Determinação da topografia de uma fruta pela técnica de moiré de sombra com multiplicação de franjas Fruit profilometry based on shadow Moiré techniques

As técnicas de moiré (TM) são um conjunto de técnicas, baseadas no fenômeno de moiré, mais comumente utilizadas em perfilometria, devido à sua simplicidade e rapidez de medição. O fenômeno de moiré consiste na interferência causada pela sobreposição de duas estruturas periódicas (retículos), sendo a TM de sombra com multiplicação de franjas mais sensível que os métodos tradicionais, além de diminuir os efeitos da diferença de iluminação na superfície do objeto em estudo. Objetivou-se com este trabalho gerar um Modelo Digital de Elevação (MDE) de uma pêra pela TM de sombra com multiplicação de franjas e compará-lo a um outro modelo gerado a partir de um scanner 3D. Para este trabalho, foram utilizados um modelo de uma pêra, em escala 1:1, confeccionado em parafina e um esquema experimental constituído de um retículo de moiré, iluminador e câmera fotográfica digital. Pelos resultados, verifica-se uma alta correlação entre os MDE obtidos pelos dois métodos. A TM de sombra com multiplicação de franjas gerou um MDE que reproduz satisfatoriamente a topografia da pêra.<br>The Moiré Techniques (MT) are a group of techniques based on the moiré phenomenon, which are commonly used in profilometry, due to your simplicity and measurement speed. The moiré phenomenon consists of the interference caused by the overlapping of two periodic structures or grids. Shadow TM with multiplication of fringes is more sensitive than the traditional method and besides, they reduce the effects of the illumination difference in the surface of the object in study. The objective of this work was to generate a digital model of the surface of the pear for shadow TM with multiplication of fringes and to compare with another model generated starting from scanner 3D. For this, a model of a pear, in scale 1:1, made in paraffin and an experimental set up outline with moiré grid, light and digital photographic camera were used. The results showed a high correlation among the results from the two methods. Shadow TM with multiplication of fringes gave a satisfactory determination of topography of the pear

Contributed Review: A review of compact interferometers

Compact interferometers, called phasemeters, make it possible to operate over a large range while ensuring a high resolution. Such performance is required for the stabilization of large instruments dedicated to experimental physics such as gravitational wave detectors. This paper aims at presenting the working principle of the different types of phasemeters developed in the literature. These devices can be classified into two categories: homodyne and heterodyne interferometers. Improvement of resolution and accuracy has been studied for both devices. Resolution is related to the noise sources that are added to the signal. Accuracy corresponds to distortion of the phase measured with respect to the real phase, called non-linearity. The solutions proposed to improve the device resolution and accuracy are discussed based on a comparison of the reached resolutions and of the residual non-linearities.SCOPUS: re.jinfo:eu-repo/semantics/publishe

A comparative study of three adhesion tests (EN 582, similar to ASTM C633, LASAT (LASer Adhesion Test), and bulge and blister test) performed on plasma sprayed copper deposited on aluminium 2017 substrates

International audienceThe aim of this study was to compare three adhesion tests carried out on plasma-sprayed copper coatings on aluminium substrates. The first test, the bond pull test, designated EN 582 or ASTM C633, involves a uniaxial static stress and is commonly used in the coating industry. The second test, the LASAT (LASer Adhesion Test), is a recently developed technique based on spallation phenomenon due to laser induced shock waves. In this test, the coating delamination results from spallation at the coating/substrate interface due to uniaxial tensile stress. The last test, the bulge and blister test, involves a quasi-static measurement of the crack propagation energy at the coating/substrate interface. These three techniques have been used to evaluate the influences of different process parameters involved in the coating adhesion such as aluminium surface roughness, substrate pre-heating and plasma spray conditions