Method and apparatus for transmitting energy via a laser beam

• US 20050190427A1
• Filed: 01/20/2005
• Published: 09/01/2005
• Est. Priority Date: 02/21/2004
• Status: Active Grant

• Current Assignee: Astrium GmbH (Airbus SE)
• Original Assignee: Astrium GmbH (Airbus SE)
• Inventors: Schaefer, Christian, Foth, Hans-Jochen, Foth, Wolf-Peter, Steinsiek, Frank, Weber, Karl-Heinz
• Granted Patent: US 7,423,767 B2
• Time in Patent Office: Days
• US Class Current: 359/237
• CPC Class Codes: B64G 1/428 Power distribution and management
• CPC Class Codes: H01S 3/0014 Monitoring arrangements not otherwise provided for photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003
• CPC Class Codes: H01S 3/0071 Beam steering, e.g. whereby a mirror outside the cavity is present to change the beam direction
• CPC Class Codes: H02J 50/30 using light, e.g. lasers
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H04B 10/118 specially adapted for satellite communication
• CPC Class Codes: H04B 10/806 Arrangements for feeding power

Abstract

To transmit energy without direct mechanical or electrical contact, a transmitter unit emits a laser beam onto a radiation receiver of a receiver unit including a photovoltaic cell arrangement surrounded by a ring-shaped reflector. A portion of the laser beam is reflected from the reflector back to the transmitter unit, where the received reflected signal is evaluated to determine the position of the laser beam impinging on the radiation receiver. The transmitter unit deflects the laser beam as necessary to impinge directly on the photovoltaic cell arrangement and track any relative motion of the receiver unit. The receiver unit orients the radiation receiver to optimize the energy reception. The position of the laser beam is modulated and the resulting variation of the reflected signal is evaluated to determine therefrom the position of the laser beam on the radiation receiver.

Claims

1. An apparatus for transmitting energy over a distance without a direct electrical or mechanical connection for the transmitting of the energy, comprising:

a transmitter unit including a laser generator adapted to emit a laser beam, a deflector arrangement including at least one movable deflector mirror that is interposed in a beam path of said laser beam and adapted to deflect said laser beam, a drive arrangement coupled to said deflector arrangement and adapted to move said at least one movable deflector mirror so as to vary a direction of an emitted beam axis of said laser beam leaving said transmitter unit, and a controller that is connected for control signal transmission to said drive arrangement and is adapted to generate control signals to control said drive arrangement; and

a receiver unit arranged at said distance away from said transmitter unit, and including a radiation receiver arrangement that is adapted to receive said laser beam incident thereon, and that comprises a photovoltaic cell arrangement and a ring-shaped reflector around said photovoltaic cell arrangement, wherein said reflector is adapted to reflect as reflected light at least some of said laser beam incident thereon.

2. The apparatus according to claim 1, wherein said transmitter unit further comprises a reflection detector arrangement including a light sensor that is adapted to detect said reflected light and is connected for signal transmission to said controller.

3. The apparatus according to claim 2, wherein said reflection detector arrangement is connected to said deflector arrangement and coupled to said drive arrangement so that said reflection detector arrangement undergoes at least gross movements together with said deflector arrangement and remains oriented with a sensitive axis of said reflection detector arrangement parallel to a basic direction of said emitted beam axis of said laser beam leaving said transmitter unit.

4. The apparatus according to claim 2, wherein said receiver unit is movable relative to said transmitter unit, and said controller is adapted to control said drive arrangement to move said at least one movable mirror so as to move said emitted beam axis of said laser beam leaving said transmitter unit to track said receiver unit during a relative movement between said receiver unit and said transmitter unit.

5. The apparatus according to claim 1, wherein said at least one movable deflector mirror is respectively mounted in said transmitter unit so as to be rotatable about a respective local axis of said laser beam impinging on said movable deflector mirror.

6. The apparatus according to claim 1, wherein said drive arrangement comprises a motor drive unit coupled to said deflector arrangement and adapted to carry out relatively slower and relatively larger gross rotational movements of at least a given mirror among said at least one movable deflector mirror, and at least one piezoelectric actuator element coupled to said given mirror and adapted to carry out relatively faster and relatively smaller fine oscillating movements of said given mirror.

7. The apparatus according to claim 1, wherein said radiation receiver arrangement is movably mounted, and said receiver unit further comprises a direction-sensitive light sensor arrangement adapted to detect an incident direction of said laser beam, a receiver drive arrangement coupled to and adapted to move said radiation receiver arrangement, and a receiver controller connected to said direction-sensitive light sensor arrangement to receive signals therefrom and connected to said receiver drive arrangement to transmit control signals thereto, so as to move and orient said radiation receiver arrangement with respect to said incident direction of said laser beam.

11. The method according to claim 1, wherein said receiver unit includes a photovoltaic cell arrangement and a reflector arranged around said photovoltaic cell arrangement, and wherein said directing of said laser beam in said step b) comprises redirecting said laser beam according to a prescribed beam redirection process so that said first and second portions of said laser beam impinge on and move along said photovoltaic cell arrangement and said reflector respectively.

12. The method according to claim 11, wherein said prescribed beam redirection process comprises a random walk process.

13. The method according to claim 12, wherein said random walk process is a weighted random walk process.

14. The method according to claim 11, wherein said prescribed beam redirection process comprises modulating a direction of said laser beam in an oscillating manner at a first frequency, which causes a resultant modulation of said reflected light including a modulated component at a second frequency that is double said first frequency, and said evaluating of said reflected light in said step e) includes evaluating said modulated component at said second frequency.

15. The method according to claim 11, wherein said prescribed beam redirection process comprises modulating a direction of said laser beam by providing an oscillating first modulation at a first frequency on a first axis and simultaneously providing an oscillating second modulation at a second frequency different from said first frequency on a second axis perpendicular to said first axis, which causes a resultant modulation of said reflected light including two modulated components at two different frequencies, and wherein said evaluating of said reflected light includes evaluating said two modulated components at said two different frequencies.

16. The method according to claim 11, wherein said prescribed beam redirection process comprises a center-of-intensity process.

17. The method according to claim 4, wherein said prescribed beam redirection process comprises a circle method.

18. The method according to claim 1, wherein said generating in said step a) generates said laser beam with a wavelength in a range from 200 nm to 10 μ

m.

19. The method according to claim 1, wherein said directing of said laser beam comprises moving said laser beam by a combination of relatively slower gross movements and relatively faster fine movements.

8. A method of transmitting energy over a distance between a transmitter unit and a receiver unit, comprising the steps:

a) generating a laser beam in said transmitter unit;

b) directing and emitting said laser beam from said transmitter unit toward said receiver unit;

c) receiving at least a first portion of said laser beam and extracting energy therefrom in said receiver unit;

d) reflecting at least a second portion of said laser beam as reflected light from said receiver unit;

e) receiving and evaluating at least some of said reflected light in said transmitter unit to determine orienting information from said reflected light; and

f) carrying out said directing of said laser beam in said step b) in response to and dependent on said orienting information.

9. The method according to claim 8, wherein said directing of said laser beam in said step b) includes modulating a direction of said laser beam, which leads to a resultant modulation of said reflected light in said step d), and said evaluating of said reflected light in said step e) determines a relative position of said laser beam relative to said receiver unit based on and dependent on said resultant modulation detected in said reflected light.

10. The method according to claim 9, further comprising moving said receiver unit relative to said transmitter unit, wherein said relative position of said laser beam relative to said receiver unit changes due to said moving of said receiver unit and due to changing of said directing of said laser beam, and wherein said evaluating of said reflected light further detects said moving of said receiver unit.