Dr. Giannis Zacharakis Profile

Dr. Giannis Zacharakis

at Foundation for Research and Technology-Hellas

SPIE Involvement:

Author

Publications (34)

Proceedings Article | 9 August 2023 Paper

A novel adaptive optics illumination device for in vivo imaging of fluorescently labeled specimens

Mikis Mylonakis, Evangelos Marakis, Athanasios Zacharopoulos, Maira Tampakaki, Joseph Papamatheakis, Dimitrios Papazoglou, Giannis Zacharakis

Proceedings Volume 12630, 1263008 (2023) https://doi.org/10.1117/12.2670906

KEYWORDS: Light sources and illumination, Microscopes, Spatial light modulators, Wavefronts, Optical components, Objectives, Light wave propagation, In vivo imaging, Adaptive optics, Opacity

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Proceedings Article | 9 December 2021 Paper

A low-cost multiwavelength time-domain LED-based optoacoustic system for unmixing absorbers

Michalis Orfanakis, George Tserevelakis, Giannis Zacharakis

Proceedings Volume 11923, 119230V (2021) https://doi.org/10.1117/12.2615919

KEYWORDS: Light emitting diodes, Optoacoustics, Absorption, Spectroscopy, Windows, Tissues, Semiconductor lasers, Scattering, Biomedical optics, Transducers

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Proceedings Article | 7 December 2021 Paper

Adaptive light sheet microscopy for in vivo imaging of fluorescently labeled specimens

Mikis Mylonakis, Athanasios Zacharopoulos, Evangelos Marakis, Dimitrios Papazoglou, Giannis Zacharakis

Proceedings Volume 11922, 119220K (2021) https://doi.org/10.1117/12.2615709

KEYWORDS: Spatial light modulators, Light scattering, Scattering, In vivo imaging, Microscopy, Wavefronts, Geometrical optics, Charge-coupled devices, Light wave propagation, Laser scattering

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Proceedings Article | 5 March 2021 Presentation + Paper

Hidden projection tomography via phase retrieval algorithm

Daniele Ancora, Diego Di Battista, Asier Marcos Vidal, Stella Avtzi, Giannis Zacharakis, Andrea Bassi

Proceedings Volume 11653, 116530P (2021) https://doi.org/10.1117/12.2582996

KEYWORDS: Tomography, Phase retrieval, Speckle pattern

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Proceedings Article | 22 July 2019 Paper

High resolution 3D imaging of primary and secondary tumor spheroids using multicolor multi-angle Light Sheet Fluorescence Microscopy (LSFM)

Stylianos Psycharakis, Evangelos Liapis, Athanasios Zacharopoulos, Mariam-Eleni Oraiopoulou, Chrysoula Aivalioti, Vangelis Sakkalis, Joseph Papamatheakis, Jorge Ripoll, Giannis Zacharakis

Proceedings Volume 11076, 110760O (2019) https://doi.org/10.1117/12.2527214

KEYWORDS: Tumors, Breast cancer, Image resolution, Microscopy, Microscopes, Cancer, 3D image processing

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Proceedings Article | 19 July 2019 Paper

Combined photoacoustic and fluorescence label-free microscopy for the ex-vivo investigation of ocular tissues

George Tserevelakis, Kostas Mavrakis, Danai Pantazopoulou, Eleni Karamouzi, Stella Avtzi, Miltiadis Tsilimbaris, Eleni Lagoudaki, Efstathios Detorakis, Giannis Zacharakis

Proceedings Volume 11077, 110771C (2019) https://doi.org/10.1117/12.2526580

KEYWORDS: Photoacoustic spectroscopy, Tissues, Eye, Luminescence, Biopsy, Microscopy, Imaging systems, Mirrors, Image segmentation, Microscopes

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Proceedings Article | 9 March 2018 Paper

Projection tomography in the NIR-IIa window: challenges, advantages, and comparison with classical optical approach

A. Marcos-Vidal, D. Ancora, G. Zacharakis, J. Vaquero, J. Ripoll

Proceedings Volume 10573, 105732F (2018) https://doi.org/10.1117/12.2293708

KEYWORDS: Scattering, Light scattering, Tissues, Absorption, Near infrared, Particles, Tomography, Optical tomography, Projection systems, Optical properties

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Proceedings Article | 21 February 2017 Presentation + Paper

Optical projection tomography via phase retrieval algorithms for hidden three dimensional imaging

Daniele Ancora, Diego Di Battista, Georgia Giasafaki, Stylianos Psycharakis, Evangelos Liapis, Athanasios Zacharopoulos, Giannis Zacharakis

Proceedings Volume 10074, 100741E (2017) https://doi.org/10.1117/12.2252894

KEYWORDS: Reconstruction algorithms, 3D image processing, Optical tomography, Tomography, Phase retrieval, 3D image reconstruction, Projection systems, Biomedical optics, Stereoscopy, Scattering, Speckle pattern, Cameras

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Proceedings Article | 18 March 2016 Paper

The role of cerebral spinal fluid in light propagation through the mouse head: improving fluorescence tomography with Monte Carlo modeling

Daniele Ancora, Athanasios Zacharopoulos, Jorge Ripoll, Giannis Zacharakis

Proceedings Volume 9700, 970015 (2016) https://doi.org/10.1117/12.2211423

KEYWORDS: Monte Carlo methods, Geometrical optics, Neuroimaging, Head, Fluid dynamics, Computational fluid dynamics, Photon transport, Diffuse optical imaging, Brain, Tissues, Luminescence, Cameras, Tissue optics

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Proceedings Article | 15 March 2016 Presentation + Paper

Structured adaptive focusing through scattering media

Diego Di Battista, Daniele Ancora, Haisu Zhang, Krystalia Lemonaki, Stella Avtzi, Stelios Tzortzakis, Marco Leonetti, Giannis Zacharakis

Proceedings Volume 9717, 971719 (2016) https://doi.org/10.1117/12.2211594

KEYWORDS: Opacity, Light scattering, Laser scattering, Scattering, Spatial light modulators, Speckle, Spatial filters, Bessel beams, Speckle pattern, Scattering media, Wavefronts, Optical filters, Cameras

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Proceedings Article | 9 March 2016 Paper

Phase-retrieved optical projection tomography for 3D imaging through scattering layers

Daniele Ancora, Diego Di Battista, Georgia Giasafaki, Stylianos Psycharakis, Evangelos Liapis, Athanasios Zacharopoulos, Giannis Zacharakis

Proceedings Volume 9718, 97181B (2016) https://doi.org/10.1117/12.2211415

KEYWORDS: Scattering, Light scattering, Tomography, 3D image processing, Image restoration, Projection systems, Optical tomography, Phase retrieval, Biomedical optics, 3D modeling

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SPIE Journal Paper | 18 February 2016 Open Access

Quantitative performance characterization of three-dimensional noncontact fluorescence molecular tomography

Rosy Favicchio, Stylianos Psycharakis, Kai Schönig, Dusan Bartsch, Clio Mamalaki, Joseph Papamatheakis, Jorge Ripoll, Giannis Zacharakis

JBO, Vol. 21, Issue 02, 026009, (February 2016) https://doi.org/10.1117/12.10.1117/1.JBO.21.2.026009

KEYWORDS: Luminescence, In vivo imaging, Imaging systems, Tomography, Fluorescence tomography, Fluorescent proteins, Optical filters, 3D image reconstruction, Calibration, Visible radiation

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Proceedings Article | 20 July 2015 Paper

Spatial frequencies selection for speckle grain reduction through semi-transparent media

Diego Di Battista, Daniele Ancora, Stella Avtzi, Marco Leonetti, Giannis Zacharakis

Proceedings Volume 9541, 95410E (2015) https://doi.org/10.1117/12.2183753

KEYWORDS: Scattering, Speckle, Light scattering, Spatial filters, Wavefronts, Speckle pattern, Optical filters, Linear filtering, Cameras, Laser scattering

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Proceedings Article | 16 July 2015 Paper

Light propagation through weakly scattering media: a study of Monte Carlo vs. diffusion theory with application to neuroimaging

Daniele Ancora, Athanasios Zacharopoulos, Jorge Ripoll, Giannis Zacharakis

Proceedings Volume 9538, 95380G (2015) https://doi.org/10.1117/12.2183899

KEYWORDS: Monte Carlo methods, Brain, Tissues, Head, Photon transport, Scattering, Neuroimaging, Skull, Optical properties, Diffusion

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Proceedings Article | 18 November 2013 Paper

Fabrication and characterization of a 3-D non-homogeneous tissue-like mouse phantom for optical imaging

Stella Avtzi, Athanasios Zacharopoulos, Stylianos Psycharakis, Giannis Zacharakis

Proceedings Volume 9032, 903206 (2013) https://doi.org/10.1117/12.2044698

KEYWORDS: Scattering, Prototyping, Brain, Skull, Absorption, Tissue optics, Head, Optical properties, Skin, Optical imaging

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SPIE Journal Paper | 9 July 2012 Open Access

Kinetics of T-cell receptor-dependent antigen recognition determined in vivo by multi-spectral normalized epifluorescence laser scanning

Rosy Favicchio, Katerina Oikonomaki, Kleo Mamalaki, Giannis Zacharakis, Athanasios Zacharopoulos, Jorge Ripoll

JBO, Vol. 17, Issue 7, 076013, (July 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.7.076013

KEYWORDS: In vivo imaging, Luminescence, Green fluorescent protein, Signal detection, Laser scanners, In vitro testing, Signal to noise ratio, Optical filters, Image filtering, Statistical analysis

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SPIE Journal Paper | 4 June 2012 Open Access

Prehistological evaluation of benign and malignant pigmented skin lesions with optical computed tomography

Athanasios Kokolakis, Giannis Zacharakis, Konstantin Krasagakis, Konstantinos Lasithiotakis, Rosy Favicchio, George Spiliopoulos, Elpida Giannikaki, Jorge Ripoll, Androniki Tosca

JBO, Vol. 17, Issue 06, 066004, (June 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.6.066004

KEYWORDS: Melanoma, Skin, Tissue optics, Signal attenuation, Scattering, Light scattering, 3D image processing, Computed tomography, Biopsy, Light emitting diodes

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Proceedings Article | 12 July 2007 Paper

Radiotherapy dosimetry assessment with optical projection tomography

Giannis Zacharakis, Antonios Papadakis, Fotini Zacharopoulou, Anikitos Garofalakis, Thomas Maris, Jorge Ripoll

Proceedings Volume 6629, 66291C (2007) https://doi.org/10.1117/12.728296

KEYWORDS: Radiotherapy, Magnetic resonance imaging, Polymers, Radio optics, Tomography, Signal attenuation, 3D image processing, Radon transform, Projection systems, Optical tomography

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Proceedings Article | 11 July 2007 Paper

Spectral unmixing of multi-color tissue specific in vivo fluorescence in mice

Giannis Zacharakis, Rosy Favicchio, Anikitos Garofalakis, Stylianos Psycharakis, Clio Mamalaki, Jorge Ripoll

Proceedings Volume 6626, 662609 (2007) https://doi.org/10.1117/12.728410

KEYWORDS: Luminescence, Green fluorescent protein, Reconstruction algorithms, Tomography, Tissues, In vivo imaging, Optical filters, Control systems, Cameras, Skin

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Proceedings Article | 11 July 2007 Paper

Autofluorescence removal from fluorescence tomography data using multispectral imaging

Stylianos Psycharakis, Giannis Zacharakis, Anikitos Garofalakis, Rosy Favicchio, Jorge Ripoll

Proceedings Volume 6626, 66260I (2007) https://doi.org/10.1117/12.728305

KEYWORDS: Luminescence, Tomography, Fluorescence tomography, Green fluorescent protein, Skin, In vivo imaging, Tissues, Absorption, Signal detection, Reconstruction algorithms

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Proceedings Article | 13 March 2006 Paper

3D in vivo imaging of GFP-expressing T-cells in mice with non-contact fluorescence molecular tomography

Anikitos Garofalakis, Heiko Meyer, Giannis Zacharakis, Clio Mamalaki, Joseph Papamatheakis, Vasilis Ntziachristos, Eleftherios Economou, J. Ripoll

Proceedings Volume 6143, 61431H (2006) https://doi.org/10.1117/12.657380

KEYWORDS: Green fluorescent protein, Tomography, In vivo imaging, Luminescence, Spleen, Lymphatic system, Imaging systems, Optical tomography, Fluorescence tomography, Cameras

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Proceedings Article | 22 June 2005 Paper

3D in-vivo imaging of GFP-expressing T-cells in mice with non-contact fluorescence molecular tomography

Anikitos Garofalakis, Heiko Meyer, Giannis Zacharakis, Eleftherios Economou, Clio Mamalaki, Joseph Papamatheakis, Vasilis Ntziachristos, Jorge Ripoll

Proceedings Volume 5771, (2005) https://doi.org/10.1117/12.634830

KEYWORDS: Imaging systems, In vivo imaging, Tomography, 3D modeling, 3D image processing, Luminescence, Green fluorescent protein, Stereoscopy, CCD cameras, Tissues

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Proceedings Article | 22 June 2005 Paper

A multi-projection non-contact tomography setup for imaging arbitrary geometries

Heiko Meyer, Anikitos Garofalakis, Giannis Zacharakis, Eleftherios Economou, Clio Mamalaki, Sifis Papamatheakis, Vasilis Ntziachristos, Jorge Ripoll

Proceedings Volume 5771, (2005) https://doi.org/10.1117/12.634623

KEYWORDS: Imaging systems, Tomography, Optical tomography, Tissues, In vivo imaging, Cameras, Optical imaging, CCD cameras, Chromophores, 3D image processing

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Proceedings Article | 28 April 2005 Paper

A multiprojection noncontact fluorescence tomography setup for imaging arbitrary geometries

H. Meyer, A. Garofalakis, G. Zacharakis, E. Economou, C. Mamalaki, D. Kioussis, V. Ntziachristos, J. Ripoll

Proceedings Volume 5693, (2005) https://doi.org/10.1117/12.590837

KEYWORDS: Imaging systems, In vivo imaging, Tomography, 3D modeling, 3D metrology, Cameras, Green fluorescent protein, Optical tomography, Tissues, Luminescence

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Proceedings Article | 13 October 2003 Paper

Spectroscopic fluorescence measurements of lamb and human heart tissue in vitro

George Filippidis, Giannis Zacharakis, G. Kochiadakis, S. Chrysostomakis, P. Vardas, Costas Fotakis, Theodore Papazoglou

Proceedings Volume 5068, (2003) https://doi.org/10.1117/12.518767

KEYWORDS: Heart, Luminescence, Tissues, Tissue optics, Fluorescence spectroscopy, Spectroscopy, Laser tissue interaction, Laser induced fluorescence, In vitro testing, Absorption

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Proceedings Article | 8 October 2003 Paper

Optical characterization of small biopsy samples

Anikitos Garofalakis, Giannis Zacharakis, George Filippidis, Elias Sanidas, Dimitris Tsiftsis, Eleftherios Stathopoulos, Maria Kafousi, Theodore Papazoglou, Jorge Ripoll

Proceedings Volume 5141, (2003) https://doi.org/10.1117/12.500546

KEYWORDS: Tissues, Scattering, Diffusion, Biopsy, Tumors, Breast, Optical properties, Absorption, Tissue optics, Light scattering

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Proceedings Article | 22 September 2003 Paper

LIF after excitation with ultrafast laser irradiation: the response of a single cell and the effect of its scattering environment

Theodore Papazoglou, Giannis Zacharakis

Proceedings Volume 5149, (2003) https://doi.org/10.1117/12.518633

KEYWORDS: Laser scattering, Scattering, Light scattering, Photons, Random lasers, Luminescence, Polymers, Picosecond phenomena, Photodynamic therapy, Skin

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New and fascinating field of highly scattering gain media, random lasers and the study of the behavior of such materials of biological significance is presented. Especially the study of the behavior of various fluorophores embedded in highly scattering matrices. The observed fluorescence signal of the fluorophore quenches in both temporal and spectral domains due to the intense scattering that the photons undergo. This happens when the excitation energy reaches and exceeds a threshold value. Above that value the narrowed fluorescence exhibits the same features as the excitation laser pulse. Lifetime in the order of 50 psec and spectral FWHM in the order of few nanometers are observed. For energies below the threshold value the amplification is negligible and the samples behave exactly as those without scatterers. As the excitation energy increases the laser action requirements are fulfilled and the sudden narrowing takes place. Similar studies are underway when various fluorophores are embedded in biological tissues. The final goal is to take advantage of this effect towards a more spatially and spectrally confined agent in Photodynamic Therapy of target tissue lesions on skin or other types of superficial lesions. Very promising in the field of skin PDT would be thin polymer sheets with various dyes, which could be applied directly on the lesion and allow the selection of different irradiation wavelengths using the same laser as excitation source. Thus, improving by far the efficiency of the destruction of different types of cancerous cells. In the biomedical arena, the materials high conversion efficiency per unit volume (≥ 50 percent in a 250 μm thickness) allows for wavelength-shifted catheters and laser creams, potentially useful for the removal of tattoos and other skin discolorations. In addition, random lasers can be used for wavelength shifting the installed base of lasers for other applications such as photodynamic therapy where narrow-band excitations are required for drugs such as benzoporphyrin derivatives (BPD). As far as detection is concerned random lasers could be implemented in various applications such as medical imaging. The combined use of these materials with chromophores that are selectively absorbed by malignant tumors and the narrowband emission along with the high-emitted intensity could boost the detection efficiency.

Proceedings Article | 16 July 2002 Paper

Single and double photon excitation of dyes in highly scattering media of biological significance

Giannis Zacharakis, Theodore Papazoglou

Proceedings Volume 4707, (2002) https://doi.org/10.1117/12.475626

KEYWORDS: Luminescence, Scattering, Laser scattering, Random lasers, Picosecond phenomena, Scattering media, Photon counting, Streak cameras, Temporal coherence, Light scattering

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Proceedings Article | 2 November 2001 Paper

Second harmonic generation and random lasing after two-photon excitation

Giannis Zacharakis, Dmitrios Anglos, Theodore Papazoglou

Proceedings Volume 4431, (2001) https://doi.org/10.1117/12.447429

KEYWORDS: Random lasers, Luminescence, Second-harmonic generation, Harmonic generation, Photons, Absorption, Scattering, Laser scattering, Tissue optics, Tumors

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SPIE Journal Paper | 1 October 2001 Open Access

In vitro optical characterization and discrimination of female breast tissue during near infrared FSEC laser pulsed propagation

Giannis Zacharakis, A. Zolindaki, V. Sakkalis, George Filippidis, Theodore Papazoglou, D. Tsiftsis, Eugenios Koumantakis

JBO, Vol. 6, Issue 04, (October 2001) https://doi.org/10.1117/12.10.1117/1.1412223

KEYWORDS: Tissues, Tissue optics, Scattering, Breast, Near infrared, Absorption, Photons, In vitro testing, Laser tissue interaction, Diffusion

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Proceedings Article | 19 January 2001 Paper

Artificial neural networks analysis of laser-induced fluorescence spectra for characterization of peripheral vascular tissue

George Filippidis, Giannis Zacharakis, A. Katsamouris, G. Rovithakis, M. Maniadakis, M. Zervakis, Theodore Papazoglou

Proceedings Volume 4158, (2001) https://doi.org/10.1117/12.413797

KEYWORDS: Tissues, Neural networks, Artificial neural networks, Luminescence, Feature extraction, Laser induced fluorescence, Laser tissue interaction, Nonlinear filtering, In vitro testing, Arteries

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Proceedings Article | 3 November 2000 Paper

Photon statistics of the laserlike emission from polymeric scattering gain media with tissuelike optical properties

Giannis Zacharakis, Nektarios Papadogiannis, George Filippidis, Theodore Papazoglou

Proceedings Volume 4162, (2000) https://doi.org/10.1117/12.405942

KEYWORDS: Laser scattering, Scattering, Picosecond phenomena, Polymers, Luminescence, Optical properties, Laser tissue interaction, Streak cameras, Laser applications, Random lasers

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Proceedings Article | 29 December 1997 Paper

Effect of liquid nitrogen and formalin-based conservation in the in-vitro measurement of laser-induced fluorescence of peripheral vascular tissue

George Filippidis, Giannis Zacharakis, A. Katsamouris, M. Kouktzela, Sune Montan, Stefan Andersson-Engels, Theodore Papazoglou

Proceedings Volume 3197, (1997) https://doi.org/10.1117/12.297984

KEYWORDS: Tissues, Liquids, Nitrogen, Luminescence, Laser induced fluorescence, Laser tissue interaction, Arteries, In vitro testing, Algorithm development, Mirrors

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Proceedings Article | 29 December 1997 Paper

Use of the polarization vector in modeling tissue fluorescence: theoretical and experimental comparison

Ourania Panou-Diamanti, Nikolaos Uzunoglou, A. Vasiliou, Giannis Zacharakis, George Filippidis, Theodore Papazoglou, Dimitrios Koutsouris

Proceedings Volume 3197, (1997) https://doi.org/10.1117/12.297953

KEYWORDS: Tissues, Luminescence, Mathematical modeling, Scattering, Electromagnetic scattering, Dielectrics, Data modeling, Polarization, Collagen, Dielectric polarization

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Showing 5 of 34 publications

Conference Committee Involvement (1)

Molecular Imaging

17 June 2007 | Munich, Germany

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