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.

A Method for Recognizing of Moiré Circle Characteristic Parameters

Abstract: In the field of ultra-precision measurement, tiny two-degree-of-freedom error information can be separated from moire fringe image generated by overlapping a pair of concentric-circle gratings. Before this process, moire fringe image need to be pre-processed to get moire circle characteristic parameters. This paper discusses the algorithm problems on moire fringe image processing and introduces pre-processing algorithms including processes of image enhancement, image filtering, edge detection, binary management, profile thinning, wild points erasing etc. Least square method is finally used to get the center and radius of moire circles. The series of methods for recognizing of single image with CCD noise mixed have an accuracy of sub-pixel level.

Vertical reflective type moire measurement structure for measuring the surface curvature of an object

Abstract: A vertical reflective type moire measurement structure for measuring the surface curvature of an object includes a light source device capable of producing light source and forming a collimation expandable light through a light beam collimator; the collimation expandable light penetrates a first amplitude gratings and reflects the collimation expandable light onto the surface of an object to be tested through a spectrometer; to generate a self- image is; the self- image is reflected again from the surface of the tested object to form an image on the second amplitude gratings to constitute a moire image; a measurement device is employed to detect the moire image and calculate the inclination angle of the moire image so that the surface curvature of the object can be measured.

Reflective oblique moire fringe displacement detection-based micro-machined gyroscope and realization method thereof

Abstract: The invention discloses a reflective oblique moire fringe displacement detection-based micro-machined gyroscope and a realization method thereof and belongs to the field of optical detection. A mechanism consists of a structural layer and a substrate, wherein sensitive movable comb teeth on the structural layer and sensitive fixed comb teeth on the substrate form a measuring optical grating pair; geometrical interference is produced under the irradiation of a light source so as to form moire fringes; the sensitive movable comb teeth move under the action of Coriolis force; the moire fringes move correspondingly in proportion; and the number of moving moire fringes can be read through a subsequent signal processing module and is used for evaluating an angular speed input from outside. The method has the advantages of no damage to a measured surface due to the adoption of non-contact measurement, high measuring speed, high detection accuracy, capability of detecting displacement under the size of nanometer and preventing the rigidity change of a system due to the introduction of unknown electrostatic force into the system in comparison to an electricity method and contribution to stabilizing system performance.

Minimizing moire fringes in contact-type 3-dimensional imaging systems

Abstract: Analytical solution for the elimination of moire fringes for high quality image display in current 3-D image display is presented. The model screen is consisted of 2 layers of squared grids. The problem is finding the angle of superposing these two pairs, which provides moire fringe with the height period without regards to the pitch ratio of the two gratings of different pairs.

Scanning Moire interferometry

Abstract: 3D measurements of industrial surfaces is increasingly needed to meet today's quality control requirements, especially in the semiconductor industry Camera based moire interferometry systems employing phase shifting analysis offer high resolution, but have not commonly been used because of limited data acquisition rates This paper presents a technique called Scanning Moire Interferometry (SMITM) which provides the advantage of high resolution offered by phase shifting analysis while acquiring data at megaHertz rates The technique is based on the use of a tri- linear CCD sensor The moire light pattern projector is fixed in position with respect to the tri-linear sensor versus traditional techniques which shift the pattern projector with respect to the sensor between image acquisitions The SMITM technique continuously moves the target with respect to the sensor/projector pair In this configuration the tri-linear sensor acquires three images, each of which represent a difference phase shift of the projected line pattern Traditional phase measurement techniques are used to derive a height map of the target from the three phase shifted images A sensitivity analysis and height measurements of a ball grid array semiconductor package are presented The advantages of the SMITM technique are high resolution, high speed and no moving parts in the sensor assembly© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only