Retro-reflective optical transceiver

• US 5,121,242 A
• Filed: 02/04/1991
• Issued: 06/09/1992
• Est. Priority Date: 02/04/1991
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Martin Marietta Corporation
• Inventors: Kennedy, William P.
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): BACARES, RAFAEL D
• Application Number:
  US07/650,223
• Time in Patent Office: 491 Days
• Field of Search: 359/152, 359/154, 359/156, 359/158, 359/159, 359/168, 359/170, 359/247, 359/169, 359/302, 359/364
• US Class Current: 398/170
• CPC Class Codes: H04B 10/2587 using a single light source for multiple stations

Abstract

A retro-reflective transceiver provides optical communications by reflecting light transmitted by a distant source. The transceiver has a corner cube reflector with a truncated apex that serves as a transmissive aperture. A portion of the incoming light passes through the aperture in the corner cube reflector to a receiver where information encoded on the incoming light beam can be detected. The remainder of the light beam is reflected back toward the source in a direction substantially parallel to the incoming light beam by the three mutually perpendicular, reflective faces of the corner cube reflector. An optical switch (e.g. ferro-electric light crystal material) located in front of the corner cube reflector is used to modulate the intensity of the reflected beam to transmit information to the source.

Claims

1. A retro-reflective optical transceiver adapted to receive information encoded on incoming light rays transmitted by a distant source and transmit information to said source by encoding light rays reflected by said transceiver to said source, said transceiver comprising:

a corner cube reflector having a first end adapted to receive said incoming light rays;

three mutually perpendicular reflective faces adapted to reflect a portion of said incoming light rays back toward said source in a direction substantially parallel to said incoming light rays; and

a substantially transmissive aperture adapted to permit a portion of said incoming light rays to pass through said corner cube reflector;

receiver means adapted to receive said incoming light rays passing through said aperture and detect information encoded on said light rays; and

an optical switch in optical alignment with said first end of said corner cube reflector, adapted to modulate the intensity of said light rays reflected by said corner cube reflector back toward said source.

2. The retro-reflective optical transceiver of claim 1, wherein said corner cube reflector further comprises a truncated apex at the area of intersection of said reflective faces, and said truncated apex forms said transmissive aperture.

3. The retro-reflective optical transceiver of claim 1, further comprising transmitter means adapted to control said optical switch to encode information on said reflected light rays.

4. The retro-reflective optical transceiver of claim 1, wherein said optical switch comprises a first polarized filter and a second polarized filter in optical alignment with said first polarized filter, the angle of polarization of at least one of said filters being adjustably controllable to permit information to be encoded on said reflected light rays by adjusting the relative polarization of said filters.

5. The retro-reflective optical transceiver of claim 4, wherein at least one of said polarized filters is comprised of a ferro-electric liquid crystal material whereby the angle of polarization of said filter can be adjustably controlled by an electrical potential applied across said liquid crystal material.

6. The retro-reflective optical transceiver of claim 1, wherein said optical switch has a substantially transmissive region allowing at least a portion of said incoming light rays to pass through said optical switch and through said aperture of said corner cube reflector to said receiver means;

and a switchable region adapted to modulate the intensity of said light rays reflected by said corner cube reflector back toward said source.

7. The retro-reflective optical transceiver of claim 1, further comprising a filter in optical alignment with said receiver means, adapted to transmit only incoming light rays having predetermined optical characteristics to said receiver means.

8. The retro-reflective optical transceiver of claim 1, wherein said receiver means comprises a PIN diode.

9. The retro-reflective optical transceiver of claim 1, further comprising an optical element adapted to focus incoming light rays passing through said transmissive aperture on said receiver means.

10. The retro-reflective optical transceiver of claim 1, further comprising telescope means adapted to gather and direct incoming light rays to said first end of said corner cube reflector.

11. The retro-reflective optical transceiver of claim 1, further comprising synchronization means adapted to facilitate simplex communications between said transceiver and said source by preventing said optical switch from transmitting information while said receiver means is receiving data.

12. A retro-reflective optical transceiver adapted to receive information encoded on incoming light rays transmitted by a distant source and transmit information to said source by encoding light rays reflected by said transceiver to said source, said transceiver comprising:

a corner cube reflector having;

(a) a first end adapted to receive said incoming light rays;

(b) three mutually perpendicular reflective faces adapted to reflect a portion of said incoming light rays back toward said source in a direction substantially parallel to said incoming light rays; and

(c) a truncated apex at the area of intersection of said reflective faces, said truncated apex providing a substantially transmissive aperture adapted to permit a portion of said incoming light rays to pass through said corner cube reflector;

receiver means adapted to receive said incoming light rays passing through said aperture and detect information encoded on said light rays; and

an optical switch in optical alignment with said first end of said corner cube reflector, said optical switch having a first transmissive region allowing at least a portion of said incoming light rays to pass through said optical switch and through said aperture of said corner cube reflector to said receiver means, and a second switchable region adapted to modulate the intensity of said light rays reflected by said corner cube reflector back toward said source.

13. The retro-reflective optical transceiver of claim 12, further comprising transmitter means adapted to control said optical switch to encode information on said reflected light rays.

14. The retro-reflective optical transceiver of claim 12, wherein said optical switch comprises a first polarized filter and a second polarized filter in optical alignment with said first polarized filter, the angle of polarization of at least one of said filters being adjustably controllable to permit information to be encoded on said reflected light rays by adjusting the relative polarization of said filters.

15. The retro-reflective optical transceiver of claim 14, wherein at least one of said polarized filters is comprised of a ferro-electric liquid crystal material whereby the angle of polarization of said filter can be adjustably controlled by an electrical potential applied across said liquid crystal material.

16. The retro-reflective optical transceiver of claim 12, further comprising a filter in optical alignment with said receiver means, adapted to transmit only incoming light rays having predetermined optical characteristics to said receiver means.

17. The retro-reflective optical transceiver of claim 12, wherein said receiver means comprises a PIN diode.

18. The retro-reflective optical transceiver of claim 12, further comprising an optical element adapted to focus incoming light rays passing through said transmissive aperture on said receiver means.

19. The retro-reflective optical transceiver of claim 12, further comprising telescope means adapted to gather and direct incoming light rays to said first end of said corner cube reflector.

20. The retro-reflective optical transceiver of claim 12, further comprising synchronization means adapted to facilitate simplex communications between said transceiver and said source by preventing said optical switch from transmitting information while said receiver means is receiving data.

21. A retro-reflective optical transceiver adapted to receive information encoded on incoming light rays transmitted by a distant source and transmit information to said source by encoding light rays reflected by said transceiver to said source, said transceiver comprising:

a corner cube reflector having;

(a) a first end adapted to receive said incoming light rays;

(b) three mutually perpendicular reflective faces adapted to reflect a portion of said incoming light rays back toward said source in a direction substantially parallel to said incoming light rays; and

(c) a truncated apex at the area of intersection of said reflective faces, said truncated apex providing a substantially transmissive aperture adapted to permit a portion of said incoming light rays to pass through said corner cube reflector;

receiver means adapted to receive said incoming light rays passing through said aperture and detect information encoded on said light rays; and

a polarized filter in optical alignment with said first end of said corner cube reflector, said filter being adapted to transmit light rays having a predetermined angle of polarization and to block light rays having a polarization substantially perpendicular to said predetermined angle of polarization;

an optical switch in optical alignment with said first polarized filter and with said first end of said corner cube reflector, said optical switch being adapted to transmit light rays having a predetermined angle of polarization and to block light rays having a polarization substantially perpendicular to said angle of polarization, the angle of polarization of said optical switch being adjustably controllable to permit modulation of the intensity of said reflected light rays by adjusting the angle of polarization of said optical switch with respect to said polarized filter.

22. The retro-reflective optical transceiver of claim 21, further comprising transmitter means adapted to control said optical switch to encode information on said reflected light rays.

23. The retro-reflective optical transceiver of claim 21, wherein said adjustably controllable filter is comprised of a ferro-electric liquid crystal material whereby the angle of polarization of said filter can be adjustably controlled by an electrical potential applied across said liquid crystal material.

24. The retro-reflective optical transceiver of claim 21, wherein said optical switch has a substantially transmissive region allowing at least a portion of said incoming light rays to pass through said optical switch and through said aperture of said corner cube reflector to said receiver means;

and a switchable region adapted to modulate the intensity of said light rays reflected by said corner cube reflector back toward said source.

25. The retro-reflective optical transceiver of claim 21, further comprising a filter in optical alignment with said receiver means, adapted to transmit only incoming light rays having predetermined optical characteristics to said receiver means.

26. The retro-reflective optical transceiver of claim 21, wherein said receiver means comprises a PIN diode.

27. The retro-reflective optical transceiver of claim 21, further comprising an optical element adapted to focus incoming light rays passing through said transmissive aperture on said receiver means.

28. The retro-reflective optical transceiver of claim 21, further comprising telescope means adapted to gather and direct incoming light rays to said first end of said corner cube reflector.

29. The retro-reflective optical transceiver of claim 21, further comprising synchronization means adapted to facilitate simplex communications between said transceiver and said source by preventing said optical switch from transmitting information while said receiver means is receiving data.