FSO Terminal Wavelength Control for Beam Divergence Tracking
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Solution Overview
Problem
High directionality in free space optical (FSO) communications requires accurate beam pointing, which can be disrupted by environmental factors like strong winds or vehicle movement, leading to unpredictable communication links and the need for rapid adjustment.
Innovation Solution
An FSO communication terminal with an optical source that produces beams at different wavelengths, allowing divergence adjustment through wavelength control, enabling beam acquisition and tracking without mechanical motion, thereby reducing system complexity and increasing operational lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high directionality is used in FSO communications, then communications capacity and privacy are improved, but beam pointing accuracy and communication reliability deteriorate due to environmental factors
Solution Approach 1:
The patent applies dynamics by making the beam divergence adjustable rather than fixed. The system dynamically changes beam divergence based on operational phase: wider divergence during acquisition to compensate for pointing errors, and narrower divergence during data transmission to maintain high directionality and capacity. This resolves the contradiction by adapting directionality to operational needs.
Solution Approach 2:
The patent changes the physical parameter of beam divergence to resolve the contradiction. By controlling beam divergence through optical elements (such as adjustable lenses or diffractive optical elements), the system achieves wider beams for reliable acquisition and narrower beams for high-capacity transmission, thus maintaining both reliability and productivity under different conditions.
2Productivity
If high directionality is used in FSO communications, then communications privacy is improved, but beam pointing accuracy deteriorates due to environmental factors like wind and vehicle movement
Solution Approach 1:
The system dynamically adjusts beam characteristics based on operational phase. During acquisition, wider beams are used to tolerate pointing inaccuracies caused by wind or vehicle movement. During data transmission, the system transitions to narrower, more directional beams for precise communication, thus adapting to changing pointing accuracy requirements.
Solution Approach 2:
The patent applies preliminary action by performing beam acquisition with wider divergence before data transmission. This preliminary wider beam ensures that even with poor pointing accuracy due to environmental factors, the initial link is established. Once acquired, the system switches to precise narrow beams for data transmission.
3Measurement precision
If mechanical adjustment systems are used to maintain beam alignment, then beam pointing accuracy is improved, but system complexity increases and operational lifetime decreases
Solution Approach 1:
The patent replaces mechanical adjustment systems with optical control methods. Instead of using motors or actuators to physically move mirrors or lenses for beam steering, the system uses adjustable optical elements (such as variable focus lenses or programmable diffractive optical elements) to change beam divergence and direction through optical means, thereby reducing mechanical complexity and improving reliability.
Solution Approach 2:
The system changes optical parameters (beam divergence, focal length) through electrical or optical control rather than mechanical movement. This allows beam pointing and shaping to be adjusted by changing optical properties dynamically, eliminating the need for complex mechanical steering mechanisms and extending operational lifetime.
4Device complexity
If fixed beam divergence is used, then system simplicity is maintained, but beam acquisition time increases and communication reliability decreases
Solution Approach 1:
The patent makes beam divergence dynamic rather than fixed. During the acquisition phase, the system automatically increases beam divergence to widen the search area and reduce acquisition time. Once the link is established, the system transitions to the data transmission phase with reduced divergence for optimized communication, thus adapting to different operational requirements without increasing overall system complexity.
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 decreases beam acquisition time and enhances communication reliability by dynamically adjusting beam divergence, optimizing alignment processes, and maintaining stable links.
Implementation Method 1
A wavelength dependence (e.g., due to the chromatic design) of the optics results in a divergence of the optical beams that depends on the wavelength of the optical beams
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
Embodiments relate to a free space optical (FSO) communication terminal. The terminal includes an optical source and optics. The optical source can produce optical beams at different wavelengths. The optics direct optical beams in a direction towards a remote FSO communication terminal. A wavelength dependence of the optics results in a divergence of the optical beam that depends on a wavelength of the optical beam. A controller may control the wavelength of the optical beam produced by the optical source, thereby adjusting the divergence of the optical beam (e.g., according to an acquisition process or a tracking process).