Acquisition, pointing, and tracking architecture for laser communication

A free-space laser communication terminal, comprising:

• a beacon aperture assembly for transmitting beacon laser beams for acquiring and tracking a remote terminal;
• a data aperture for transmitting and receiving data laser beams for communicating with a remote terminal and for receiving the beacon laser beams;
• a steering mirror for controlling an angle at which laser beams are transmitted and received by the data aperture;
• a gimbal system on which is mounted the beacon aperture assembly and the data aperture and the steering mirror;
• a position sensor detector for detecting a direction of beacon laser beams received by the data aperture;
• and
• a controller for controlling positioning of the gimbal system to effect coarse steering of the beacon aperture assembly and the data aperture toward the remote terminal and for controlling positioning of the steering mirror to effect fine steering of the data aperture based on feedback from the position sensor detector.

A free-space laser communication system, comprising:

• first and second laser communication terminals configured to communicate by exchanging data laser beams modulated with data, each of the first and second laser communication terminals including a beacon aperture assembly and a data aperture, wherein:
• the first and second laser communication terminals are configured to exchange acquisition beacon laser beams to perform initial acquisition, exchange position information using RF signals, and to steer the acquisition beacon laser beams based on the position information;
• the first and second laser communication terminals are configured to exchange tracking beacon laser beams to perform tracking to steer the data laser beams, wherein the tracking beacon laser beams have a beam divergence no greater than the acquisition beacon laser beams;
• each beacon aperture assembly is configured to transmit the acquisition and tracking beacon laser beams;
• each data aperture is configured to transmit and receive the data laser beams and to receive the acquisition and tracking beacon laser beams;
• and
• each of the first and second laser communication terminals comprises a beacon receiver that receives incoming acquisition and tracking beacon laser beams from the data aperture.

A method for acquisition and tracking of laser communication terminals in a free-space laser communication system, comprising:

• (a) pointing the laser communication terminals by exchanging position data by RF signals and exchanging beacon laser beams between laser communication terminals by transmitting the beacon laser beams via respective beacon apertures of the laser communication terminals and detecting the beacon laser beams received via respective data apertures of the laser communication terminals, wherein the beacon laser beams are modulated on and off such that the beacon laser beams are chopped beacon laser beams;
• (b) acquiring the laser communication terminals using the chopped beacon laser beams received via the respective data apertures;
• and
• (c) tracking the laser communication terminals using the chopped beacon laser beams received via the respective data apertures such that data laser beams exchanged by transmitting and receiving the data laser beams via the respective data apertures of the laser communication terminals to effect communication are steered based on feedback from detection of the chopped beacon laser beams.

A method for acquisition and tracking of laser communication terminals in a free-space laser communication system, comprising:

• (a) pointing the laser communication terminals by exchanging position data by RF signals via respective data apertures of the laser communication terminals and acquiring the laser communication terminals by exchanging beacon laser beams between the laser communication terminals, wherein acquisition of the laser communication terminals relies on the beacon laser beams received via the respective data apertures;
• (b) communicating between the laser communication terminals by exchanging data laser beams respectively transmitted from and received by the respective data apertures of the laser communication terminals;
• and
• (c) tracking the laser communication terminals by detecting the data laser beams with a detector array to determine a direction of the data laser beams and steering the data laser beams based on feedback from the detector array.