The emitter and receiver fibers are installed in the same housing and light normally does not return to the receiver. When light from the emitter strikes the sensing object, the object reflects the light and it enters the receiver where the intensity of light is. Radiation absorption excites an orbital electron to a higher energy level. Radiation absorption creates electronic excited states that are trapped by localized defects for extended periods of time. Detection in Narrow Locations The small sensing section and flexible Fiber Unit cable enable a Fiber Sensor to detect. A fiber optic sensor is a measurement device that uses light traveling through a glass or plastic filament to determine a physical quantity such as temperature, pressure, or strain. The optical. birth of fiber optic sensors. Further there are many points why fiber optic sensors are used in place of traditional size and. Fiber optic current sensors are revolutionizing the way electrical currents are measured, providing high sensitivity, immunity to electromagnetic interference (EMI), and the ability to function in harsh environments.