Varyshchuk V. The polymer optical fiber-based interferometer as a transducer for measuring mechanical values

The thesis is devoted to the development of theoretical and practical principles of construction functional schemes of fiber optic measuring transducers of mechanical values based on polymer optical fiber interferometer. Theoretical generalization of the main physical properties of speckle structures formed at the output of multimode polymer optical fibers due to intermodal interference for their possible use as an informative parameter for metrological applications was conducted. Based on the research results, a new approach to the development of fiber-optic sensors and measuring transducers of mechanical values based on multimode polymer optical fibers is proposed. The developed method for processing signals of polymer optical fiber interferometer which is based on a direct correlation comparison of the intensity distributions between the reference and current speckle images allows to carry out automated control of the deformation parameters of technical objects. As a result of studies of the mechanism of radiation intensity modulation in multimode polymer fibers with selective excitation of modes, a method for measuring the frequency of mechanical oscillations and vibrations is proposed, which allows increasing the efficiency of phase modulation conversion into the modulation of radiation intensity. Researches in the processing and interpretation of measuring transducers on multimode polymer fibers can be used as a basis for the creation of control and measuring devices designed to study different physical fields, as well as for control and diagnosis of stress-strain state of technical objects. Given the mechanical properties of the sensitive elements of measuring transducers based on polymer optical fibers as well as their ability for multiplexing and creating long channels for information signal transmission, distributed fiber-optic measuring systems can be implemented.