along the fiber core of said fiber.

17. The device as in claim 15, wherein said oscillator array is a two-dimensional array.

18. The device as in claim 11, wherein said micro mechanical oscillator has a mechanical resonance frequency approximately equal to a frequency of said electromagnetic signal.

19. The device as in claim 11, further comprising a substrate on which said micro mechanical oscillator is formed, wherein said micro mechanical oscillator includes:

two support units spaced from each other and formed on said substrate;

a mechanical suspension having one end engaged to one of said two support units and another end engaged to another support unit.

20. The device as in claim 19, wherein said mechanical suspension is formed of a material exhibiting said electromagnetic polarization.

21. The device as in claim 19, wherein said micro mechanical oscillator includes a layer of a material formed on said mechanical suspension, said material exhibiting said electromagnetic polarization.

22. The device as in claim 19, wherein said circuit unit is integrated on said substrate.

23. The device as in claim 11, wherein said micro mechanical oscillator comprises a ferromagnetic component which exhibits a static magnetic dipole moment.

24. The device as in claim 11, wherein said micro mechanical oscillator comprises a ferroelectric component which exhibits a static electric dipole moment.

25. The device as in claim 11, wherein said micro mechanical oscillator comprises a micro electromechanical system.

26. The device as in claim 11, wherein said micro mechanical oscillator comprises a suspension member and at least a portion of said suspension member exhibits said electromagnetic polarization.

27. The device as in claim 26, wherein said micro mechanical oscillator comprises an optically reflective surface that is fixed relative to said suspension member.

28. The device as in claim 11, further comprising a substrate, wherein said micro mechanical oscillator comprises:

two support units spaced from each other and formed on said substrate, and

a mechanical suspension comprising one end engaged to one of said two support units and another end engaged to another support unit, said mechanical suspension operable to oscillate around an axis.

29. The device as in claim 28, wherein said mechanical suspension comprises a material exhibiting said electromagnetic polarization.

30. The device as in claim 28, wherein said micro mechanical oscillator comprises a layer of a material formed on said mechanical suspension, said material exhibiting said electromagnetic polarization.

31. The device as in claim 30, wherein said material is a ferroelecric material.