Dr. Susobhan Das Profile

Dr. Susobhan Das

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Publications (6)

SPIE Journal Paper | 18 March 2020 Open Access

Laser-induced elastic wave classification: thermoelastic versus ablative regimes for all-optical elastography applications

Susobhan Das, Alexander Schill, Chih-Hao Liu, Salavat Aglyamov, Kirill Larin

JBO, Vol. 25, Issue 03, 035004, (March 2020) https://doi.org/10.1117/12.10.1117/1.JBO.25.3.035004

KEYWORDS: Absorption, Liver, Pulsed laser operation, Laser energy, Tissues, Elastography, Laser tissue interaction, Optical coherence tomography, Tissue optics, Signal attenuation

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Significance: Shear wave optical coherence elastography is an emerging technique for characterizing tissue biomechanics that relies on the generation of elastic waves to obtain the mechanical contrast. Various techniques, such as contact, acoustic, and pneumatic methods, have been used to induce elastic waves. However, the lack of higher-frequency components within the elastic wave restricts their use in thin samples. The methods also require moving parts and/or tubing, which therefore limits the extent to which they can be miniaturized. Aim: To overcome these limitations, we propose an all-optical approach using photothermal excitation. Depending on the absorption coefficient of the sample and the laser pulse energy, elastic waves are generated either through a thermoelastic or an ablative process. Our study aimed to experimentally determine the boundary between the thermoelastic and the ablative regimes for safe all-optical elastography applications. Approach: Tissue-mimicking graphite-doped phantoms and chicken liver samples were used to investigate the boundary between thermoelastic and ablative regimes. A pulsed laser at 532 nm was used to induce elastic waves in the samples. Laser-induced elastic waves were detected using a line field low coherence holography instrument. The shape of the elastic wave amplitude was analyzed and used to determine the transition point between thermoelastic and ablative regimes. Results: The transition from the thermoelastic to the ablative regime is accompanied by the nonlinear increase in surface wave amplitude as well as the transformation of the wave shape. Correlation between the absorption coefficient and the transition point energy was experimentally determined using graphite-doped phantoms and applied to biological samples ex vivo. Conclusions: Our study described a methodology for determining the boundary region between thermoelastic and ablative regimes of elastic wave generation. These can be used for the development of a safe method for completely noncontact, all-optical microscale assessment of tissue biomechanics using laser-induced elastic waves.

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Proceedings Article | 7 March 2019 Presentation

Longitudinal elastic wave imaging using nanobomb optical coherence elastography (Conference Presentation)

Chih -Hao Liu, Dmitry Nevozhay, Susobhan Das, Alexander Schill, Manmohan Singh, Achuth Nair, Konstantin Sokolov, Kirill Larin

Proceedings Volume 10867, 108672D (2019) https://doi.org/10.1117/12.2511547

KEYWORDS: Tissue optics, Elastography, Coherence (optics), Tissues, Optical imaging, Wave propagation, Laser beam diagnostics, Nanoparticles, Pulsed laser operation, Optical coherence tomography

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Proceedings Article | 4 March 2019 Presentation

An analytical model of laser-induced dynamic thermoelastic deformation of the viscoelastic half-space (Conference Presentation)

Salavat Aglyamov, Susobhan Das, Chih -Hao Liu, Shang Wang, Alexander Schill, Kirill Larin

Proceedings Volume 10880, 108800E (2019) https://doi.org/10.1117/12.2506194

KEYWORDS: Tissues, Biological research, Elastography, Pulsed laser operation, Signal attenuation, Laser applications, Optical coherence tomography, Acoustics, Absorption, Natural surfaces

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Proceedings Article | 21 February 2019 Paper

Differentiation of murine colon pathology by optical and mechanical contrast using optical coherence tomography and elastography

Achuth Nair, Susobhan Das, Chih-Hao Liu, Manmohan Singh, Triet Le, Salavat Aglyamov, Yong Du, Sanam Soomro, Chandra Mohan, Kirill Larin

Proceedings Volume 10880, 108800P (2019) https://doi.org/10.1117/12.2510183

KEYWORDS: Tissues, Tissue optics, Colon, Optical coherence tomography, Pathology, Elastography, Cancer, Colorectal cancer

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Proceedings Article | 15 March 2018 Presentation

Optical elastography using dye nanoparticles (Conference Presentation)

Chih-Hao Liu, Alexander Schill, Susobhan Das, Dmitry Nevozhay, Manmohan Singh, Achuth Nair, Konstantin Sokolov, Kirill Larin

Proceedings Volume 10496, 1049605 (2018) https://doi.org/10.1117/12.2290886

KEYWORDS: Elastography, Holography, Nanoparticles, Tissue optics, Coherence (optics), Tissues, Neptunium, Optical coherence tomography, Statistical modeling, Laser ablation

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Proceedings Article | 19 February 2018 Presentation + Paper

Comparison between thermoelastic and ablative induced elastic waves in soft media using ultra-fast line-field low coherent holography

Susobhan Das, Chih-Hao Liu, Alexander Schill, Kirill Larin

Proceedings Volume 10496, 104960G (2018) https://doi.org/10.1117/12.2290384

KEYWORDS: Absorption, Pulsed laser operation, Holography, Tissues, Laser energy, Tissue optics, Ultrafast phenomena, Imaging systems, Laser tissue interaction, Signal attenuation

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