1,721,613 research outputs found
Fourier transform for sandwich holograms evaluation
No full textA system based on 2D Fourier transform method for accurate determination of the interference phase distribution from a sandwich interferogram with carrier fringes is presented. The technique is particularly suitable for an evaluation of surface deformation in static as well as dynamic processes. Some practical applications are shown
Application of fibre optic digital diagnosticsspeckle interferometry to mural painting
No full textA fiber optic digital speckle pattern Interferometer is reported for mural painting diagnostics. As a result, the influence of flaws and cracks on fringe patterns, characterizing the displacement fields of mural paintings, has been visualized in real time also in an outdoor environment. Preliminary tests establish
that this method, by as flexibility and compactness, allows us to welcome some drawbacks of existing conventional arrangements in non-destructive testing of artworks
Atmospheric electricity in a rural site and its possible correlation with pollution: a preliminary study
No full textMesure de la conductivité électrique atmosphérique en présence de traces de polluants (oxydes d'azote) sous différentes conditions météorologiques afin d'établir une possible corrélationThe purpose of this work is to investigate the variations of the small ion concentrations of both polarities and the conductivity of the lower atmosphere, simultaneously with the presence of small traces of pollutants (NOx) under different meteorological conditions, in order to establish a possible correlation. Although the behaviour of these air components has been investigated previously, to our knowledge no systematic study has been carried out on the modifications induced in particular by small concentrations of nitrogen oxides on the ionic densities. Preliminary experimental results are presented
A System for the sampling of inhalable airborne particles
No full textThis paper describes an instrument developed for the semi-continuous measurement of aerosol mass and its classification into three classes. These classes have been chosen to evaluate the health hazards caused by inhalable particles. The instrument takes samples through three probes, each providing different cut-off points approximately 15 microm, approximately 4 microm, approximately 2 microm) and collects airborne particles on circular membrane filters. The increase in weight is measured by the beta-ray attenuation method
Sandwich holospecklegram: a practical tool for studying damage in concrete
No full textAn application of sandwich speckle holography with an image processing system is proposed to investigate the deformation behaviour of a concrete specimen under a cyclic thermal load simulating ambient temperature variations. A photographic sequence of concrete disaggregation is presented. Fringe systems relative to in-plane strains around incipient cracks are suitable for automated measurement
Fiber optics DSPI for in situ diagnostics
No full textA simple and accurate digital speckle pattern interferometer (DSPI), that uses a single mode bidimensional fiber coupler as beam splitter is described. As a result, the in-plane or out-of-plane displacement components can be measured in real-time and also in an outdoor environment. Preliminary tests have been carried out using a HeNe laser. Further tests are now in progress; the flexibility and compactness of such a system lends itself to use for non-destructive testing of structures, difficult to analyze with a conventional optical arrangement
Automated digital speckle pattern interferometry contouring in artwork surface inspection
No full textA contouring technique, based on digital speckle pattern interferometry, is developed for investigation of surface defects in artwork deterioration studies. Skeletonized fringes are used for a quantitative automatic evaluation of the defect dimension. Some experimental tests effected on samples and ancient artworks have demonstrated the suitability of the method
Fast Fourier transformed electronic speckle contouring for diffuse surfaces profilometry
No full textA method of contouring three-dimensional objects using an out-of-plane sensitive ESPI apparatus with optical fibers is presented. The contour map is obtained by shifting the object illumination beam. A Fourier transform method is suggested for automatic quantitative analysis of specklecorrelograms in terms of phase. An example of application is presented
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