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RESEARCH PROGRAM

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Research Units
Similar research programs:
Scientific and education field classification
International Patent Classification
  • ELECTRICITY
  • PHYSICS
    • MEASURING (counting G06M); TESTING
      • INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (separating components of materials in general B01D, B01J, B03, B07; apparatus fully provided for in a single other subclass, see the relevant subclass e.g. B01L; measuring or testing processes other than immunoassay, involving enzymes or micro-organisms C12M, C12Q; investigation of foundation soil in situ E02D1/00; sensing humidity changes for compensating measurements of other variables or for compensating readings of instruments for variations in humidity, see G01D or the relevant subclass for the variable measured; testing or determining the properties of structures G01M; measuring or investigating electric or magnetic properties of materials G01R; systems or methods in general, using reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; determining sensivity, graininess, or density of photographic materials G03C5/02; testing component parts of nuclear reactors G21C17/00; [N: controlling or regulating non-electric variables G05D; measuring degree of ionisation of ionised gases, i.e. plasma H05H1/00A; testing electrographic developer properties G03G15/08H6])
      • MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRA-RED, VISIBLE OR ULTRA-VIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)
Geographical classification
Keywords
LASER ABLATION; LASER CLEANING; SURFACE INTERACTIONS; SCANNING ELECTRON MICROSCOPY (SEM); FOURIER TRANSFORM INFRARED SPECTROSCOPY (FTIR); SPECTROPHOTOMETRY; LASER INDUCED BREAKDOWN SPECTROSCOPY (LIBS); CULTURAL HERITAGE

Evaluation of effects of laser Cleaning/Ablation tretment on materials of interest in cultural heritage

Università degli Studi di Napoli "Federico II"
Abstract
About one half of the whole world cultural heritage is located in Italy. This is therefore a fundamental resource requiring and implying a serious responsibility for its conservation and restoration. Physics is nowadays bringing a more and more significant contribution to the field of cultural heritage, even if with some delay with respect to other fields, such as Medicine, regarded as primary. It is depressing to observe that Italy, despite its natural inclination, is far from reaching the experience of other countries as Japan or United Kingdom. We believe that the time is ripe to begin fundamental scientific research oriented not only to the execution of actions with sophisticated instrumentation, but also to the development of new devices and to the optimization of their use.

Laser Cleaning/Ablation (LC/LA) technique is currently accepted, likewise other "traditional" (mechanical or chemical) ones, as a technique to remove extraneous materials from a solid substrate. The technique, born in microelectronic industry, in recent years has been successfully applied in the field of conservation and restoration of cultural heritage, with promising results.

Within the field of cultural heritage the evaluation of the effects of laser radiation interaction with the surface under treatment must be considered from a global point of view, taking into account artistical, historical, cultural aspects. Final result of a LC/LA operation must be obviously estimated >>>

Principal Investigator
Luciano Rosario Maria VICARI Università degli Studi di NAPOLI "Federico II"
Research Objectives
The use of Laser Cleaning/Ablation (LC/LA) techniques, i.e. the use of pulsed laser radiation to remove extraneous materials from a solid substrate, has found in recent years an increasing interest in several fields ranging from microelectronic industry to applications in conservation and restoration of cultural heritage. Within this field the most common application of LC/LA is the removal of undesired surface layers (pollution crusts, corrosion layers, surface treatments, fungi, bacteria, etc.) from artifacts of both organic (paper, parchment, textiles, wood, etc.) and inorganic (stones, metals, glass, terracotta, etc.) materials. Application of LC/LA techniques requires knowledge of effects of laser radiation interaction with both the substrate and the substance to be removed. Radiation, thermal and mechanical effects must be taken into account in order to determine the parameters (laser wavelength, laser beam fluence, pulse repetition rate, etc.) to be used in LC/LA operation. In order to achieve good results LC/LA operating parameters must be below "damage threshold" of substrate and above the "cleaning threshold" of the material to be removed.

Determination of such threshold values is non easy, especially in cultural heritage field since involved materials are usually very complex (substrate is often inhomogeneous and surface is often irregular) and the result of treatment must be mainly evaluated from point of view of the fruition of the artwork, even if on >>>

First Results
Results of first phase will be

* avaiability of sample sets

* definition of LC/LA treatment protocols

* purchasing of instrumentationResults of second phase will be

* preliminary chemical/physical analysis of reference samples

* sample sets treated following prevoously defined LC/LA treatment protocols

* set-up of purchased instrumentationAt the end of this phase the results of a large number of chemical and physical analysis will be available for selected sample sets.Results of this phase will be main results of the research project:

* definition of interventions suitable for each material

* individuation of the most relevant chemical/physical parameters to be monitored during or analyzed before/after LC/LA treatment

* determination of a set of quantitative evaluation rules arranged in a way to be meningful for both workers (technicians) and managers (Museum and Fine Arts Agency etc.) of restoration treatment

Timescale
24 months
National and international background
Laser Cleaning (LC) birth-date can be placed at the beginning of the 1990s1,2 even if the idea of using laser radiation to remove some substance from a substarate has been shown in 1965 by A. L. Schawlow3 to remove typewritten characters without damaging the underlying paper. In Dry LC (DLC) particle removal is due to sudden expansion of both substrate and particle as a consequence of pulsed laser irradiation, while in Stream LC (SLC), also called "wet" or "liquid assisted" LC2,4,5, particle removal is due to vaporization of a thin liquid layer sprayed over surface to be cleaned. Besides these "direct" (laser radiation directly impinges on the surface to be treated) LC techniques some "indirect" (laser radiation does not impinge on the surface to be treated) techniques, such as "Shock-wave Laser Cleaning"6 or "Verso Laser Cleaning"7, have been proposed and used.

"Laser Ablation" (LA) refers to the interaction of a laser beam with a solid target producing vaporization of a small amout of irradiated material and has been extensively used and studied since high-power lasers have been available8. If the laser pulse is short enough, laser radiation interacts only with the irradiated zone, without involving the underlying or adjacent layers. Since both pulse repetition rate and number of pulses can be easily controlled, ablation can be carried out for sub-micrometric depths. The removal of a surface layer >>>