Simulation results and experimental data on the operation of an inductively heated sensor of flow velocity, using fiber Bragg gratings as sensitive elements, are presented. The principle of operation of the sensor is based on the cross-correlation method. In the course of the experiment, it was possible to detect the transit time of the heat pulse between the temperature sensors from 0.2 to 0.5 s, which corresponds to the flow velocity in the range of 0.1–0.5 m/s.

The paper presents simulating and experimental results of flowmeter operation with induction heating, where fiber Bragg gratings were used as sensitive elements of temperature sensors. The operating principle of flowmeter based on cross-correlation method. During the experiment, it was detected time response of heat pulse from 0.2 s to 0.5 s that corresponds to a flow velocity range 0.1-0.5 m/s.

The results of theoretical calculations and experimental studies of the characteristics of an acoustic test signal when using an acoustic enclosure of the “open-shield” type are presented. The enrichment of the test acoustic signal spectrum due to the use of the developed enclosure was up to +30 dB in the frequency range of up to 500 Hz and from +4 to +20 dB in the frequency range of 1500–5000 Hz in comparison with the loudspeaker without an enclosure. The effect of room characteristics on the acoustic signal at the measurement point was studied and a method for compensation of this influence was proposed. As a result of applying it, the nonuniformity of the amplitude–frequency response of the acoustic signal at the measurement point decreased from 7 to 1.5 dB and the slopes of its spectral characteristic were eliminated.

This article is devoted to the study of the influence of acoustic environmental impacts on the operation of fiber-optic interferometers and measuring systems that are based on them. A method for reducing this influence by using an acoustically conditioned sound-proofing case for operation in the presence of external impacts in a frequency range of 20 to 20 000 Hz is considered. A mathematical model and the results of its research are presented; the calculated dependence of the degree of reducing the acoustic sensitivity of a fiber-optic interferometer on the degree of acoustic sealing of its case is obtained. An experimental setup and a technique for experimental evaluation of the degree of acoustic sealing when studying the cases of devices were developed.

The influence of environmental acoustic vibrations on cavities of fiber lasers may significantly decrease their parameters. It is shown that protective coatings for desensitization of fiber laser cavities with efficiency up to -95 dB compared to the level of acoustic sensitivity of optical fiber with standard acrylate coating can be produced by application of composite multi-layer structures of different-type materials.

Theoretical calculations and an experimental study of the degree of decrease in the acoustic sensitivity of an optical fiber in the frequency range of 20–20 000 Hz inside the cables of special design were carried out. A substantial decrease in acoustic sensitivity has been achieved, that is, more than –29 dB with respect to the standard single-mode SMF-28 fiber in a polymer shell. This result can significantly increase the threshold sensitivity of measuring systems based on fiber optic interferometers.

Theoretical calculations and experimental study of the acoustic sensitivity suppression level of optical fiber inside the cables of a special design in the frequency range 20-20000 Hz were carried out. A high degree of reduction in acoustic sensitivity has been achieved. It was more than 29 dB suppression relatively to the standard single-mode SMF - 28 fiber in a polymer shell. This result can significantly increase the sensitivity of measuring systems based on fiber-optic interferometers.