Abstract
The fibre optic current sensor demonstrated here uses the intrinsic temperature and wavelength dependence of the Verdet constant of a terbium gallium garnet (TGG) magneto-optic material and the two micro-optic linear polarizers attached, to simultaneously extract the values of temperature and the optical Faraday rotation (induced by the presence of the magnetic field due an electric current on a conductor) without any extra optical component attached to the optical sensor head. The simultaneous measurement is achieved by illuminating the sensor head with a broadband optical source and by careful signal processing of the originated channelled-spectrum, compensate the sensor's temperature dependence.

Abstract
Laser-induced breakdown spectroscopy allows fast chemical analysis of light elements without significant sample preparation, turning it into a promising technique for on-site mining operations. Still, the performance for quantification purposes remains its major caveat, obstructing a broader application of the technique. In this work, we present an extensive comparison of the performances of distinct algorithms for quantification of Lithium in a mining prospection stage, using spectra acquired with both a commercial handheld device and a laboratory prototype. Covering both linear and non-linear methodologies, the results show that, when covering a wide range of concentrations typical on a mining operation, non-linear methodologies manage to achieve errors compatible with a semi-quantitative performance, offering performances better than those obtained with linear methods, which are more affected by saturation and matrix effects. The findings enclosed offer support for future applications in the field and may possibly be generalized for other elements of interest in similar mining environments.

Abstract
Thin films of titanium dioxide (TiO2) and titanium (Ti) were deposited onto glass and optical fiber supports through DC magnetron sputtering, and their transmission was characterized with regard to their use in optical fiber-based sensors. Deposition parameters such as oxygen partial pressure, working pressure, and sputtering power were optimized to attain films with a high reflectance. The films deposited on glass supports were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Regarding the deposition parameters, all three parameters were tested simultaneously, changing the working pressure, the sputtering power, and the oxygen percentage. It was possible to conclude that a lower working pressure and higher applied power lead to films with a higher reflectance. Through the analysis of the as-sputtered thin films using X-ray diffraction, the deposition of both Ti and TiO2 films was confirmed. To study the applicability of TiO2 and Ti in fiber sensing, several thin films were deposited in single mode fibers (SMFs) using the sputtering conditions that revealed the most promising results in the glass supports. The sputtered TiO2 and Ti thin films were used as mirrors to increase the visibility of a low-finesse Fabry-Perot cavity and the possible sensing applications were studied.

Abstract
It is presented a study of the dependence between the free spectral range (FSR) and the cavity length in Fabry-Perot interferometers. Furthermore, the effect of frequency modulation on the FSR is studied when an optical spectrum analyser (OSA) is used as an interrogator. For low frequency range it is possible to observe this behaviour in the OSA and using an appropriate processing signal it is possible to use the white light interferometry technique.

Abstract
The evaluation of the diffusion properties of optical clearing agents in biological tissues, which are necessary to characterize the transparency mechanisms, has been traditionally made using ex vivo tissues. With the objective of performing such evaluation in vivo, this study was made to evaluate and compare those properties for propylene glycol in skeletal muscle, as obtained with the collimated transmittance and diffuse reflectance kinetics. The diffusion time and the diffusion coefficient of propylene glycol in the muscle that were calculated both from transmittance and reflectance kinetics presented a deviation of 0.8%, a result that opens the possibility to use such a method in vivo. © 2022 IEEE.

Abstract
The direct calculation of the absorption coefficient spectra of various tissues from spectral measurements allowed to retrieve the contents of melanin and lipofuscin. In the rabbit brain cortex, 1.8 times higher melanin content is explained by the neuron degeneration process. Similar melanin and lipofuscin contents were found in the rabbit pancreas as a result of the tissue aging process. The conversion of 83 % of the melanin in the human normal kidney into lipofuscin in the cancer kidney indicates that lipofuscin can be considered a kidney cancer marker in humans. © 2022 IEEE.