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Changes in Cell Viability of Wounded Fibroblasts following Laser Irradiation in Broad-Spectrum or Infrared LightEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusion. Wounded cells irradiated in IR light showed an undesirable thermal effect that was proportional to the duration of exposure. (Source: Laser Chemistry)
Source: Laser Chemistry - November 3, 2009 Category: Laser Surgery Source Type: journals

Effect of Potential, Temperature, and Fluoride Ions on the Repassivation Kinetics of Titanium in Phosphate Buffered Saline Solution with the Photon Rupture MethodEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The effect of the applied potentials, temperature, and F− ions on the localized repassivation kinetics of titanium was investigated by the photon rupture method, PRM, and electrochemical techniques in phosphate buffered saline solution. The log⁡ I versus log⁡ t plots after laser beam irradiation showed a rapid increase, then a decrease with a slope of about −1.5, which is steeper than that expected from high field oxide film formation theory, suggesting that the repassivation of titanium is a combination of electrochemical and chemical reactions. The repassivation current increas...
Source: Laser Chemistry - July 14, 2009 Category: Laser Surgery Source Type: journals

Development, Characterization, and Application of a Versatile Single Particle Detection Apparatus for Time-Integrated and Time-Resolved Fluorescence Measurements—Part I: Theoretical ConsiderationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Recent progress in aerosol science has resulted in more challenging demands in the design of new particle beam introduction systems. In this paper, the concept of a variable orifice aerodynamic lens system is presented and supported by the numerical simulation results. This novel particle beam inlet can serve as either a narrow band pass filter (a particle segregator) that only confines particles with a specific size or a broad band pass filter (a particle concentrator) that allows particles with a wide size range to be concentrated on the beam axis. Following a brief description of the inlet system, computational details ...
Source: Laser Chemistry - July 8, 2009 Category: Laser Surgery Source Type: journals

Development, Characterization, and Application of a Versatile Single Particle Detection Apparatus for Time-Integrated and Time-Resolved Fluorescence Measurements—Part II: Experimental EvaluationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper describes the experimental realization and characterization of a versatile single particle detection apparatus. The system utilizes a novel particle beam inlet that can serve as either an on-line particle concentrator (i.e., all diameters confined in a narrow beam) or as a segregator (i.e., selected diameters confined in a narrow beam) and can be operated in a high-speed mode as well as in a low-speed mode, thus allowing different interaction times between the particles and the laser beam. An aerodynamic sizing technique has been incorporated into the system to provide rapid, real-time, and high-resolution sizin...
Source: Laser Chemistry - July 8, 2009 Category: Laser Surgery Source Type: journals

Development, Characterization, and Application of a Versatile Single Particle Detection Apparatus for Time-Integrated and Time-Resolved Fluorescence Measurements—Part I: Theoretical ConsiderationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Recent progress in aerosol science has resulted in more challenging demands in the design of new particle beam introduction systems. In this paper, the concept of a variable orifice aerodynamic lens system is presented and supported by the numerical simulation results. This novel particle beam inlet can serve as either a narrow band pass filter (a particle segregator) that only confines particles with a specific size or a broad band pass filter (a particle concentrator) that allows particles with a wide size range to be concentrated on the beam axis. Following a brief description of the inlet system, computational details ...
Source: Laser Chemistry - June 28, 2009 Category: Laser Surgery Source Type: journals

Development, Characterization, and Application of a Versatile Single Particle Detection Apparatus for Time-Integrated and Time-Resolved Fluorescence Measurements—Part II: Experimental EvaluationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper describes the experimental realization and characterization of a versatile single particle detection apparatus. The system utilizes a novel particle beam inlet that can serve as either an on-line particle concentrator (i.e., all diameters confined in a narrow beam) or as a segregator (i.e., selected diameters confined in a narrow beam) and can be operated in a high-speed mode as well as in a low-speed mode, thus allowing different interaction times between the particles and the laser beam. An aerodynamic sizing technique has been incorporated into the system to provide rapid, real-time, and high-resolution sizin...
Source: Laser Chemistry - June 28, 2009 Category: Laser Surgery Source Type: journals

Development, Characterization, and Application of a Versatile Single Particle Detection Apparatus for Time-Integrated and Time-Resolved Fluorescence Measurements—Part 1: Theoretical ConsiderationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Recent progress in aerosol science has resulted in more challenging demands in the design of new particle beam introduction systems. In this paper, the concept of a variable orifice aerodynamic lens system is presented and supported by the numerical simulation results. This novel particle beam inlet can serve as either a narrow band pass filter (a particle segregator) that only confines particles with a specific size or a broad band pass filter (a particle concentrator) that allows particles with a wide size range to be concentrated on the beam axis. Following a brief description of the inlet system, computational details ...
Source: Laser Chemistry - June 25, 2009 Category: Laser Surgery Source Type: journals

Laser Cleaning Tests on Archaeological Copper Alloys Using an ND:YAG LaserEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Laser cleaning tests were performed on five archaeological copper alloy objects using a Q-switched Nd:YAG laser at 1064 nm. As a comparison, a section of each object was cleaned mechanically. Prior to cleaning, cross-sections were prepared to characterise the corrosion crust and help to locate the position of the original surface. Laser cleaning was not successful at removing burial deposits on two of the objects. For the other three objects, the laser removed most of the corrosion crust. This was not always satisfactory, as cleaning was sometimes accompanied by the loss of the original surface. In addition, laser-cleaned ...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Characterization of Laser-Generated Microparticles by Means of a Dust Monitor and SEM ImagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Nanosecond laser (1064 nm wavelength) cleaning of artificially soiled paper as a model sample simulating a real-world artwork was performed. During the cleaning process, the ejection of particles was monitored in situ by means of a dust monitor (8 size classes, ranging from 0.3 μm to >2 μm) and ex situ using a mini-cascade impactor (MKI, 5 stages). The cleaning result was analyzed by scanning electron microscopy (SEM) considering possible laser-induced damages to the substrate. Size distributions of emitted particles were measured depending on the processing parameters: laser fluence, F, and puls...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Assisted Interpretation of Laser-Induced Fluorescence Spectra of Egg-Based Binding Media Using Total Emission Fluorescence SpectroscopyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Laser-induced fluorescence (LIF) spectroscopy can provide nondestructive, qualitative analysis of protein-based binding media found in artworks. Fluorescence emissions from proteins in egg yolk and egg white are due to autofluorescent aromatic amino acids as well as other native and age-related fluorophores, but the potential of fluorescence spectroscopy for the differentiation between binding media is dependent on the choice of a suitable excitation wavelength and limited by problems in interpretation. However, a better understanding of emission spectra associated with LIF can be achieved following comparisons with total ...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Remote Multicolor Excitation Laser-Induced Fluorescence ImagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Remote laser-induced fluorescence of stone materials was performed with application towards cultural heritage. Fluorescence was induced in targets ∼60 m from a mobile lidar laboratory by ultraviolet laser light, either from a frequency-tripled Nd:YAG laser or from an optical parametric oscillator system. Analysis was performed on combined spectra from the different excitation wavelengths and it was noted that important additional information can be gained when using several excitation wavelengths. (Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Observation of the Laser Cleaning Effect on the Gotland Sandstone Elemental CompositionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Changes of the elemental composition due to laser surface cleaning of a naturally crusted historical sandstone were investigated by means of the SEM/EDX technique. Data obtained for stone samples prior to and after laser irradiation were compared with those for noncrusted, reference ones. It has been observed that the crust removal resulting from ablative cleaning was accompanied by a decrease of the partial content of elements Al, S, K, Ca, and Mg in the range of 60–80% of their initial value recorded for the noncleaned, crust-covered stone surface. In the stone layer just under the crust coverage, a structur...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Laser Cleaning of Easel Paintings: An OverviewEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The application of laser cleaning to paintings is relatively recent despite its use on stone-based materials for over 30 years. The cleaning of paintings is of high importance, because it is the least reversible invasive intervention, as well as the most usual of all conservation treatments. Paintings are multilayer system of heterogeneous nature, often very sensitive and inherent difficult to clean. Being a noncontact method, laser cleaning has advantages compared to alternative techniques. Over the last decade, there have been important research studies and advances. However, they are far from sufficient to study the eff...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Varnish Ablation Control by Optical Coherence TomographyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT) to the control of a varnish ablation process, are presented. Examination of the ablation craters made with an Er:YAG laser allows optimization of the laser emission parameters controlling fluence with respect to efficiency and safety of the ablation process. Results of measurements of ablation crater depth as a function of the number of pulses for a given fluence are presented for selected resins. This validates the applicability of SOCT to calibration of ablation conditions for the particular laser-varni...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Optical Coherence Tomography for Tracking Canvas DeformationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT), to tracking of deformations in paintings on canvas caused by periodical humidity changes are presented. The setup is able to monitor the position of a chosen point at the surface of a painting with micrometre precision, simultaneously in three dimensions, every 100 seconds. This allows recording of deformations associated with crack formation. For the particular painting model examined, it was shown that the surface moves in-plane towards the corner, and bulges outwards (Z-direction) in response to a ris...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Optical Coherence Tomography for Examination of Parchment DegradationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A novel application of Optical Coherence Tomography utilizing infrared light of 830 nm central wavelength for non invasive examination of the structure of parchment, some covered with iron gall ink, is presented. It is shown that both the parchment and the ink applied are sufficiently transparent to light of this wavelength. In the study, Spectral OCT (SOCT) as well as Polarisation Sensitive OCT (PS-OCT) techniques were used to obtain cross-sectional images of samples of parchment based on scattering properties. The second technique was additionally employed to recover the birefringence properties and the optical axis orie...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Preliminary Laser Cleaning Studies of a Consolidated Prehistoric Basketry Coming from the Pile Building of Fiavè-Carera in the North-East of ItalyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the archaeological field, some specific advantages are recognized to laser cleaning, like, for example, the absence of mechanical contacts with the sample. The cleaning procedures generally involve a multilayer structure (dust, dirty, organic deposits, and, in some cases, consolidant substances). In this work, prehistoric wood samples (found and consolidated in 1970s) have been laser irradiated (KrF excimer laser) in order to restore their original surface aspect. A certain amount of burned matter was also present. Samples came from a fragment of a prehistoric basketry found in the lake dwelling site of Fiavè-Care...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Optical Coherence Tomography for Artwork DiagnosticsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
An overview of the optical coherence tomography (OCT) technique is given. Time domain, spectral and sweep source modalities are briefly described, and important physical parameters of the OCT instrument are discussed. Examples of the application of OCT to diagnosis of various art objects such as oil paintings on canvas (imaging of glaze and varnish layers), porcelain, faience, and parchment are presented. Applications to surface profilometry of painting on canvas are also discussed. (Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

A Comprehensive Study for the Laser Cleaning of Corrosion Layers due to Environmental Pollution for Metal Objects of Cultural Value: Preliminary Studies on Artificially Corroded CouponsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper is focused on the systematic investigation of the layer-by-layer removal of corrosion products on artificially corroded metal coupons aiming to introduce a methodology for the optimum laser cleaning approach of historical metal objects. Thus, it is very important to determine the chemical composition of the studied surfaces before and after irradiation. A series of laser cleaning studies has been performed on test coupons (reference and artificially corroded). Wavelength and pulse duration effects are investigated. Initial studies were focused on the use of infrared (1064 nm) and ultraviolet (355 nm and 248 nm...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Lasers in the Preservation of Cultural HeritageEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Characterization of Stone Cleaning by Nd:YAG Lasers with Different Pulse DurationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The present work is a comparative study on the laser cleaning of stonework using Nd:YAG lasers at different pulse durations. The ablation rate, the degree of cleaning, and the appearance of the treated surface were studied irradiating a simulated sample and a real stone artefact using three different Nd:YAG laser systems with pulse duration of 90 microseconds, 15 nanoseconds, and 150 picoseconds. To our knowledge, the picosecond laser is here used for the first time in stone conservation. Differences in efficiency and in cleaning result are shown and discussed. (Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Multianalytical Study of Laser Pulse Duration Effects in the IR Laser Cleaning of Wall Paintings from the Monumental Cemetery of PisaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The feasibility of laser cleaning for the removal of a variety of surface deposits from fragments of real wall paintings from the monumental cemetery of Pisa using Nd:YAG at 1064 nm at (μs), (ns), and (ps) regimes is presented. Multianalytical investigations of the samples from irradiated surfaces of fragments were carried out in order to characterize the original and added materials and to detect any laser-induced alterations; analysis included scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), laser-induced breakdown spectroscopy (LIBS), pyrolysis-gas chromatography-mass spectromet...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Photostability of Uranine via Crossed-Beam Thermal Lens TechniqueEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Uranine is a diagnostic aid in ophthalmology and is used as an immunohistological stain. A photostability study on this important compound using a crossed-beam thermal lens (TL) technique was carried out. The study is based on the photodegradation (PD) behavior and rate regarding some experimental parameters such as the incident laser power, wavelength, modulation frequency, and sample concentration. The effects of such parameters on the TL signal and PD rate are discussed in details. It has been found that the PD rate is proportional to the power of the pumping laser and the concentration of the sample within the investig...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

How Should an Increase in Alkaline Phosphatase Activity Be Interpreted?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusion: since the exact role of ALP is unknown, the ALP enzyme activity assay should be considered in conjunction with other cell proliferation assays such as neutral red, optical density, or more specifically bFGF expression. (Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Cellular Damage in Diabetic Wounded Fibroblast Cells following Phototherapy at 632.8, 830, and 1064 nmEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusion. This study showed that the comet assay and LDH release were sensitive enough to pick up changes in laser-irradiated cells. This study also showed that cellular and genetic damage inflicted on diabetic wounded cells was dependent on dose and wavelength and that cells are able to recover and respond. (Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Induced Bragg Gratings in Optical Fibers and Waveguides Using an Ultrafast Infrared Laser and a Phase MaskEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Since its development in 2003, the technique of Bragg grating inscription in optical fibers and waveguides with ultrafast infrared radiation and a phase mask has proven to be as simple as the standard UV-laser grating writing techniques but far more versatile. The ultrafast IR laser-based process allows for the creation of grating structures in glassy and crystalline materials that are not typically UV photosensitive. In this article, we will review the studies that have been performed at the Communications Research Centre Canada on the grating formation processes as well as applications of the ultrafast laser technique to...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Ultrafast Four-Wave Optical Parametric Amplification in Transparent Condensed Bulk MediaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present a short overview of recent advances in ultrashort pulse four-wave optical parametric amplification in transparent condensed bulk media with Kerr nonlinearity. Highly efficient (10% to 15% pump-to-signal energy conversion) four-wave optical parametric amplification in water and fused silica is experimentally demonstrated. The amplification process highly benefits from 1-dimensional spatial soliton propagation regime, which sets in under proper combination of cylindrical beam focusing and noncollinear phase matching geometry with millijoule pumping. Under these operating conditions, strong four-wave coupli...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Physical and Spectroscopic Properties of Yb3+-Doped Fluorophosphate Laser GlassesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The physical properties including refractive index, Abbe number, nonlinear refractive index, microhardness and thermal expansion coefficient, and spectroscopic properties of Yb3+-doped fluorophosphate laser glasses were investigated. The results show that due to the addition of fluoride, mechanical and thermal properties are promoted, emission cross-section σemi is also greatly enhanced. The largest gain coefficient σemi·τm (0.824 pm2·ms) can be obtained with the minimum pump intensity Imin (1.112 kw/cm2). This kind of Yb3+-doped fluorophosphate glass is an excellent candida...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Three-Dimensional Residue-Free Volume Removal inside Sapphire by High-Temperature Etching after Irradiation of Femtosecond Laser PulsesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We applied the femtosecond laser-assisted etching technique, that is, irradiation of focused femtosecond laser pulses followed by selective chemical etching, to volume removal inside sapphire. At room temperature, volume etching only slightly advanced while residue remained inside the volume. By increasing the etching temperature, complete volume etching without residue was achieved. Complete etching was, however, accompanied by undesirable phenomena of surface pits or cracks, which are expected to be excluded through further improvement of processing. (Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Processing of Dielectric Optical Coatings by Nanosecond and Femtosecond UV Laser AblationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Microprocessing of dielectric optical coatings by UV laser ablation is demonstrated. Excimer laser ablation at deep UV wavelengths (248 nm, 193 nm) is used for the patterning of thin oxide films or layer stacks. The layer removal over extended areas as well as sub-μm-structuring is possible. The ablation of SiO2, Al2O3, HfO2, and Ta2O5 layers and layer systems has been investigated. Due to their optical, chemical, and thermal stability, these inorganic film materials are well suited for optical applications, even if UV-transparency is required. Transparent patterned films of SiO2 are produced by patter...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Two-Photon Polymerization of Hybrid Sol-Gel Materials for Photonics ApplicationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present our investigations into the structuring by two-photon polymerization of a new class of photosensitive sol-gel composites exhibiting ultra-low shrinkage. We particularly focus on two composites, the first containing a zirconium alkoxide and the second a nonlinear optical chromophore. The three-dimensional photonic crystal structures fabricated using these materials demonstrate high resolution and clear bandstops in the near IR region. (Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Three-Dimensional Modeling of the Heat-Affected Zone in Laser Machining ApplicationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Thermal load as well as its three-dimensional (3D) spatial distribution has been estimated inside representative materials: glass (low thermal diffusion), silicon (semimetal properties), and sapphire (a crystalline dielectric of a high thermal conductivity) for typical laser processing and direct laser writing applications. The 3D temperature distribution allows to calculate thermal stress around the focal region. This provides an assessment tool for optimization of laser microprocessing conditions for controlled laser dicing and cutting applications. (Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Laser-Induced Backside Wet Etching of Transparent Materials with Organic and Metallic AbsorbersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Laser-induced backside wet etching (LIBWE) allows the high-quality etching of transparent materials for micro- and nanopatterning. Recent own results of LIBWE with hydrocarbon and metallic absorbers (H- and M-LIBWE) are summarized and compared with selected results of other groups regarding the etching process and the etched surface. Significant results on the impact of the liquid absorber, the material and the wavelength, and the pulse length of the laser to the etching are selected for this comparison. The etching of submicron-sized periodic structures in sapphire and fused silica with interference techniques and the sel...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Photosensitivity of the Er/Yb-Codoped Schott IOG1 Phosphate Glass Using 248 nm, Femtosecond, and Picosecond Laser RadiationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The effect of 248 nm laser radiation, with pulse duration of 5 picoseconds, 500 femtoseconds, and 120 femtoseconds, on the optical properties and the Knoop hardness of a commercial Er/Yb-codoped phosphate glass is presented here. Refractive index changes of the order of few parts of 10-4 are correlated with optical absorption centers induced in the glass volume, using Kramers-Kroning relationship. Accordingly, substantially lower refractive index changes are measured in volume Bragg gratings inscribed in the glass, indicating that, in addition to the optical density changes, volume dilation changes of nega...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Gratings in Structured Optical FibresEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Grating writing in structured optical fibres and their properties and applications are reviewed. To date, most gratings have been written in a straightforward manner into structured fibres containing a photosensitive germanosilicate step-index core. However, gratings have also been written directly into single material, structured silica fibres and into air-clad cores using two and higher-photon processes with both UV and near IR pulsed (nanosecond-femtosecond) light. Given the intrinsic-added functionality possible within a structured optical fibre, structured fibre gratings offer further capabilities for sensors, diagno...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Chemical and Physical Changes Induced in Optical Materials under High-Intensity Laser IrradiationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Laser Chemistry)
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Laser-Induced Photon-Branched Chain Reaction in a Chemically-Active Gas-Dispersed MediumEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A promising avenue in the development of high-energy pulsed chemical HF/DF lasers and amplifiers is the utilization of a photon-branched chain reaction initiated in a two-phase active medium, that is, a medium containing a laser working gas and ultradispersed passivated metal particles. These particles are evaporated under the action of IR laser radiation which results in the appearance of free atoms, their diffusion into the gas, and the development of a photon-branching chain process, which involves photons as both reactants and products. The key obstacle here is the formation of ...
Source: Laser Chemistry - June 10, 2009 Category: Laser Surgery Source Type: journals

Automatic Identification of Artistic Pigments by Raman Spectroscopy Using Fuzzy Logic and Principal Component AnalysisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This work offers an automatic identification system of Raman spectra of artistic pigments. The proposed methodology is based on a fuzzy logic system, and uses principal component analysis to reduce redundancies in data and the correlation operator as an index of similarity between two Raman spectra. Moreover, as sometimes pigments are used in mixtures by artist, the designed system is able to recognize binary mixtures of pigments on the basis of their Raman fingerprints. (Source: Laser Chemistry)
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Laser Cleaning Tests on Archaeological Copper Alloys Using an ND:YAG LaserEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Laser cleaning tests were performed on five archaeological copper alloy objects using a Q-switched Nd:YAG laser at 1064 nm. As a comparison, a section of each object was cleaned mechanically. Prior to cleaning, cross-sections were prepared to characterise the corrosion crust and help to locate the position of the original surface. Laser cleaning was not successful at removing burial deposits on two of the objects. For the other three objects, the laser removed most of the corrosion crust. This was not always satisfactory, as cleaning was sometimes accompanied by the loss of the original surface. In addition, laser-cleaned ...
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Characterization of Laser-Generated Microparticles by Means of a Dust Monitor and SEM ImagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Nanosecond laser (1064 nm wavelength) cleaning of artificially soiled paper as a model sample simulating a real-world artwork was performed. During the cleaning process, the ejection of particles was monitored in situ by means of a dust monitor (8 size classes, ranging from 0.3 μm to >2 μm) and ex situ using a mini-cascade impactor (MKI, 5 stages). The cleaning result was analyzed by scanning electron microscopy (SEM) considering possible laser-induced damages to the substrate. Size distributions of emitted particles were measured depending on the processing parameters: laser fluence, F, and puls...
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Assisted Interpretation of Laser-Induced Fluorescence Spectra of Egg-Based Binding Media Using Total Emission Fluorescence SpectroscopyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Laser-induced fluorescence (LIF) spectroscopy can provide nondestructive, qualitative analysis of protein-based binding media found in artworks. Fluorescence emissions from proteins in egg yolk and egg white are due to autofluorescent aromatic amino acids as well as other native and age-related fluorophores, but the potential of fluorescence spectroscopy for the differentiation between binding media is dependent on the choice of a suitable excitation wavelength and limited by problems in interpretation. However, a better understanding of emission spectra associated with LIF can be achieved following comparisons with total ...
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Observation of the Laser Cleaning Effect on the Gotland Sandstone Elemental CompositionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Changes of the elemental composition due to laser surface cleaning of a naturally crusted historical sandstone were investigated by means of the SEM/EDX technique. Data obtained for stone samples prior to and after laser irradiation were compared with those for noncrusted, reference ones. It has been observed that the crust removal resulting from ablative cleaning was accompanied by a decrease of the partial content of elements Al, S, K, Ca, and Mg in the range of 60–80% of their initial value recorded for the noncleaned, crust-covered stone surface. In the stone layer just under the crust coverage, a structur...
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Remote Multicolor Excitation Laser-Induced Fluorescence ImagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Remote laser-induced fluorescence of stone materials was performed with application towards cultural heritage. Fluorescence was induced in targets ∼60 m from a mobile lidar laboratory by ultraviolet laser light, either from a frequency-tripled Nd:YAG laser or from an optical parametric oscillator system. Analysis was performed on combined spectra from the different excitation wavelengths and it was noted that important additional information can be gained when using several excitation wavelengths. (Source: Laser Chemistry)
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Laser Cleaning of Easel Paintings: An OverviewEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The application of laser cleaning to paintings is relatively recent despite its use on stone-based materials for over 30 years. The cleaning of paintings is of high importance, because it is the least reversible invasive intervention, as well as the most usual of all conservation treatments. Paintings are multilayer system of heterogeneous nature, often very sensitive and inherent difficult to clean. Being a noncontact method, laser cleaning has advantages compared to alternative techniques. Over the last decade, there have been important research studies and advances. However, they are far from sufficient to study the eff...
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Varnish Ablation Control by Optical Coherence TomographyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT) to the control of a varnish ablation process, are presented. Examination of the ablation craters made with an Er:YAG laser allows optimization of the laser emission parameters controlling fluence with respect to efficiency and safety of the ablation process. Results of measurements of ablation crater depth as a function of the number of pulses for a given fluence are presented for selected resins. This validates the applicability of SOCT to calibration of ablation conditions for the particular laser-varni...
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Optical Coherence Tomography for Tracking Canvas DeformationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT), to tracking of deformations in paintings on canvas caused by periodical humidity changes are presented. The setup is able to monitor the position of a chosen point at the surface of a painting with micrometre precision, simultaneously in three dimensions, every 100 seconds. This allows recording of deformations associated with crack formation. For the particular painting model examined, it was shown that the surface moves in-plane towards the corner, and bulges outwards (Z-direction) in response to a ris...
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Optical Coherence Tomography for Examination of Parchment DegradationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A novel application of Optical Coherence Tomography utilizing infrared light of 830 nm central wavelength for non invasive examination of the structure of parchment, some covered with iron gall ink, is presented. It is shown that both the parchment and the ink applied are sufficiently transparent to light of this wavelength. In the study, Spectral OCT (SOCT) as well as Polarisation Sensitive OCT (PS-OCT) techniques were used to obtain cross-sectional images of samples of parchment based on scattering properties. The second technique was additionally employed to recover the birefringence properties and the optical axis orie...
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Preliminary Laser Cleaning Studies of a Consolidated Prehistoric Basketry Coming from the Pile Building of Fiavè-Carera in the North-East of ItalyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the archaeological field, some specific advantages are recognized to laser cleaning, like, for example, the absence of mechanical contacts with the sample. The cleaning procedures generally involve a multilayer structure (dust, dirty, organic deposits, and, in some cases, consolidant substances). In this work, prehistoric wood samples (found and consolidated in 1970s) have been laser irradiated (KrF excimer laser) in order to restore their original surface aspect. A certain amount of burned matter was also present. Samples came from a fragment of a prehistoric basketry found in the lake dwelling site of Fiavè-Care...
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals

Optical Coherence Tomography for Artwork DiagnosticsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
An overview of the optical coherence tomography (OCT) technique is given. Time domain, spectral and sweep source modalities are briefly described, and important physical parameters of the OCT instrument are discussed. Examples of the application of OCT to diagnosis of various art objects such as oil paintings on canvas (imaging of glaze and varnish layers), porcelain, faience, and parchment are presented. Applications to surface profilometry of painting on canvas are also discussed. (Source: Laser Chemistry)
Source: Laser Chemistry - January 21, 2009 Category: Laser Surgery Source Type: journals