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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.


Papers
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Journal ArticleDOI
TL;DR: In this paper, a laser interferometer system is used to record two mutually perpendicular diffraction gratings on a photoresist coated specimen, and when either grating is re-illuminated by the fringe pattern used to form it, real-time observations can be made of moire fringes corresponding to surface displacements which occur as a tensile load is applied to the specimen.
Abstract: A laser interferometer system is used to record two mutually perpendicular diffraction gratings on a photoresist coated specimen. When either grating is re-illuminated by the fringe pattern used to form it, real-time observations can be made of moire fringes corresponding to surface displacements which occur as a tensile load is applied to the specimen. The technique has been used to study the in-plane deformations of carbon-fibre composites, and typical results are given.

23 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a graphical method for determining the 2D displacement components from the moire patterns more easily instead of the complex Fourier transformation method, which is necessary to assume that the transmittance is sinusoidal.
Abstract: Purpose – Researchers in the past have used Fourier transformation method to determine the in‐plane displacement components from moire fringes generated by a pair of overlapping circular gratings. In this approach it is necessary to assume that the transmittance is sinusoidal. The purpose of this paper is to propose a graphical method for determining the 2D displacement components from the moire patterns more easily instead of the complex Fourier transformation method.Design/methodology/approach – The moire patterns were spatially transformed from Cartesian‐to‐polar coordinate system. The morphological grayscale dilation operation was used to eliminate the residual gratings in the transformed pattern while preserving the moire fringes. The center line of the moire fringe was fitted with a sine curve and the in‐plane displacement values were determined directly from the peak‐to‐valley height and the position of the peak in the fitted curve.Findings – Experimental results showed that the proposed moire patt...

23 citations

Journal ArticleDOI
TL;DR: An elegant technique for the simultaneous measurement of in-plane and out-of-plane displacements of a deformed object in digital holographic interferometry using sensitivity vectors of the optical configuration is proposed.
Abstract: This paper proposes an elegant technique for the simultaneous measurement of in-plane and out-of-plane displacements of a deformed object in digital holographic interferometry. The measurement relies on simultaneously illuminating the object from multiple directions and using a single reference beam to interfere with the scattered object beams on the CCD plane. Numerical reconstruction provides the complex object wave-fields or complex amplitudes corresponding to prior and postdeformation states of the object. These complex amplitudes are used to generate the complex reconstructed interference field whose real part constitutes a moire interference fringe pattern. Moire fringes encode information about multiple phases which are extracted by introducing a spatial carrier in one of the object beams and subsequently using a Fourier transform operation. The information about the in-plane and out-of-plane displacements is then ascertained from the estimated multiple phases using sensitivity vectors of the optical configuration.

23 citations

Journal ArticleDOI
TL;DR: In this article, a phase-modulated grating was proposed to compensate for nonorthogonal errors in a moire linear encoder, where the detectors are aligned perpendicular to the line of the moire fringes.
Abstract: A new hardware compensation method reducing displacement measurement errors, caused by tilt of the index scale in a moire linear encoder, has been developed. In conventional moire linear encoders, the detectors are aligned perpendicular to the line of the moire fringes and this structure is very sensitive to an unwanted tilt of the gratings. In this article, a newly designed grating, called a phase-modulated grating, is developed to compensate for nonorthogonal errors. By using the phase-modulated grating instead of a conventional index, it is possible to reduce nonorthogonal errors of the moire linear encoder.

23 citations

Journal ArticleDOI
TL;DR: The authors revisited reflection moire using novel methods for displaying the generating grating and analyzing the reflected gratings for slope measurement, and plate vibration can also be analyzed in a unique manner.
Abstract: Reflection moire is revisited using novel methods for displaying the generating grating and analyzing the reflected gratings for slope measurement. Furthermore, plate vibration can also be analyzed in a unique manner. Additionally, a digital scheme for analyzing curved objects is also demonstrated.

23 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023181
2022321
202126
202048
201946
201844