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Center of Gravity Estimation Using a Reaction Board Instrumented With Fiber Bragg Gratings

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Photonic Sensors 2018年第1期8卷 1-6页

作者： Rui OLIVEIRA Paulo RORIZ Manuel B. MARQUES orlando frazao INESC TEC Rua do Campo Alegre 687 4150-179 Porto Portugal CIDESD-ISMAI-Institute University of Maia (ISMAl) Av. Carlos Oliveira Campos Castelo da Maia 4475-690 MaiaPortugal Department of Physics and Astronomy Faculty of Sciences University of Porto Rua do Campo Alegre 687 4169-007Porto Portugal

The purpose of the present work is to construct a reaction board based on fiber Bragg gratings （FBGs） that could be used for estimation of the 2D coordinates of the projection of center of gravity （CG） of an object. The apparatus is consisted of a rigid equilateral triangular board mounted on three supports at the vertices, two of which have cantilevers instrumented with FBGs. When an object of known weight is placed on the board, the bending strain of the cantilevers is measured by a proportional wavelength shift of the FBGs. Applying the equilibrium conditions of a rigid body and proper calibration procedures, the wavelength shift is used to estimate the vertical reaction forces and moments of force at the supports and the coordinates of the object＇s CG projection on the board. This method can be used on a regular basis to estimate the CG of the human body or objects with complex geometry and density distribution. An example is provided for the estimation of the CG projection coordinates of two orthopaedic femur bone models, one intact, and the other with a hip stem implant encased. The clinical implications of changing the normal CG location by means of a prosthesis have been discussed.

关键词： Optical fiber sensors fiber Bragg gratings cantilever center of gravity hip prosthesis

Interferometer Based on a D-shape Chaotic Optical Fiber for Measurement of Multiparameters

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Photonic Sensors 2012年第4期2卷 381-384页

作者： Susana SILVA Luis COELHO Philippe ROY orlando frazao INESC Porto Rua do Campo Alegre 687 4169-007 Porto Portugal and Dept. de Fisica e Astronomia da Faculdade de Ciencias da Universiclacle do Porto Rua do Campo Alegre 687 4169-007 Porto Portugal Xlim UMR 6172 CNRS-University of Limoges 123 Avenue Albert Thomas 87060 Limoges Cedex France

An interferometer based on a D-shape chaotic optical tiber tor measurement ot multiparameters was proposed. The sensing structure relied on a D-shape fiber section spliced in between two singlemode fibers and interrogated in transmission. The optical spectrum was composed by multiple interference loss peaks, which were sensitive to the refractive index, temperature and strain-maximum sensitivities of 95.2 nm/RIU, 10.5 pm/℃ and -3.51 pm/με, respectively, could be achieved.

关键词： Optical fiber sensors interferometer chaotic fiber

Temperature-Independent Torsion Sensor Based on ＂Figure-of-Eight＂ Fiber Loop Mirror

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Photonic Sensors 2013年第1期3卷 52-56页

作者： Ricardo M. SILVA António B. Lobo RIBEIRO orlando frazao INESC Porto Rua do Campo Alegre 687 4169-007 Porto Portugal Departamento de Fisica da Faculdade de Cidnciasda Universidade do Porto Rua do Campo Alegre 687 4169-007 Porto Portugal Faculty of Health Sciences University Fernando Pessoa R. Carlos da Maia 296 4200-150 Porto Portugal

An 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. Keywords： Torsion sensor, fiber loop mirror, interferometer

关键词： Torsion sensor fiber loop mirror interferometer

Advanced Fiber-Optic Acoustic Sensors

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Photonic Sensors 2014年第3期4卷 198-208页

作者： Joao G. V. TEIXEIRA Ivo T. LEITE Susana SILVA orlando frazao EQS Group Rua Joaquim Dias Rocha 354 4470-221 Maia Portugal lNESC TEC (coordinated by INESC Porto) Rua Campo Alegre 687 4169-007 Porto Portugal Department of Physics and Astronomy Faculty of Sciences- University of Porto Rua Campo Alegre 687 4169-007 Porto Portugal

Acoustic sensing is nowadays a very demanding field which plays an important role in modern society, with applications spanning from structural health monitoring to medical imaging. Fiber-optics can bring many advantages to this field, and fiber-optic acoustic sensors show already performance levels capable of competing with the standard sensors based on piezoelectric transducers. This review presents the recent advances in the field of fiber-optic dynamic strain sensing, particularly for acoustic detection. Three dominant technologies are identified - fiber Bragg gratings, interferometric Mach-Zehnder, and Fabry-Perot configurations - and their recent developments are summarized.

关键词： Acoustic sensors fiber optics optical fiber sensors

Nanostrain Measurement Using Chirped Bragg Grating Fabry-Perot Interferometer

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Photonic Sensors 2012年第1期2卷 77-80页

作者： Ricardo M. SILVA Marta S. FERREIRA Jose L. SANTOS orlando frazao INESC Porto Rua do Campo Alegre 687 4169-007 Porto Portugal and Faculty of Sciences of University of Porto Rua do Campo Alegre 687 4169-007 Porto Portugal

A simple nanostrain direct current （DC） measurement system based on a chirped Bragg grating Fabry-Perot （FP） structure is presented. The FP cavity, formed between the chirped fiber Bragg grating （CFBG） and the fiber end face, presents an aperiodic behavior due to the CFBG. A laser located in the fringe pattern slope is used to interrogate the sensing head. The optical power parameter is analyzed when strain is applied, for long and short period fringe pattern wavelengths, and sensitivities of-2.87 μW/με and-5.48μW/με are respectively obtained. This configuration presents a resolution of 70 ε.

关键词： Optical fiber sensor Fabry-Perot interferometer chirped fiber Bragg grating

Ammonia Sensing System Based on Wavelength Modulation Spectroscopy

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Photonic Sensors 2015年第2期5卷 109-115页

作者： Duarte VIVEIROS Joao FERREIRA Susana O. SILVA Joana RIBEIRO Deolinda FLORES Jose L. SANTOS orlando frazao Jose M. BAPTISTA INESC Porto Rua do Campo Alegre 687 4169-007 Porto Portugal Geology Center of the University of Porto and Department of Geosciences Environment and Spatial Plannings Facultyof Science at University of Porto Rua do Campo Alegre 687 4169-007 Porto Portugal Department of Physics and Astronomy Faculty of Science at University of Porto Rua do Campo Alegre 687 4169-007 Porto Portugal Competence Center of Exact Sciences and Engineering University of Madeira Campus da Penteada 9000-390 Funchal Portugal

A sensing system in the near infrared region has been developed for ammonia sensing based on the wavelength modulation spectroscopy （WMS） principle. The WMS is a rather sensitive technique for detecting atomic/molecular species, presenting the advantage that it can be used in the near-infrared region by using the optical telecommunications technology. In this technique, the laser wavelength and intensity were modulated by applying a sine wave signal through the injection current, which allowed the shift of the detection bandwidth to higher frequencies where laser intensity noise was typically lower. Two multi-pass cells based on free space light propagation with 160 cm and 16 cm of optical path length were used, allowing the redundancy operation and technology validation. This system used a diode laser with an emission wavelength at 1512.21nm, where NH3 has a strong absorption line. The control of the NH3 gas sensing system, as well as acquisition, processing and data presentation was performed.

关键词： Ammonia sensing fiber optic system near infrared region wavelength modulation spectroscopy,environment

Fiber Fabry-Perot Interferometer for Curvature Sensing

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Photonic Sensors 2016年第4期6卷 339-344页

作者： Catarina S. MONTEIRO1 Marta S. FERREIRA Susana O. SILVA Jens KOBELKE Kay SCHUSTER JOrg BIERLICH orlando frazao Department of Physics and Astronomy Sciences Faculty Porto University Rua do Campo Alegre 687 4169-007 Porto Portugal INESC-TEC Rua do Campo Alegre 687 4169-007 Porto Portugal IPHT Jena - Leibniz Institute of Photonic Technology Albert-Einstein-Str. 9 07745 Jena Germany

A curvature sensor based on an Fabry-Perot （FP） interferometer was proposed. A capillary silica tube was fusion spliced between two single mode fibers, producing an FP cavity. Two FP sensors with different cavity lengths were developed and subjected to curvature and temperature. The FP sensor with longer cavity showed three distinct operating regions for the curvature measurement. Namely, a linear response was shown for an intermediate curvature radius range, presenting a maximum sensitivity of 68.52 pm/m-1. When subjected to temperature, the sensing head produced a similar response for different curvature radii, with a sensitivity varying from 0.84 pm/℃ to 0.89 pm/℃, which resulted in a small cross-sensitivity to temperature when the FP sensor was subjected to curvature. The FP cavity with shorter length presented low sensitivity to curvature.

关键词： Curvature measurement Fabry-Perot interferometer optical fiber sensor

Suspended-core Fibers for Sensing Applications

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Photonic Sensors 2012年第2期2卷 118-126页

作者： orlando frazao Ricardo M. SILVA Marta S. FERREIRA Jose L. SANTOS Antonio B. LOBO RIBEIRO INESC Porto Rua do Campo Alegre 687 4169-007 Porto Portugal Faculty of Sciences of University of Porto Rua do Campo Alegre 687 4169-007 Porto Portugal Faculty of Health Sciences University Fernando Pessoa Rua Carlos da Maia 296 4200-150 Porto Portugal

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.

关键词： Optical fiber sensor suspended core fiber interferometry

Strain Sensitivity Enhancement in Suspended Core Fiber Tapers

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Photonic Sensors 2013年第2期3卷 118-123页

作者： Ricardo M. ANDRE Susana O. SILVA Martin BECKER Kay SCHUSTER M. ROTHARDT H. BARTELT Manuel B. MARQUES orlando frazao INESC Porto Rua do Campo Alegre 687 4169-007 Porto Portugal Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto Rua do Campo Alegre 687 4169-007 Porto Portugal PHT Institute for Photonic Technology Jena Albert-Einstein-Str. 9 07745 Jena Germany

Suspended core fiber tapers with different cross sections （with diameters from 70μm to 120 μm） are produced by filament heating. Before obtaining the taper, the spectral behavior of the suspended core fiber is a multimode interference structure. When the taper is made, an intermodal interference between a few modes is observed. This effect is clearly visible for low taper core dimensions. Since the core and cladding do not collapse, two taper regions exist, one in the core and the other in the cladding. The cladding taper does not affect the light transmission, only the core is reduced to a microtaper. The spectral response of the microtaper based-suspended core fiber is similar to a beat of two interferometers. The strain is applied to the microtaper, and with the reduction in the transverse area, an increase in sensitivity is observed. When the taper is immersed in a liquid with a different index of refraction or subjected to temperature variations, no spectral change Occurs.

关键词： Optical fiber sensor taper microstructured fiber