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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Patent•
13 Jun 2013
TL;DR: In this paper, a two-way interferometer is used to measure the 3D shape of the object by interferometric fringe projection, also known as moire method, and, when the twoway interferer is associated with a recording or imaging device, the instrument is able to perform shearographic measurements on the object, the direction of the traversing light beam in the interfacer being reversed when shifting from one measurement configuration to the other one.
Abstract: PROBLEM TO BE SOLVED: To provide a portable industrial instrument for performing, in an integrated and two-way manner, an interferometric fringe projection and shearography, on an object to be tested.SOLUTION: When a two-way interferometer (1) is associated with a coherent or quasi-coherent projection device (2), the portable industrial instrument is able to measure the 3D shape of the object by interferometric fringe projection, also known as moire method, and, when the two-way interferometer (1) is associated with a recording or imaging device (4), the instrument is able to perform shearographic measurements on the object, the direction of the traversing light beam in the interferometer (1) being reversed when shifting from one measurement configuration to the other one.
1 citations
22 Apr 2010
TL;DR: In this article, an LCD-based system was developed to generate grid lines with a sinusoidal intensity pattern, which gave the technique superior linearity as compared to the use of classical Ronchi-rulings.
Abstract: In moire profilometry, a grid of lines is projected onto an object. When the grid is observed under an angle with the projection direction, a deformed line pattern is seen. The phase of this deformed grid contains the information about the object height. In dual‐grid moire projection profilometry, the deformed line pattern is projected onto a second straight grid, leading to the generation of moire fringes. To obtain the fringe phase, at least three phase shifted moire topograms are needed. The phase shifts are obtained by translating one grid in its own plane and along the direction perpendicular to the grid lines. We have developed an LCD‐based system, in which phase shifting is obtained without any mechanical moving parts. By using LCD’s, we can generate grids with a sinusoidal intensity pattern, which gives the technique superior linearity as compared to the use of classical Ronchi‐rulings. The non‐linear response of the LCD’s is compensated using a gamma‐correction function, so that grid lines with nearly perfectly sinusoidal intensity patterns are obtained. In this paper we will present results obtained with this profilometer, and demonstrate how the use of sinusoidal line patterns improves the linearity of the phase extraction.
1 citations
Patent•
24 Mar 2008TL;DR: In this article, a device for measuring the shape of moire using a LCD panel is provided to make the controlling of direction and pitch easy using the characteristic of LCD, and a drive unit adjusts the direction and the pitch to form the lattice of the tunable grating.
Abstract: PURPOSE: A device for measuring the shape of moire using a LCD panel is provided to make the controlling of direction and pitch easy using the characteristic of LCD CONSTITUTION: A device for measuring the shape of moire using a LCD panel comprises a light source(1), a tunable grating, imaging lenses(5,6), a photo diode(7), am operation unit, and a drive unit(9) The light source radiates the light The tunable grating generates the projection grating pattern by penetrating the outgoing light The imaging lenses image the lattice pattern reflected from an object The photo diode light receives the reflected light of the lattice pattern passing the imaging lens The operation unit computes the shape of the object, forms the moire fringe by overlapping the lattice pattern light-received from the photo diode, and previously stores the standards lattice pattern The drive unit adjusts the direction and the pitch to form the lattice of the tunable grating
1 citations
Patent•
02 Nov 2006
TL;DR: In this paper, a method for avoiding disagreeable moire in the color image is indicated and, in this method, the angle of unreliable excitation related to the unreliable excitations in a marking process or the colour image is specified.
Abstract: PROBLEM TO BE SOLVED: To avoid disagreeable moire in a color image. SOLUTION: The method for avoiding disagreeable moire in the color image is indicated and, in this method, the angle of unreliable excitation related to the unreliable excitation in a marking process or the color image is specified and at least two sets of halftone screens for drawing at least two disassemblies of the color image are selected. In this case, the set of halftone screens is selected to avoid the inclusion of the significant fundamental frequency, the harmonic frequency, and the beat frequency of the screen at an angle approximated to the angle of specified unreliable excitation by less than 1 degree substantially. Further, the color image is made so as to be halftone in accordance with the set of selected screens in this method. COPYRIGHT: (C)2007,JPO&INPIT
1 citations
Journal Article•
1 citations