Brillouin correlation domain reflectometer (BOCDR)

ʻIke wela optic, Pūnaehana nānā naʻauao, Hāʻawi ʻia ka mea hana fiber optic ma Kina

Fiber optic sensors that use optical fibers as sensors to measure various physical quantities such as stress, strain, mahana wela, etc. This fiber optic sensor is based on the light received by incident light from the first end of the fiber optic sensor and receiving transmitted light (or scattered light) emitted from the second end of the fiber optic, or reflected light (or scattered light) emitted from the first end, to determine the aforementioned physical quantities. As representative examples of such fiber optic sensors, FBG type fiber optic sensors, scattered light type fiber optic sensors, etc. can be cited.

In FBG type fiber optic sensors, FBG (Pākuʻi Fiber Bragg) is formed in the core of the fiber optic. FBG type fiber optic sensors are used to determine the distribution of various physical quantities in the length direction of optical fibers by utilizing the reflection characteristics of FBG that change according to the surrounding environment. Kahi mea hou aʻe, FBG type fiber optic sensors are used, for example, through OFDR (Optical Frequency Domain Reflectometry). In scattered light type fiber optic sensors, commonly used fibers without FBG are used as sensors. Scattered light type fiber optic sensors are used to measure the distribution of various physical quantities along the length direction of the fiber optic by utilizing the characteristics of scattered light generated within the fiber optic (such as Rayleigh scattered light) that changes according to the surrounding environment.

If light is directed into the fiber, a reflection light with a frequency reduction of only about 11GHz is generated due to phenomena such as Brillouin scattering, which is called Brillouin shift. The offset is proportional to strain and temperature. As a distributed fiber optic sensor utilizing this phenomenon, a Brillouin optical correlation domain reflectometer (BOCDR) has been proposed, which can measure the magnitude of strain or temperature changes at any position along the fiber optic.