Frequency analysis of the new prototype of the security window sensor

摘要

The paper describes the use of fiber-optic interferometer as a security sensor, which was built in a prototype of a plastic window. Its primary function is detecting the vibration and acoustic impulses, which affect the transparent glass part of the window prototype. The presented results are focused on the analysis of the frequency characteristic of the created prototype to verify of the sensitivity of the sensor. The knowledge of the frequency characteristic of the proposed window sensor is necessary due to the correct interpretation of the measured data. The interferometer is a Mach-Zehnder type and operates with an optical fibers G.652.D. As a radiation source, we used DFB laser with the wavelength of 1550 nm. The input optical power is 1 mW. Optical signal was detected by PbSe photodetector. The generator of the harmonic signal with fixed amplitude of the signal and digital sound level meter were used to the analysis of the frequency characteristic of the prototype. The analyzed frequency spectrum was in a range of 35 Hz to 8 kHz. The paper showed that this system is suitable for measurements of vibration impulses and acoustic waves in the audible range from 40 Hz up to 3 kHz.