Strain sensor using phase measurement techniques in polymer optical fibers

POF elongation sensors have been proposed e.g. by [1] as a low-cost alternative to FBG (single mode fiber Bragg gratings) sensors targeting the lower sensitivity range. A recently recovered detection system known from laser distance meters turned out to be very sensitive while staying simple. The approach is based on measuring the phase shift of a sinusoidally modulated light signal guided in a POF under different tensions resulting in different transit times and thus different phase shifts.