Fast Tracking Module for Free Space Optical Alignment
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Solution Overview
Problem
Conventional two-node bi-directional Free Space Optical (FSO) communication systems face challenges in alignment and tracking, leading to increased system complexity, alignment errors, and inefficiencies due to the need for multiple optical components and fixed terminal optics, which hinder precise and fast beam alignment, especially over long distances.
Innovation Solution
The implementation of a Fast Tracking Module (FTM) that includes alignment optics, a wave front sensor, and multi-mode fiber, allowing for precise movement of receive optics in a plane perpendicular to the optical path, enabling fine positioning and alignment corrections, including focus adjustments, to achieve sub-microradian accuracy and reduce system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple optical components (beam splitters, fixed terminal optics) are used for alignment and detection, then beam alignment capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the alignment optic and terminal optic into a single integrated unit. The alignment optic (wave front sensor) and terminal optic (multi-mode fiber) are merged into one component assembly, eliminating the need for separate beam splitters and multiple discrete optical components. This integration maintains alignment precision while significantly reducing device complexity.
Solution Approach 2:
The integrated optic serves multiple functions simultaneously: it acts as both the alignment sensor (detecting beam angle) and the terminal receiver (capturing optical data). This multi-functional design replaces multiple specialized components with a single universal optic that performs both alignment and detection tasks.
2Adaptability or versatility
If terminal optics are moved for alignment, then alignment flexibility is improved, but positioning speed and precision deteriorate due to weight and complexity
Solution Approach 1:
The patent segments the optical system into two distinct parts: a lightweight, movable alignment optic that can be quickly repositioned, and a fixed terminal optic that remains stationary. The alignment optic (wave front sensor) is designed to be movable on the focal plane, while the terminal optic (multi-mode fiber) stays fixed. This segmentation allows fast, precise alignment movements without compromising the stability and precision of the terminal reception.
3Device complexity
If transmit and receive paths are integrated into a single aperture, then system compactness is improved, but alignment errors increase due to additional beam splitting
Solution Approach 1:
Instead of using beam splitters to separate and then recombine paths (the conventional approach that introduces alignment errors), the patent inverts the approach by using a single integrated optic that directly receives both alignment and data functions. The wave front sensor and multi-mode fiber are positioned to receive light directly from the aperture without requiring multiple beam splitting and recombining operations, thereby eliminating the accumulation of alignment errors.
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 FTM enables fast and precise alignment of optical beams with sub-microradian accuracy, reducing alignment errors and system complexity, while allowing for efficient long-term use by integrating transmit and receive paths and providing active focus capabilities, thus enhancing the robustness of FSO communication systems.
Implementation Method 1
the alignment optic comprises a wave front sensor (WFS) with a plurality of cells... an alignment of the received optical path can be determined relative to the receive optic by comparing a ratio sensed between different cells of the alignment optic
Implementation Method 2
The receive optic may comprise a multi-mode fiber (MMF) configured to transmit and receive light
Data Source
AI summary
A fast tracking module for use in free space optical communications includes a primary motion stage supporting receive optics, where the primary motion stage is configured to move the receive optic relative to an optical path.