Optical Fiber Shape Sensing via Polarization Evolution
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Solution Overview
Problem
Current optical fiber shape sensing technologies face limitations in accurately monitoring shape changes due to electromagnetic interference immunity and multiplexing capabilities, particularly in applications requiring high accuracy and biocompatibility.
Innovation Solution
The use of single- and multi-core optical fibers with coherent optical time domain reflectometry (OTDR) or optical frequency domain reflectometry (OFDR) to measure polarization evolution, enabling precise monitoring of shape-related optical polarization changes through linear and circular birefringence analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical fiber shape sensing is used, then basic shape monitoring is achieved, but measurement precision and accuracy are limited
Solution Approach 1:
The patent changes the measurement parameter from simple intensity or phase to optical polarization state. By monitoring polarization evolution through birefringence analysis, the system achieves higher shape sensing accuracy. The polarization state is a new parameter that provides more information about fiber deformation, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent replaces traditional mechanical or electrical sensing mechanisms with optical polarization-based sensing. By using polarization evolution monitoring instead of conventional strain gauges or mechanical sensors, the system achieves higher precision while maintaining optical fiber's inherent advantages of being lightweight and immune to electromagnetic interference.
2Measurement precision
If multi-core fiber with polarization monitoring is implemented, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent makes the optical fiber serve multiple functions simultaneously: it acts as both the transmission medium and the sensing element. The multi-core fiber structure allows each core to function as an independent sensing channel while sharing the same protective jacket and routing, reducing overall system complexity despite enhanced measurement capabilities.
Solution Approach 2:
The patent divides the fiber sensing function into multiple independent cores, where each core can be monitored separately for polarization evolution. This segmentation allows distributed measurement along the fiber length with high precision, while the modular core structure simplifies the overall fiber design compared to using a single complex sensor.
3Measurement precision
If optical interferometry is used for shape sensing, then measurement precision increases, but immunity to electromagnetic interference decreases
Solution Approach 1:
The patent replaces electromagnetic-based sensing (such as electrical strain gauges) with optical polarization sensing. Since the measurement is based on polarization state changes rather than electrical signals, the system maintains high measurement precision while achieving complete immunity to electromagnetic interference. The optical domain operation eliminates susceptibility to EM fields.
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 provides high accuracy and immunity to electromagnetic interference, enabling precise distributed measurements of twist and bending in optical fibers, enhancing shape sensing capabilities for various applications, including medical devices and aerospace.
Implementation Method 1
measuring polarization of returned probe light from each sensing fiber core... based on optical reflectometry... measure polarization evolution, enabling precise monitoring of shape-related optical polarization changes through linear and circular birefringence analysis
Implementation Method 2
measuring polarization of returned probe light from each sensing fiber core... based on optical reflectometry... measure polarization evolution, enabling precise monitoring of shape-related optical polarization changes through linear and circular birefringence analysis
Implementation Method 3
operating an optical detector to convert the optical output from the optical interferometer into an electrical signal that carries information on a local shape change
Data Source
AI summary
This patent document discloses fiber sensing techniques and devices for shape monitoring by using single- and multi-core optical fiber implementations and optical interferometry. Implementations can be made based on coherent optical time domain reflectometry (OTDR) or optical frequency domain reflectometry (OFDR).