Differential reflective fiber-optic angular displacement sensor

• A differential reflective fiber-optic sensor is proposed to measure angular displacement.
• A theoretical model verified by the experimental measurements was established to characterize the sensor׳s performance.
• The sensor can improve sensitivity and anti-interference capability.
• The sensor is more suitable for bipolar absolute angular displacement measurement.

Using the characteristic that the distance apart between the emitting fiber and receiving fiber only shifts the angular-power curve, a differential reflective fiber-optic sensor for angular displacement measurement is presented through subtraction of two power signals from two receiving fibers placed on both sides of one emitting fiber. A theoretical model is established to characterize the performance of the differential reflective fiber-optic angular displacement sensor. The measurements made indicate that the general behavior of the experimental results agrees with that of the theoretical results, and the sensor can improve sensitivity by about 120%, resulting in the significant improvement of anti-interference capability, which will be more suitable for high accuracy bipolar absolute angular displacement measurement. Design guidelines are also suggested to achieve desired sensor performances.