Directional Light Transmitter and Receiver

• US 20090103925A1
• Filed: 09/27/2006
• Published: 04/23/2009
• Est. Priority Date: 09/27/2005
• Status: Active Grant

• Current Assignee: Wi-Charge Ltd.
• Original Assignee: Wi-Charge Ltd.
• Inventors: Alpert, Ortal
• Granted Patent: US 9,705,606 B2
• Time in Patent Office: Days
• US Class Current: 398/130
• CPC Class Codes: H04B 10/11 Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
• CPC Class Codes: H04B 10/1123 Bidirectional transmission
• CPC Class Codes: H04B 10/807 Optical power feeding, i.e. transmitting power using an optical signal

Abstract

A system for supplying power wirelessly to a remote mobile device including (i) a transmitting unit for directing radiation into the region of the mobile device, the transmitting unit having a gain medium with a front surface directed towards the space, and a retroreflector on its back surface, and (ii) a receiver unit connected with or attached to the mobile device for receiving radiation transmitted from the transmitting unit. The receiver unit includes (i) a retroreflector for reflecting part of the radiation received from the transmitting unit back in the direction of the transmitting unit, where it is amplified and retransmitted back in the direction of the receiver unit, and (ii) a power detection element for absorbing that part of the radiation not reflected by the retroreflector, and converting it to electrical power for use by the mobile device. Modulation of the transmitted beam enables it to transmit data also.

Claims

1. A system for transmitting power wirelessly to a remote device disposed in a space, comprising:

a transmitting unit adapted to direct radiation generally into said space, said transmitting unit comprising a gain medium having a front surface adapted to emit radiation generally towards said space, and a rear surface having a retro-reflector in optical association therewith; and

a receiver unit associated with said device and adapted to receive radiation transmitted from said transmitting unit, and comprising a retro-reflector adapted to retro reflect a first portion of said radiation received from said transmitting unit back in the direction of said transmitting unit, such that said transmitting unit amplifies said radiation reflected back from said receiver unit and retransmits it in the direction of said receiver unit, and adapted to transmit a second portion of said radiation, such that it is utilized by said device.

2. A system according to claim 1 and wherein said receiver unit also comprises a power adaptor converting said second portion of said radiation to electrical power.

4. A system according to claim 2 wherein said adaptor is a photoelectric device.

5. A system according to claim 1 and wherein said second part of said radiation is utilized as optical power.

6. A system according to claim 1 and wherein said gain medium is excited by either one of electrical and optical excitation.

8. A system according to claim 1 and wherein said transmitting unit is adapted to modulate said radiation transmitted, such that data can be transmitted to said receiver.

9. A system according to claim 8 and wherein said transmitted radiation is modulated by either modulation of said gain medium excitation or by use of a liquid crystal modulator.

11. A system according to claim 1 and wherein said receiver unit is adapted to modulate said radiation reflected therefrom, such that data can be transmitted to said transmitting unit.

13. A system according to claim 2 and wherein said adaptor converts said modulation of said transmitted radiation into a data signal for use by said mobile electronic device.

15. A system according to claim 1 and wherein said gain medium is any one of a rare earth doped glass and a rare earth doped crystal, Nd:

YAG, Ti;

Sapphire, Ruby, Er;

YAG, Er;

Glass and a semiconductor.

17. A system according to claim 1 and wherein at least one of said retro-reflectors is either one of a corner-cube retro-reflector and a cat'"'"'s-eye retro-reflector.

19. A system according to claim 1 and further comprising at least one detector disposed outside of the optical path between said transmitting unit and said receiver unit, said detector being operative to cut off said radiation if a predetermined level of change of said transmitted radiation is detected.

21. A system according to claim 1 and wherein said transmitter is adapted to have a limited range, such that the time elapsing before said radiation is stopped by an intruding object in the path between said transmitting unit and said receiver unit is limited accordingly.

22. A system according to claim 21 and wherein said time elapsing is determined by the round-trip travel time of said radiation between said transmitter unit and said receiver unit.

23. A system according to claim 21 and wherein said limited range is generated by either one of the use of at least one retro-reflector adapted to reflect an incident beam in at least one of a focused, defocused, shifted and misaligned state or by active measurement of the receiver distance from said transmitting unit, and use of said measured distance to cut off said radiation when it exceeds said limited range.

25. A system according to claim 21, and wherein said system is laser safe.

27. A system according to claim 1, and further comprising at least one beam blocking arrangement, disposed relative to at least one of said transmitting unit and receiver unit such that reflections from surfaces within any one of said transmitting unit and said receiver unit are not emitted into said space.

28. A system according to claim 27 and wherein any beam reflected in a direction not collinear with said receiver and transmitter units is blocked.

29. A wireless power transmitter according to claim 1 and wherein said gain medium is modulated at a predetermined frequency, such that its gain is switched between a higher and a lower value at said modulation frequency, such that a receiver unit located at a characteristic distance from the transmitter unit such that the round trip optical transit time of radiation between said transmitting unit and said receiver unit is equal to the period associated with said modulating frequency, will have a more efficient optical coupling to said transmitting unit than a receiver located at another distance from said transmitting unit.

30. A wireless power transmitter according to claim 29 and wherein said receiver unit located at said characteristic distance from said transmitter unit is mode locked to said transmitting unit.

31. A wireless power transmitter according to claim 29 and wherein optical lasing is limited to between a predetermined receiver and said transmitting unit by either one of mode locking or by selection of said modulation frequency.

3. (canceled)

7. (canceled)

10. (canceled)

12. (canceled)

14. (canceled)

16. (canceled)

18. (canceled)

20. (canceled)

24. (canceled)

26. (canceled)

32. (canceled)

33. A free-space lasing system comprising:

a power transmitting unit comprising a first retroreflector;

a power receiver unit comprising a second retroreflector, said power receiving unit being remotely located relative to said transmitting unit;

a gain medium disposed between said retroreflectors, in close proximity to said first retroreflector of said power transmitting unit; and

an element for extracting part of the radiation reflected between said retro reflectors and for utilizing said extracted radiation.

34. A system according to claim 33 and wherein said second retroreflector is partially reflective, and wherein said element is a power detector disposed in said receiving unit for enabling utilization of that part of said radiation received from said transmitting unit and not reflected by said partially reflective retro reflector.

35. A system according to claim 33 and wherein said second retroreflector is a full reflector, and said element is a partially transmissive power detector disposed at the incident surface of said full retroreflector.

36. A system according to claim 33 and wherein at least one of said transmitting unit and said receiving unit further comprises a detector for measuring the amount of radiation received, said detector being operative to perform at least one of the decoding of data and the increasing of the safety of the system.

37. A system according to claim 36 and wherein said increased safety of said system is achieved by utilizing said detector to detect a change in the level of radiation outside of the optical path between said transmitting and said receiving units.

40. A system according to claim 33 and wherein at least one of said transmitting and receiver units has an optical aperture, and also comprises at least one beam blocking surface positioned so that reflections from a beam entering said optical aperture are blocked by said at least one beam blocking surface.

41. A system according to claim 40 and wherein said optical aperture has a limited field of view such that it enables entry only of incident beams having an angle of incidence such that reflections of said incident beams impinge on one of said at least one beam blocking surface.

38. (canceled)

39. (canceled)

42. (canceled)

43. A wireless power transmitter comprising a laser gain medium and a retroreflector, wherein said transmitter is adapted to transmit power wirelessly to a remote receiver unit.

44. A wireless power transmitter according to claim 43 wherein said gain medium emits light at wavelengths between 700 nm to 2500 nm n.

45. A wireless power transmitter according to claim 43, and having an optical aperture, and further comprising at least one beam blocking surface positioned so that reflections from any beam entering said optical aperture will be blocked by said at least one beam blocking surface.

46. A wireless power transmitter according to claim 43 wherein the maximal power transmission capability is selected to be lower than the limit imposed by a predetermined class of laser product specifications.

51. A wireless power transmitter according to claim 43 and wherein said laser gain medium is modulated at a predetermined frequency, such that its gain is switched between a higher and a lower value at said modulation frequency, such that a receiver unit located at a characteristic distance from the transmitter unit such that the round trip optical transit time of radiation between said transmitting unit and said receiver unit is equal to the period associated with said modulating frequency, will have a more efficient optical coupling to said transmitting unit than a receiver located at another distance from said transmitting unit.

52. A wireless power transmitter according to claim 51 and wherein said receiver unit located at said characteristic distance from said transmitter unit is mode locked to said transmitting unit.

53. A wireless power transmitter according to claim 51 and wherein optical lasing is limited to between a predetermined receiver and said transmitting unit by either one of mode locking or by selection of said modulation frequency.

47. (canceled)

48. (canceled)

49. (canceled)

50. (canceled)

54. (canceled)

55. A wireless power receiver comprising a retro reflector and a light coupler capable of converting optical power into electrical power, wherein said receiver is adapted to receive power wirelessly from a remote transmitter unit.

56. A wireless power receiver according to claim 55 further comprising a wireless data link for transmission of the status of said receiver.

57. A wireless power receiver according to claim 55 wherein said retro reflector is semi transparent.

58. A wireless power receiver according to claim 55 and wherein said retro reflector comprises either one of at least one cube corner retro reflector or a hollow corner retro reflector such that undesired surface reflections from said retro reflector are reduced.

59. A wireless power receiver according to claim 55 and further comprising a beam blocker disposed such that reflections in directions other than 180 degree from that of the incident beam direction are blocked.

61. A wireless power receiver according to claim 55 further comprising at least one anti reflective coating to minimize undesired surface reflections.

60. (canceled)

62. A method of directing radiation in a system between a transmitting unit having a modulated gain medium, and a receiver unit disposed at a predefined characteristic distance from said transmitting unit, by selecting said modulation frequency such that the round trip optical transit time of radiation between said transmitting unit and said receiver unit is equal to the period associated with said modulating frequency.

63. A method according to claim 62 wherein said receiver unit located at said characteristic distance from said transmitter unit is mode locked to said transmitting unit.

64. A method according to claim 62 and wherein said round trip optical transit time can be measured.

65. A method according to claim 64 wherein said measurement is performed by any one of passive mode locking, frequency scanning and measuring a single pulse round trip optical transit time.

66. A method according to claim 62 and wherein said modulating frequency is controlled by a phase locked loop.

67. A method of directing radiation in a system between a transmitting unit capable of lasing at more than a single wavelength, and a receiver unit having a characteristic wavelength response by adapting said transmitting unit to preferentially lase at said characteristic wavelength such that said receiver unit has a more efficient optical coupling to the transmitter than other receiver units having a different characteristic wavelength response.

68. A method according to claim 67 and wherein said preferential lasing is generated either by use of a filter set including at least a filter for said characteristic wavelength response of said receiver unit or by changing at least one of the wavelength and power parameters of said pump of said transmitting unit.

70. A method according to claim 67 and wherein said preferential lasing is generated by adjusting mechanical placement of parts of said system.

69. (canceled)