Fiber optic measurement system for determination of extended object position and bends in 3D space

Abstract

Subject of Research. Fiber optic measurement systems are widely used in various industries. Most of these systems are fiber optic devices for detecting physical quantities. The development and creation of a measurement system for determination of the location and bends of extended objects in 3D space are actual at the moment. We propose the implementation of the sensitive part of the fiber optic measurement system based on seven single-mode fibers with an array of fiber Bragg gratings fixed to each other. Method. The method for determining the position and bends of extended objects in space is based on finding the level of axial deformation (compression, tension) of the fiber Bragg gratings during bending, and provides the calculation of the curvature direction and magnitude. Further reconstruction of the curve in space is realized by solving a system of differential equations with given initial conditions containing Frenet-Serre formulas. Main Results. The paper presents experiment results on writing fiber Bragg grating arrays into single-mode optical fibers, taking into account the features of the optical scheme and the source spectrum. The design and prototype of the fiber optic measurement system are developed. The results on the reconstruction of the shape based on experimental data are obtained. Practical Relevance. A special feature of this system is the fiber Bragg grating arrays formed in a wide range of wavelengths. Each Bragg grating corresponds to its own reflection wavelength, providing a sensitive part 1 m long. The geometry of the structure is based on seven fiber-optic armored microcables twisted with a given lay length during manufacturing, and provides the measurement of the kink value and direction.