Which part is the fiber optic sensor located in

A fiber optic sensor is typically located within the optical fiber itself for intrinsic sensors, or connected externally for extrinsic sensors, with hybrid types combining both approaches.Intrinsic Fiber Optic SensorsIn intrinsic sensors, the sensing element is embedded directly in the optical fiber. The fiber itself acts as the sensor, and the measurand (such as strain, temperature, or pressure) directly affects the light traveling through the fiber. Changes in light intensity, phase, polarization, wavelength, or transit time occur within the fiber, allowing the sensor to detect the physical quantity without external transducers . This type is ideal for remote monitoring and applications in small or complex structures.Extrinsic Fiber Optic SensorsFor extrinsic sensors, the optical fiber serves primarily as a light conduit. The actual sensing element is external to the fiber, and the fiber transmits light to and from this element. The modulation of the light occurs outside the fiber, and the fiber simply relays the signal to the processing electronics . This setup is useful when the sensing environment requires separation from the fiber or when specialized transducers are needed.Hybrid Fiber Optic SensorsHybrid sensors combine both intrinsic and extrinsic principles. The fiber carries light into and out of the device, while part of the sensing occurs within the fiber and part externally. This allows for flexible design and can optimize sensitivity and measurement range .Practical PlacementIn practical applications, the fiber optic sensor can be installed in tight or narrow spaces, often close to the object being measured. The fiber unit is flexible and can be routed to the desired location, while the light source and processing electronics are typically housed separately in a fiber amplifier or control unit . This separation allows the sensor to operate in harsh environments, including high temperatures, vibration, or areas with electrical interference. In summary, the sensor is either integrated into the fiber itself or positioned externally, depending on the type of fiber optic sensor, with hybrid designs offering a combination of both approaches for enhanced flexibility and performance.