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.

Method and apparatus for measuring surface shape

Abstract: PROBLEM TO BE SOLVED: To easily apply the phase shift method to a stereoscopic lattice type moire method without any difficulty. SOLUTION: The stereoscopic lattice type moire optical system is used as an inspection optical system, a moire fringe having a specific order of fringes is accurately shifted without any shift errors by a desired shift, and at the same time a line sensor camera is used for example for an image pickup camera for limiting the measurement range close to a specific order of fringes for obtaining image data of at least three moire fringes that are phase-shifted, thus eliminating the need for considering the accurate phase shift of the total order of fringes, easily applying the phase shift method to the stereoscopic lattice type moire method without any difficulty, and accurately measuring the surface shape of an object to be measured.

Moiré fringe measurement system of optical length modulation based on FPGA

Abstract: A novel method for measuring moire fringe is proposed according to moire fringe characteristics in each interference region of double grating interferometer. Moire fringe pattern in Talbot image region II only shifts with the thickness of phased object when adjusting its position. The phased object is composed by two relative movable optic wedges. The method of micro-displacement measurement using this optic characteristic in this region can be verified by MATLAB. A new embedded differential direction recognizing and 4-subdividing method for moire fringes is adopted by using EP2C8Q208. In moire fringe hardware detecting system, 4-subdividing, direction recognizing and counting module are designed, and logical and timing diagram is simulated by VHDL. In comparison with others, this design possesses low cost, high flexibility, high system synchronization and easy upgrade.

On the Method of Measuring Strain by Use of Diffraction at Mis-matched Moire Fringes

Abstract: In the usual moire method and the multiplication method, the sensitivity to deformation is not sufficient at present. Then, how to increase the sensitivity is studied. In the measurement of a usual sheet metal specimen, moire fringes with large mis-match is photographed on a film at first. Such fringes are equivalent to grating lines on the specimen, as thy displace corresponding to strain, and they can be amplified by applying the multiplication method to that film. When strain is expressed by two beam interference fringes, one of the beams is tilted by a small amount, then fine fringes are obtained. They are equivalent to moire fringes with large mis-match and the multiplication method can be applied. Applications in various conditions have been shown. Consequently, concerning a sheet metal, measurement of elastic-plastic strain (eb 0.001) becomes possible and in the special condition that the surface of a specimen has been finished mirror-like, elastic strain (eb 0.001) can be measured.

New Apparatus of Moiré Iso-hypsigraphy by Parallel Light Projection and Parallel Reflecting Light Recording

Abstract: A new apparatus of moire iso-hypsigraphy was designed and produced to examine relatively small materials such as human skulls, innominate bones and scapulae. The parallel light source method producing moire fringes was adopted, which is much appropriate for the small objects. The reflected light, furthermore, was considered, because moire fringes produced by the parallel light needed to be recorded by the camera system in condition of nearly parallel reflected light. For recording system a 35mm camera with a 800mm focal length lens was selected. In this system one can measure the photographs with moire fringes under the permissible error, i. e. 1%. Moire producing parts of an apparatus has many improvements for the small objects: condenser lens, field lens, reflecting mirror and threads in grating. In the apparatus the skull fixer and co-ordinates indicator, in particular, were specially designed. By them the skulls on which the moire fringes are produced can be fixed in the Frankfort horizontal plane. In the photographs of them the moire fringes on the skull will indicate coronal sections as exact equal contours.