Showing papers on "Moiré pattern published in 1981"
Patent•
22 Oct 1981TL;DR: In this article, the authors used collimated radiation deflected from the object to generate a moire pattern and measured linear deflections in the pattern, variations in characteristics of the object is determined.
Abstract: Equipment and method for mapping an object using moire deflectometry wherein collimated radiation deflected from the object is used to generate a moire pattern and wherein by measuring linear deflections in the pattern, variations in characteristics of the object is determined.
37 citations
TL;DR: In this article, the factors affecting the quality of the moire fringes for an arbitrary displacement and deformation of the object surface are analyzed. And the physical significance of speckle displacement, both in the image plane and in the pupil plane, is pointed out.
25 citations
Patent•
IBM1
TL;DR: In this article, a method for testing optical imaging systems by the use of moire stripes was proposed, where two copies of an optical grating are made and simultaneously illuminated to produce a moire pattern which is a measure of the distortion of the imaging system.
Abstract: A method for testing optical imaging systems by the use of moire stripes, wherein two copies of an optical grating are made and simultaneously illuminated to produce a moire pattern which is a measure of the distortion of the imaging system. In a first step an original grating is transferred by a light beam as a contact copy onto a substrate. In a second step, the imaging system to be tested copies the original grating for a second time onto the substrate, except that the second grating copy is rotated slightly with respect to the first grating copy. The points of intersection of the two superimposed gratings produce moire stripes when illuminated, the positions of the stripes being calculated precisely with the assumption that ideal gratings were used. If the imaging system to be tested shows distortions, the position of the moire stripes that are observed will not correspond to these calculated positions. The deviation therefrom is a measure of the imaging system errors.
13 citations
TL;DR: In this article, a specific beat pattern can be extracted from superposed periodic structures by adding three spatially shifted versions of a conventional moire, which is automatically achieved using color component gratings and the beat discrimination by the color sequence within them.
12 citations
TL;DR: In this paper, the authors applied Moire Topography technique to online shape measurement of hot steel at high temperature up to 1300°C, using an Ar-Laser and a heat resisting grating.
3 citations
TL;DR: In this paper, a projected linear grating moire technique was developed to determine the feasibility of studying the behavior of model marine propeliers rotating in a variable-pressure water tunnel, and full-field deflections were determined from photographs of moire interference fringes on the propeller roating at speeds up to 2000 rpm.
Abstract: A projected-linear-grating moire technique has been developed to determine the feasibility of studying the behavior of model marine propeliers rotating in a variable-pressure water tunnel. Full-field deflections were determined from photographs of moire interference fringes on the propeller roating at speeds up to 2000 rpm.
2 citations
01 Mar 1981
TL;DR: In this article, a brief review of various techniques to produce moire patterns for use in making in-plane and out-of-plane displacement measurements is presented, and a detailed description of a device which uses one of these techniques to obtain quantitative measurement of the out ofplane displacement of surfaces experiencing dynamic stimulation is also given.
Abstract: : A brief review of various techniques to produce moire patterns for use in making in-plane and out-of-plane displacement measurements is presented. A detailed description of a device which uses one of these techniques to obtain quantitative measurement of the out-of-plane displacement of surfaces experiencing dynamic stimulation is also given. High-speed photography of images formed by the device is used to provide a series of photographs which are analyzed to provide a time-sequence description of the motion of the deformed surface. Examples of measurement of the response of simulated fuel tank panels subjected to the impact of high-speed fragments and the response of aircraft transparencies experiencing a birdstrike are presented. (Author)
2 citations
Patent•
21 Oct 1981
TL;DR: In this paper, a photodetected image is formed by forming the image of an incident grid 2 imaged on the surface of a spherical body 1 to be measured further on a photoderifecting grid 7 by a lens 5.
Abstract: PURPOSE:To detect the deviations of the shape of an actual three-dimensional object to be measured from its ideal shape with good accuracy and ease by setting incident grating lines and photodetecting grating lines properly and observing the moire fringes formed of the photodetected image of the cut grating lines and the photodetecting grating lines. CONSTITUTION:A photodetected image 6 is formed by forming the image of an incident grid 2 imaged on the surface of a spherical body 1 to be measured further on the surface of a photodetecting grid 7 by a lens 5. Moire fringes can be formed by the gratings 2, 7. The grating fringes of the grating 2 are so set that if a three-dimensionally shaped object 1 to be measured is of an ideal shape, the photocut curves by the grating 2 imaged on the surface of the object 1 are imaged at equal intervals (a) on the photodetected image 6. In a measuring system, the photodetecting grating 7 consisting of linear fringes spaced equally at the intervals (b) differing from the above-described equal intervals is superposed on the image 6 to form moire fringes. Thus the deviation of the shapes between the object to be measured and the ideal object are measured by measuring the three-dimensional shape of the three-dimensionally shaped object by the formation of the moire fringes in the above-mentioned way.