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.

Detection of particle on wafer supporting base surface

Abstract: PROBLEM TO BE SOLVED: To surely detect contaminated particles by forming first patterns on a wafer, moving this wafer, forming second patterns thereon to form moire patterns by the interaction of both patterns and identifying the visual distortions in the moire patterns formed by the particles on the supporting base surface during the formation of the first patterns. SOLUTION: The distorted test patterns 42' are superposed in the inspection patterns 52 to form the moire patterns appearing as fringes 54. The inspection patterns 52 have the same line width and pitch as the line width and pitch of the test patterns and cover the entire area of the test patterns for inspecting the entire area of the wafer. The inspection patterns 52 are inclined by an angle θwith the test patterns in order to form the moire patterns. If the inspection patterns are inclined by the angle θ, the moire fringes are parted by a distance 56 equal to the value dividing the pitch of the patterns by θ. The moire fringes are distorted to a zigzag form at the time of passing the distortion area. The undulations thereof appear as sinusoidal waves and saw tooth waves having amplitude 60 even if the fringes are undulated to the extent of making the distortions invisible. The waveforms thereof are thus easily visible.

Three-dimensional shape, displacement, and strain measurement device and method using periodic pattern, and program therefor

Abstract: In a conventional moire method, achieving both measurement accuracy and dynamic measurement and balancing field of view and measurement accuracy have been difficult. The present invention makes it possible to handle conventional moire fringes as a grating for generating phase-shifted second-order moire fringes, use a spatial phase shift method algorithm to accurately analyze the phases of the second-order moire fringes before and after deformation, and determine shape from the phase differences between gratings projected onto the surface of an object of measurement and a reference surface and determine deformation and strain from the phase differences between the second-order moire fringes, before and after deformation, of a repeating pattern on the object surface or a produced grating. As a result, it is possible to measure the three-dimensional shape and deformation distribution of an object accurately and with a wide field of view or dynamically and with a high degree of accuracy.

Multifunctional moire fringes camera

Abstract: The utility model discloses a multifunctional moire fringes camera, belonging to the key instrument of the strain field of the measure material of a moire fringes method in experimental mechanics. The multifunctional moire fringes camera is formed by four sections of metallic cylinders. The multifunctional moire fringes camera can freely flex. A distance between the shot and the image surface of the camera can be changed between 360 mm to 740 mm, and imaging ratio can be changed according to needs. The multifunctional moire fringes camera can shoot vivid specimen gratings by once focusing. An analyzer grating can be rotated 90 DEG, which obtains the goal of separating the displacement fields of U and V. The camera can be used as the cameras of speckle and defocusing speckle, and can accurately measure defocusing amount.

Real-time moire interferometry

Abstract: A high-frequency moire interferometric technique to continuously monitor in-plane surface displacement is presented. This technique employs fiber optics and a thermoplastic device to holographically record the initial carrier pattern produced on the surface of a test specimen. The carrier is modulated as the specimen deforms and moire fringes, indicative of in-plane displacement, are observed in real time. Unwanted holointerferometric patterns are eliminated by appropriately adjusting the polarization of the reference wavefront. This paper describes a demonstration of the real-time technique as applied to the study of deformations in a notched beam subjected to three-point loading.

Method and apparatus for four-color zero-moire halftoning

Abstract: PROBLEM TO BE SOLVED: To eliminate three-color moire patterns in four-color (CMYK) print. SOLUTION: This invention provides the method for using single-cell non- orthogonal cluster screen to satisfy the moire-free (zero moire) conditions for four-color halftoning. The selection of these single-cell halftone screens is determined by identifying combinations of four of the halftone cells which satisfy moire-free conditions provided in the respective frequency equations. Constraints may be applied and the combinations not meeting such constraints can be removed.