Three-Arm, Self-Referencing Fiber-Optic Sensor

Sensor reading relatively immune to spurious variations in illumination and transmission. No separate reference channel necessary; provides own internal reference. Illumination for sensor provided by pulsed source of light. Pulses of light travel along optical fiber into sensor assembly including two 1 X 3 fiber-optic couplers and three optical fibers. After entering sensor assembly through left coupler, pulse of light split into three fibers. Three fibers have different lengths chosen to delay pulses by different amounts of time in equal increments.