In this paper, we present research carried out in our laboratory in the field of applications of high power lasers in cleaning surfaces. More specifically, overviews of three different applications are presented; the use of lasers in the... more
In this paper, we present research carried out in our laboratory in the field of applications of high power lasers in cleaning surfaces. More specifically, overviews of three different applications are presented; the use of lasers in the cleaning of marble antiquities, in the restoration and cleaning of painted artworks nad in the repair of the paint of ship hulls.
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MTh5C.3.pdf POEM/MP3 (LTST) Technical Digest © OSA 2012 ... Direct fs Laser Writing: Principles and Applications ... I. Sakellari,1 E. Kabouraki,1 K. Terzaki,1 D. Gray,1 C. Fotakis,1 A. Pikulin,2 N. Bityurin,2 M. Vamvakaki,1 and M.... more
MTh5C.3.pdf POEM/MP3 (LTST) Technical Digest © OSA 2012 ... Direct fs Laser Writing: Principles and Applications ... I. Sakellari,1 E. Kabouraki,1 K. Terzaki,1 D. Gray,1 C. Fotakis,1 A. Pikulin,2 N. Bityurin,2 M. Vamvakaki,1 and M. Farsari1,* 1IESL-FORTH, N. Plastira 100, 70013, Heraklion, Crete, Greece 2Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia *mfarsari@iesl.forth.gr ... Abstract: We present our most recent work on Direct fs Laser Writing and its applications in Photonics, Metamaterials ...
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Temporally shaped, femtosecond laser pulses have been used for controlling the size and the morphology of micron-sized metallic structures obtained by using the Laser Induced Forward Transfer (LIFT) technique. We report the effect of... more
Temporally shaped, femtosecond laser pulses have been used for controlling the size and the morphology of micron-sized metallic structures obtained by using the Laser Induced Forward Transfer (LIFT) technique. We report the effect of pulse shaping on the size and morphology of the deposited structures of Au, Zn, Cr on a function of the pulse separation time ??t (from 0 to 10 ps) of double pulses of variable intensities generated by using a liquid crystal spatial light modulator (SLM). The observed differences in size and morphology are correlated with the outcome of pump-probe experiments for the study of electron-phonon scattering dynamics and subsequent energy transfer processes to the bulk in the different metals employed. We propose that in metals with weak electron-lattice coupling, the electron ballistic motion and the resulting fast electron scattering at the film surface, as well as the internal electron thermalization process are crucial to the morphology and size of the transferred material. Therefore, temporal shaping within the corresponding time scales of these processes may be used for tailoring the features of the metallic structures obtained by LIFT.
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Two-photon polymerisation of photosensitive materials has emerged as a very promising technique for the fabrication of photonic crystals and devices. In this paper we present our investigations into the structuring by two-photon... more
Two-photon polymerisation of photosensitive materials has emerged as a very promising technique for the fabrication of photonic crystals and devices. In this paper we present our investigations into the structuring by two-photon polymerisation 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 molecule. The three-dimensional photonic crystal structures fabricated using these ...
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The laser cleaning of painted artefacts relies on the synergy of thermal, photochemical and photomechanical effects, which are involved in laser ablation. A crucial issue, however, for a successful cleaning intervention is the spatial... more
The laser cleaning of painted artefacts relies on the synergy of thermal, photochemical and photomechanical effects, which are involved in laser ablation. A crucial issue, however, for a successful cleaning intervention is the spatial confinement and control of these effects for ...
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... interferometry in conservation; 3. Controlled laser cleaning; 4. An integrated approach; 4.1 ... based techniques have been investigated in a variety of artwork conservation applications ... on a close collaboration between... more
... interferometry in conservation; 3. Controlled laser cleaning; 4. An integrated approach; 4.1 ... based techniques have been investigated in a variety of artwork conservation applications ... on a close collaboration between conservators and laser scientists for a systematic investigation of ...
Research Interests: Computer Science, Process Control, Art Conservation, Structural Integrity, Holographic Interferometry, and 11 moreNondestructive testing, Laser Cleaning, Laser Ablation, Structure Analysis, Structural Change, Optical physics, Optics and lasers, Laser Induced Breakdown Spectroscopy, Materials Processing, Long Term Effect, and Optics and Lasers In Engineering
Research Interests: Materials Science, Polymer Chemistry, Photochemistry, Medicine, Multidisciplinary, and 15 morePolymerization, Mice, Animals, Light, Emulsion polymerisation, Photons, Ketone, Langmuir, Cell Proliferation, Biocompatible Materials, Equipment Design, Copolymer, Ethylene Glycol, Caprolactone, and Benzophenone
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ABSTRACT
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AlN thin films with a thickness in the nanometer range were prepared by pulsed laser deposition technique. We investigated the effect of laser wavelength, pulse duration, and ambient gas pressure on the composition and morphology of the... more
AlN thin films with a thickness in the nanometer range were prepared by pulsed laser deposition technique. We investigated the effect of laser wavelength, pulse duration, and ambient gas pressure on the composition and morphology of the deposited films. In all experiments we used AlN targets. We worked with three laser sources generating pulses of 34 ns@ 248 nm (source A), 450 fs@ 248 nm (source B), and 50 fs@ 800 nm (source C). XRD, SEM, and profilometric measurements were performed on the obtained AlN thin ...
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The elucidation of the molecular mechanisms that lead to the development of metabolic syndrome, a complex of pathological conditions including type-2 diabetes, hypertension, and cardiovascular diseases, is an important issue with high... more
The elucidation of the molecular mechanisms that lead to the development of metabolic syndrome, a complex of pathological conditions including type-2 diabetes, hypertension, and cardiovascular diseases, is an important issue with high biological significance and requires accurate methods capable of monitoring lipid storage distribution and dynamics in vivo. In this study, the nonlinear phenomena of second and third harmonic generation (SHG, THG) have been employed simultaneously as label-free, nondestructive diagnostic techniques, for the monitoring and the complementary three-dimensional (3D) imaging and analysis of the muscular areas and the lipid content localization. THG microscopy was used as a quantitative tool in order to record the accumulation of lipids in nonadipose tissues in the pharyngeal muscles of 18 Caenorhabditis elegans (C. elegans) specimens, while the SHG imaging provided the detailed anatomical information about the structure of the muscles. The ectopic accumula...
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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... more
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.
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We present an appropriate methodology and results for using third-harmonic generation (THG) modality for nondestructive high resolution imaging measurements of varnished structures in model painted artifacts. Detection takes place in the... more
We present an appropriate methodology and results for using third-harmonic generation (THG) modality for nondestructive high resolution imaging measurements of varnished structures in model painted artifacts. Detection takes place in the reflection mode, demonstrating the ability of the technique to be applied to the evaluation of original artworks. Furthermore, multi-photon excitation fluorescence images were obtained, providing complementary information related to the identification of the chemical composition of the artifacts.
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Research Interests: Condensed Matter Physics, Materials Science, Analytical Chemistry, Cultural Heritage Conservation, Fluorescence, and 10 moreFemtosecond Laser, Confocal Microscopy, Raman microscopy, Layered Structure, Diode Laser, Spatial resolution, Raman Spectra, Lamellar Structure, Third Harmonic Generation, and Linseed Oil
Research Interests: Materials Engineering, Condensed Matter Physics, Image Processing, Caenorhabditis elegans, Microscopy, and 14 moreImaging, Nondestructive testing, Cell morphology, Animals, Three Dimensional Imaging, 3-D Reconstruction, SHG, In Vivo Imaging, Degeneration, Three Dimensional, Interdisciplinary Engineering, Third Harmonic Generation, Micron, and Diagnostic Tool
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We present our research into the fabrication of fully three-dimensional metallic nanostructures using diffusion-assisted direct laser writing, a technique which employs quencher diffusion to fabricate structures with resolution beyond the... more
We present our research into the fabrication of fully three-dimensional metallic nanostructures using diffusion-assisted direct laser writing, a technique which employs quencher diffusion to fabricate structures with resolution beyond the diffraction limit. We have made dielectric 3D nanostructures by multiphoton polymerization using a metal-binding organic-inorganic hybrid material, and we covered them with silver using selective electroless plating. We have used this method to make spirals and woodpiles with 600 nm ...
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Control over the wettability of solids and manufacturing of functional surfaces with special hydrophobic and self-cleaning properties has aroused great interest because of its significance for a vast range of applications in daily life,... more
Control over the wettability of solids and manufacturing of functional surfaces with special hydrophobic and self-cleaning properties has aroused great interest because of its significance for a vast range of applications in daily life, industry and agriculture. We report here a simple method for preparing stable superhydrophobic surfaces by irradiating silicon (Si) wafers with femtosecond (fs) laser pulses and subsequently coating them with chloroalkylsilane monolayers. It is possible, by varying the laser pulse fluence on the ...
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ABSTRACT Sequential double exposure holographic interferometry is employed for examining the mechanical effects induced in the UV ablation of polymers. Deformations, evidenced by changes in the refractive index of the substrate, are... more
ABSTRACT Sequential double exposure holographic interferometry is employed for examining the mechanical effects induced in the UV ablation of polymers. Deformations, evidenced by changes in the refractive index of the substrate, are observed to develop at unexpectedly long distances (approximately equals 2 - 5 cm) from the irradiation area. The morphology of the induced effects depends on the substrate properties, with the major types observed being tentatively ascribed to delaminations and local fractures. For accounting for the highly delocalized spatial spread of the effects, laser doppler vibrometry was used for monitoring the propagation of the stresses generated by the ablation process. The examination confirms the development of intense vibrations far from the ablation point. The present results suggest that in UV laser processing of molecular substrates, the photomechanical effects can be significant and special attention should be paid in their characterization and their minimization.
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In this work, non-destructive techniques were employed for the spectrofluorimetric and micro-Raman differentiation of solid films of egg yolk and egg white as a function of exposure to light. Using both techniques it is possible to... more
In this work, non-destructive techniques were employed for the spectrofluorimetric and micro-Raman differentiation of solid films of egg yolk and egg white as a function of exposure to light. Using both techniques it is possible to discriminate between the samples on the basis of composition and follow some chemical changes involved during the light-ageing of egg proteins and fatty acid esters. In egg white, fluorescence emission spectra highlighted the presence of multiple fluorophores, with an effective broadening of the fluorescence emissions following light exposure, ascribed to the partial oxidation and depletion of tryptophan; in the Raman spectrum of dark-aged egg white a peak at 758 cm−1 is ascribed to the vibrational mode of tryptophan, which is completely absent in the spectrum of samples exposed to light. Changes in the fluorescence of egg yolk following exposure to light are ascribed to the degradation of amino acids, cross-linking between amino acids and the formation o...
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The non-destructive determination of layer structures in works of art remains a significant challenge. Non-linear microscopy and confocal Raman microscopy (CRM) were employed for characterisation of varnish-media layers in model samples,... more
The non-destructive determination of layer structures in works of art remains a significant challenge. Non-linear microscopy and confocal Raman microscopy (CRM) were employed for characterisation of varnish-media layers in model samples, providing important information regarding the thickness of materials and the identification of different media in depth. Commonly found triterpenoid varnishes mastic and dammar were applied over a single layer of films of linseed oil. Non-linear microscopy of samples was carried out using a 1028-nm femtosecond laser source; both third-harmonic generation signals (THG) and three-photon fluorescence signals (3PEF) of samples were collected in an effort to measure the thickness of mono- and bi-layers; in parallel scans of larger areas were undertaken to assess heterogeneities in samples with spatial resolution of ∼2 μm. Complementary spectroscopic information from CRM collected with both a 514.5-nm argon-ion and a 785-nm diode lasers coupled with a 100X objective and a motorised stage was carried out. Comparison of C–H stretching regions of Raman spectra allowed the differentiation between different molecular materials and the fingerprint region was employed for the depth profiling of the samples.
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The elucidation of the molecular mechanisms that lead to the development of metabolic syndrome, a complex of pathological conditions including type-2 diabetes, hypertension, and cardiovascular diseases, is an important issue with high... more
The elucidation of the molecular mechanisms that lead to the development of metabolic syndrome, a complex of pathological conditions including type-2 diabetes, hypertension, and cardiovascular diseases, is an important issue with high biological significance and requires accurate methods capable of monitoring lipid storage distribution and dynamics in vivo. In this study, the nonlinear phenomena of second and third harmonic generation (SHG, THG) have been employed simultaneously as label-free, nondestructive diagnostic techniques, for the monitoring and the complementary three-dimensional (3D) imaging and analysis of the muscular areas and the lipid content localization. THG microscopy was used as a quantitative tool in order to record the accumulation of lipids in nonadipose tissues in the pharyngeal muscles of 18 Caenorhabditis elegans (C. elegans) specimens, while the SHG imaging provided the detailed anatomical information about the structure of the muscles. The ectopic accumulation of fat on the pharyngeal muscles increases in wild-type (N2) C. elegans between 1 and 9 days of adulthood. This suggests a correlation of ectopic fat accumulation with the process of aging. Our results can contribute to the unraveling of the link between the deposition of ectopic fat and aging, but mainly to the validation of SHG and THG microscopy modalities as new, noninvasive tools to localize and quantify selectively lipid formation and distribution. Microsc. Res. Tech. 78:523–528, 2015. © 2015 Wiley Periodicals, Inc.
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The present work investigates the applicability of nonlinear imaging microscopy for the precise assessment of degradation of the outer protective layers of painted artworks as a function of depth due to aging. Two fresh and artificially... more
The present work investigates the applicability of nonlinear imaging microscopy for the precise assessment of degradation of the outer protective layers of painted artworks as a function of depth due to aging. Two fresh and artificially aged triterpenoid varnishes, dammar and mastic, were tested. Nonlinear imaging techniques have been employed as a new diagnostic tool for determination of the exact thickness of the affected region due to artificial aging of the natural varnishes. The measured thicknesses differ from the calculated mean penetration depths of the samples. These nondestructive, high resolution modalities are valuable analytical tools for aging studies and they have the potential to provide unique in-depth information. Single photon laser induced fluorescence measurements and Raman spectroscopy were used for the integrated investigation and analysis of aging effects in varnishes.