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Your search keyword '"TSEREVELAKIS, GEORGE J."' showing total 148 results
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148 results on '"TSEREVELAKIS, GEORGE J."'

5. Non-Invasive Optoacoustic Imaging for In-Depth Cultural Heritage Diagnostics.

Author

Tserevelakis, George J., Pirgianaki, Eleanna, Melessanaki, Kristalia, Zacharakis, Giannis, and Fotakis, Costas

Subjects
LIGHT absorption, CULTURAL property, ART materials, LIGHT scattering, ACOUSTIC imaging
Abstract

The complex composition of cultural heritage (CH) items presents significant challenges in assessing their condition and predicting potential risks of material degradation. Typically employed diagnostic optical methods are inevitably limited by light scattering, thus restricting in-depth investigations of objects with complex structural and optical properties. To address this issue, we introduce a novel reflection-mode optoacoustic (OA) diagnostic system for non-contact and non-invasive measurements of CH, placing emphasis on the detection of ageing-related modifications in artistic media such as paints. In this direction, the sensitivity of OA measurements was proven to be up to two orders of magnitude higher than conventional absorption spectroscopy assessments. Furthermore, we have evaluated the in-depth imaging capabilities of the developed OA system, demonstrating that it can offer superior contrast levels of sketches beneath opaque paint layers compared to standard near-infrared diagnostic techniques. The current OA imaging technology may advance state-of-the-art diagnostic capabilities in CH preservation by delivering unprecedented depth-to-resolution ratios combined with exceptional optical absorption sensitivity in a non-invasive manner. These features are crucial for the early detection of material degradation and the comprehensive analysis of CH objects, facilitating the development of optimal conservation strategies to prolong their lifespan and preserve their aesthetic value. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Development of a hybrid photoacoustic and optical monitoring system for the study of laser ablation processes upon the removal of encrustation from stonework

Author

Papanikolaou Athanasia, Tserevelakis George J., Melessanaki Kristalia, Fotakis Costas, Zacharakis Giannis, and Pouli Paraskevi

Subjects
photoacoustic monitoring, laser cleaning, encrusted marble, real time monitoring, two-wavelengths cleaning, Optics. Light, QC350-467
Abstract

In the context of this work, a prototype hybrid photoacoustic (PA) and optical system for the on-line monitoring of laser cleaning procedures is presented. The developed apparatus has enabled the detection of MHz frequency range acoustic waves generated during the laser ablation process. The intrinsically generated PA signals combined with high resolution optical images provide the opportunity to follow the cleaning process accurately and in real time. Technical mock-ups have been used to demonstrate the potential of this novel technique with emphasis given to applications that refer to the restoration of Cultural Heritage (CH) surfaces. Towards this purpose, the real time monitoring of the laser assisted removal of unwanted encrustation from stonework has been achieved using IR and UV wavelengths. This novel approach has allowed for the precise determination of the critical number of laser pulses required for the elimination of the encrustation layer, while highlighting the dominant ablation mechanisms according to the irradiation wavelength. The promising results obtained using the prototype hybrid PA and optical system can open up new perspectives in the monitoring of laser cleaning interventions, promoting an improved restoration outcome.

Published
2020
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33. Towards affordable biomedical imaging: Recent advances in low‐cost, high‐resolution optoacoustic microscopy.

Author

Kalitsounakis, Pavlos, Zacharakis, Giannis, and Tserevelakis, George J.

Subjects
*SEMICONDUCTOR lasers, *OXYGEN saturation, *SPEED measurements, *MICROSCOPY, *FLOW measurement, *MULTISPECTRAL imaging
Abstract

This short review discusses the recent developments in low‐cost, high‐resolution optoacoustic microscopy systems, integrating laser diodes for signal excitation, which are 20–40 times cheaper than the typically employed Q‐switched nanosecond laser sources. The development of laser diode‐based microscopes can substantially improve not only cost efficiency, but also multispectral capabilities, robustness, portability and overall imaging performance of the optoacoustic technique. To this end, we demonstrate relevant implementations in both time and frequency domain, highlighting their representative applications in biomedical research such as microvasculature imaging, oxygen saturation assessments, hybrid and multiview microscopy of model organisms and tissues and Doppler flow speed measurements. Finally, we analyse the benefits and limitations of each approach, identifying the respective application contexts where they achieve optimum performance. [ABSTRACT FROM AUTHOR]

Published
2024
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