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.

Accurate Strain Distribution Measurement Based on the Sampling Moiré Method

Abstract: To obtain accurate measurement of non-uniform strains over the entire surface of materials or structures, in this study, the sampling moire method is applied to two-dimensional measurement of in-plane displacement and strain distributions. The two-dimensional displacement distribution is obtained by detecting the phase difference of the moire fringes, and the strain distribution is determined by measuring the change of grating pitches on the specimen in vertical and horizontal directions before and after deformations. A compensation technique of fringe order is proposed to eliminate the pitch error of fabricated grating. In addition, a spatial filtering procedure in phase distribution is suggested to reduce the random measurement error. The deformations of an aluminum specimen with a through hole under different tensile loads were measured by the proposed method. Experimental results indicated that the measurement accuracy of strain distribution can be dramatically improved by combination the above-mentioned two techniques. This method is useful to evaluate mechanical properties of various materials under tension/compression or heating/cooling testing.

Review of phonons in moiré superlattices

Abstract: Moiré patterns in physics are interference fringes produced when a periodic template is stacked on another similar one with different displacement and twist angles. The phonon in two-dimensional (2D) material affected by moiré patterns in the lattice shows various novel physical phenomena, such as frequency shift, different linewidth, and mediation to the superconductivity. This review gives a brief overview of phonons in 2D moiré superlattice. First, we introduce the theory of the moiré phonon modes based on a continuum approach using the elastic theory and discuss the effect of the moiré pattern on phonons in 2D materials such as graphene and MoS2. Then, we discuss the electron–phonon coupling (EPC) modulated by moiré patterns, which can be detected by the spectroscopy methods. Furthermore, the phonon-mediated unconventional superconductivity in 2D moiré superlattice is introduced. The theory of phonon-mediated superconductivity in moiré superlattice sets up a general framework, which promises to predict the response of superconductivity to various perturbations, such as disorder, magnetic field, and electric displacement field.

Design of color screen tile vector sets

Abstract: For electrophotographic printers, periodic clustered screens are preferable due to their homogeneous halftone texture and their robustness to dot gain. In traditional periodic clustered-dot color halftoning, each color plane is independently rendered with a different screen at a different angle. However, depending on the screen angle and screen frequency, the final halftone may have strong visible moire due to the interaction of the periodic structures, associated with the different color planes. This paper addresses issues on finding optimal color screen sets which produce the minimal visible moire and homogeneous halftone texture. To achieve these goals, we propose new features including halftone microtexture spectrum analysis, common periodicity, and twist factor. The halftone microtexture spectrum is shown to predict the visible moire more accurately than the conventional moire-free conditions. Common periodicity and twist factor are used to determine whether the halftone texture is homogeneous. Our results demonstrate significant improvements to clustered-dot screens in minimizing visible moire and having smooth halftone texture.