In this paper, a two-dimensional wireless displacement sensor with high sensitivity composed of a bilayer graphene-based frequency selective surface (FSS) is proposed. The lengths of the strip-type resonators on the t...
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In this paper, a two-dimensional wireless displacement sensor with high sensitivity composed of a bilayer graphene-based frequency selective surface (FSS) is proposed. The lengths of the strip-type resonators on the top and bottom layers of the FSS are different and perpendicular to each other. Based on the resonance and polarization characteristics of the FSS, two-dimensional displacement sensing can be realized. It is well validated both in simulation and experiment that the direction of the displacement can be distinguished by the variation trend of the resonant frequencies of the top and bottom layers. In experiment, the measured results of the FSS based wireless displacement sensor in the dynamic range of 5mm show high sensitivity of 280 MHz/mm in x direction and 370 MHz/mm in y direction. Moreover, the excellent mechanical and chemical stability of the multi-layer graphene also makes it suitable for harsh environments, showing good prospects in application.
We report in this work the theoretical analysis of a linear displacement sensor based on the magneto-optical Faraday effect. The sensor consists of a rod of a magneto-optically active material that can be dislocated a...
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We report in this work the theoretical analysis of a linear displacement sensor based on the magneto-optical Faraday effect. The sensor consists of a rod of a magneto-optically active material that can be dislocated along the axis of a magnetic configuration formed by two equal hollow cylindrical permanent magnets, uniformly magnetized, arranged with opposite polarities. The performance of the sensor is discussed in terms of the inner and outer diameters of the two magnets, the sample and magnet lengths, the residual magnetic-field strength of the permanent magnets, the Verdet constant of the magneto-optically active material and the wavelength of the light source employed. We show that it is possible to have a practical sensor system that is almost linear over a distance equivalent to 90% of the total sample length, with a departure from linearity smaller than 1% and capable of detecting displacements as small as 1 mu m when a rod of HOYA FR-5 paramagnetic glass is used as the magneto-optically active medium and a He-Ne laser at 543 nm as light source. (C) 1998 Elsevier Science S.A. All rights reserved.
Distribution of precise time reference in an Ethernet network allows the implementation of distributed measurement systems, overcoming the limitations of a complex architecture. This paper deals with a displacement se...
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Distribution of precise time reference in an Ethernet network allows the implementation of distributed measurement systems, overcoming the limitations of a complex architecture. This paper deals with a displacement sensor network that is built over Ethernet and synchronized according to IEEE 1588. Measurement devices share the same time reference, enabling accurate calculation of cross-derived quantities (multidimensional speed and acceleration). In this paper, a description of the sensor architecture is given, and attention is focused on the IEEE 1588 implementation. In particular, the proposed low-cost system does not use any dedicated synchronization hardware, but it can reduce the deviation from time reference down to 20 mu s.
A low-finesse fiber-optic Fabry-Perot interferometer displacement sensor has been developed and tested. The sensor consists of a single-mode fiber-optic interferometer and a high performance signal processing system. ...
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A low-finesse fiber-optic Fabry-Perot interferometer displacement sensor has been developed and tested. The sensor consists of a single-mode fiber-optic interferometer and a high performance signal processing system. The displacement resolution of the sensor is 0.005 nm, the accuracies are 0.05 nm over dynamic range 0.005-79.1 nm and 0.5 nm over dynamic range 79.1-3200 nm, respectively. (C) 1998 Elsevier Science S.A. All rights reserved.
Optical sensors are used extensively for displacement measurement. A cost-effective optical displacement sensor will be invaluable in applications where very high resolutions are not required. In this work, the optica...
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Optical sensors are used extensively for displacement measurement. A cost-effective optical displacement sensor will be invaluable in applications where very high resolutions are not required. In this work, the optical mouse has been investigated to determine its suitability for two-dimensional displacement measurement. While the mouse worked only on objects with opaque surfaces, experiments conducted with a commercial unit with 0.0635 mm resolution showed that highly linear (average R-2-value of 0.9914) and low error (mean square error (M.S.E.) value below 0.018 mm(2)) measurements could be attained. On the flipside, the unit could only operate if placed at a distance no greater than 1.25 mm from the object surface. Overall, the optical mouse has been found to be a viable two-dimensional displacement sensor. Its efficacy was demonstrated in measuring the viscoelastic elongation of polyethylene. (C) 2003 Elsevier B.V. All rights reserved.
A fiber-optic displacement sensor based on a side-polished single-mode (SM) fiber in contact with a tapered planar waveguide (PWG) is investigated theoretically and experimentally. The thickness variation of the taper...
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A fiber-optic displacement sensor based on a side-polished single-mode (SM) fiber in contact with a tapered planar waveguide (PWG) is investigated theoretically and experimentally. The thickness variation of the tapered PWG in the side-polished region leads to a shift in the resonance wavelength, and the sensor revealed a highly linear relation between the variation of the resonance wavelength and the displacement of the tapered PWG. The design and fabrication technique are presented, and the spectral and polarization characteristics measured and explained. (c) 2004 Elsevier B.V. All rights reserved.
In this paper, a displacement sensor utilizing a Mach-Zehnder interferometer with a single-multi-air-gap-single mode (SMAS) fiber structure is proposed and demonstrated. A 30-cm-long four-mode step index fiber (FMSIF)...
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In this paper, a displacement sensor utilizing a Mach-Zehnder interferometer with a single-multi-air-gap-single mode (SMAS) fiber structure is proposed and demonstrated. A 30-cm-long four-mode step index fiber (FMSIF) is used as the multimode fiber in the SMAS structure, with the left end of the FMSIF fusion spliced to a 50-cm-long single-mode fiber (SMF-28). The right end of the FMSIF is aligned to another 50-cm SMF-28 on the v-groove of Fitel S178A fusion splicer but without splicing, creating an air gap with a tunable length of 0-300 mu m. The performance of the displacement sensor is investigated over the range of 1.1-1.7 mu m using a supercontinuum source. Through the experiment wavelength range, the highest sensor sensitivity is achieved at 1.7 mu m with a sensitivity of 12.3 pm/mu m and an R-2 coefficient of 0.926. The implementation of a displacement sensor utilizing the simple and cost-effective concept of the SMAS will be beneficial for use in various areas, such as biomedicine, manufacturing, and engineering.
A novel temperature-insensitive displacement sensor based on a fiber Bragg grating (FBG) is presented. A FBG was glued into a V-shaped groove, which lies on the lower surface of a double trapezoidal beam. It is found ...
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A novel temperature-insensitive displacement sensor based on a fiber Bragg grating (FBG) is presented. A FBG was glued into a V-shaped groove, which lies on the lower surface of a double trapezoidal beam. It is found that the 3-dB bandwidth of the reflection spectra and output optical power of the FBG changed linearly with the variation of the displacement of the beam. High sensitivity of 0.25 nm mm(-1) and 3.70 mW mm(-1) were achieved. The sensor is temperature-insensitive through measuring the bandwidths of the reflection spectra and optical power of the reflected signal.
displacement sensors are necessary for bearingless motors and magnetic bearings. A sensor target ring is needed in a rotor shaft, thus, the axial length has to be extended. The shaft extension is considerable when a g...
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displacement sensors are necessary for bearingless motors and magnetic bearings. A sensor target ring is needed in a rotor shaft, thus, the axial length has to be extended. The shaft extension is considerable when a gap length is large because a wide gap sensor needs a large diameter in a sensor head coil. To solve this problem, search coils have been installed in a stator for rotor displacement estimation. However, there is serious interference between suspension winding current and search coils. In this paper, the interference is theoretically and experimentally investigated. Two search coil connections are compared. sensor output characteristics of one of the proposed connection are found to be effective in the interference elimination, even though suspension windings are driven by a three-phase inverter.
This paper presents a fiber Bragg grating (FBG) displacement sensor for crack monitoring in high-speed railway tunnels. Two FBGs placed in a single-mode optical fiber around two cylindrical rods are employed and confi...
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This paper presents a fiber Bragg grating (FBG) displacement sensor for crack monitoring in high-speed railway tunnels. Two FBGs placed in a single-mode optical fiber around two cylindrical rods are employed and configured in a pre-stretched and suspended status with the two ends fixed to two beams. This design can effectively avoid the pasting process of the grating area and the concomitant problem of chirp phenomenon in the reflection spectrum and promises a high sensitivity and resolution. The mechanical structure, operation principle, and corresponding theoretical model are presented in detail in sequence. Full-scale tests including the accuracy of this sensing system have been performed. The experimental results show that the sensor possesses a high sensitivity of 3304.7 pm/mm, a high accuracy of 20 mu m within a range of 0-2 mm, and a low repeatability error of 2.71%. Furthermore, excellent creep resistance (fluctuant value is within 2 pm) and good temperature compensation capacity (maximum value is 27 pm) have also been verified. The proposed sensor shows good performance that satisfies the actual requirements of long-term crack monitoring.
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