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.

Scan type dual moire inspection apparatus and inspection method

Abstract: A scan type dual moire inspection apparatus and method are provided to inspect the three dimensional shape of an object by scanning the object while transferring it at the state a lattice element for generating the moire pattern is fixed, thereby reducing the manufacturing cost of a moire inspection apparatus. In a scan type dual moire inspection apparatus which comprises an X-Y table(10), a pattern projector(20), and a plurality of first and second imaging units(30,40), the pattern projector irradiates pattern beam to an object positioned in the X-Y table and the object is transferred with the X-Y table N times by 1/N pitch of the irradiated pattern. The first and second imaging units take a pattern image by the reflected pattern beam every 1/N pitch transfer. In order to acquire a stable pattern image, the measurement reference surface of the first and second imaging units is adjusted for the X-Y table every 1 pitch transfer of the object.

Solving the Two-Objective Shop Scheduling Problem in MTO Manufacturing Systems by a Novel Genetic Algorithm

Abstract: With the characteristics of un-touching, high-automatic and high-speed, we measured 3D shape by digital moire patterns. And it can measure 3D shape without compensator, auxiliary mirror, hologram and other assistant modules. So it is widely used in measurement of 3D shape. But with the negative effect of grating area and CCD resolution of the camera, it has some problems in large aperture, steep aspheric surface, even off-axis aspheric testing. Focus on these problems; this paper established a sub-region splicing measurement of aspheric surface by using the combination of digital moire patterns and digital phase shifting technology. This paper also illustrated the basic theory, and the mathematical implementation procedure. In all, sub-region splicing digital moire patterns can be considered as another method, which beyond compensation tests to measurement of aspheric surface.

Endoscopic moiré metrology

Abstract: We demonstrate a real endoscopic moire metrology by using a fiberscope as an image transmitting system. For grating projection interference fringes from two single-mode fibers were used. The substraction of the projected grating from a reference was provided in real-time and moire fringes could be observed on a live image which is important for medical diagnostic.

Shape Survey of Symmetric Bodies Through the Moiré Interferometry

Abstract: This research work reports a study of shape determination of bodies with regular geometry as cubes, cylinders and spheres by employing a moire method. The selected method is named geometric projection moire, which consists in projecting a grid onto a background and in a second step to project the same grid onto the object in study before the background. Both images were captured by a digital camera and the archives transferred to a PC for further processing. Generated fringes are then multiplied pixel to pixel as well as contrast increased and equalized by means of "COREL PHOTO-PAINT" software. Fringes are transformed into sharp contour lines by means of the "RISING SUN MOIRE" software. The dimensions of the object are proportional to the number of fringes generated onto its surface.. The procedure of image analysis involved the software named "COREL PHOTO-PAINT", and "RISING SUN MOIRE". Geometrical measurements of cubes, cylinders and spheres of ten different sizes were obtained by means of a digital caliper and compared with those generated by the optical method under study. The paper presents conclusions based on probable error sources as well as future automation process development.

A super-grayscale and real-time computer-generated Moiré profilometry using video grating projection.

Abstract: By using the time-division multiplexing characteristics of the projector and the integral exposure characteristics of the charge coupled device (CCD) camera, a super-grayscale and real-time computer-generated Moire profilometry based on video grating projection is proposed. The traditional digital static grating is of 256-grayscale at most. If an expected super-grayscale grating with a maximum grayscale of 766 is designed and divided into three 256-grayscale fringe patterns with balanced grayscale as far as possible, they can be synthesized into a repeated playing video grating instead of the traditional static grating. When the video grating is projected onto the measured object, as long as the exposure time is set to three times the refresh cycle of the video grating, the super-grayscale deformed patterns in the 766-grayscale can be captured with a 10-bit CCD camera, so that the deformed patterns are realistic. The digital error in computer-generated Moire profilometry is effectively reduced. In addition, this method can expand the linear range of the deformed pattern by 20% in computer Moire profilometry. Therefore, the proposed method has the perspectives of high accuracy and real-time measurement. Theoretical analysis and experimental results demonstrate the validity and capability of the proposed method.