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A method for the detection and measurement of surface defects is described: it includes the use of a holographic contouring system and the application of digital image processing and automated computer analysis for quantitative information. Calibration tests on defects of known sizes have been carried out and the possibility of applying the method to studying the state of artwork conservation is examined.

An electro-optical system for the detection and quantitative measurements of surface or subsurface defects is presented; it is based on a holographic contouring technique and digital image processing for an automatic analysis of fringe patterns. Several approaches have been followed on models, so that the defects can be unambiguously detected and possibly quantitatively analyzed. Some examples of applications in deterioration investigations of ancient artworks are reported.

The suitability of sandwich holography for displacement derivative measurement is demonstrated. Holographic carrier fringes are produced by shearing one plate relative to the other in a sandwich pair. Some experimental results are presented.

Sandwich hologram interferometry and sandwich speckle photography tend to complement each other as displacement measuring methods; a sandwich hologram is best suited for out-of-plane movements, while speckle photography is used to determine in-plane components. The two techniques can be combined and both holographic and speckle photographic data can be stored on the same sandwich pair. Fringes caused by in-plane rigid body motion can be compensated for and local displacement evaluated.

A simple method of fringe control in HNDT is described; some experimental results in defects diagnostic are shown.

A simple and compact method of optical differentiation of displacement patterns is proposed. It utilizes sandwich-double exposure holograms. Some typical experimental results are presented.

The technique of sandwich holography is proposed for the study of diffusion in transparent liquid mixtures. The diffusion coefficient may be measured simply and directly from the interferogram obtained by shearing a sandwich hologram during reconstruction. Some preliminary results for the KCI-water system are presented. On propose une technique d'holographie de sandwich pour l'étude de la diffusion dans les mélanges liquides transparents. Le coefficient de diffusion peut ětre mesuré simplement et directement à partir de l'interférogramme obtenu en comprimant un hologramme de sandwich lors de la reconstruction. On présente des résultats préliminaires pour le système KCI-eau. Le coefficient de diffusion peut être mesuré directement à partir de l'interférogramme obtenu en comprimant un hologramme de sandwich lors de la reconstruction. On présente des résultats préliminaires pour le système KCl-eau

The application of holography to works of art for the diagnosis of their state of conservation or for studying the behavior under mechanical or thermal stresses has been successfully demonstrated and described ; its use in revealing damaged areas or structural alterations in embryo of both statues and panel paintings has already been proved while other possibilities are regularly coming to attention. In this paper these various applications are summarized. Some experimental results obtained in works of art diagnostics with double exposure holograms, sandwich holograms are reported. Cette recherche présente l’application de l’holographie aux 0153uvres d’art : diagnostic de l’état de conservation ou étude des procédés de fabrications sous contraintes mécaniques ou thermiques. On a ainsi prouvé son intérêt dans la mise en évidence de surfaces endommagées ou détériorées ainsi que dans la détection des altérations structurales embryonnaires de statues et de peintures de chevalet. D’autres applications intéressantes apparaissent régulièrement. Cet article résume les différentes applications et principalement l’étude des déformations dynamiques du support en bois d’une 0153uvre d’art liées aux variations thermiques du milieu. Il mentionne également les résultats expérimentaux obtenus par holographie avec double exposition ainsi que par holographie sandwich.

A simple technique using the characteristics of image-plane holography is suggested for strain measurement and for non-destructive testing. White light reconstruction is used. Some preliminary applications of the method in art conservation are presented.

Sandwich holography has been just used in artwork conservation; its capability in detecting incipient faults or cracks in wooden panel paintings and statues has been tested successfully on models and ancient artifacts under restoration; a part from its ability to render significant services in non destructive inspection, sandwich hologram is expected to find application in other problems having considerable interest as displacement derivative measurement. The purpose of this paper is to extend this simple method of measurement to the study of lining canvas behaviour under a slight mechanical stress, in order to characterize the material employed to line painted canvases, both for improving the existing techniques and for selecting new materials. Some preliminary experimental results on models of lining canvases are presented.

An application of real-time holography to detect microcracks in ancient golden paintings is presented. The technique does not require sophisticated laboratory equipment and enables us not only to pinpoint the presence of a crack in embryo, inaccessible by more conventional methods of inspection, but also to monitor its growth in real time, giving, therefore, a valid aid to artworkers for determining the best conditions for the preservation of paintings.

The suitability of sandwich holography for diffusion coefficient measurement in transparent liquid mixtures is demonstrated. Preliminary results concerning the NaCl-water diffusion system are presented.

A holographic non destructive test procedure as a diagnostics tool in art conservation and preservation of ancient wooden panel paintings is presented. A brief discussion of the reability of the method is given. Some examples of experimental results are reported; they show that the defects can be detected in real and non real time on laboratory models, at varying depths,through ambient drift.The examination is made combining sandwich holography and real time holography, without any modification of holographic set up.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

It is shown that a combined system, utilizing sandwich real time holography with a CW laser can be used in artwork diagnostics to yield information about the state of conservation and the kinetic behaviour of a painted gesso wood statue, in response to ambient parameter variations (ambient drift). Such testing is an interesting and convenient engineering application of HNDT to artworks.

The suitability of sandwich holography for measurement of the diffusion coefficient in transparent liquid mixtures is demonstrated. Studies concerning the NaCI-water diffusion system are presented.