Browsing by Author "Santos, J. L."
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- All-fibre interrogation technique for fibre Bragg sensors using a biconical fibre filterPublication . Lobo Ribeiro, Antonio B.; Ferreira, L. A.; Tsvetkov, M.; Santos, J. L.A passive self-referencing all-fibre technique for Bragg wavelength shift detection using a biconical fibre filter is described. This filter, basically a tapered depressed-cladding fibre, exhibits a periodic spectral power dependence which permits direct tracking of wavelength shifts in a 20nm unambiguous range. Dynamic strain resolution of 1.5 μstrain/√Hz has been achieved.
- Fiber-Optic Inclinometer Based on Taper Michelson InterferometerPublication . Amaral, L. M. N.; Frazao, O.; Santos, J. L.; Lobo Ribeiro, Antonio B.A compact fiber-optic inclinometer based on a fiber-taper Michelson interferometric sensor is constructed and demonstrated. The sensor consist of a single symmetrically taper waist of 80 micron distanced 30 mm from the single-mode fiber end-tip right-angled cleaved. The amplitude of the bending angle of the fiber taper interferometer is obtained by passive interferometric interrogation based on the generation of two quadrature phase-shifted signals from two fiber Bragg gratings with different resonant wavelengths. Optical phase-to-bending sensitivity of ~1.13 rad/degree and a bend angle resolution of ~0.014degree/Hz^1/2 were achieved.
- Large range coherence tuned fiber optic interferometric system for application in accelerometersPublication . Lobo Ribeiro, Antonio B.; Santos, J. L.; Jackson, D. A.A low coherence interferometric system with large tracking range and self‐initialization to be used for remote signal processing of fiber optic accelerometers is investigated. The tracking range of the low coherence system is 1.1 mm at low frequency. Phase resolution better than 1 mrad/√Hz at frequencies below 600 Hz is obtained, with a dynamic range of ≊90 dB. Data are presented which show that if the system were used to process the output from a compliant cylinder‐type accelerometer, resolutions of ∼10−7 g/√Hz could be achieved.
- Optical Fiber Sensor Technology in PortugalPublication . Lobo Ribeiro, Antonio B.; Santos, J. L.; Baptista, J. M.; Ferreira, L. A.; Araújo, F. M.; Leite, A. P.A general overview of the R&D activity in fiber optic sensing developed over the last fifteen years in Portugal is given. Different topics are addressed, including inter- ferometric, intensity and Bragg grating based fiber optic sensors, signal processing and multiplexing techniques, optical current sensors, together with some references to field trials and applications. Possible guidelines for present and future national R&D activity on this subject are outlined.
- Progressive ladder network topology combining interferometric and intensity fiber-optic-based sensorsPublication . Lobo Ribeiro, Antonio B.; Caleya, R. F.; Santos, J. L.Progressive ladder topology is studied by consideration of its properties of power budget and coupler tailoring. Optimization criteria are addressed for lossless and real systems, and their basic characteristics are compared with other topologies. Numerical results are presented, and an experiment is described for the case in which the network supports interferometric and intensity (with referentiation) fiber-optic-based sensors.