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.

Contouring Method by Parallel Light Moire Holography

Abstract: Moire contouring method by parallel light is realized using holography. In Fourier-transform holography, the object placed at the focus of a collimating lens is equivalent to the one placed at infinity. Regular fringes are projected onto the object by tilting the illuminating parallel light slightly between the exposures of double exposure holography. These fringes are deformed by the relief of the object. Imaginary hyperboloids of interference fringes are formed by fine lateral displacement between the two exposures. As the plate is located at the focus of the lens, it is considered that the hyperboloids can be approximated by a set of parallel planes after passing through the lens. These parallel fringes are observed at infinity as a regular grid. The combination of this regular grid with the deformed fringes produces contouring fringes on the object at infinity.

Analysis of moire fringes for application in ophthalmology

Abstract: The contrast and the form of the interference fringes are calculated which are obtained by simple optical filtering of the diffraction spectrum of two similar gratings in contact when illuminated by spatially coherent light (moire technique). The conditions to be fulfilled by the gratings in order to produce fringes of high contrast and simple form, that is, with only one maximum and one minimum per period, are indicated. Such properties of the fringes are required when retinal visual acuity is to be measured by an apparatus proposed by Lotmar using the method of Le Grand. The proposed computation method as well as the results could be useful for applications as for example in metrology. The computed results are confirmed by experimental findings on a variety of gratings.

Fabrication of moiré on curved surfaces.

Abstract: Moire is an appealing visual effect observable when two or more repetitive patterns are superposed. Fabrication of moire effects has already proven to be useful in a range of applications, from art to engineering. Here, we introduce a method for designing and fabricating level-line moires on curved surfaces. These moire shapes are obtained by superposing a partly absorbing layer and a layer formed by an array of cylindrical lenses or by two layers of cylindrical lenses. We formulate the problem of placing an array of cylindrical lenses on a curved surface as a design problem with a small number of dimensions. The range of possible solutions can therefore be explored by a human observer. We demonstrate the quality of our method by rendered simulations and by fabrication. The resulting static displays can be manufactured using different fabrication techniques, from multi-material 3D printing to molding.

Moire topograms: a simple method for their evaluation.

Abstract: Pacific University, College of Optometry, Forest Grove, Oregon 97116 Received 8 December 1986. 0003-6935/87/071166-02$02.00/0. © 1987 Optical Society of America. We have found that moire fringes can be easily evaluated by using the fringe spacing without knowing the dimensions of the actual experiment involved. That is similar to interferometry where the depth of a defect or other surface irregu­ larities can be found directly from the fringe distortions. Consequently, determining the magnification, or the rota­ tion of one grid relative to the other, and calibration of the apparatus in general, are not much of a problem anymore. Following Rayleigh's first observation, the evaluation of moire fringes is easy when one of two identical linear grids is rotated through an angle θ. If the separation of the lines in the original grids is d, the spacing M of the resulting moire fringes is

Measurement of Distortion Using the Moire Interferometry

Abstract: Image forming lens systemsdo not provide perfect images Lens abberations can be detected with complex optical ray-tracing A single aberration in lenses, the distortion, can be detected at the image plane with optical mapping Therefore moire interferometry can be adapted to detect and measure distortion This method is adaptable by serial testing of the universal measuring cameras, projection cameras, photogrammetrical cameras, etc The distortion of the whole image plane can be represented on one moire image This can be useful if the distortion is not rotationally symmetrical for example because of errors of assembly The distortion of 1 µm regarding the focal plane can be measured by using the moire method presented in this paper