Browsing by Author "Caldas, P."
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Combined Neodymium–Ytterbium-Doped ASE Fiber-Optic Source for Optical Coherence Tomography ApplicationsPublication . Trifanov, I.; Caldas, P.; Neagu, L.; Romero, R.; Berendt, M. O.; Salcedo, J. A. R.; Podoleanu, A. Gh.; Lobo Ribeiro, Antonio B.Optical coherence tomography (OCT) imaging at the 1060-nm region proved to be a successful alternative in oph- thalmology not only for resolving intraretinal layers, but also for enabling sufficient penetration to monitor the subretinal vascu- lature in the choroid when compared to most commonly used OCT imaging systems at the 800-nm region. To encourage further clinical research at this particular wavelength, we have developed a compact fiber-optic source based on amplified spontaneous emission (ASE) centered at 1060 nm with 70-nm spectral bandwidth at full-width at half-maximum and output power 20 mW. Our approach is based on a combination of slightly shifted ASE emission spectra from a combination of Neodymium- and Ytterbium-doped fibers. Spectral shaping and power op- timization have been achieved using in-fiber filtering schemes. We have tested the performance of the source in an OCT system optimized for this wavelength.
- Electrical current metering with a dual interferometric configuration and serrodyne signal processingPublication . Jorge, P A S; Caldas, P.; Ferreira, L A; Lobo Ribeiro, Antonio B.; Santos, J L; Farahi, FA bulk interferometric configuration for electrical current remote sensing in high voltage environments based on the Faraday effect is described. The combination of Sagnac’s reciprocal properties with a Mach–Zehnder processing interferometer in the same sensing head is used to implement serrodyne processing for current sensing. A theoretical analysis based on the Jones matrix is presented. Experimental results that validate the exploited concept are obtained, showing linearity up to 1800Arms and waveform reproduction at 50 Hz. The possibility of using the proposed interferometric concept to simultaneously fulfil the requirements associated with metering and relaying applications is also addressed.