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.

Method and device for position adjustment of solid-state image pickup element

Abstract: PURPOSE:To perform the position adjustment of each solid-state image pickup element (CCD) for a prism at high speed and with high accuracy by performing gate adjustment after performing focusing adjustment, and furthermore, applying vertical and horizontal adjustment. CONSTITUTION:A focusing adjusting means adjusts the CCDs 3-5 at a position where the peak of the amplitude of a moire abutting with the center part of a moire pattern plate can be obtained from moire image data obtained by image-picking up the moire pattern plate via an image pickup optical system 1 by the CCDs 3-5. Also, a gate adjusting means adjusts the CCDs 3-5 at the position where the difference of amplitude of each moire abutting with the upper and lower parts of the moire pattern plate can be eliminated from the moire image data, and also, the difference of amplitude of each moire abutting with the right and left parts can be eliminated. Thereby, the position adjustment of the CCDs 3-5 for the prism can be performed at high speed and with high accuracy.

The Nyquist criterion and its relevance in phase-stepping digital shearography: a quantitative study

Abstract: The Nyquist criterion, or Nyquist sampling theorem, has been used as a gold standard in signal processing and in digital imaging. In this work, we examine its applicability and relevance in phase-stepping digital shearography, which has become a useful tool in the generation of displacement gradient maps of extended objects, and in non-destructive testing (NDT). We show, with experimental data and quantitative measurements from our digital shearography experiments, that it is not necessary to comply strictly with the Nyquist criterion in digital shearography. Operation of the digital imaging device in the sub-Nyquist domain is perfectly feasible, and even desirable, in many cases. This will suggest, to the experimentalist in shearography, the best possible ways to perform image sampling in the case of digital shearography.

Direct observation of moiré flat-band breakdown at the edge of magic-angle twisted bilayer graphene

Abstract: Low-energy moir\'e flat bands in magic-angle twisted bilayer graphene (tBG) have demonstrated incredible potential to exhibit rich exotic quantum phenomena. Theoretically, the moir\'e flat bands of tBG are based on the extended structures, i.e., the moir\'e patterns with periodic boundary conditions. However, a fundamental question of whether the flat bands can exist in the graphene moir\'e patterns with a reduced structure symmetry, such as sample edges, remains unanswered. Here, via scanning tunneling microscopy and spectroscopy, we study the local electronic properties of magic-angle tBG near the sample terminated edge and report a direct observation of breakdown of the moir\'e flat bands. We show that the moir\'e electronic structures, including the low-energy flat bands, can sufficiently exist in a complete moir\'e spot, i.e., a moir\'e supercell, right at the edge even if the translational symmetry of the moir\'e patterns is broken in one direction. However, the flat-band characteristic is obviously absent in the incomplete moir\'e spots that are partly terminated by the edge. Our results indicate that a whole moir\'e spot is sufficient and indispensable for the generation of the effective moir\'e flat bands in tBG.