Fiber Bragg Grating Mandrel With Projection For Strain Isolation
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Solution Overview
Problem
Fiber optic sensors with FBGs experience unwanted changes in optical characteristics due to differential strain caused by supporting the grating collar on the sensor mandrel, affecting their accuracy in measuring physical parameters like temperature, pressure, and sound intensity.
Innovation Solution
A mandrel with a cylindrical projection supports a grating collar and optical fiber coil, providing a smooth transition and integrated solid support to minimize environmental perturbations, preventing differential strain and maintaining FBG stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the grating collar is supported on the sensor mandrel, then the FBG can be mounted and positioned, but differential strain is caused which leads to unwanted changes in optical characteristics
Solution Approach 1:
The patent introduces an intermediary component - a collar - that mediates between the mandrel and the FBG. This collar provides a smooth transition and distributes the mechanical load, preventing direct differential strain transmission to the FBG while still enabling secure mounting and positioning on the mandrel.
Solution Approach 2:
The patent modifies the geometric parameters of the mandrel by adding a projection at its end, which changes the structural configuration. This parameter change allows the collar to be mounted securely while providing a smooth transition zone that minimizes strain on the FBG, thereby maintaining optical characteristics stability.
2Ease of operation
If the grating collar is supported on the sensor mandrel, then the FBG can be mounted, but environmental perturbations cause unwanted changes in optical characteristics
Solution Approach 1:
The collar acts as a protective intermediary between the external environment and the FBG. By providing a smooth transition and distributing mechanical stresses, it shields the FBG from environmental perturbations such as temperature and pressure changes, thereby reducing unwanted optical characteristic changes.
Solution Approach 2:
The projection on the mandrel provides beforehand cushioning by creating a robust mounting structure that anticipates and absorbs environmental stresses before they can affect the FBG. This pre-engineered structural support cushions against environmental perturbations and maintains FBG stability.
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 solution effectively reduces unwanted changes in FBG optical characteristics, enhancing the accuracy and reliability of fiber optic sensors in measuring physical parameters by minimizing environmental perturbation effects.
Implementation Method 1
The purpose of the FBG is to reflect an optical signal of a selected wavelength back through the optical fiber to a detector and to transmit optical signals of other wavelength to subsequent transducers in the array
Implementation Method 2
an acoustic wave that is incident thereon causes dimensional changes in the circumference of the mandrel, which modulates the phase of an optical signal propagating in the optical fiber
Data Source
AI summary
A fiber optic acoustic transducer includes a mandrel having a first portion that preferably formed generally as a cylinder having a projection extending from one end. A grating collar also preferably formed in a generally cylindrical configuration. The grating collar has a passage extending therethrough so that it may mounted on the projection. An optical fiber has a sensor portion wound around the first portion of the mandrel and a second portion wound around the grating collar with a fiber Bragg grating being formed in the second portion of the optical fiber.