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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21 May 2010TL;DR: In this article, a system includes a camera and a projector for capturing spatial detail having resolution exceeding that afforded by the imaging optics, and recovering topographic information lost to the projective nature of imaging.
Abstract: A system includes a camera and a projector for capturing spatial detail having resolution exceeding that afforded by the imaging optics, and recovering topographic information lost to the projective nature of imaging. The projector projects a spatial pattern onto the scene to be captured. The spatial patterns may include any pattern or combination of patterns that result in complex sinusoidal modulation. Spatial detail such as texture on the objects in the scene modulate the amplitude of the spatial pattern, and produce Moire fringes that shifts previously unresolved spatial frequencies into the camera's optical passband. The images may be demodulated, and the demodulated components may be combined with the un-modulated components. The resulting image has spatial detail previously inaccessible to the camera owing to the band-limited nature of the camera optics. A spatial pattern may also be projected and received by the camera to estimate topographic information about the scene.
14 citations
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TL;DR: The three fundamental optical phenomena of diffraction, two-beam interference, and transformation by a lens form the basis of modern moire strain-measurement techniques as mentioned in this paper, which can be found in the literature.
Abstract: The three fundamental optical phenomena of diffraction, two-beam interference, and transformation by a lens form the basis of modern moire strain-measurement techniques. The improved understanding of diffraction by superimposed gratings and optical spatial filtering leads to a general gain of freedom in designing moire experiments. Benefits characteristic of refined but very simple optical-data-processing techniques include simpler apparatus, less-demanding procedure, possible large gains in sensitivity, and the ability to choose certain moire parameters, such as sensitivity,after an experiment is concluded and the raw data stored. Sample results from a study of strains near cold-worked holes demonstrate that acceptable results can be had with elementary apparatus and systematic exploitation of optical-data processing.
14 citations
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TL;DR: In this article, a method of refractive power mapping of a lens is presented which is based on Talbot interferometry and utilizes a digital image processor, where a test lens is placed in front of two collinearly arranged gratings and the light passing through the test lens produces a shifted Talbot image of the first grating on the second grating and generates moire fringes.
Abstract: A method of refractive power mapping of a lens is presented which is based on Talbot interferometry and utilizes a digital image processor. By adding a digital image processing system, fast measurement of a lens power distribution is feasible. A test lens is placed in front of two collinearly arranged gratings. The light passing through the test lens produces a shifted Talbot image of the first grating on the second grating and generates moire fringes. Given the inclination angle of moire fringes, the refractive power of the lens can be calculated. The calculation is performed using a digital image processor. This method is effective in finding the refractive power distribution of progressive power lenses.
14 citations
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17 Feb 1987
TL;DR: In this paper, a modified version of the Moire topography is described, in which the contour interval has been greatly increased so that, in some cases, the entire depth of the object lies within one fringe.
Abstract: One of the widely recognised limitations of moire topography is its inability to provide unambiguous data from objects which have discontinuities in their shape. Similar limitations arise when two parts of an object are separated by a region which is in shadow. This feature of moire topography has limited its use to the measurement of objects which have continuous surfaces. With the development of phase measuring techniques for fringe pattern analysis, moire fringe contour patterns can now be analysed to high levels of accuracy, the contour interval being subdivided into, perhaps, 200 increments of measurement by the phase calculation procedure. This paper describes a modified version of moire topography in which the contour interval has been greatly increased so that, in some cases, the entire depth of the object lies within one fringe. By applying high accuracy phase measuring techniques to the analysis of these moire fringe patterns, sub-millimetre accuracy can be obtained in measurements of objects which would normally be thought of as unmeasurable by moire topography.
14 citations
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23 Apr 1980
TL;DR: In this article, alternate scan lines are sampled with clock signals of different phases to produce a displacement between adjacent scan lines in the output image, which reduces the increase in spot width which would otherwise produce moire interference.
Abstract: System and method for forming a halftone image by scanning without visible moire interference. Alternate scan lines are sampled with clock signals of different phases to produce a displacement between adjacent scan lines in the output image. This displacement reduces the increase in spot width which would otherwise produce moire interference, with no increase in the rate at which the video signal is sampled.
14 citations