Beaconless Laser Alignment Using mm-Wave Beamforming
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Solution Overview
Problem
Pointing loss due to imperfect acquisition and tracking between satellites with different relative velocities hinders the establishment of reliable optical communication links, particularly in CubeSat networks, leading to inefficiencies in alignment and communication reliability.
Innovation Solution
A beaconless alignment approach using millimeter-wave beamforming with a uniform phased array antenna to guide laser beams for alignment, employing a two-stage scanning process with a coarse non-optical and fine optical alignment to reduce scanning time and improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional optical beam alignment scanning is used, then alignment coverage is comprehensive, but scanning time is excessive and acquisition is slow
Solution Approach 1:
A non-optical intermediary beam (mm-wave beam) is introduced to perform preliminary alignment between satellites. This intermediary beam has wider coverage and easier detection properties, allowing rapid coarse alignment to reduce scanning time, after which the optical beam takes over for precise final alignment, thus resolving the contradiction between fast acquisition and reliable alignment.
Solution Approach 2:
The alignment process is segmented into two distinct stages: a first stage using non-optical beamforming for rapid coarse alignment to reduce scanning time, and a second stage using optical beam scanning for precise final alignment to ensure reliability. This segmentation allows each stage to optimize for its specific purpose without compromising the other.
2Measurement precision
If wide beam scanning is used for acquisition, then coverage area is large, but alignment precision is insufficient
Solution Approach 1:
The search field is segmented into a coarse alignment phase covering a wide area using non-optical beams, followed by a fine alignment phase focusing on a smaller refined search area using optical beams. This segmentation allows the system to first establish broad coverage and then concentrate precision where needed.
Solution Approach 2:
Preliminary coarse alignment using non-optical beams is performed before the final optical alignment. This preliminary action narrows down the search area and establishes an initial alignment reference, enabling the subsequent optical beam to achieve high precision without needing to scan the entire wide area.
3Productivity
If narrow beam scanning is used for precision alignment, then alignment accuracy is high, but scanning time increases and acquisition becomes slower
Solution Approach 1:
The alignment task is segmented such that the non-optical beam handles the time-critical coarse search over wide areas, while the optical beam handles the precision-critical fine alignment over a smaller refined area. This segmentation allows the narrow optical beam to operate efficiently without bearing the burden of wide-area scanning.
Solution Approach 2:
Preliminary coarse alignment using the non-optical beam establishes an initial reference and reduces the search space before the narrow optical beam begins its precision alignment. This preliminary action eliminates the need for the narrow beam to perform extensive scanning, thereby maintaining high acquisition speed while achieving precise alignment.
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
The method reduces scanning time and enhances the reliability of optical communication links by utilizing millimeter-wave beamforming to achieve precise alignment between satellites, even in the presence of rigid body perturbations, thus improving communication efficiency in CubeSat networks.
Implementation Method 1
A beamforming approach can be used, such as at or near a millimeter-wave (mm-wave) wavelength
Implementation Method 2
scanning an optical field according to a second specified search pattern within a refined search field
Data Source
AI summary
A beaconless alignment approach can be used such as to facilitate establishment of an optical communication link or to enhance reliability of such an optical communication link. When laser-based free-space optical communication is used, such an approach can be referred to as an agile beaconless laser beam alignment (ABLBA) technique. Such an ABLBA technique can consume less scanning time as compared to other approaches and can be used for alignment in relation to establishing an optical communication link between stations, such as between satellites. For example, at a transmitting station, a non-optical beam can be scanned according to a first specified search pattern within an initial search field, and an optical field can be scanned according to a second specified search pattern within a refined search field, the refined search field established at least in part using an alignment identified from the scanning of the non-optical beam.