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.

Phase shifting applied to four-wave holographic interferometers

Abstract: A phase-shifting procedure that is applicable to four-wave holographic inteferometry is described. The technique can be used to obtain whole-field phase maps with all methods that use holographic moire fringes.

Two-dimensional Moiré phase analysis for accurate strain distribution measurement and application in crack prediction.

Abstract: Aimed at the low accuracy problem of shear strain measurement in Moire methods, a two-dimensional (2D) Moire phase analysis method is proposed for full-field deformation measurement with high accuracy. A grid image is first processed by the spatial phase-shifting sampling Moire technique to get the Moire phases in two directions, which are then conjointly analyzed for measuring 2D displacement and strain distributions. The strain especially the shear strain measurement accuracy is remarkably improved, and dynamic deformation is measurable from automatic batch processing of single-shot grid images. As an application, the 2D microscale strain distributions of a titanium alloy were measured, and the crack occurrence location was successfully predicted from strain concentration.

Method and system for minimizing the appearance of image distortion in a high speed inkjet paper printing system

Abstract: A method and system for a printing device is disclosed. The method and system comprise printing a test pattern on a print medium and generating a digital image of the printed test pattern by an imaging device. The method and system include analyzing an interference pattern to measure for distortion of the print medium and calibrating the printing device based upon the measured distortion. In a preferred embodiment, the present invention utilizes the reticle patterns, which are printed in the margins of the paper, which are measured real-time during printing. The interference or Moire patterns created by superimposed reticles may be used to measure image distortion, process direction misalignment, and misregistration caused by web distortion. The advantage of this invention is that image distortion compensation, RIP (Raster Image Processor) parameters, timing, or other printer characteristics may be adjusted on-the-fly in a closed feedback system, for high-speed textile or paper color printing, utilizing on-the-fly distortion or stretch measurement for accurate color and/or duplex images registration. In a duplex printer, automatic images alignment front-to-back is obtained by combining optically or logically the two images for the evaluation of interference patterns and amount of distortion in the process and scan direction.

The magic of carrier fringes in moiré interferometry

Abstract: Practical applications in which carrier fringes are used with moire interferometry for strain measurements are presented. Examples illustrate how moire carrier fringes are applied to obtain the desired data in complex laminated composite specimens. In many cases, carrier fringes permit extraction of much more detailed information, with procedures that are easier and more accurate than those using loadinduced fringes alone. The fringe vector for carrier fringes is introduced and its application to the interpretation of fringe patterns is explained. In moire interferometry, the carrier fringes are produced easily by adjustments of optical elements that control the virtual reference grating.

Three-channel phase stepped system for moire interferometry

Abstract: A use of the multichannel phase stepped interferometry approach to automated fringe pattern analysis in moire interferometry is described. Polarization optics is used to implement the appropriate phase shifts in each channel. The channels are created by inserting a diffraction grating at the output of the interferometer. It is possible to work at one frame rate. This system enables studies in unstable environmental conditions and studies of time dependent events.