In 1972 Ente Nazionale Idrocarburi sponsored a program to holographically record the images of Venetian sculptural treasures for archival purposes. At Laboratorio San Gregorio, where the initial holography took place, G. Musumeci and K. Hempel suggested an experiment to determine whether the concentrated beam from the ruby holographic laser could ablate black-patina crusts from decaying marble. Initial success of a laser-divestment test on a Palazzo Ducale capital launched a search for funding to enable a full-scale laser-conservation demonstration. Later, at a Caltech reunion one of the author's physics professors (Carl Anderson, the discoverer of mu mesons and the positron), noting the prominence of the Venice Film Festival suggested our approaching the motion picture industry. Many years earlier Anderson's Caltech classmate, Frank Capra, had supported the research that led to the discovery of cosmic-ray-generated antimatter on Pikes Peak. (After Caltech, Capra had become a director at Columbia Studios.) Anderson's chance comment led to an introduction to producer Jack Warner at a festival screening of his "A Clockwork Orange" in Asolo. He and his friends contributed US$5000 toward the laser conservation of a marble relief of "The Last Supper" in the Porta della Carta of Venice. This work was conducted in 1980 under the direction of Arch. G. Calcagno. In 1981 it was found that the granite veneer or the newly completed Warner Center Tower had been stained during transit from the quarry. The Venice laser successfully restored the veneer, thereby returning the Warner Brothers' favor.

The state of the art of laser techniques employed in conservation of cultural heritage is continuously growing in Europe. Many research projects organised at the European level have contributed to this achievement, being complementary to the development carried out at national level. The COST Action G7 is playing its unique role since the year 2000 in promoting the experimentation, comparing the experiences and disseminating best practices. This role has been particularly effective for monitoring of the results of many short-term research projects completed along the G7 Action lifetime. After that several laser cleaning techniques have been followed and evaluated it appears now clear an evolution of the systems, a specialization of the cleaning task, the achievement of side-effect free procedures. The validation of these advanced cleaning techniques has been extensive and diffused in many European countries, especially for stone and metals. Laser-based diagnostics have also specialised their tasks toward material analysis, defects detection and multidimensional documentation. Laser and optical methods successfully monitor deterioration effects. In many European countries interdisciplinary networks are managing the experimentation of these techniques giving them a sound scientific approach, but also a technology transfer to end-users. So doing the appreciation for these techniques is growing in all the conservation institutions involved at national level, disseminating a positive evaluation about the benefits provided by laser techniques in conservation. Several laser systems became products for the activity of professional restorers and their increasing sales demonstrate a growing utilisation throughout all Europe.

Surface ablation with nanosecond laser pulses was applied to preservation, cleaning and compositional identification of objects of cultural value. On one hand, treatments of fabrics, coins, bones, and other archeological objects are shown, as well as applications to the preservation of covers, front of books and old manuscripts made in rag paper. Damage fluence thresholds for 17 different XIXth century types of papers, made by processing textiles, were determined. On the other hand, we use the spectroscopic analysis of the plasma generated as a result of laser ablation (LIBS- laser Induced Breakdown Spectroscopy-) for the determination of the elementary composition of unique pieces in anthropology and archaeology. In particular, we show applications to the identification of trace elements in Hominide teeth, of interest concerning the analysis of eating habits. We also apply LIBS to the determination of the composition of acheological objects belonging to different pre-Columbian cultures.

Since the inception of the laser-divestment process, emphasis has focused on the treatment of reasonably durable materials. Marble, limestone, sandstone, and bronze are foremost among these. In most situations the objective of laser divestment is the removal of superficial corrosion or chemical-decomposition products. To a lesser extent laser ablation is also used to treat diverse surface problems for a spectrum of other historic and artistic substrates such as paper, vellum, ivory, paint, and plaster. Although materials of this sort are not particularly strong, their optical, thermodynamical, and mechanical properties are sufficiently propitious to enable successful laser treatment (with the exercise of precise control). There is another, quite different, cleaning problem encountered in the maintenance of museum collections. This is often referred to as "dusting" (in contrast to "divestment" or "conservation"). Vacuuming, wiping, blowing, and feather dusting are used most often to improve the cosmetic appearance of museum objects after dust and aerosols have accumulated on exposed surfaces. However, many collections include extremely friable pieces composed of feathers, fir, hair, plant fibers, or mummified skin. Conventional dusting may be impossible in such instances. From experimental observations and theoretical analyses we speculate that at very low fluxes laser-induced acoustic and electrostatic forces are responsible for the ejection of debris. Laboratory experiments demonstrated that laser dusting was effective on feathers and textiles, The practical viability of laser dusting was demonstrated by laser-cleaning two very large sand sculptures by San Diego artist C.R. Faust. In contrast, all conventional cleaning techniques damaged the surface by dislodging sand grains.

In this work we report the preliminary experimental results on the selective ablation of sulphur in ancient stones. The sulphur concentration was reduced after laser action. For this goal an excimer laser operating at 308 nm wavelength and time duration of 20 ns was used. In order to estimate the sulphur concentration before and after laser cleaning, a portable apparatus for energy-dispersive X-ray fluorescence (EDXRF) was utilised. The processed sample were characterized by an initial sulphur concentration of 2.8% w/w. After the laser treatment, sulphur concentration decreased after a total deposited energy of about 30 J/cm² up to 1.2% w/w value. Due to the porosity of the stone, in fact, it is difficult to eliminate completely the S presence in the composition of the stones. It was also observed that after a few laser shots the initial black area of the stone became white showing in this way the great potential of the laser action on the cleaning process of the pietra leccese.

The National Research Council of Canada (NRC) has developed a range of 3D imaging technology tools, which have been applied to a wide range of museum and heritage recording applications. The technology suite includes the development of high-resolution laser scanner systems as well as software for the preparation of accurate 3D models and for the display, analysis and comparison of 3D data. This paper will offer an overview of the technology and its museum and heritage applications with particular reference to the 3D examination of paintings and recording of archaeological sites.

For archiving, art historical purposes and restoration, "two dimensional" (2-D) works of art such as paintings or photo-graphs have, in modern times, traditionally been documented using (colour) photography and/or digital imaging tech-niques. While current technology allows reproductions with high spatial and colour resolution, these techniques only document the 2-D form and colour of the surface of the object. Surfaces also have, however, three dimensional (3-D) properties which play just as important a role in determining an objects appearance and how it is perceived. Among these, surface roughness/texture and the optical properties of transparent layers are particularly important. Both determine the way light is scattered from the surface, and influence not only colour perception, but also glossiness, illusions of transparency, and depth perception. These properties are often the first to be affected before colour changes happen or are perceived in a measurable quantity. They are difficult, if not, impossible to document using current 2-D techniques, while current 3-D scanners do not have the resolution necessary to document the micro-roughness of surfaces which actually determine appearance. The Netherlands Institute of Cultural Heritage has started a multidisciplinary programme to study the effect of 3-D pro-perties of surfaces on the appearance of works of art. The combined effects of colour, roughness, and optical properties of transparent layers are being investigated in situ using standard engineering micro-roughness measurements, colour spectroscopy, and digital imaging techniques. Initial work indicates that these are excellent methods for documenting, for example, the effects of cleaning of paintings and face-mounted photographs. Combined with light scattering models, they will provide a good tool for understanding the appearance of objects, and for their conservation. Rendering models, for example, could help conservators make selections of retouching materials based on colour and texture, or varnishes based on optical properties.

We present a new 3D full-frame profilometer based on structured laser light projection method. This device takes advantage of the polarization states splitting technique for producing and shifting multiple sinusoidal Young's interference patterns that are projected on the inspected surface. The principle of the technique is presented and we discuss the advantages of monochromatic light projection method as a mean to overcome ambient lighting for in-situ measurement. Some results that we obtained on objects from the Egyptian Department of the British Museum are presented to demonstrate that 3D laser profilometry is a worthwhile technique for epigraphic investigations where naked-eye inspections fail.

Offine rendering techniques have nowadays reached an astonishing level of realism but paying the cost of a long computational time. The new generation of programmable graphic hardware, on the other hand, gives the possibility to implement in realtime some of the visual effects previously available only for cinematographic production. In a collaboration between the Visual Computing Lab (ISTI-CNR) with the Institute for Creative Technologies of the University of Southern California, has been developed a realtime demo that replicate a sequence from the short movie "The Parthenon" presented at Siggraph 2004. The application is designed to run on an immersive reality system, making possible for a user to perceive the virtual environment with a cinematographic visual quality. In this paper we present the principal ideas of the project, discussing design issues and technical solution used for the realtime demo.

In this paper, an integrated system based on a phase-shift laser scanning for measuring shape and a imaging spectrograph for measuring color is described. The system is designed for acquisition of large areas, such as chapels or frescoed walls. The phase-shift laser range-finder provides accurate distance measurement, up to 10 meters, pointing at most target surfaces through the measurement of the phase shift. The acquisition of a complete object is performed point by point by a 2D scanning. The imaging spectrograph measures the spectrum of the light coming from on a narrow rectangular region having width and height equal to the image of the entrance slit projected on the object plane. A complete 2D image is acquired by scanning the region in the direction perpendicular to the slit height. The merging of these multiple acquisitions yields the complete spectral and spatial description of the color of the object.

This paper presents the activity carried out to perform the three-dimensional acquisition of the "Vittoria Alata", a 2m-high, bronze statue, symbol of our City, located at the Civici Musei di Arte e Storia (S. Giulia) of Brescia. The acquisition of the statue has been performed by using a three-dimensional vision system based on active triangulation and on the projection of non-coherent light. This system, called OPL-3D, represents one of the research products of our Laboratory, which has been active for years in the development of techniques and systems for the contactless acquisition of free-form, complex shapes. The study, originally motivated by the need to explore a new hypothesis on the origin of the "Vittoria Alata", led to its complete digitization and description in terms of both polygonal and NURBS-based models. A suite of copies of the whole statue has been obtained in the framework of the collaboration between the City Museum and the EOS Electro Optical Systems GmbH, located in Munich, Germany. As a first step, one 30 cm-high replica of the whole statue has been produced using a low-resolution triangle model of the statue (3.5 millions of triangles). As a second step, two 1:1 scale copies of the statue have been produced. For them, the Laboratory has provided the high resolution STL file (16 millions of triangles). The paper discusses in detail the hardware and the software facilities used to implement the whole process, and gives a comprehensive description of the results.

This paper presents a full processing path from 3D-object scanning to its virtual representation with special focus on virtual museum application. Measurement technique is based on opto-numerical approach using structured light projection. The processing path consists of three main steps: filtering and preparing 3D-clouds of points, merging of directional measurements by local co-ordinate spaces unification and transforming from cloud of point representation to triangle mesh with photorealistic texture. The applicability of this path for objects with mixed diffusive-reflective surfaces and a very complex shape is shown on the example of results of a measurement session in the Kórnik Castle and our own 3D objects. The main goal of the session was 3D digitizing of a set cultural objects such as armours, bas-reliefs, sculptures and many more. The exemplary results of these full 3D models (including geometry and texture) scanning is presented.

A quantitative morphological analysis of archaeological objects represents an important element for historical evaluations, artistic studies and conservation projects. At present, a variety of contact instruments for high-resolution surface survey is available on the market, but because of their invasivity they are not well received in the field of artwork conservation. On the contrary, optical testing techniques have seen a successful growth in last few years due to their effectiveness and safety. In this work we present a few examples of application of high-resolution 3D techniques for the survey of archaeological objects. Measurements were carried out by means of an optical micro-profilometer composed of a commercial conoprobe mounted on a scanning device that allows a maximum sampled area of 280×280 mm². Measurements as well as roughness calculations were carried out on selected areas, representative of the differently degraded surface, of an ellenestic bronze statue to document the surface corrosion before restoration intervention started. Two highly-corroded ancient coins and a limestone column were surveyed to enhance the relief of inscriptions and drawings for dating purposes. High-resolution 3D survey, beyond the faithful representation of objects, makes it possible to display the surface in an image format that can be processed by means of image processing software. The application of digital filters as well as rendering techniques easies the readability of the smallest details.

Laser-Induced Breakdown Spectroscopy (LIBS) is a promising technique for in-situ analysis of Cultural Heritage. The potential of this technique for accurate quantitative analysis could be greatly improved using an innovative experimental setup - based on the use of two laser pulses suitably retarded - and analyzing the results with a standard-less procedure which overcomes the problems related to matrix effects. A new mobile instrument for Cultural Heritage analysis, developed at the Applied Laser Spectroscopy Laboratory in Pisa, is presented, and some experimental results are given.

LIBS is one of the most promising techniques for rapid, in-situ elemental analyses of artworks. It does not require sample preparation, it is almost non destructive (micro sampling) and information both about major and trace elements could be obtained simultaneously. LIBS has been used to recognize the elements present in different archaeological materials and has been also proposed for on-line monitoring during the object cleaning by lasers. Quantitative determination of the material composition can supply useful information to restorers and help the object cataloguing. However, the analytical LIBS measurements on the archaeological materials were rarely reported, mainly due to difficulties to obtain the corresponding matrix-matched standards, required for the initial calibration. Alternatively, Calibration-Free (CF) approach could be used on some class of materials if all the major sample elements are detected and if the laser plasma preserves the material stochiometry. The latter condition is sometimes missing, as in the case of bronzes under nanosecond pulse laser ablation. We have developed a theoretical model for laser ablation of quaternary copper alloys, which allows for correction of the missing plasma stochiometry in CF approach. The model also predicts the optimal calibration for this type of material. In our recent work, we also obtained quantitative LIBS results on marbles by realizing the calibration standards starting from doped CaCO₃ powders and by applying the corrections on the plasma parameters, different for the laboratory standards and marbles. Semi-quantitative LIBS results have been also obtained on multi-layered renaissance ceramics by subtraction of the contribution to plasma of each ceramic layer.

Qualitative UV-fluorescence of varnishes is commonly used to locate repaints on paintings or to specify the homogeneousness of a varnish layer. Photographers can now use flash UV-lamps coupled with a CCD camera to obtain colour images of the fluorescence of paintings, unveiling thus both interest and difficulty to interpret these colours. Starting from this point of view, UV-fluorescence spectra appear to be a potential technique to characterize the nature of varnishes and, if possible, their state of degradation. This identification will be non-invasive, without contact, obtained in real time and workable in situ, as the identification of pigments or dyes by reflectance spectrometry which is already done in our group. The last goal will be to realize both identifications with the same device. Emission fluorescence spectra are implemented with the Jobin-Yvon Fluorolog-3, providing an incident wavelength laying between 200 and 850 nm. The emission spectra are implemented with an optical fiber linked to a Jobin-Yvon spectrometer HR460 and a multi-channel CCD detector. In a first step, popular, fresh, raw resins used between the XVI th and the XIX th century, as mastic, dammar and sandarac, have been used to prepare varnishes films with different solvents. The fluorescence spectra of these films have been carried out at different excitation wavelengths to build databases. After having tested the coherence, the limits and the accuracy of the method, we suggest different applications of our method. A synthesis of the results will be presented to characterize each varnish by their fluorescence spectra.

The research is part of the pursuit for a comprehensive method of non-invasive diagnostic techniques for art. It involves conservators as well as art historians, since the specific techniques of the artists are regarded as the most interesting aspects of the new art history.

3D measurement and modelling have been traditionally applied to statues, buildings, archeological sites or similar large structures, but rarely to paintings. Recently, however, 3D measurements have been performed successfully also on easel paintings, allowing to detect and document the painting's surface. We used 3D models to integrate the results of various 2D imaging techniques on a common reference frame. These applications show how the 3D shape information, complemented with 2D colour maps as well as with other types of sensory data, provide the most interesting information. The 3D data acquisition was carried out by means of two devices: a high-resolution laser micro-profilometer, composed of a commercial distance meter mounted on a scanning device, and a laser-line scanner. The 2D data acquisitions were carried out using a scanning device for simultaneous RGB colour imaging and IR reflectography, and a UV fluorescence multispectral image acquisition system. We present here the results of the techniques described, applied to the analysis of an important painting of the Italian Reinassance: `Madonna dei Fusi', attributed to Leonardo da Vinci.

Reflectance spectroscopy supplies fundamental information for investigating art objects and diagnosing their state of conservation. Until recently, reflectance spectra could be measured only on samples taken from the art objects. Recent progresses in fiber optics reflectance spectroscopy (FORS) and image spectroscopy (IS) have made it possible, however, to perform non-invasive measurements. Moreover, the two techniques can supply data in large enough quantities as to make the use of sophisticated statistical methods significant for detecting variations due to ageing and degradation. FORS and IS are, in a sense, complementary techniques as the former provides information on single points, while the latter provides 2-D maps from which the reflectance spectrum of each pixel can be displayed. Both FORS and IS were applied in the case study on the Lansdowne version of the Madonna dei fusi (Madonna of the Yarnwinder). In particular, IS was realized by means of a hyper-spectral scanner recently assembled at the "Nello Carrara" Istituto di Fisica Applicata. The characteristics of the scanner are: 0.1 mm spatial sampling over a 1x1 m² surface and ~1 nm spectral sampling in the wavelength range from 400 nm to 900 nm. The information provided by these two techniques was consistent with what supplied by the non-invasive techniques employed by the other teams participating in the case study, in particular as regards the pigments, the preparatory layer, the binding medium, and the previous restoration works.

A new prospective for the study, documentation and presentation of Cultural Heritage is opened by the joint usage of the tools for the automatic reconstruction of digital 3D models and the instruments for interactive 3D visualization. New techniques are available to perform high-resolution sampling of both the shape and the multi-band reflection properties of painted surfaces. The digital 3D models produced are extremely accurate and rich of information, as it has been proved in the experiments run on the Leonardo's Madonna of the Yarnwinder. This paper presents an overview of the techniques needed to build high-quality 3D models from the raw data produced by the scanning devices and describes how to process those models to make them usable in interactive applications. A very critical point is how to integrate the reflection properties with 3D shape models; this integration (based on texture mapping) allows us to produce textured 3D models that allow a joint visualization of shape and color attributes. The interactive visualization tools developed by ISTI-CNR are described, presenting both their features and potential for the visual presentation and analysis of works of art. Examples of the results obtained on the Madonna of the Yarnwinder are presented.

In the framework of the extensive study on the wood painting "Madonna dei fusi" attributed to Leonardo da Vinci, Ion Beam Analysis (IBA) techniques were used at the Florence accelerator laboratory to get information about the elemental composition of the paint layers. After a brief description of the basic principle and the general features of IBA techniques, we will illustrate in detail how the analysis allowed us to characterise the pigments of original and restored areas and the substrate composition, and to obtain information about the stratigraphy of the painting, also providing an estimate of the paint layer thickness.

The new SIRIS (Scanning InfraRed Imaging System) camera developed at the National Gallery in London allows high-resolution images of paintings to be made in the near infrared region (900-1700 nm). Images of 5000 × 5000 pixels are made by moving a 320 × 256 pixel InGaAs array across the focal plane of the camera using two orthogonal translation stages. The great advantages of this camera over scanning infrared devices are its relative portability and that image acquisition is comparatively rapid - a full 5000 × 5000 pixel image can be made in around 20 minutes. The paper describes the development of the mechanical, optical and electronic components of the camera, including the design of a new lens. The software routines used to control image capture and to assemble the individual 320 × 256 pixel frames into a seamless mosaic image are also mentioned. The optics of the SIRIS camera have been designed so that the camera can operate at a range of resolutions; from around 2.5 pixels per millimetre on large paintings of up to 2000 × 2000 mm to 10 pixels per millimetre on smaller paintings or details of paintings measuring 500 × 500 mm. The camera is primarily designed to examine underdrawings in paintings; preliminary results from test targets and paintings are presented and the quality of the images compared with those from other cameras currently used in this field.

Atomic Force Microscopy (AFM) has been used to study fiber degradations, as they appear on paper surface, aiming -in the mid term- at assessment of a micro-destructive technique capable of providing qualitative and semi-quantitative information on deterioration and ageing. AFM topographies of pure cellulose paper samples artificially aged were considered as well as topographies of original paper samples naturally aged showing different kind of deterioration. Whatman N.1 chromatography paper was used as a model system to study ageing effect on sub-micron structures on cellulose fibers. Chemical and biological deterioration processes were modeled, as well, by mean of artificial degradation treatments, following the criteria of reproducing effects frequently isolated from library materials. The effects of chemical reaction induced by accelerated ageing in climatic chamber (80°C, R.H. 65%) on paper surface, and the effects of a fungal attack reproduced in vitro inoculating paper samples with Aspergillus terreus Thom (6000spores/100μl, 27°C, R.H. 100%) were evaluated by means of Atomic Force Microscopy imaging, and spectrophotometric measurement in the UV-Vis-NIR. In order to map structure local properties, morphological variations repeated with statistical relevance were correlated to chemical, biological and spectroscopic characterization. Information achieved from such analysis is then used for a comparison with measurements of naturally aged paper, providing insight in analysis and classification of typical phenomena, like yellowing and foxing stains, usually affecting valuables in libraries.

The deteriorating effect of light on artworks exposed in museums and galleries has been noticed for many years. A number of methods, which act on the illumination source, are presently in use to reduce the damage. A complementary approach is proposed here that consists in blocking the radiation, outside the range of sensitivity of the human eye, before it reaches the artwork. This result can be achieved by an optical coating deposited on the glass pane that is usually put in front of the artworks to protect them from vandalism. In addition to the preservation from illumination induced damage, the proposed coating is also able to improve the observation of the artwork by reducing the reflection effects of uncoated glass. Optical, colorimetric and psychophysical measurements on test samples are reported.

In the last few years multispectral imaging has entered the field of painting diagnostics and conservation because of its effectiveness and safety. It provides spectral and colorimetric characterization of the whole paint layer, suitable to document the conservation state of the artwork and useful in the study for the identification of pigments. Here we present a high-resolution scanning system for 32-band multispectral imaging of paintings in the 380÷800 nm spectral region. This system is based on a fast spectrometer for contact-less single-point measures mounted on two orthogonal XY translation stages. It can scan an area of 1 m² with a spatial resolution of 4 dots/mm and a spectral resolution of 10 nm. Spectral reflection factor and tristimulus value measurements were carried out on coloured ceramic tiles and the results were compared with the corresponding certified values. Multispectral analysis was performed on a few ancient paintings and spectrophotometric results are shown.

Cast plaster dries with different densities depending on the surrounding media. Liquid plaster filled into a lubricated casting mould will acquire a surface boundary of high density, once set. The second and third cast layers into the still moist form will dry to a lower density. Later additions of plaster, due to sculptural reworking and restorative measures, will also have discernible densities. With computerized tomography (CT) the density in each volume element can be measured. With 3D - μCT the total body of a sculpture can be scanned to a high spatial resolution. Cracks within and cuts through the original cast become visible along with internal structures and armouring. The results from two studies on plaster statues (by Christian Daniel Rauch and Honoré Daumier), done in support of the conservation process as well in the intent of revealing a relative chronology within a series, are presented and placed into the art-historical context.

Computed Tomography (CT) is one of the principal non-invasive techniques for the investigation of the inner structure of works of art. The main advantage of using CT is that it provides high resolution 3D information of the analyzed object. CT of large objects can be hampered by the long time needed and by the difficulties regarding the experimental arrangements required. In this paper we present a CT study of an ancient large globe (diameter of about 2.2 m). We set-up an ad hoc system for the analysis of the globe in situ. The system consists of an X-ray tube, a detector made of a GOS scintillator and an EBCCD camera, the movement axes, a vertical moving axis for the tube, a horizontal-vertical axis for the detector, and a rotating platform for the globe. The investigation of the entire globe has required the acquisition of about 32000 planar images, for providing the 3D tomographic reconstruction. The analysis of the reconstructed volume has allowed to estimate the composition of the inner structure of the globe.

It is current practice to take tiny samples from a painting to mount and examine in cross-section under a microscope. However, since conservation practice and ethics limit sampling to a minimum and to areas along cracks and edges of paintings, which are often unrepresentative of the whole painting, results from such analyses cannot be taken as representative of a painting as a whole. Recently in a preliminary study, we have demonstrated that near-infrared Optical Coherence Tomography (OCT) can be used directly on paintings to examine the cross-section of paint and varnish layers without contact and the need to take samples. OCT is an optical interferometric technique developed for in vivo imaging of the eye and biological tissues; it is essentially a scanning Michelson's interferometer with a "broad-band" source that has the spatial coherence of a laser. The low temporal coherence and high spatial concentration of the source are the keys to high depth resolution and high sensitivity 3D imaging. The technique is non-invasive and non-contact with a typical working distance of 2 cm. This non-invasive technique enables cross-sections to be examined anywhere on a painting. In this paper, we will report new results on applying near-infrared en-face OCT to paintings conservation and extend the application to the examination of underdrawings, drying processes, and quantitative measurements of optical properties of paint and varnish layers.

Non-destructive optical testing techniques are widely used in the field of painting diagnostics because of their effectiveness and safety. At present, many techniques for non-destructive investigations of paintings are available. Optical Coherence Tomography (OCT) is a non invasive technique allowing cross sectional imaging of partially transparent or scattering tissue which is now well-established for biomedical applications. Particularly, the OCT techniques allow evaluating multilayer tissues. Being applied to painting diagnostics, the OCT gives a possibility to measure the actual varnish thickness that is very important in painting restoration by the cleaning process. Because of complicated local structure of layers and light scattering, noise-immune signal processing methods should be used. In the paper, the Kalman filtering method involving random fringe model applied to the OCT signals is investigated and compared with conventional fringe amplitude demodulation method. Experimental results obtained when recovering OCT tomograms of paintings are presented and discussed.

In the last few years many non-destructive techniques have entered the field of painting conservation, and most of them are routinely applied to study and monitoring the painting status. Among them optical techniques are by now widely diffused and extremely well received because of their effectiveness and safety, nevertheless none of them is suitable for a quantitative characterization of varnish. One of the most important and often controversial stages of painting restoration is the surface cleaning process up to now being carried out without any tool to measure the actual varnish thickness but microscope observation of micro-detach. In this work we present an application of Optical Coherence Tomography to non-destructive diagnostics of artwork: the potentiality of this technique is demonstrated by measuring the thickness of the varnish layer in a fragment of a nineteenth-century oil painting.

National monuments are at ever-increasing risk of severe and permanent damage. The 3D laser scanning of stone monuments brings a new dimension in the field of cultural heritage by providing means of preserving, visualizing, accessing and analysing some of its most invaluable artefacts. In this article, we present the results obtained with our project "Profilometry of Medieval Irish Stone Monuments" hosted at the Centre for the Study of Human Settlement and Historical Change, NUI Galway. This project aims to create a virtual archive of selected incised stones from 3D scans taken in the field. The raw scans are processed into watertight 3D models and new processing techniques have been developed to enhance the surface features of the stones. Also, textured 3D models of the artefacts have been made available online for the benefit of both the historian community and the broader public. This article focuses on the analysis we performed on the shaft of the east cross at Toureen Peacaun, Co Tipperary, which shows the longest inscription in Ireland with geometrical capitals.

This study applies 3D Laser scanning technology to develop a high-precision measuring system for digital survey of historical building. It outperformed other methods in obtaining abundant high-precision measuring points and computing data instantly. In this study, the Pei-tien Temple, a Chinese Taoism temple in southern Taiwan famous for its highly intricate architecture and more than 300-year history, was adopted as the target to proof the high accuracy and efficiency of this system. By using French made MENSI GS-100 Laser Scanner, numerous measuring points were precisely plotted to present the plane map, vertical map and 3D map of the property. Accuracies of 0.1-1 mm in the digital data have consistently been achieved for the historical heritage measurement.

Inks constitute the main element in Medieval manuscripts and their examination and analysis provides an invaluable source of information on the authenticity of the manuscripts, the number of authors involved and dating of the manuscripts. Most existing methods for the analysis of ink materials are based on destructive testing techniques that require the physicochemical sampling of data. Such methods cannot be widely used because of the historical and cultural value of manuscripts. In this paper we present a novel approach for discriminating and identifying inks based on the correlations of image variations under visible and infrared illumination. Such variations are studied using co-occurrence matrices and detect the behavior of the inks during the scripting process.

The paper presents the results of experiments obtained using different analytical techniques (optical and electronic microscopy, infrared spectroscopy, powder X-ray diffraction, X-ray fluorescence, microanalysis) performed on stucco's samples collected in churches and historical buildings in Canton Ticino and Canton Grigioni (Southern Switzerland). The research is principally oriented towards establishing the better analytical sequence for an efficacious characterization of materials and techniques used in making stuccos, in order to satisfy restoration requests. Plastic decorations (stuccoes of 17th and 18th century), imitation marble vertical surfaces - stucco lustro - (19th century) and decorative elements as stucco lustro (17th century) were studied. The experimental data showed the same bottom layer for all the samples; different categories of stucco are distinguishable observing finishing layer characteristics. Petrographic examinations and spectroscopic infrared analyses represent a suitable survey sequence, working on samples of millimetric size (low invasive and high representative criteria for sampling), considering that it is an usual necessity to divide mechanically the different parts of the same material, as for example bottom layer and finishing one, to detect the presence of organic compounds in each layer. More significant results should be obtained employing electron microscope and microanalysis, using the same thin polished section of optical examinations. Mineralogical and chemical analyses performed by X-ray diffraction and X-ray fluorescence require a greater sample availability but in this way it is possible to obtain more complete and representative information specifying compounds bound to alteration processes and/or to previous restoration interventions.

Raman Spectroscopy is a fast, rugged analytical technique based on the Raman Effect. When monochromatic light encounters matter, most of the scattered light has the same wavelength as the incident light. However, a small fraction of the scattered light is shifted in a different wavelength by the molecular vibrations and rotations in the sample. The representation of this shifted light is called Raman spectrum, and contains many sharp bands characteristics of the sample, allowing its identification without ambiguity. In this communication, a fuzzy logic system to recognize Raman spectra of artistic pigments is presented. The identification is based on the comparison between an unknown spectrum, and pattern spectra. Frequently the comparison is made by the spectrospist by visual inspection, but this is slow and imprecise. In order to mitigate this problematic, a system based on the fuzzy logic technique to identify Raman spectra is presented. The methodology consists on implementing the comparison with the Correlation. However, a Raman spectrum is inevitably affected by noise which introduces ambiguity into the correlation values. Fuzzy Logic provides a simple way to draw conclusions from imprecise data. The fuzzy identification system is based on the following statement: when the correlation between the unidentified and the pattern is enough high, the analysed pigment is recognized as the pigment which corresponds to this pattern. The membership functions, which characterize the fuzzy sets at the input (Correlation) and output (Identified/ Not_Identified) of the system, and the inference mechanism suitable for the problem, are chosen.