Dual Fiber Grating Sensor Phase Difference Noise Cancellation
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Solution Overview
Problem
Existing optical fiber-based sensor systems face challenges in achieving precise measurements due to extrinsic noise and drift, which affect single phase difference measurements from fiber gratings.
Innovation Solution
The system employs two optical fibers with fiber gratings at different locations reflecting distinct wavelengths, measuring phase differences at each wavelength and providing a measurement result based on the difference between these phase differences, which cancels out noise and drift, thereby enhancing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single phase difference measurement is performed using one fiber grating, then the measurement process is simple, but extrinsic noise and drift significantly affect measurement precision
Solution Approach 1:
The patent combines multiple fiber gratings (at least two) into a single sensing system, where each grating reflects a different wavelength. The system measures phase differences from multiple gratings and processes these measurements together to cancel extrinsic noise and drift, thereby improving measurement precision while managing system complexity through integrated design
2Reliability
If multiple fiber gratings at different wavelengths are used, then noise and drift cancellation is achieved, but the system complexity increases
Solution Approach 1:
The patent utilizes different wavelength parameters for different fiber gratings. By assigning each grating a distinct reflected wavelength, the system can independently measure phase differences at multiple wavelengths and process these measurements to cancel extrinsic noise and drift, improving reliability while organizing complexity through parameter differentiation
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 results in more precise measurements by correlatively addressing extrinsic noise and drift, leading to improved accuracy in detecting physical quantities like vibration, strain, temperature, and elongation.
Implementation Method 1
a first fiber grating at a first location in the first optical fiber and reflecting light of a first wavelength; and a second fiber grating at a second location in the first optical fiber and reflecting light of a second wavelength
Implementation Method 2
to measure a first phase difference between light of the first wavelength emanating from the first optical fiber and light of the first wavelength emanating from the second optical fiber
Data Source
AI summary
An optical fiber-based sensor system includes a sensing optical fiber having fiber gratings that reflect light at respective wavelengths. A first fiber grating reflects light at a first wavelength. A second fiber grating reflects light at a second wavelength. The system also has a reference optical fiber. An optical read-out arrangement generates light at the first and second wavelengths. The light is injected in the sensing optical fiber and in the reference optical fiber. A first phase difference is measured between light at the first wavelength emanating from the sensing optical fiber and the reference optical fiber. In addition, a second phase difference is measured between light at the second wavelength emanating from the sensing optical fiber the reference optical fiber. A measurement result is based on a difference between the first phase difference and the second phase difference.