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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: This report describes the employment of moiré patterns to model visually interference phenomena in general and laser Doppler anemometer signals in particular, which includes signals created in dual beam and reference beam anemometers by both single particles and particle pairs.
Abstract: This report describes the employment of moire patterns to model visually interference phenomena in general and laser Doppler anemometer signals in particular. The modeling includes signals created in dual beam and reference beam anemometers by both single particles and particle pairs. The considerations are extended to visual modeling of multiparticle signals and the decay of signal quality in the presence of many particles. The fringe model of the laser Doppler anemometer is also considered, and moire patterns are employed to demonstrate the interference fringes in the crossover region of two intersecting laser beams. Gaussian beam properties are taken into account to allow the effects of improperly designed optical systems to be studied. Instructions for using computer generated transparencies to produce the different moire patterns are provided to allow the reader to study in detail the various interference phenomena described.

17 citations

Journal ArticleDOI
TL;DR: In this article, the reflection of a reference grating from the specularly polished surface of a vibrating plate with a second similar grating created a moire pattern consisting of straight equidistant lines corresponding to the nodal regions of the plate.
Abstract: The reflected image moire method was used to yield the vibration modes of plates. Interference of the reflection of a reference grating from the specularly polished surface of a vibrating plate with a second similar grating created a moire pattern consisting of straight equidistant lines corresponding to the nodal regions of the plate. The moire pattern produced when the plate was illuminated by a continuous parallel light beam yielded the nodal configuration of the vibrating plate. When the vibrating plate was illuminated by a stroboscopic light source the moire pattern showed the contour map of partial slopes of the plate at the instant of illumination. While the first technique, with continuous illumination, yielded the exact form and location of the nodes and antinodes of a vibrating plate at its natural frequencies, the second technique, with intermittent light, gave the local amplitude and phase distribution of the plate.

17 citations

Patent
28 Feb 1991
TL;DR: In this paper, a plurality of halftone screen density data structures are used to create a screened halftones separation. But, the human eye is confused into perceiving continuous patterns and is less likely to perceive any Moire pattern than when using conventional methods.
Abstract: A plurality of halftone screen density data structures utilizing halftone dot patterns which arrays the halftone dots at preselected screen angles and at a preselected distance to create a screened halftone separation. By arraying the halftone dots at preselected screen angles, the human eye is confused into perceiving continuous patterns and is less likely to perceive any Moire pattern than when using conventional methods. The data structures are created by arranging for every halftone dot in at least one halftone dot pattern of the data structures to be surrounded by a plurality of dots having their dot centers at preselected screen angles and at a preselected distance from the dot center of the center halftone dot. The halftone dots are superimposed over a plurality of bits arranged as a bit map which is representative of a pixel format utilized to produce screens wherein each bit in the bit map is assigned a value in a predetermined fashion. The values are utilized when binary representations of the density of an image for a sampled area are transformed to pixel format. Through this process, the halftone screen density data structures are utilized to transform binary representations of images to a pixel format which is utilized to reproduce a desired artwork.

17 citations

Journal ArticleDOI
TL;DR: In this paper, an interferometer is used to detect small translations of a diffuse object by illuminating the object with a speckle pattern and recording its image before and after the motion in the same way as above.
Abstract: In all methods of photographic optical processing presented here, the carrier frequency is derived from an intensity speckle pattern, the advantage of which is to spread out information in the Fourier plane. Furthermore, they are based on the fact that the Fourier spectrum of two laterally translated speckle patterns displays Young’s fringes, the visibility of which represents the correlation of the speckle patterns. The problems of comparing intensities of two transparencies, multiplexing optical signals, and detecting small translations of a diffuse object will be successively considered. The optical process of comparing two transparencies A and B is the following. The two signals are modulated by the same speckle pattern and recorded successively on a photographic plate which is laterally translated between the exposures. After processing, H displays Young’s fringes at infinity. If the intensity distributions of A and B are not identical, the two corresponding speckle images are not completely correlated and therefore the fringe visibility is not maximum. The difference A–B can easily be obtained by filtering the minima of the fringes. For multiplexing operations, each of the signals to be stored is modulated by a speckle pattern and recorded at least twice on a photographic plate which is laterally translated between successive exposures. The amount of translation given to the plate is different for each of the signals. The spectrum of the photographic record has as many fringe systems as the signals. By filtering the maxima of a particular fringe system, the corresponding signal is reconstructed and the others are removed. Small translations of a diffuse object can be detected by illuminating the object with a speckle pattern and recording its image before and after the motion in the same way as above. The decorrelation of the two recorded speckle patterns is only due to the motion of the object which can thus be revealed by the visibility of the corresponding Young’s fringes. With such a method it is not possible to detect the direction of the translation suffered by the object. We suggest therefore an interferometer consisting of a Michelson interferometer in which both mirrors are replaced by two scattering surfaces O1 and O2 shifted longitudinally. The interferometer is illuminated by a parallel beam of laser light, and a photographic plate twice records (before and after the translation of one of the surfaces) irradiances lying in the Fourier plane of O1 and O2. After processing, H exhibits Moire fringes. These fringes are rectilinear if the translation suffered by the object is lateral and they are circular if the translation is longitudinal. The sensitivity of the interferometer depends only on the geometrical characteristics of the recording setup.

17 citations

Journal ArticleDOI
TL;DR: The automation of the fringe pattern analysis in Fizeau interferometry combining the moiré effect with the phase-stepping evaluation method is presented, and a detailed description of theMoiré image formation as an incoherent superposition is developed.
Abstract: The automation of the fringe pattern analysis in Fizeau interferometry combining the moire effect with the phase-stepping evaluation method is presented. In this case the phase modulator is a Ronchi grid placed at the interferometer image plane yielding a moire image, and the necessary phase steps are obtained, simply translating the grid in its own plane, perpendicular to the optical axis. A detailed description of the moire image formation as an incoherent superposition is developed. Measurements were carried out in a Fizeau interferometer built by the authors, and rms repeatabilities of less than 3 deg in the phase-difference values were attained.

17 citations


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