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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
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Journal ArticleDOI
TL;DR: In this article, the effects of thinning out of scanning lines and the relation between moire fringes and strain are studied by the sampling theorem, where deformed model gratings are sampled by a television camera and they are thinned out properly by using an image processing system.
Abstract: A master camera. scanning-moire method is a moire method in which the grating is replaced by the scanning lines of a television In the present paper, the principle of moire pattern appearance. the effects of thinning out of scanning lines and the relation between moire fringes and strain are studied by the sampling theorem. If deformed model gratings are sampled by a television camera and they are thinned out properly by using an image processing system, the strain distribution in a wide strain range can be analyzed from one picture.

19 citations

Journal ArticleDOI
TL;DR: In this paper, an optical method known as moire is proposed for acquiring quasi-simultaneous measurements of bed topography and flow depth in laboratory experiments based on projecting a fringe pattern (grating) on the bed and analyzing the deformation of the pattern caused by the topography with respect to a reference plane.
Abstract: . We describe an optical method known as moire for acquiring quasi-simultaneous measurements of bed topography and flow depth in laboratory experiments. The moire method is based on projecting a fringe pattern (grating) on the bed and analyzing the deformation of the pattern caused by the topography with respect to a reference plane. The height of the object is encoded in the phase of the pattern and can be retrieved either through Fourier transform or phase shifting algorithms. The methodology enables image-based non-contact measurements over a continuous surface at very high spatial and temporal resolutions. We use a commercial software package of a moire method called Light3D to map bed topography and flow depth in an experimental braided channel and demonstrate how the method can be used to characterize a full range of statistics not previously possible.

19 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the maximum number of fringes that can be observed for a given model is independent of the gratings utilized and depend only on the geometry of the employed optical system.
Abstract: Two principal problems associated with the practical application of moire fringes are to obtain sufficient sensitivity for measuring small strains and to develop a simple and inexpensive technique for engraving lines on the surface of a model. This paper deals with simple solutions to both problems. It is shown that the maximum number of fringes that can be observed for a given model is independent of the gratings utilized and depend only on the geometry of the employed optical system. Examples of moire patterns corresponding to the equivalent of 6000 lines per inch and patterns of the derivatives of the displacements corresponding to the same number of lines illustrate the paper.

19 citations

Journal Article
TL;DR: In this paper, the authors proposed a method for the detection of defects based on a comparison of the responses of two macroscopically identical specimens. But the method is contactless and is not suitable for non-destructive quality assessment of mechanical parts.
Abstract: The development of comparative holographic moire interferometry is accelerated by the need for nondestructive testing. This paper describes a holographic moire technique for the detection of defects that is based on a comparison of the responses of two macroscopically identical specimens. At identical loading of the master and test objects, the moire fringes obtained are areas of equal differences in the mechanical responses, and they form closed curves around the defect. The schemes of additive and multiplicative moire are studied experimentally, and their advantages and disadvantages are discussed. Comparison of the suggested technique with conventional holographic interferometry shows its reliability for localizing defects. The comparative method is contactless and is especially appropriate for nondestructive quality assessment of mechanical parts.

19 citations

Book ChapterDOI
01 Jan 2000
TL;DR: The task to be solved in fringe analysis can be defined as the conversion of the fringe pattern into a continuous phase map taking into account the quasi sinusoidal character of the intensity distribution.
Abstract: The basic principle of modern optical methods in experimental solid mechanics such as holographic interferometry, speckle metrology, fringe projection and moire techniques consists either in a specific structuring of the illumination of the object by incoherent projection of fringe patterns onto the surface under test or by coherent superposition (interference) of light fields representing different states of the object. A common property of the methods is that they produce fringe pattern as output. In these intensity fluctuations the quantities of interest — coordinates, displacements, refractive index and others — are coded in the scale of the fringe period. Consequently the task to be solved in fringe analysis can be defined as the conversion of the fringe pattern into a continuous phase map taking into account the quasi sinusoidal character of the intensity distribution. The course starts with a physical modeling of the image content that contains the relevant disturbances in optical metrology. After that the main techniques for quantitative phase reconstruction together with the most commonly used image processing methods are presented. Because image processing is an important prerequisite for holographic non-destructive evaluation (HNDE) an overview of modern approaches in automatic flaw detection based on knowledge assisted and neural network techniques is given. Finally modern software tools for digital processing of fringe patterns are presented.

19 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023181
2022321
202126
202048
201946
201844