A Fabry-Perot Interferometer-Based Fiber Optic Dynamic Displacement Sensor With an Analog in-Phase/Quadrature Generator

• Published in: IEEE sensors journal 2020-12, Vol.20 (24), p.14764-14771
• Main Authors: Acharya, Anisha, Kawade, Nitin
• Format: Article
• Language: English
• Subjects: Algorithms; Condition monitoring; Demodulation; Displacement; double pass sensor head; Fabry-Perot fiber optic interferometer; Fabry-Perot interferometers; Fiber optics; Frequency modulation; Generators; I/Q generator; Luminous intensity; Optical fiber sensors; Optical fibers; Optical interferometry; phase generated carrier modulation; Phase unwrapping; Piezoelectric actuators; Predictive maintenance; Quadratures; Sensors
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2020.3009587

In this paper, the design details of a low-cost and high resolution Fiber Optic Dynamic Displacement sensor are discussed. The sensor is designed based on the principle of extrinsic Fiber Optic Fabry-Perot Interferometer (FPI). Higher sensitivity is achieved by using a double pass sensor head configuration. To resolve direction ambiguity, quadrature signals are generated by employing Phase Generated Carrier (PGC) demodulation technique. An Analog In-phase/Quadrature phase (I/Q) generator is designed to perform light intensity compensation, carrier mixing, and filtering operations to obtain the quadrature signals. Arctangent algorithm and phase unwrapping algorithms are used to obtain dynamic displacement from the quadrature signals. The sensor is demonstrated to measure non-contact dynamic displacement at a working distance of 5 cm with an amplitude resolution of 12 nm, a precision of 1.4 nm, and a standard deviation of 2%. The sensor is also able to measure multi-frequency dynamic displacements generated by piezo actuators. Potential applications of the sensor include condition monitoring and predictive maintenance in industries.