Laser-based acousto-optic uplink communications technique

• US 6,859,419 B1
• Filed: 08/18/2003
• Issued: 02/22/2005
• Est. Priority Date: 08/18/2003
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy, United States Secretary of the Navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Antonelli, Lynn T., Blackmon, Fletcher A., Fain, Gilbert, Estes, Lee E.
• Primary Examiner(s): PIHULIC, DANIEL T
• Application Number:
  US10/644,574
• Time in Patent Office: 554 Days
• Field of Search: 367/134, 367/3, 367/1
• US Class Current: 367/134
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves

Abstract

An apparatus for enabling acousto-optic communication comprising an in-water platform comprising means for emitting an acoustic signal to an acousto-optic interaction zone, an in-air platform comprising the ability for transmitting a first optical interrogation beam, the ability for receiving a portion of the first interrogation beam and a second laser beam formed from the reflection of the first interrogation beam off of the acousto-optic interaction zone, the ability for measuring and outputting a plurality of optical interferences between the portion of the first interrogation beam and the second reflected beam, and a signal converter receiving as input the plurality of optical interferences and outputting an electrical signal representing the received acoustic telemetry signal at the interrogation point at the air-water interface.

Claims

1. An apparatus for enabling acousto-optic communication from water to air comprising:

an acoustic projector positionable below a surface of the water;

an optical interrogation beam transmitter to transmit an interrogation beam from the air toward the surface of the water;

an optical interrogation beam receiver to receive a reflection of the interrogation beam from the surface of the water;

an interferometer joined to said optical interrogation beam transmitter and said optical interrogation beam receiver to measure differences between said interrogation beam and said reflection of the interrogation beam;

a signal converter joined to said interferometer to receive said measured differences and provide an electrical signal corresponding to said measured differences; and

a signal processor joined to said acoustic projector to provide a signal to the acoustic projector.

2. The apparatus of claim 1 wherein said optical interrogation beam transmitter is a laser.

3. The apparatus of claim 2 further comprising a beam splitter joined in communication with said optical interrogation beam transmitter and said interferometer, said beam splitter splitting off a portion of said interrogation beam to provide to said interferometer.

4. The apparatus of claim 3 wherein said interferometer is a laser Doppler vibrometer.

5. The apparatus of claim 1 wherein said signal is translated into a scheme selected from the group consisting of multi-frequency shift keying, M-ary phase shift keying, and M-ary quadrature amplitude modulation.

6. The apparatus of claim 5 further comprising a telemetry receiver joined to said signal converter to receive the electrical signal and translate the electrical signal back into the original signal.

7. A method for transferring a signal from below a water surface to air above the surface comprising the steps of:

transmitting an acoustic signal below the water surface to an acousto-optic interaction zone;

transmitting an optical interrogation beam from the air to the acousto-optic interaction zone;

receiving a reflection of said optical interrogation beam from the acousto-optic interaction zone;

comparing said transmitted optical interrogation beam with said reflection to obtain interferences;

converting said interferences into an electrical signal;

providing a signal of interest below the surface prior to said step of transmitting;

modulating said provided signal with one modulation selected from a group consisting of multi-frequency, shift keying, M-ary phase shift keying, and M-ary quadrature amplitude modulation; and

providing said modulated signal as said acoustic signal.

8. The method of claim 7 further comprising the step of demodulating said electrical signal to restore said signal of interest above the surface.

9. The method of claim 7 further comprising the step of splitting said transmitted optical interrogation beam into a first optical interrogation beam transmitted from the air to the acousto-optic interaction zone and a second optical interrogation beam provided as said transmitted optical interrogation beam for said step of comparing.