Demodulation of Spatial Carrier Images: Performance Analysis of Several Algorithms Using a Single Image

http://link.springer.com/article/10.1007%2Fs11340-013-9741-6#Optical full-field techniques have a great importance in modern experimental mechanics. Even if they are reasonably spread among the university laboratories, their diffusion in industrial companies remains very narrow for several reasons, especially a lack of metrological performance assessment. A full-field measurement can be characterized by its resolution, bias, measuring range, and by a specific quantity, the spatial resolution. The present paper proposes an original procedure to estimate in one single step the resolution, bias and spatial resolution for a given operator (decoding algorithms such as image correlation, low-pass filters, derivation tools ...). This procedure is based on the construction of a particular multi-frequential field, and a Bode diagram representation of the results. This analysis is applied to various phase demodulating algorithms suited to estimate in-plane displacements.GDR CNRS 2519 “Mesures de Champs et Identification en Mécanique des Solide

Caractérisation métrologique des méthodes de décodage d’images à porteuses spatiales

La présente communication propose une démarche originale permettant en une seule étape l'estimation de la résolution, de la résolution spatiale et du biais induit par un opérateur utilisé dans une méthode optique de champ (par exemple : algorithme de corrélation, filtrage passe-bas, dérivation...). Cette approche s'appuie sur la génération et le traitement d'un champ particulier multi-fréquentiel. Elle est appliquée à l'extraction de phase d'une image à porteuse spatiale

Méthodologie d’analyse métrologique d’algorithmes de traitement d’images à porteuse : résolution et résolution spatiale

Les méthodes optiques de champs ont pris une grande importance dans la mécanique expérimentale moderne. La présente communication propose une démarche originale permettant en une seule étape l'estimation de la résolution, de la résolution spatiale et du biais induit par un opérateur donné (système de décodage de l'information, par exemple un algorithme de corrélation, fonction de filtrage passe-bas, ou de dérivation, ...)

Nanosecond pulsed laser-processing of CVD diamond

This work considers the resulting material structural effects of laser-processing chemical vapor deposited (CVD) diamond. The utilized 532 nm wavelength laser had a pulse duration of 40 ns together with a spot diameter of ca. 40 mu m. The effect of cutting fluence on the CVD diamond microstructure was investigated using both Raman and transmission electron microscopy (TEM) analyses. While Raman analysis showed that increasing the laser fluence led to a transition from diamond to graphite, the spread of the beam and consequent interrogation volume leads to limitations in understanding the precise structure over the ablated diamond surface. As such, TEM showed that at a low fluence (4.9 J/cm(2)), the subsurface microstructure is a mix of both graphite and amorphous carbon (aC). At 15 J/cm(2), only the graphite phase was identified. As the fluence increases further, the thickness of the graphite layer decreases until it disappears at a fluence of 50 J/cm(2). In contrast, a crystalline diamond phase began to be identified at 15 J/cm(2) and grows with increasing fluence. Moreover, cracks were visible only until a fluence of 15 J/cm(2), while at higher fluences, no cracks were observed. A simulation model was developed to predict the residual graphitization thickness formed in CVD diamond by a laser beam. Despite some differences in the graphite layer thickness, the results obtained from the model were consistent with the TEM results, supporting the findings of this study. Finally, cracks were only located in the graphite phase at the two lowest laser fluences. This was due to the low fracture toughness of graphite as compared to diamond

Metrological analysis of several algorithms used to demodulate images with spatial carrier

International audienc

Methodology for metrological analysis of periodic coding images: measurement resolution and spatial resolution

Optical full-field techniques have a great importance in modern experimental mechanics. Even if they are reasonably spread among the university laboratories, their diffusion in industrial companies remains very weak for several reasons, especially a lack of metrological performance assessment. A full-field measurement can be characterized by its resolution, bias, measuring range, and by a specific quantity, the spatial resolution. The present communication proposes an original procedure for the estimation in one single step of the resolution, bias and spatial resolution for a given operator (decoding algorithm, such as image correlation, low-pass filters, derivation tools, ...). This procedure is based on the construction of a particular multi-frequential field, and a Bode diagram representation of the results. This analysis is applied to various phase demodulating algorithms for the estimation of in-plane displacements

Caractérisation métrologique du décodage de l’information dans les méthodes optiques de champ : application à l’inter-comparaison de méthodes à codage périodique.

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Non-dissipative internal optical filtering with solution-grown perovskite single crystals for full-colour imaging

Herein we demonstrate that solution-grown single crystals of semiconducting methylammonium lead halide perovskites (MAPbX3, where MA=CH3NH3+, X=Cl−, Br− and Br/I−) can be used as semiconductor absorbers for full-colour imaging. A one-pixel photodetector prototype was constructed by stacking three layers of blue-, green- and red-sensitive MAPbCl3, MAPbBr3 and MAPb(Br/I)3 crystals, respectively. The prototype detector was demonstrated to recognize and faithfully reproduce coloured images by recombination of the signals from each individual colour channel. This layered structure concept, besides imparting a two- to three-fold reduction in the number of required pixels, also offers several other advantages over conventional technologies: three times more efficient light utilization (and thus higher sensitivity) than common Bayer scheme devices based on dissipative optical filters, colour moiré suppression and no need for de-mosaic image processing. In addition, the direct band gap structure of perovskites results in optical absorption that is several orders of magnitude greater than silicon. This opens a promising avenue towards the reduction of pixel-size in next-generation devices as compared with conventional silicon-based technologies