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.

Single-frame evaluation of object-adapted fringes

Abstract: We present two fast methods for the evaluation of object- adapted fringe images. One method, a fast and simple skeleton method, is purely digital. The method is stable against varying object reflectivities and illumination conditions. We also demonstrate the optical evaluation of object-adapted fringe images by means of a moire technique. This second method uses a Ronchi grating for the optical processing of the images in order to detect topographic defects with high speed. Additionally, we present a new method for the generation of object-adapted fringe masks where only a few images have to be recorded in order to obtain the mask.

Three-dimensional moiré display

Abstract: In this paper, we present an autostereoscopic 3D display based on the moire effect. The left and right images are built of the moire patterns. When observed from a proper location, these moire images can be perceived stereoscopically without special eyeglasses. The principle is confirmed by preliminary experiments.

Two-channel wavefront sensor arrangement employing moire deflectometry

Abstract: A wavefront sensor which takes advantage of the moire deflectometry has been constructed for measuring atmosphere induced wavefront distortions. In this sensor a collimated laser beam propagates through turbulent atmosphere, then a beam splitter splits it into two beams and the beams pass through a pair of moire deflectometers. Directions of the grating's rulings are parallel in each moire deflectometer but are perpendicular in the two beams. Using a suitable array of lenses and mirrors two sets of moire patterns are projected on a CCD camera. A suitable spatial filter removes the unwanted frequencies. Recording the successive moire patterns by the CCD camera and feeding them to a computer, allow temporal fluctuations of the laser beam wavefront phase to be measured highly accurately. Displacements of the moire fringes in the recorded patterns correspond to the fluctuations of two orthogonal components of the angle of arrival (AA) across the wavefront. The fluctuations have been deduced in successive frames, and then evolution of the wavefront shape is determined. The implementation of the technique is straightforward and it overcomes some of the technical difficulties of the Schlieren and Shack-Hartmann techniques. The sensitivity of detection is adjustable by merely changing the distance between two gratings in both moire deflectometers and relative grating ruling orientation. This overcomes the deficiency of the Shack-Hartman sensors in that these require expensive retrofitting to change sensitivity. Besides, in the moire deflectometry, the measurement is relatively insensitive to the alignment of the beam into the device. Hence this setup has a very good potential for adaptive optics applications in astronomy. Since tilts are measured in the Shack-Hartmann method at discrete locations, it cannot detect discontinuous steps in the wavefront. By this method discontinuous steps in the wavefront are detectable, because AA fluctuations are measured across the wavefront.

Structural Model Analysis by Means of Moire Fringes

Abstract: Use of moire fringes in measurement of displacements and rotations in structural models; method, applied to case of simply supported beam, continuous beam, and 2 plane frames, gave results in satisfactory agreement with theory, whenever such comparison was made; techniques used are extremely simple and inexpensive.