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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 paper, the authors combine the advantages of the two techniques by applying a configuration of simultaneous dual projection in the fringe projection technique, which generates a superimposed fringe pattern containing a moire pattern that is phase modulated according to the topography.
Abstract: In optical metrology, fringe projection and moire techniques have been widely used to measure the topography of objects. We can combine the advantages of the two techniques by applying a configuration of simultaneous dual projection in the fringe projection technique, which generates a superimposed fringe pattern containing a moire pattern that is phase modulated according to the topography. In this work, we present an analytic and comparative study of three methods to demodulate the phase of the moire pattern: the spatial, spatial-temporal, and temporal methods. Those methods consist of two steps: first, the moire pattern is extracted from the superimposed fringe pattern; next, the phase of the moire pattern is demodulated. The analytical results show that the resulting phase map has double phase sensitivity compared to that of the classical fringe projection technique. Experimental and numeric results prove the feasibility of this technique.

2 citations

Proceedings ArticleDOI
03 Dec 2007
TL;DR: In this paper, the information of effective shadow moire fringes by using digital image processing technique is extracted from the data of the two-dimensional fringe matrix and a 3D image of the three-dimensional image is drawn.
Abstract: Warpage measurement of PWB board and BGA package is considered as the most popular but difficult issue in microelectronic fabrication. Ordinary measuring method cannot afford the requirement of direct observation, efficiency, immediacy, high-precision as well as low cost. Moire fringe is a kind of interference pattern by which we are able to measure the flatness of surface of an object. This paper mainly concentrates on how to extract the information of effective shadow moire fringes by using digital image processing technique. It presents some algorithms applied to moire fringe image processing, such as preliminary extraction algorithm of moire fringes, intensity enhancing algorithm of fringe, fringe thinning algorithm, removal of the forficate fringe etc. In the end, the three-dimensional image from data of the two-dimensional fringe matrix has been drawn. Experiment result shows the effect of methods for extracting effective moire fringes.

2 citations

Proceedings ArticleDOI
18 Jun 2007
TL;DR: In this paper, the authors used the projection moire technique to measure the out-of-plane deflections of composite plates subject to bird strike impact in the leading edge of an aircraft.
Abstract: For the new generation aircraft families, the use of fibre-reinforced plastics is considered for the leading edge of the wings. However, this leading edge is very prone to bird strike impact. This paper presents the use of the projection moire technique to measure the out-of-plane deflections of composite plates subject to bird strike. Very strict constraints with regard to: (i) high speed image acquisition, (ii) vibrations of the impact chamber, and (iii) projection and observation angles - complicated substantially the development of the set-up. Moreover, the high frame rates (12000 fps) required a very intensive illumination. In the optimized configuration, a specially designed grating with gradually changing period is projected by means of special Metal Hydride lamps through one of the side windows of the impact chamber onto the composite plate riveted in a steel frame. The digital high speed camera is mounted on the roof of the impact chamber and records through a mirror the object surface with the projected fringe pattern on it. Numerical routines based on Local Fourier Transform were developed to process the digital images, to extract the phase and the out-of-plane displacements. The phase evaluation is possible due to the carrier frequency nature of the projected moire pattern. This carrier frequency allows separation of the unwanted additive and multiplicative fringe pattern components in the frequency domain via the application of a proper mask. The numerical calculations were calibrated for the bird strike of an aluminium plate, where the plastic deformation could be checked after the test.

2 citations

Journal ArticleDOI
TL;DR: In this article, the authors considered the image formed in the electron microscope of two crystals stacked one above the other when these show a relative rotation about an axis perpendicular to the electron beam.
Abstract: Consideration is given to the image formed in the electron microscope of two crystals stacked one above the other when these show a relative rotation about an axis perpendicular to the electron beam. Dark‐field moire fringe patterns are predicted when certain conditions relating to the relative proximity to the Bragg condition of the two crystals are fulfilled. The limits of these conditions and the spacings of the fringes are formulated in terms of the angle of tilt and the direction of the tilt axis.

2 citations


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