Browsing by Author "Frazão, Orlando"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- Optical Current Sensors for High Power Systems: A ReviewPublication . Silva, Ricardo M.; Martins, Hugo; Nascimento, Ivo; Baptista, José M.; Lobo Ribeiro, Antonio B.; Santos, José L.; Jorge, Pedro; Frazão, OrlandoThe intrinsic advantages of optical sensor technology are very appealing for high voltage applications and can become a valuable asset in a new generation of smart grids. In this paper the authors present a review of optical sensors technologies for electrical current metering in high voltage applications. A brief historical overview is given together with a more detailed focus on recent developments. Technologies addressed include all fiber sensors, bulk magneto-optical sensors, piezoelectric transducers, magnetic force sensors and hybrid sensors. The physical principles and main advantages and disadvantages are discussed. Configurations and strategies to overcome common problems, such as interference from external currents and magnetic fields induced linear birefringence and others are discussed. The state-of-the-art is presented including commercial available systems.
- Review of fiber-optic pressure sensors for biomedical and biomechanical applicationsPublication . Roriz, Paulo; Frazão, Orlando; Lobo Ribeiro, Antonio B.; Santos, José L.; Simões, José A.As optical fibers revolutionize the way data is carried in telecommunications, the same is happening in the world of sensing. Fiber-optic sensors (FOS) rely on the principle of changing the properties of light that propagate in the fiber due to the effect of a specific physical or chemical parameter. We demonstrate the potentialities of this sensing concept to assess pressure in biomedical and biomechanical applications. FOSs are introduced after an overview of conventional sensors that are being used in the field. Pointing out their limitations, particularly as minimally invasive sensors, is also the starting point to argue FOSs are an alternative or a substitution technology. Even so, this technology will be more or less effective depending on the efforts to present more affordable turnkey solutions and peer-reviewed papers reporting in vivo experiments and clinical trials.
- Suspended-core fibers for sensing applicationsPublication . Frazão, Orlando; Silva, Ricardo M.; Ferreira, Marta S.; Santos, José L.; Lobo Ribeiro, Antonio B.A brief review on suspended-core fibers for sensing applications is presented. A historical overview over the previous ten years about this special designed microstructure optical fiber is described. This fiber presents attractive optical properties for chemical/biological or gas measurement, but it can be further explored for alternative sensing solutions, namely, in-fiber interferometers based on the suspended-core or suspended-multi-core fiber, for physical parameter monitoring.
- Temperature-independent torsion sensor based on “figure-of-eight” fiber loop mirrorPublication . Silva, Ricardo M.; Lobo Ribeiro, Antonio B.; Frazão, OrlandoAn interrogation sensor system combining the “figure-of-eight” fiber loop mirror using a single directional 3×3 fiber optic coupler was proposed. One fiber loop mirror was formed by inserting a length of high birefringent optical fiber at the input ports of the 3×3 coupler. Splicing the output ports of the 3×3 coupler between them created the other fiber loop mirror. The introduction of this second loop gave rise to two polarization states of light with the same frequency but different optical phase. The mechanical torsion sensing head was located at the second loop and was exhibited an average modulus torsion sensitivity of 7.9×10−4 degree/dB. The performance of the sensor was not affected by environmental temperature variations.