Reflective fibre optical displacement sensors for the inspection of tilted objects

1996 ◽  
Vol 28 (11) ◽  
pp. 1655-1668 ◽  
Author(s):  
H. Wang
Keyword(s):  
Displacement Sensors ◽  
Optical Displacement

6-DOF Single-Inertial Mass, Isotropic Accelerometer With Optical Displacement Sensors

2006 ◽  
Author(s):  
Vladimir Chapsky ◽  
Vladimir Portman ◽  
Ben-Zion Sandler
Keyword(s):  
Light Source ◽  
Optical Sensors ◽  
Optical Measurement ◽  
Data Gathering ◽  
Inertial Mass ◽  
Symmetrical Structure ◽  
Mathematical Algorithm ◽  
Displacement Sensors ◽  
Optical Displacement ◽  
Experimental Apparatus

A novel design of high isotropy single mass six-degree-of-freedom (6-DOF) accelerometer has been developed and investigated. In the accelerometer, six spatial coordinates (three linear and three angular) of the inertial mass and their derivatives are observed by simple measurement of linear displacements of six optimally chosen points of the inertial mass. Calculation of the six acceleration components is then possible according to a specially developed mathematical algorithm. To provide the isotropy of the device’s sensitivity and to achieve the accuracy in the measurement of the linear and angular accelerations, three subsystems of the device — inertial, suspension, and measurement subsystems — have a spatially symmetrical structure. To provide the symmetrical structure of the inertial subsystem, the proof mass is manufactured from uniform material and has a cubic shape. All structural cavities in this cube (light guides and a light source cavity) are symmetrical relative to three coordinate axes. To provide the symmetry of suspension subsystem 24 elastic supports (springs) are mounted by three in all vertexes of the cube in the directions of X-, Y- and Z-axes. The springs have the same dimensions and stiffness. The damping elements (the rubber insets) are inserted into the springs. They are made of the same material and have the identical dimension. The measurement subsystem consists of six differential optical displacement sensors and the light source which is mounted in the center of the cube. Each optical sensor is based on three-component position-sensitive detectors (PSD) of a segmented type. This design ensures output signals that are independent of fluctuations in light source brightness and of optical and electromagnetic interferences. Optical sensors are mounted on the frame of the accelerometer and situated symmetrically opposite to the centers of the square faces of the cube. Six orts of measurement directions form three orthogonal pairs. The experimental model of isotropic 6-DOF accelerometer with differential optical measurement subsystem is manufactured, adjusted and tested. For this purpose the experimental apparatus consisting of the stand with standard accelerometers and computer-controlled data gathering and analysis system (multi-channel amplifier, analog-digital converter and LabView software system) is developed. The preliminary experiment results show that proposed device has high level of signal isotropy and it is hoped to have a good perspective for industrial application were it can replace the complex gyroscopic and combined multi-axis devices.

Methodology for the design, production, and test of plastic optical displacement sensors

2016 ◽  
Vol 5 (4) ◽  
Author(s):  
Maik Rahlves ◽  
Christian Kelb ◽  
Eduard Reithmeier ◽  
Bernhard Roth
Keyword(s):  
Large Scale ◽  
Mechanical Performance ◽  
Mechanical Test ◽  
Numerical Models ◽  
Testing Machine ◽  
Displacement Sensor ◽  
Optical Simulation ◽  
Displacement Sensors ◽  
Optical Displacement ◽  
Design Production

AbstractOptical displacement sensors made entirely from plastic materials offer various advantages such as biocompatibility and high flexibility compared to their commonly used electrical and glass-based counterparts. In addition, various low-cost and large-scale fabrication techniques can potentially be utilized for their fabrication. In this work we present a toolkit for the design, production, and test of such sensors. Using the introduced methods, we demonstrate the development of a simple all-optical displacement sensor based on multimode plastic waveguides. The system consists of polymethylmethacrylate and cyclic olefin polymer which serve as cladding and core materials, respectively. We discuss several numerical models which are useful for the design and simulation of the displacement sensors as well as two manufacturing methods capable of mass-producing such devices. Prior to fabrication, the sensor layout and performance are evaluated by means of a self-implemented ray-optical simulation which can be extended to various other types of sensor concepts. Furthermore, we discuss optical and mechanical test procedures as well as a high-precision tensile testing machine especially suited for the characterization of the opto-mechanical performance of such plastic optical displacement sensors.

Measurements of Self-Excited Rotor-Blade Vibrations Using Optical Displacements

1984 ◽  
Vol 106 (1) ◽  
pp. 44-49 ◽  
Author(s):  
A. P. Kurkov
Keyword(s):  
Strain Gage ◽  
Rotor Blade ◽  
Inlet Pressure ◽  
Turbofan Engine ◽  
Displacement Spectra ◽  
Displacement Sensors ◽  
Optical Displacement ◽  
Blade Vibrations

During the operation of a turbofan engine at part speed, near stall, and elevated inlet pressure and temperature, several vibratory instabilities were excited simultaneously on the first fan rotor. The torsional and bending contributions to the main flutter mode were resolved by using casing-mounted optical displacement sensors. Strain-gage spectra were used to identify other instabilities in the blade-deflection spectra. The characteristics of optical-displacement spectra and their role of monitoring rotor-blade vibrations are discussed.

scholarly journals New experimental techniques for dynamic crack localization

2009 ◽  
pp. 255-283
Author(s):  
David Grégoire ◽  
Hubert Maigre ◽  
Fabrice Morestin
Keyword(s):  
Crack Propagation ◽  
Crack Tip ◽  
Image Correlation ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Displacement Sensors ◽  
Optical Displacement ◽  
Propagation Parameters ◽  
Tip Position

The determination of relevant constitutive crack propagation laws under dynamic loading is a rather challenging operation. In dynamic impact cases, the variations of propagation parameters and exact crack positions are difficult to control. This paper focuses on different techniques for measuring accurate crack tip position histories in dynamic crack propagation experiments. Two different methods are considered: very accurate crack tip localization by optical displacement sensors is first described for transparent materials; then, an automatic method based on digital image correlation is presented for crack localization in all brittle materials whatever their opacity.

Noncontact Measurement Method of Vibration Stress Using Optical Displacement Sensors for Piping Systems in Nuclear Power Plants

2015 ◽  
Vol 1 (3) ◽  
Author(s):  
Akira Maekawa ◽  
Tsuneo Takahashi ◽  
Takashi Tsuji ◽  
Michiyasu Noda
Keyword(s):  
Nuclear Power ◽  
Measurement Method ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Vibration Measurement ◽  
Piping System ◽  
Noncontact Measurement ◽  
Displacement Sensors ◽  
Optical Displacement ◽  
Vibration Stress

In nuclear power plants, vibration stress of piping is frequently measured to prevent the occurrence of fatigue failure. A simpler and more efficient measurement method is desired for rapid integrity evaluation of piping. In this study, a method to measure vibration stress in a noncontact manner using optical displacement sensors is presented and validated. The proposed method estimates vibration-induced stress of small-bore piping directly using noncontact sensors based on a light-emission diode. First, the noncontact measurement method was proposed, and the measurement instrument based on the proposed method was developed for the validation. Next, vibration measurement experiments using the instrument were conducted for a mock-up piping system and an actual piping system. The measurement results were compared with the values measured by the conventional method of known accuracy using strain gauges. From this comparison, the proposed noncontact measurement method was demonstrated to be able to provide sufficient accuracy for practical use.

Liquid-crystal-grating-based optical displacement sensors

2016 ◽  
Vol 55 (35) ◽  
pp. 10045 ◽  
Author(s):  
Michinori Honma ◽  
Tatsuya Miura ◽  
Toshiaki Nose
Keyword(s):  
Liquid Crystal ◽  
Displacement Sensors ◽  
Optical Displacement ◽  
Liquid Crystal Grating
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