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.
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08 Sep 1992
TL;DR: In this article, a high-speed three-dimensional surface measurement system for use in determining the surface of an object from at least one electronic signal produced by a mini-moire sensor is presented.
Abstract: A high-speed three-dimensional surface measurement system for use in determining the surface of an object from at least one electronic signal produced by a mini-moire sensor. At least one light source illuminates at least a surface area of the object with at least one fringe pattern. The light source has a hidden change distribution grating or matrix of gratings for producing the fringe pattern. The grating has hidden variations distributed substantially across the grating. The grating has a pseudo-random grating pattern in which a nominal fringe pattern has a small uniform period with the hidden variations distributed statistically across the grating. The hidden variations are so small that at any one point on the grating a noise-like value of the hidden variations is on the order of an overall noise equivalent phase value. A CCD camera receives reflected illumination from the surface area and provides an electronic signal representative of reflected illumination received thereby.
135 citations
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TL;DR: The method lends itself to image enhancement and is extended to the study of vibration analysis in real time and in the latter application, time-average moiré fringes appear according to the zeroth-order Bessel function, which contains the modal amplitude function in its argument.
Abstract: A grid is projected onto an object and focused into a viewing camera which is offset from the angle of illumination. When the image is superimposed by double exposure or by filtering with the image of another object, contour-difference moire fringes appear. By the use of two offset projectors, measurements of contour sums or contour doubling may be accomplished. The properties, limitations, sensitivity, and procedures are analyzed and discussed. The method lends itself to image enhancement and is extended to the study of vibration analysis in real time. In the latter application, time-average moire fringes appear according to the zeroth-order Bessel function, which contains the modal amplitude function in its argument.
130 citations
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25 Dec 2003
TL;DR: In this paper, the authors present a system capable of X-ray imaging through a convenient structure at first, a specimen (10) is placed between an Xray source (1) and a first diffraction grating (2) and then X-rays are applied from the X-Ray source toward the first diffusion grating.
Abstract: A system capable of X-ray imaging through a convenient structure At first, a specimen (10) is placed between an X-ray source (1) and a first diffraction grating (2) and then X-rays are applied from the X-ray source (1) toward the first diffraction grating (2) When the X-rays pass through the first diffraction grating (2), Talbot’s effect occurs in the first diffraction grating (2) Since the phase of the X-rays is shifted by the specimen (10), self image of the first diffraction grating (2) is deformed Subsequently, the X-rays pass through a second diffraction grating (3) Since the deformed self image of the first diffraction grating (2) is superposed on the second diffraction grating (3), an image contrast, generally moire fringes, can be created in the X-rays The moire fringes thus created can be detected by an X-ray image detector (4) Since the moire fringes thus created have been modulated by the specimen (10), the specimen (10) and its internal structure can be detected by analyzing the detected moire fringes
128 citations
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TL;DR: In this paper, the authors describe the phenomenon of moire magnification, which occurs whenever an array of identical objects is viewed through a set of lenses with approximately the same pitch, and each moire fringe is in the form of a magnified and rotated image of the repeat element in the array.
Abstract: We describe the phenomenon of moire magnification, which occurs whenever an array of identical objects is viewed through an array of lenses with approximately the same pitch. As with any pair of similar grids, a moire pattern is seen, but in this case each moire fringe is in the form. of a magnified and rotated image of the repeat element in the object array.
125 citations
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TL;DR: A fast technique for automatic 3-D shape measurement that can automatically and accurately obtain the phase map or the height information of a measured object at every pixel point without assigning fringe orders and interpreting data in the regions between the fringe orders is proposed and verified by experiments.
Abstract: A fast technique for automatic 3-D shape measurement is proposed and verified by experiments. The technique, based on the principle of phase measurement of the deformed grating pattern which carries the 3-D information of the measured object, can automatically and accurately obtain the phase map or the height information of a measured object at every pixel point without assigning fringe orders and interpreting data in the regions between the fringe orders. Only one image pattern is sufficient for obtaining the phase map. In contrast to the fast Fourier transform based technique, the technique processes a fringe pattern in the real-signal domain instead of the frequency domain by using demodulation and convolution techniques, can process an arbitrary number of pixel points, and is much faster. Theoretical analysis, simulation results, and experimental results are presented.
118 citations