In the laser treatment of a workpiece (9), e.g. for surface hardening, melting, alloying, cladding, welding or cutting, the adverse effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1). The two beams (1)(5) may be combined by a beam coupler (4) or may reach the workpiece (9) by separate optical paths (not shown). The shorter wavelength beam (1) improves the coupling efficiency of the higher- powered laser beam (5).

Laser Material Processing

Laser induced breakdown spectroscopy (LIBS) is basically an emission spectroscopy technique where atoms and ions are primarily formed in their excited states as a result of interaction between a tightly focused laser beam and the material sample. The interaction between matter and high-density photons generates a plasma plume, which evolves with time and may eventually acquire thermodynamic equilibrium. One of the important features of this technique is that it does not require any sample preparation, unlike conventional spectroscopic analytical techniques. Samples in the form of solids, liquids, gels, gases, plasmas and biological materials (like teeth, leaf or blood) can be studied with almost equal ease.LIBS has rapidly developed into a major analytical technology with the capability of detecting all chemical elements in a sample, of real- time response, and of close-contact or stand-off analysis of targets. The present book has been written by active specialists in this field, it includes the basic principles, the latest developments in instrumentation and the applications of LIBS. It will be useful to analytical chemists and spectroscopists as an important source of information and also to graduate students and researchers engaged in the fields of combustion, environmental science, and planetary and space exploration. It features: recent research work, possible future applications and LIBS Principles.

Chapter 12 – Laser-Induced Breakdown Spectroscopy: Advanced Analytical Technique

Calibration-Free Laser-Induced Breakdown Spectroscopy: State of the art

Analytical applications of Laser Induced Breakdown Spectroscopy (LIBS), namely optical emission spectroscopy of laser-induced plasmas, have been constantly growing thanks to its intrinsic conceptual simplicity and versatility. Qualitative and quantitative analysis can be performed by LIBS both by drawing calibration lines and by using calibration-free methods and some of its features, so as fast multi-elemental response, micro-destructiveness, instrumentation portability, have rendered it particularly suitable for analytical applications in the field of environmental science, space exploration and cultural heritage. This review reports and discusses LIBS achievements in these areas and results obtained for soils and aqueous samples, meteorites and terrestrial samples simulating extraterrestrial planets, and cultural heritage samples, including buildings and objects of various kinds.

Laser induced breakdown spectroscopy for elemental analysis in environmental, cultural heritage and space applications: a review of methods and results.

▪ Abstract We provide an overview of the present understanding of the transition from hadrons to a quark-gluon plasma, its signatures, and the experimental results so far. We discuss results of numerical simulations of the lattice gauge theory and critically evaluate the various observables that have been proposed as signatures of the QCD phase transition. We place the existing data from relativistic heavy-ion experiments at the Brookhaven Alternating Gradient Synchrotron (AGS) and CERN Super Proton Synchrotron (SPS) into perspective and provide an overview of the techniques and strategies that will be employed in the search for the quark-gluon plasma at heavy-ion colliders, such as the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC).

http://cds.cern.ch/record/295684/files/9602235.pdf

The search for the quark-gluon plasma

The aim of this work is to analyze the feasibility of artificial neural networks (ANN) for the classification, in function of the provenance, of archaeological ceramics Terra Sigillata analyzed by means of laser-induced breakdown spectroscopy (LIBS). In order to automate and facilitate the task of comparison of LIBS spectra, two ANN algorithms are proposed: One is fed with the whole LIBS spectra and the other with the areas of the most intense peaks of the spectra. In both cases, an analysis of the network architecture as a function of the number of hidden neurons and number of epochs of training was carried out in order to optimize the performance of the network. Following both procedures, the correct classification (higher than the 95% of success) of Terra Sigillata pieces from their LIBS spectra can be achieved in a systematic and objective way.

Application of artificial neural networks for the rapid classification of archaeological ceramics by means of laser induced breakdown spectroscopy (LIBS)

Alberto Ramil

Papers

Application of artificial neural networks for the rapid classification of archaeological ceramics by means of laser induced breakdown spectroscopy (LIBS)

Effectiveness of granite cleaning procedures in cultural heritage: A review.

Nd:YVO4 laser removal of graffiti from granite. Influence of paint and rock properties on cleaning efficacy

Effectiveness and harmfulness evaluation of graffiti cleaning by mechanical, chemical and laser procedures on granite

Modelling of temperature evolution on metals during laser hardening process