Topic
Moiré pattern
About: Moiré pattern is a research topic. Over the lifetime, 1917 publications have been published within this topic receiving 27176 citations. The topic is also known as: moiré fringes & moire pattern.
Papers published on a yearly basis
Papers
More filters
01 Sep 1996
TL;DR: Moire fringes of elongated circular gratings to precisely measure the linear displacements are presented in this article, where the moving direction of a grating can be easily determined and the moving displacement can be measured within the accuracy of 1/10 pitch of the grating.
Abstract: Moire fringes of elongated circular gratings to precisely measure the linear displacements are presented. The moving direction of a grating can be easily determined and the moving displacement can be measured within the accuracy of 1/10 pitch of the grating by using moire fringes of elongated circular gratings.
1 citations
10 Dec 1993
TL;DR: In this article, the authors analyzed and measured the contrast degradation of the image of the first grating (G 1 ) image and the second grating image (G 2 ) and concluded that the determinative factors affecting the contrast of the grating images are the black-white ratio of grating and the distance between the image and grating.
Abstract: In a moire deflectometric phase object measuring system the contrast of the moire fringes formed by the first grating (G 1 ) image and the second grating (G 2 ) degrates and it causes some measurement errors in the system because of the diffraction effect of G 1 . This paper analyzes and measures the contrast degradation of the image of G 1 directly. The complex amplitude, intensity, and contrast expressions of the G 1 images with varied distance to the grating are also formulated and it is concluded that the determinative factors affecting the contrast of the grating image, in other words, the moire deflectometric fringes, are the black-white ratio of grating and the distance between the image and the grating.
1 citations
TL;DR: In this article, the departure from isotropic nature of stresses, as clearly depicted by the fringe pattern, is analyzed and the error introduced by the assumption of isotropically state is shown to be only about 8.33%.
Abstract: Residual stresses present in thin films can be rpecisely measured by optical techniques. Four different techniques, namely (1) Reflection Moire, (2) Reflection Moire with shift, (3) Holographic Moire with shift and (4) Interferometry were evaluated. Based on the accuracy, sensitivity and simplicity, interferometry was chosen and applied in a practical investigation. The deflection fringe pattern was processed along principal directions. Slopes, derivatives and hence stresses wee evaluated using cubic spline numerical technique. The departure from isotropic nature of stresses, as clearly depicted by the fringe pattern, is analysed and the error introduced by the assumption of isotropic state is shown to be only about 8.33%.
1 citations
01 Jan 2002
TL;DR: In this article, a method of spatial straightness measurement by means of non diffracting beam and moire fringe is proposed, where a ring grating is mounted on the moving object.
Abstract: A method of spatial straightness measurement by means of non diffracting beam and moire fringe is proposed. The non diffracting beam is used as a straightness datum. A ring grating is illuminated by this beam. Because the cross section pattern of the non diffracting beam is also a set of ring fringes, a ring moire fringe on the grating surface will be generated. The grating is mounted on the moving object. If the movement track of the grating depart from the center line of the non diffracting beam, the position of the moire ring will also depart. The quantity of the moire ring departure is many times greater than that of the grating. Therefore an amplified two dimensional straightness signal is generated. Image processing techniques are used to calculate the center of the moire ring. Theoretical analyses and experiment results show that the proposed straightness measurement method has the advantages of high sensitivity and resistance of laser beam drift.
1 citations
20 Mar 1997
TL;DR: In this paper, a structured light system based on the projection moire method is used for shape measurement and defect detection using a charge coupled device (CCD) camera operating at the time delay and integrating (TDI) mode.
Abstract: Automated machine visual inspection, using non-contact optical means, is a fast and efficient approach for quality control and manufacturing process monitoring. One application is in shape measurement and defect detection which employs a structured light system based on the projection moire method. The fringe patterns of these specimens are obtained by pulsing a single strip of light from a diode laser on the rotating specimens. Defects on these surfaces can be observed when a single strip of light bends proportionally to their depths. The imaging of these fringes is done by a charge coupled device (CCD) camera operating at the time delay and integrating (TDI) mode. By synchronizing the camera scanning speed and the specimen's rotational speed, the 'unwrapped' surface fringe patterns can be obtained and viewed by a computer. The fast Fourier transformation (FFT) technique is used for quantitative measurement of the surface defect.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
1 citations