Papers by Keyword: Optical Interferometry

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Authors: Jiang Hong Gan, Li Ping Zhou, Liang Zhou Chen, Long Xu
Abstract: This paper aimed to use a novel optic interferometric fringe projection to measure the three-dimensional shape of small object with high resolution. In this method, the projecting fringe pattern, which has a sinusoidal density distribution, good contrast and equal spacing, is generated by a spherical wave incident into a triangle-section prism. Project the fringe onto the subject under test, the image of the deformed fringe pattern modulated by object surface is captured by a high-speed CMOS camera and processed by the Fourier Transform technique to extract the phase distribution which is related to height information. An experimental system is set to conduct 3-D shape measurement and the result shows the validity of the proposed method. The projecting system is simple and compact, which helps to realize the integration and miniaturization of the system.
1981
Authors: Qian Kemao, Seah Hock Soon
Abstract: Phase unwrapping is an important and challenging process in optical interferometry. Difficulties in phase unwrapping are usually caused by either noise (“bad” pixels) or invalid areas (“bad” regions). If the “bad” pixels can be removed, the problems due to the noise are solved. Further, if the “bad” regions can be identified, they can be avoided in phase unwrapping. In our previous work the noise can be successfully removed using a windowed Fourier transform [Optics and Lasers Technology, 37:458-462 (2005)]. In this paper we will show that the invalid areas can be identified by the same windowed Fourier transform. Thus a single windowed Fourier transform is able to process both “bad” pixels and “bad” regions simultaneously, which makes the phase unwrapping simple and effective.
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Authors: Li Ming Chu, Jaw Ren Lin, Yuh Ping Chang
Abstract: This paper presents a novel experiment method to investigate the microscopic mechanism of the oil film under the pure squeeze elastohydrodynamic lubrication (EHL) motion. An optical EHL squeeze tester is used to measure the interference fringe patterns of the contact region. In order to show the dimple thickness clearly, the grayscale interferometry method is employed to obtain the film thickness map. In addition, the effects of squeeze speed, load, and lubricant viscosity on the dimple film thickness are explored under a quasi-static condition.
164
Authors: Khaled Habib
Abstract: In the present work, thermal expansion coefficients of a number of ceramic coatings were studied by a non-destructive technique (NDT) known as shearography. Ceramic coatings, i.e., a white enamel and a yellow Acrylic Lacquer on a metallic alloy, i.e., carbon steels, were investigated at a temperature range simulating the severe weather temperatures in Kuwait, especially between the daylight and the night time temperatures, 20-60 0C. The investigation was focused on determining the in-plane displacement of the coating, which corresponds to the thermal deformation (strain), with respect to the applied temperature range. A mathematical relationship was derived along with the experimental data. The mathematical relationship described the thermal deformation of a coated film as a function of temperature. Furthermore, results of shearography indicate that the technique is found very useful NDT method not only for determining the thermal expansion coefficients of different coatings, but also the technique can be used as a 2D- microscope for monitoring the deformation of various coatings in at a submicroscopic scale.
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Authors: Khaled Habib
Abstract: In the present work, thermal expansion coefficients of a number of organic coatings were studied by a non-destructive technique (NDT) known as shearography. An organic coating, i.e., epoxy, on a metallic alloy, i.e., carbon steels, was investigated at a temperature range simulating the severe weather temperatures in Kuwait especially between the daylight and the night time temperatures, 20-60 0C. The investigation focused on determining the in-plane displacement of the coating, which amounts to the thermal deformation (strain ) with respect to the applied temperature range. Along with the experimental data, a mathematical relationship was derived describing the thermal deformation of a coated film as a function of temperature. Furthermore, results of shearography indicate that the technique is very useful NDT method not only for determining the thermal expansion coefficients of different coatings, but also the technique can be used as a 2Dmicroscope for monitoring the deformation of the coatings in real-time at a submicroscopic scale.
67
Authors: Qing Chen Bao, Shu Hai Jia, Yong Xu, Chao Jiang
Abstract: The 3D shape measurement has been one of research hotspots in the field of Mechanical measurement. But general optical 3D shape measurement techniques can only measure the continuous object through the phase unwrapping. It’s very difficult to unwrap the phase of the discontinuous object. To solve this problem, a novel digital holographic interferometry used for measuring the 3D shape is proposed in this paper. In this method, holographic interferograms are generated by object beam and reference beam at different incident angles. Height information of every point at the object surface is extracted independently without the phase unwrapping, thus it can measure the discontinuous object. The simulation and initial experiment results suggest that the method is completely feasible and low-cost, so it has great potential to apply in the industrial production.
857
Authors: Cho Jui Tay, S.H. Wang, C. Quan
Abstract: In this paper, we describe an optical interferometer applied to 3D inspection of microcomponents. The resulting interference fringes that are related to the deformation and surface contour of MEMS-components are analyzed by the fast Fourier transform (FFT) and 3-step phaseshifting algorithms. Experimental results show the feasibility of the proposed method for 3D deformation and surface contour measurement of micro-components.
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Authors: Siripong Somwan, Khem Chirapatpimol, Apichart Limpichaipanit, Komsanti Chokethawai, Athipong Ngamjarurojana
Abstract: Michelson interferometric technique was modified in the setup and used to measure very small changes in optical path length for electric field induced-strain phenomena. Induced-strain is established in the sample when the beam of light propagating through the sample surface undergoes a shift in phase, which in turn leads to a change in the intensity of the interference pattern formed where the reference and probing beams recombine. In this work the electric field induced-strain was measured as a function of electric field (s-E loop) and polarization (s-P loop) of PbMg1/3Nb2/3O3 (PMN) and 0.7PbMg1/3Nb2/3O3-0.3PbZr0.52Ti0.48O3 (0.7PMN-0.3PZT) ceramics, which showed electrostrictive (quadratic shape curve) and piezoelectric (butterfly shape curve) behavior at various frequency (0.01-1Hz).
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Authors: Lev Zuev, Svetlana A. Barannikova
Abstract: The localized plastic flow auto-waves observed for the stages of easy glide and linear work hardening in a number of metals are considered. The propagation rates were determined experimentally for the auto-waves in question with the aid of focused-image holography. The dispersion relation of quadratic form derived for localized plastic flow auto-waves and the dependencies of phase and group rates on wave number are discussed. A detailed comparison of the quantitative characteristics of phase and group waves has revealed that the two types of wave observed for the stages of easy glide and linear work hardening are closely related. An invariant is introduced for localized plastic flow phenomena occurring on the micro- and macro-scale levels in the deforming solid.
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Authors: Siripong Somwan, Narit Funsueb, Apichart Limpichaipanit, Athipong Ngamjarurojana
Abstract: In this study, leadbased ferroelectric ceramics Pb0.91La0.09Zr0.65Ti0.35O3 PLZT (9/65/35) were fabricated by solid solution method. The electrical and mechanical properties were measured by modified Michelson interferometer and Sawyer-Tower circuit to investigate electric field induced strain and polarization (s-P-E) of PLZT (9/65/35) at 30-70 °C. The induced strain and polarization were changed when the temperature was increased indicating the change of spontaneous polarization inside the ferroelectric materials.
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