Explain about the term extrinsic fiber optic sensors.
Extrinsic sensors:
Extrinsic fiber optic sensors utilize an optical fiber cable, usually a multimode one, to transmit modulated light by either a non-fiber optical sensor, or else an electronic sensor linked to an optical transmitter. A main benefit of extrinsic sensors is their capability to reach places that are otherwise inaccessible. An illustration is the measurement of temperature into aircraft jet engines via using a fiber to transmit radiation within a radiation pyrometer located outside the engine. These sensors can also be used in similar way to measure the internal temperature of electrical transformers; there the extreme electromagnetic fields present create other measurement techniques not possible.