CLEO/Europe. 2005 Conference on Lasers and Electro-Optics Europe, 2005.
Various laser interferometric techniques successfully applied in medical and industrial diagnosti... more Various laser interferometric techniques successfully applied in medical and industrial diagnostic sectors not yet fully developed and adjusted in the field of conservation of cultural heritage are being considered. The drawback is that each technique implies distinct operation characteristics solving specific problems that cannot correspond to the complexity of diagnostic problems involved in the field of cultural heritage. As such
Environmental conditions dominate materials’ equilibrium processes with surrounding environment. ... more Environmental conditions dominate materials’ equilibrium processes with surrounding environment. The environmental fluctuations are accused for decay mechanisms of artworks even if the latter are kept in stable conditions, some for centuries inside controlled rooms and more recent in environmental-controlled galleries. Environmental control is considered the central issue in most modern museums and artwork display rooms to minimise equilibrium demanding processes. Conservators and conservation scientists concluded to keep the conditions stable and within short range of values in order to avoid the displacement of the materials in response to condition change. Hence if environmental change is kept within safety limits the environmental control is considered safe for the hosting artworks and the crucial parameter of fatigue and deterioration is accused only if these safety limits are not kept in uncontrolled environmental conditions.
... Spatial multiplexing for large-area 3D holographic recording. 1312367 abstract; Rights And Pe... more ... Spatial multiplexing for large-area 3D holographic recording. 1312367 abstract; Rights And Permissions; Georgian, E.; Stassinopouls, A.; Tornari, V.; Dept. of Electr. Eng., Tech. Eductional Inst. of Crete, Greece. This paper appears in: Lasers and Electro-Optics Europe, 2003. ...
In this paper, investigation of photochemical and photomechanical effects induced in polymer subs... more In this paper, investigation of photochemical and photomechanical effects induced in polymer substrates under pulsed UV ablation is presented. The examined laser parameters are the wavelength at 248 nm and 193 nm in the nanosecond regime, and the fluence below and above the ablation threshold. The two polymeric substrates used are PMMA and blends of PMMA and PS.
ABSTRACT In this paper, modeling of photochemical and photomechanical effects that may be induced... more ABSTRACT In this paper, modeling of photochemical and photomechanical effects that may be induced during laser assisted cleaning of painted artworks using pulsed UV ablation is presented. The examined laser parameters are the wavelength at 248 nm and 193 nm in the nanosecond regime, and the fluence below and above the ablation threshold. The two polymeric substrate models used are PMMA and blends of PMMA and PS. A test case study is presented.
Excimer laser ablation utilized in artwork restoration generates pressure waves that may influenc... more Excimer laser ablation utilized in artwork restoration generates pressure waves that may influence the structural integrity. By means of holographic interferometry a non- destructive highly sensitive mapping for evaluating the structural state is provided. The long-term sequential recording enables comparison between time resolved optical wave fronts scattered from the artwork before and after the selective ablation of material. Thus, comparative
A phase-shifting digital holography scheme developed to investigate internal defects in artworks ... more A phase-shifting digital holography scheme developed to investigate internal defects in artworks is described. Phase-shifting is utilized to obtain a clear reconstructed object wave from a rough surface texture. A reverse-transform algorithm is employed to reconstruct the object wave on its original position of unknown distance or the imaging position from the object wave information on the holographic plane. To get the clearest reconstruction the exact registration of the unknown distance is determined by applying the intensity sum as the auto-focusing function. The spatial resolution of the reconstruction image is also investigated for a variety of affecting factors. Laboratory results of reconstruction images under deformation are presented.
XIII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference, Jan 25, 2001
Chemical and mechanical modifications are expected to be the two major types of side effects in t... more Chemical and mechanical modifications are expected to be the two major types of side effects in the UV laser ablationbased processing of strongly absorbing molecular substrates. For the systematic characterization of these effects, studies on model polymeric systems are presented. As far as photochemical effects are concerned, UV ablation is shown to promote chemical pathways over the ones observed in the sub-ablative regime. However, the extent of these effects can be limited by an optimal etching depth vs. effective optical penetration depth in substrates of high absorptivity. Concerning mechanical effects, UV ablation is similarly shown to result in structural defects that are not observed in the irradiation at low energy fluence values. In practice, these may be limited by the inhomogeneous and stratified structure of the substrates encountered in real-life applications. The applicability of the results to the implementations of UV laser ablation is exemplified using the procedures that have been defined in laser restoration of painted artworks as a study case. Besides their implications for laser material processing implementations, the present results indicate that UV ablation introduces new physical and chemical paradigms that are of scientific importance in their own right.
Curators have developed preventive conservation strategies and usually try to control the tempera... more Curators have developed preventive conservation strategies and usually try to control the temperature (T) and relative humidity (RH) variations in the museum rooms to stabilise the artworks. The control systems chosen by museums depend on the size and age of the building, the financial means and the strategies that can be adapted. However, there is a lack of methods that can monitor mechanical changes or chemical reactions of objects in real-time or regularly. It would therefore ideally be preferable to monitor each of them to alert them to preserve them. For this purpose, a non-destructive, non-contact, full-field technique, Digital Holographic Speckle Pattern Interferometry (DHSPI), has already been developed and allows direct tracking of changes on the surface of artworks. This technique is based on phase-shifting speckle interferometry and gives the deformation of the surface below the level of the micro-meter of the analysed object. In order to monitor the deformation continuou...
Digital holographic speckle pattern interferometry (DHSPI) is a tool that retrieves the mechanica... more Digital holographic speckle pattern interferometry (DHSPI) is a tool that retrieves the mechanical reaction of a work of art after a shock or vibration, perhaps as a result of mishandling. It provides a method for the assessment of the impact of transportation and reliable risk analysis. In order to assess the effect of handling and transportation on canvas paintings, an investigation was conducted at Bern University of Applied Sciences, University of the Arts, Conservation and Restoration employing DHSPI. Samples of canvas were used for a series of measurements simulating transportation vibrations. The surface deformation topology of the samples was studied with DHSPI in order to acquire information about all the alterations caused on the canvas samples by the vibration ‘fatigue’ (i.e. the repeated deformation due to vibration). Crack maps, provided by analysis of the DHSPI measurements, illustrate the crack growth with time. Risk areas, located before any vibration loading, also proved to be those most likely to develop cracks. The tests of the transportation of canvas paintings have been successful in detecting cracks and areas with defects, and also in monitoring their propagation with high precision
The heat transfer effect is observed from existing defects through heat diffusion to the sound ar... more The heat transfer effect is observed from existing defects through heat diffusion to the sound area of the sample in long term after the sample has reached values close to the initial, signifying equilibrium with the environment. Two complementary systems providing the kinetic and thermal information of the samples were used to construct a real-time monitoring workstation in order to monitor the real-time responses of the sample after thermal excitation. Results indicate that the defect boundaries and the sound non-defect area continue to exchange thermal values long after the total area of the sample reaches initial temperature in equilibrium with environment. Hence, it is here suggested that the continuous aging of artworks in controlled environments may be a result of the ongoing low thermal heat transfer from the defect to the sound areas provoking a slow but steady surface displacement and consequently deterioration mechanism against the preventive conservation measures based on environmental equilibrium.
Proceedings of the International Conference Lacona VII, Madrid, Spain, 17 - 21 September 2007, 2008
... Stuttgart, Germany S. Hackney Conservation Department, Tate, London, UK E. Kouloumpi Conserva... more ... Stuttgart, Germany S. Hackney Conservation Department, Tate, London, UK E. Kouloumpi Conservation Department, National GalleryAlexandros Soutzos Museum ... like to thank Marc Georges and Cèdric Thizy at the Centre Spatial Liège and Kostas Hatzi-giannakis, Eirini ...
CLEO/Europe. 2005 Conference on Lasers and Electro-Optics Europe, 2005.
Various laser interferometric techniques successfully applied in medical and industrial diagnosti... more Various laser interferometric techniques successfully applied in medical and industrial diagnostic sectors not yet fully developed and adjusted in the field of conservation of cultural heritage are being considered. The drawback is that each technique implies distinct operation characteristics solving specific problems that cannot correspond to the complexity of diagnostic problems involved in the field of cultural heritage. As such
Environmental conditions dominate materials’ equilibrium processes with surrounding environment. ... more Environmental conditions dominate materials’ equilibrium processes with surrounding environment. The environmental fluctuations are accused for decay mechanisms of artworks even if the latter are kept in stable conditions, some for centuries inside controlled rooms and more recent in environmental-controlled galleries. Environmental control is considered the central issue in most modern museums and artwork display rooms to minimise equilibrium demanding processes. Conservators and conservation scientists concluded to keep the conditions stable and within short range of values in order to avoid the displacement of the materials in response to condition change. Hence if environmental change is kept within safety limits the environmental control is considered safe for the hosting artworks and the crucial parameter of fatigue and deterioration is accused only if these safety limits are not kept in uncontrolled environmental conditions.
... Spatial multiplexing for large-area 3D holographic recording. 1312367 abstract; Rights And Pe... more ... Spatial multiplexing for large-area 3D holographic recording. 1312367 abstract; Rights And Permissions; Georgian, E.; Stassinopouls, A.; Tornari, V.; Dept. of Electr. Eng., Tech. Eductional Inst. of Crete, Greece. This paper appears in: Lasers and Electro-Optics Europe, 2003. ...
In this paper, investigation of photochemical and photomechanical effects induced in polymer subs... more In this paper, investigation of photochemical and photomechanical effects induced in polymer substrates under pulsed UV ablation is presented. The examined laser parameters are the wavelength at 248 nm and 193 nm in the nanosecond regime, and the fluence below and above the ablation threshold. The two polymeric substrates used are PMMA and blends of PMMA and PS.
ABSTRACT In this paper, modeling of photochemical and photomechanical effects that may be induced... more ABSTRACT In this paper, modeling of photochemical and photomechanical effects that may be induced during laser assisted cleaning of painted artworks using pulsed UV ablation is presented. The examined laser parameters are the wavelength at 248 nm and 193 nm in the nanosecond regime, and the fluence below and above the ablation threshold. The two polymeric substrate models used are PMMA and blends of PMMA and PS. A test case study is presented.
Excimer laser ablation utilized in artwork restoration generates pressure waves that may influenc... more Excimer laser ablation utilized in artwork restoration generates pressure waves that may influence the structural integrity. By means of holographic interferometry a non- destructive highly sensitive mapping for evaluating the structural state is provided. The long-term sequential recording enables comparison between time resolved optical wave fronts scattered from the artwork before and after the selective ablation of material. Thus, comparative
A phase-shifting digital holography scheme developed to investigate internal defects in artworks ... more A phase-shifting digital holography scheme developed to investigate internal defects in artworks is described. Phase-shifting is utilized to obtain a clear reconstructed object wave from a rough surface texture. A reverse-transform algorithm is employed to reconstruct the object wave on its original position of unknown distance or the imaging position from the object wave information on the holographic plane. To get the clearest reconstruction the exact registration of the unknown distance is determined by applying the intensity sum as the auto-focusing function. The spatial resolution of the reconstruction image is also investigated for a variety of affecting factors. Laboratory results of reconstruction images under deformation are presented.
XIII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference, Jan 25, 2001
Chemical and mechanical modifications are expected to be the two major types of side effects in t... more Chemical and mechanical modifications are expected to be the two major types of side effects in the UV laser ablationbased processing of strongly absorbing molecular substrates. For the systematic characterization of these effects, studies on model polymeric systems are presented. As far as photochemical effects are concerned, UV ablation is shown to promote chemical pathways over the ones observed in the sub-ablative regime. However, the extent of these effects can be limited by an optimal etching depth vs. effective optical penetration depth in substrates of high absorptivity. Concerning mechanical effects, UV ablation is similarly shown to result in structural defects that are not observed in the irradiation at low energy fluence values. In practice, these may be limited by the inhomogeneous and stratified structure of the substrates encountered in real-life applications. The applicability of the results to the implementations of UV laser ablation is exemplified using the procedures that have been defined in laser restoration of painted artworks as a study case. Besides their implications for laser material processing implementations, the present results indicate that UV ablation introduces new physical and chemical paradigms that are of scientific importance in their own right.
Curators have developed preventive conservation strategies and usually try to control the tempera... more Curators have developed preventive conservation strategies and usually try to control the temperature (T) and relative humidity (RH) variations in the museum rooms to stabilise the artworks. The control systems chosen by museums depend on the size and age of the building, the financial means and the strategies that can be adapted. However, there is a lack of methods that can monitor mechanical changes or chemical reactions of objects in real-time or regularly. It would therefore ideally be preferable to monitor each of them to alert them to preserve them. For this purpose, a non-destructive, non-contact, full-field technique, Digital Holographic Speckle Pattern Interferometry (DHSPI), has already been developed and allows direct tracking of changes on the surface of artworks. This technique is based on phase-shifting speckle interferometry and gives the deformation of the surface below the level of the micro-meter of the analysed object. In order to monitor the deformation continuou...
Digital holographic speckle pattern interferometry (DHSPI) is a tool that retrieves the mechanica... more Digital holographic speckle pattern interferometry (DHSPI) is a tool that retrieves the mechanical reaction of a work of art after a shock or vibration, perhaps as a result of mishandling. It provides a method for the assessment of the impact of transportation and reliable risk analysis. In order to assess the effect of handling and transportation on canvas paintings, an investigation was conducted at Bern University of Applied Sciences, University of the Arts, Conservation and Restoration employing DHSPI. Samples of canvas were used for a series of measurements simulating transportation vibrations. The surface deformation topology of the samples was studied with DHSPI in order to acquire information about all the alterations caused on the canvas samples by the vibration ‘fatigue’ (i.e. the repeated deformation due to vibration). Crack maps, provided by analysis of the DHSPI measurements, illustrate the crack growth with time. Risk areas, located before any vibration loading, also proved to be those most likely to develop cracks. The tests of the transportation of canvas paintings have been successful in detecting cracks and areas with defects, and also in monitoring their propagation with high precision
The heat transfer effect is observed from existing defects through heat diffusion to the sound ar... more The heat transfer effect is observed from existing defects through heat diffusion to the sound area of the sample in long term after the sample has reached values close to the initial, signifying equilibrium with the environment. Two complementary systems providing the kinetic and thermal information of the samples were used to construct a real-time monitoring workstation in order to monitor the real-time responses of the sample after thermal excitation. Results indicate that the defect boundaries and the sound non-defect area continue to exchange thermal values long after the total area of the sample reaches initial temperature in equilibrium with environment. Hence, it is here suggested that the continuous aging of artworks in controlled environments may be a result of the ongoing low thermal heat transfer from the defect to the sound areas provoking a slow but steady surface displacement and consequently deterioration mechanism against the preventive conservation measures based on environmental equilibrium.
Proceedings of the International Conference Lacona VII, Madrid, Spain, 17 - 21 September 2007, 2008
... Stuttgart, Germany S. Hackney Conservation Department, Tate, London, UK E. Kouloumpi Conserva... more ... Stuttgart, Germany S. Hackney Conservation Department, Tate, London, UK E. Kouloumpi Conservation Department, National GalleryAlexandros Soutzos Museum ... like to thank Marc Georges and Cèdric Thizy at the Centre Spatial Liège and Kostas Hatzi-giannakis, Eirini ...
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