Optical PAT Receiver Alignment Without a Fast-Steering Mirror
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Solution Overview
Problem
Existing pointing, acquisition, and tracking (PAT) systems for quantum and classical free-space optical communications on mobile platforms face stringent space, weight, and power (SWAP) constraints, particularly due to the need for a fast-steering mirror (FSM) on the receiver, which adds weight and complexity, and struggle to maintain alignment under dynamic and noisy conditions.
Innovation Solution
A PAT system that eliminates the FSM on the receiver by using a reflective layer to reflect an alignment beam for camera detection, enabling coarse and fine alignment with a transmitting platform's FSM, and a gimbal for orientation adjustment based on a beacon signal, without requiring a second FSM on the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fast-steering mirror (FSM) is added to the receiver for fine alignment, then alignment precision is improved, but weight and device complexity increase significantly
Solution Approach 1:
The patent extracts the fast-steering mirror from the receiver and relocates it to the transmitter only. The receiver uses a stationary optics platform with a reflective layer and camera system instead, eliminating the need for a second FSM while maintaining alignment precision through the transmitter's FSM and receiver's gimbal-mounted optics.
Solution Approach 2:
The patent introduces a reflective layer and camera system as intermediary components between the incoming optical signal and the detector. This intermediary system enables alignment measurement and feedback without requiring a heavy FSM on the receiver, using light reflection and image processing instead.
2Stability of the object's composition
If a second FSM is added to the receiver for tip and tilt control, then alignment stability is improved, but device complexity increases considerably
Solution Approach 1:
The patent removes the second FSM from the receiver system entirely. Alignment stability is maintained through the transmitter's FSM controlling the outgoing beam and the receiver's gimbal-mounted optics providing coarse positioning, eliminating the need for complex tip and tilt control mechanisms on the receiver.
Solution Approach 2:
The system uses the transmitter's FSM to actively stabilize the outgoing beam and compensate for platform movements. The receiver's optics platform is gimbal-mounted to provide passive stability and coarse alignment, with the system self-correcting through feedback from the camera detecting the reflected alignment beam.
3Weight of moving object
If a reflective layer and camera system are added to eliminate the receiver FSM, then weight is reduced, but alignment measurement capability must be maintained
Solution Approach 1:
The patent introduces a reflective layer positioned in the path of the alignment beam and a camera system to detect the reflected beam. This intermediary arrangement allows the lightweight receiver to measure alignment by observing where the alignment beam reflects off the known position of the reflective layer, maintaining measurement precision without heavy FSM hardware.
Solution Approach 2:
The camera captures an optical copy or image of the alignment beam's position on the reflective layer. This optical copy provides sufficient information for alignment measurement and feedback control, replacing the need for direct electronic sensing that would require FSM hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces SWAP requirements by nearly an order of magnitude, allowing lightweight mobile platforms to maintain optical communication links under dynamic conditions with reduced weight, power consumption, and complexity, suitable for platforms like small UAVs, while supporting quantum and classical optical signals.
Implementation Method 1
a reflective layer over (in front of) at least a portion of the surface, to at least partially reflect an alignment beam that is substantially coincident with the optical communication signal
Implementation Method 2
a camera positioned to detect the reflected alignment beam
Implementation Method 3
a gimbal for orientation adjustment based on a beacon signal
Data Source
AI summary
An optical communication receiver system for a mobile platform includes: a surface having an entrance aperture for entry of an optical communication signal from a remote source; an optical receiver to receive the optical communication signal through the entrance aperture; a reflective layer over at least a portion of the surface to at least partially reflect an alignment beam that is substantially coincident with the optical communication signal; a camera positioned to detect the reflected alignment beam; a processor to determine alignment information about the alignment beam relative to the entrance aperture based on the reflected alignment beam detected by the camera; and a transmitter to transmit the alignment information to the remote source to enable the remote source to center the optical communication signal in the entrance aperture.