The paper describes the implementation of a fiber-optic single-channel vibration sensor built on the basis of two fiber Bragg gratings, a broadband source, a photodetector and a sound card of a computer used as an ADC
Keywords: vibration, fiber optic sensor, fiber Bragg grating, Fourier transform
The complexity and high cost of multiplexing optical fiber sensors is still the main limitation for the widespread introduction of sensory systems, both distributed and quasi-distributed, and point-like. The article proposes a new multiplexing method that takes advantage of both broadband and two-frequency radio-photon multiplexing systems. The simplest broadband radiator is taken from the first, but a complicated and expensive system of spectrometry is not used to determine the central wavelength of fiber Bragg gratings. From the second, a recording system is used at the beat frequency between two components, but an expensive system for generating two- and polyharmonic probing systems is not used. The multiplexing parameter is determined by the frequency of separation between the transparency windows of a fiber Bragg grating, for example, with two phase π-shifts, which differs by a certain value for each of the sensors. The mechanism of modeling of gratings of the specified type is given, in principle the possibility of multiplexing of various number of sensors is shown. When using sensor networks built on the basis of passive optical, the number of multiplexed sensors can reach 256, with all sensors having the same Bragg wave of the wave, and can be combined into tree, bus and other topologies.
Keywords: fiber Bragg grating, phase inhomogeneity, fiber optic sensor, multiplexing, transparency window, frequency difference between transparency windows, beat frequency