OFDR Vibration Sensor With Segmented Fiber Cavities
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Solution Overview
Problem
Current optical methods for monitoring vibration in components like electronic submersible pumps face challenges in achieving localized strain measurements and high spectral resolution, particularly in providing meaningful sampling frequencies for dynamic strain measurements.
Innovation Solution
The use of a vibration sensor system with three broadband reflectors along an optical fiber, employing optical frequency domain reflectometry (OFDR) to perform distributed vibration measurements, allowing for simultaneous measurement at multiple locations with high sampling rates exceeding 120 Hz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If cavity-based techniques are used for optical strain measurement, then measurement coverage is improved, but measurement precision deteriorates due to integration over long lengths
Solution Approach 1:
The optical fiber is segmented into multiple measurement sections, each with its own cavity. By dividing the long fiber into discrete segments, the system achieves both distributed measurement coverage and localized precision within each segment. The interference signal from each cavity corresponds to a specific spatial location rather than an integration over the entire fiber length.
2Measurement precision
If grating-based techniques are used for vibration measurement, then localized strain measurement is improved, but sampling frequency deteriorates due to interrogation speed limitations
Solution Approach 1:
The patent replaces traditional mechanical scanning interrogation methods with a parallel optical processing approach. Multiple cavities are interrogated simultaneously using optical frequency domain reflectometry, eliminating the sequential scanning bottleneck and enabling high sampling frequencies exceeding 120 Hz while maintaining localized measurement precision.
3Device complexity
If traditional optical methods are used for vibration monitoring, then system simplicity is maintained, but spectral resolution deteriorates
Solution Approach 1:
The patent transitions from time-domain or frequency-domain single-point measurements to a spatial-frequency domain approach. By introducing the spatial dimension through distributed cavities along the fiber and combining it with frequency domain reflectometry, the system achieves high spectral resolution while maintaining relative system simplicity through the use of standard optical components.
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 enables accurate and localized vibration detection, overcoming limitations of existing methods by providing high spectral resolution and fast sampling rates, effectively predicting component failures and minimizing operational disruptions.
Implementation Method 1
performing optical frequency domain reflectometry (OFDR) to perform distributed vibration measurements
Implementation Method 2
obtaining an interference signal from the vibration sensor
Data Source
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AI summary
A vibration detector and method of measuring vibration are described. The vibration detector includes an optical fiber comprising a reference reflector and a delay coil, and one or more sensors comprised at respective one or more locations in the optical fiber, each of the one or more sensors including a center reflector and two side reflectors on either side of the center reflector, the delay coil eliminating detection of interference among reflections from the one or more sensors. The vibration detector also includes a light source to introduce light into the optical fiber to interrogate the optical fiber, a detector to obtain interference signals, each of the interference signals being based on interference between reflections from the reference reflector and one of the one or more sensors; and a processor to process each of the interference signals to obtain vibration measurements.