Optical Position Sensor for Fast Steering Mirror Alignment
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Solution Overview
Problem
Free-space optical (FSO) communications systems face challenges in maintaining alignment due to the narrow beam spread and movement of transceivers, requiring real-time beam steering systems that can respond to rapid changes in position, but existing positioning sensors can affect performance.
Innovation Solution
A position sensor system for FSO transceivers that includes a printed circuit board with a light source and detector, coupled to a base substructure, which emits and receives sensor light to determine the angular position of a repositionable mirror, allowing for real-time alignment adjustments using a gimbal assembly that rotates the mirror about two axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If real-time positioning sensors are implemented for rapid beam steering response, then the response speed and alignment accuracy are improved, but the device complexity and weight increase
Solution Approach 1:
The patent replaces traditional mechanical positioning sensors with an optical sensing system that uses a light source and photodetector to measure mirror position. This substitution of mechanical components with optical components achieves rapid response speed while reducing device complexity and weight, as the optical system requires no moving parts and can be integrated into the existing optical path.
Solution Approach 2:
The patent introduces an optical element as an intermediary that directs sensor light to the mirror and reflects it to the detector. This intermediary optical system enables position sensing without direct mechanical contact or complex sensor assemblies, achieving fast response while keeping the overall device structure simple and lightweight.
2Measurement precision
If traditional positioning sensors are used for beam steering, then position measurement is achieved, but the weight and complexity of the beam steering assembly increase
Solution Approach 1:
The patent merges the position sensing function with the existing optical components of the beam steering system. The light source and detector are integrated into the same housing as the mirror assembly, and the optical elements serve dual purposes in the optical path. This merging eliminates the need for separate, heavy sensor assemblies while maintaining measurement precision.
Solution Approach 2:
The patent discards traditional mechanical positioning sensors that add weight and complexity. Instead, it recovers and repurposes existing optical components (light source, optical elements, detector) originally intended for other functions, using them to achieve position measurement. This approach eliminates unnecessary weight while preserving measurement capability.
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
Enables precise and rapid repositioning of the mirror to maintain alignment with a remote transceiver, improving communication stability and reliability by reducing complexity and weight in the beam steering assembly.
Implementation Method 1
A position sensor includes a printed circuit board with a light source and a detector. The light source is oriented to emit sensor light towards the mirror and the detector is oriented to receive sensor light reflected from the mirror.
Data Source
AI summary
A free-space optical transceiver includes a repositionable mirror for receiving and sending light beams with another transceiver. To properly align the light beams, the position of the mirror is determined in using a position sensor. The position sensor is mounted within a base substructure that is coupled to a steerable mirror substructure containing the mirror. The position sensor reflects sensor light off of the mirror to determine the position of the mirror along two different axes. The position sensor includes an optical element for shaping the sensor light. The components of the position sensor are mounted to the base substructure such that alignment of the position sensor is not required. Further, by coupling the position sensor to the base substructure and not the steerable mirror substructure, the moment of inertia and center of gravity of the steerable mirror substructure is improved, thereby improving the steering responsiveness of the mirror.