An optical fiber sensor system fundamentally consists of a light source, optical fiber, a sensing element/transducer, and a detector.
Here's a breakdown of each component and its role:
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Light Source: Provides the initial light signal that is sent through the optical fiber. The properties of the light source (e.g., intensity, wavelength) are crucial for the sensor's performance. Common light sources include lasers, LEDs, and broadband light sources.
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Optical Fiber: Serves as the transmission medium, guiding the light from the source to the sensing element and then to the detector. The characteristics of the fiber (e.g., core diameter, refractive index) affect the light propagation and sensor sensitivity.
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Sensing Element (or Transducer): This is the key part of the system where the physical quantity being measured interacts with the light. The sensing element modifies one or more properties of the light (e.g., intensity, wavelength, phase, polarization) in response to the measurand. It essentially converts the physical quantity into an optical signal.
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Detector: Receives the modified light signal from the sensing element via the optical fiber. The detector converts the optical signal back into an electrical signal, which can then be processed and analyzed to determine the value of the measured physical quantity. Photodiodes and photomultiplier tubes are common types of detectors used in optical fiber sensor systems.
In summary, an optical fiber sensor system works by launching light into an optical fiber, using a sensing element to modulate the light based on the parameter being measured, and then detecting the changes in the light to determine the value of that parameter.
