Sector Mirror Fiber-Optic Sensor for Force Measurement
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Solution Overview
Problem
Existing fiber-optic force and displacement sensors, such as Fiber Bragg grating sensors and wavelength-dependent sensors, face issues with weak axial tensile strength and temperature dependency, and lack intensity-dependent measurement capabilities.
Innovation Solution
A fiber-optic sensor assembly utilizing a mirror with multiple sectors, each having distinct reflective properties, projects single wavelength light beams from a laser source and calculates force and displacement based on changes in radiant flux as the sectors displace towards or away from the center of projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Fiber Bragg grating sensors or wavelength-dependent sensors are used, then force and displacement measurement is enabled, but the sensor suffers from weak axial tensile strength and temperature dependency
Solution Approach 1:
The patent replaces traditional mechanical FBG sensors with an optical lever system using a mirror and laser. The mirror rotates in response to applied force, changing the reflection angle of laser light. This optical measurement system eliminates the weak axial tensile strength and temperature dependency of mechanical FBG sensors, providing more reliable measurements through non-contact optical detection of displacement and force.
Solution Approach 2:
The patent changes the measurement parameter from wavelength-dependent (FBG) to intensity-dependent detection. By measuring changes in light intensity reflected from the mirror at different angles, the system achieves force and displacement measurement without the temperature sensitivity inherent in wavelength-based methods. The rotation angle of the mirror directly correlates to applied force, providing a more stable measurement parameter.
2Measurement precision
If wavelength-dependent sensors are used, then spectral feature reflection or transmission is measured, but intensity-dependent measurement capability is lost
Solution Approach 1:
The patent uses changes in light intensity (analogous to color/brightness changes) reflected from the mirror to measure force and displacement. As the mirror rotates, the intensity of reflected laser light varies, providing intensity-dependent measurement capability. This approach maintains measurement precision while enabling versatile intensity-based detection that wavelength-dependent sensors cannot provide.
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 solution provides an intensity-dependent measurement system that effectively measures force and displacement along three degrees of applied force, overcoming the limitations of existing sensors by using a mirror with sectors of varying reflectance to determine displacement and force through changes in radiant flux.
Implementation Method 1
Each of the sectors of the mirror have a reflectance (also known as reflectivity) corresponding to one of a plurality of single wavelength light beams transmitted from a laser light source
Data Source
AI summary
A fiber-optic force and displacement sensor includes a mirror comprising a plurality of sectors extending from a center point to a peripheral edge. Each of the sectors has a high reflectance corresponding to only one of a plurality of single wavelength light beams having different wavelengths transmitted from a laser light source. A method of measuring force and displacement includes measuring the radiant flux between each of a plurality of reflected single wavelength light beams that change as the area of the sectors are displaced towards and away from a center of projection of a combination light beam that comprises the plurality of single wavelength light beams projected towards the center point of the mirror when the mirror is in a rested position. Forces acting upon the mirror are measured as a function of the displacement of the mirror and the transverse and the axial stiffness of a connector.