Resumo em Inglês:
Abstract Low frequency noise (LFN) of highly coherent laser (linewidth below 10 kHz) is analyzed using an unbalanced Mach- Zehnder interferometer (UMZI) with adjustable long arm span. Furthermore, the Laser Relative Excess Noise (LREN) is introduced here to set a comparison of the laser coherence in relation to its emission power. The LREN is obtained using the addition of laser high and low frequency noises that appear in excess to the ideal power spectral density (PSD) Lorentzian distribution. Using this approach, it is possible to compare the tested laser in relation to an ideal laser with the same linewidth.Resumo em Inglês:
Abstract This article presents the development of a liquid-level sensor using fiber optic Bragg gratings (FBG). The sensor comprises a carbon-fiber-reinforced polymers (CFRP) diaphragm packaging an embedded FBG to measure strain. A mathematical analysis determines the FBG response to the pressure exerted by a liquid column over the packaged sensor. The experimental arrangement consists of an acrylic tube with a sensor at the bottom. FBG signals were acquired using a DI 410 optical interrogator manufactured by HBM. A finite element simulation with Ansys was performed to determine the most reposeful position from the FBG sensor. The experimental results show the analysis of eight repetitions of the water column ranging from 10 cm to 60 cm using 10 cm steps. The sensor showed a linear response, with a coefficient of determination of 0.999, and a sensitivity of 4.1 pm/cm; and the maximum standard deviation is 0.64 pm. Although water is used in the calibration process, other liquids could also be used, obtaining a different angular coefficient depending on the density of the liquid used.Resumo em Inglês:
Abstract This paper discusses the through-wall detection of targets behind walls using an ultra-wideband radar operating in the 2 to 15 GHz frequency range. Tests were conducted to verify its use with static and moving targets. Two real-world cases were tested: a laboratory with students sitting on benches, and an adult person standing behind a door. A fast method, based on the standard deviation, was used to transform the time-domain data matrix into a simpler waveform. This method has the potential to quickly detect the presence of human targets behind physical obstacles.