Dr. Achuth Nair Profile

Dr. Achuth Nair

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Author

Publications (38)

SPIE Journal Paper | 18 September 2024 Open Access

Dual optical elastography detects TGF-β-induced alterations in the biomechanical properties of skin scaffolds

Taye T. Mekonnen, Yogeshwari S. Ambekar, Christian Zevallos-Delgado, Achuth Nair, Fernando Zvietcovich, Hoda Zarkoob, Manmohan Singh, Yi Wei Lim, Marc Ferrer, Salavat R. Aglyamov, Giuliano Scarcelli, Min Jae Song, Kirill V. Larin

JBO, Vol. 29, Issue 09, 095002, (September 2024) https://doi.org/10.1117/12.10.1117/1.JBO.29.9.095002

KEYWORDS: Skin, Tissues, Elastography, Biomechanics, Microscopy, Tissue optics, Elasticity, Collagen, Optical coherence tomography, Wave propagation

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SignificanceThe skin’s mechanical properties are tightly regulated. Various pathologies can affect skin stiffness, and understanding these changes is a focus in tissue engineering. Ex vivo skin scaffolds are a robust platform for evaluating the effects of various genetic and molecular interactions on the skin. Transforming growth factor-beta (TGF-β) is a critical signaling molecule in the skin that can regulate the amount of collagen and elastin in the skin and, consequently, its mechanical properties.AimThis study investigates the biomechanical properties of bio-engineered skin scaffolds, focusing on the influence of TGF-β, a signaling molecule with diverse cellular functions.ApproachThe TGF-β receptor I inhibitor, galunisertib, was employed to assess the mechanical changes resulting from dysregulation of TGF-β. Skin scaffold samples, grouped into three categories (control, TGF-β-treated, and TGF-β + galunisertib-treated), were prepared in two distinct culture media—one with aprotinin (AP) and another without. Two optical elastography techniques, namely wave-based optical coherence elastography (OCE) and Brillouin microscopy, were utilized to quantify the biomechanical properties of the tissues.ResultsResults showed significantly higher wave speed (with AP, p<0.001; without AP, p<0.001) and Brillouin frequency shift (with AP, p<0.001; without AP, p=0.01) in TGF-β-treated group compared with the control group. The difference in wave speed between the control and TGF-β + galunisertib with (p=0.10) and without AP (p=0.36) was not significant. Moreover, the TGF-β + galunisertib-treated group exhibited lower wave speed without and with AP and reduced Brillouin frequency shift than the TGF-β-treated group without AP, further strengthening the potential role of TGF-β in regulating the mechanical properties of the samples.ConclusionsThese findings offer valuable insights into TGF-β-induced biomechanical alterations in bio-engineered skin scaffolds, highlighting the potential of OCE and Brillouin microscopy in the development of targeted therapies in conditions involving abnormal tissue remodeling and fibrosis.

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Proceedings Article | 13 March 2024 Presentation

Convolutional neural networks estimate strain in quasistatic optical coherence elastography

Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

Proceedings Volume PC12844, PC1284404 (2024) https://doi.org/10.1117/12.3001717

KEYWORDS: Optical coherence, Elastography, Convolutional neural networks, Biomechanics, Nervous system, Data processing, Biomedical applications, Neurological disorders, Neural networks, Education and training

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Proceedings Article | 13 March 2024 Presentation

Optical coherence elastography detects changes in corneal stiffness due to LASIK in ex vivo porcine cornea

Achuth Nair, Fernando Zvietcovich, Manmohan Singh, Mitchell Weikert, Salavat Aglyamov, Kirill Larin

Proceedings Volume PC12824, PC128240O (2024) https://doi.org/10.1117/12.3000545

KEYWORDS: LASIK, Cornea, Optical coherence, Elastography, Biomechanics, Eye, Ultrasonography, In vivo imaging, Ablation

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Proceedings Article | 12 March 2024 Presentation + Paper

3D heartbeat optical coherence elastography to map the elasticity of the cornea

Sharon Shajan, Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

Proceedings Volume 12844, 1284408 (2024) https://doi.org/10.1117/12.2692996

KEYWORDS: Cornea, Elastography, Tissues, Biomechanics, Eye, Optical coherence, Elasticity, Optical coherence tomography

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Proceedings Article | 15 March 2023 Paper

Simultaneous Hb-OCE and compression OCE to measure the biomechanical properties of the cornea in vivo

Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

Proceedings Volume 12381, 123810E (2023) https://doi.org/10.1117/12.2660523

KEYWORDS: Cornea, Tissues, In vivo imaging, Biomechanics, Elastography, Optical coherence tomography

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Proceedings Article | 15 March 2023 Paper

Multimodal optical elastography assessment of a murine collagen XII knockout

Achuth Nair, Yogeshwari Ambekar, Christian Zevallos-Delgado, Mei Sun, Manmohan Singh, Fernando Zvietcovich, Taye Mekonnen, Salavat Aglyamov, Manuel Koch, Giuliano Scarcelli, Edgar Espana, Kirill Larin

Proceedings Volume 12381, 123810F (2023) https://doi.org/10.1117/12.2661151

KEYWORDS: Cornea, Collagen, Elastography, Tissues, Microscopy, Tissue optics, Medicine, Biomechanics

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Proceedings Article | 15 March 2023 Presentation + Paper

Assessment of corneal stiffness ex-vivo at various IOPs measured by heartbeat OCE

Andres Bryan, Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

Proceedings Volume 12381, 123810D (2023) https://doi.org/10.1117/12.2651304

KEYWORDS: Cornea, Eye, Biomechanics, Elastography, Optical coherence tomography, Diseases and disorders, Diagnostics, Tissues

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Proceedings Article | 7 March 2022 Paper

Single-shot dynamic line-field optical coherence elastography at 11.5 MHz

Manmohan Singh, Alexander Schill, Achuth Nair, Salavat Aglyamov, Irina Larin, Kirill Larin

Proceedings Volume 11948, 119480B (2022) https://doi.org/10.1117/12.2609979

KEYWORDS: Ultrafast phenomena, Optical coherence tomography, Cornea, Tissues, Elastography, Imaging systems, Wave propagation, Coherence (optics), Singular optics, Signal to noise ratio

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Proceedings Article | 4 March 2022 Paper

Mapping corneal stiffness with compressional optical coherence elastography

Manmohan Singh, Achuth Nair, Salavat Aglyamov, Kirill Larin

Proceedings Volume 11941, 1194106 (2022) https://doi.org/10.1117/12.2610012

KEYWORDS: Cornea, In vivo imaging, Elastography, Optical coherence tomography, In situ metrology, Coherence (optics), Therapeutics, Image resolution, Image compression, Tissues

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Proceedings Article | 9 December 2021 Paper

Heartbeat optical coherence elastography to measure corneal stiffness in vivo

Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

Proceedings Volume 11924, 1192407 (2021) https://doi.org/10.1117/12.2616012

KEYWORDS: Cornea, In vivo imaging, Elastography, Tissues, Coherence (optics), Tissue optics, Optical coherence tomography, Transducers, Imaging systems, Glasses

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Proceedings Article | 5 March 2021 Presentation

Understanding the biomechanical role of limbus using optical coherence elastography

Fernando Zvietcovich, Achuth Nair, Manmohan Singh, Salavat Aglyamov, Michael Twa, Kirill Larin

Proceedings Volume 11645, 1164514 (2021) https://doi.org/10.1117/12.2579089

KEYWORDS: Sclera, Cornea, Elastography, Coherence (optics), Finite element methods, Wave propagation, Tissues, Phase velocity, Optical coherence tomography, Eye

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Proceedings Article | 5 March 2021 Poster + Paper

Heartbeat optical coherence elastography: using heartbeat to measure corneal biomechanical properties

Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

Proceedings Volume 11630, 116301U (2021) https://doi.org/10.1117/12.2579108

KEYWORDS: Elastography, Cornea, Coherence (optics), Tissues, Tissue optics, In vivo imaging, Visualization, Ultrasonography, Transducers, Pathology

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Proceedings Article | 5 March 2021 Presentation

In vivo assessment of corneal mechanical response to heartbeat measured by heartbeat OCE

Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

Proceedings Volume 11645, 116450H (2021) https://doi.org/10.1117/12.2579139

KEYWORDS: Cornea, In vivo imaging, Elastography, Tissues, Optical coherence tomography, Collagen, Coherence (optics)

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Proceedings Article | 5 March 2021 Presentation

Confocal air-coupled acoustic radiation force probe for the optical coherence elastography of tissues

Fernando Zvietcovich, Achuth Nair, Yogeshwari Ambekar, Manmohan Singh, Salavat Aglyamov, Michael Twa, Kirill Larin

Proceedings Volume 11645, 116450G (2021) https://doi.org/10.1117/12.2584510

KEYWORDS: Tissues, Tissue optics, Elastography, Confocal microscopy, Coherence (optics), Acoustics, Optical coherence tomography, Transducers, Wave propagation, Ultrasonics

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SPIE Journal Paper | 23 February 2021 Open Access

Heartbeat optical coherence elastography: corneal biomechanics in vivo

Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

JBO, Vol. 26, Issue 02, 020502, (February 2021) https://doi.org/10.1117/12.10.1117/1.JBO.26.2.020502

KEYWORDS: Cornea, In vivo imaging, Elastography, Tissues, Optical coherence tomography, Coherence (optics), Glasses, Tissue optics, Transducers, Heart

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SPIE Journal Paper | 5 May 2020 Open Access

Heartbeat OCE: corneal biomechanical response to simulated heartbeat pulsation measured by optical coherence elastography

Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

JBO, Vol. 25, Issue 05, 055001, (May 2020) https://doi.org/10.1117/12.10.1117/1.JBO.25.5.055001

KEYWORDS: Cornea, Tissues, Elastography, Eye, Optical coherence tomography, Coherence (optics), In vivo imaging, Tissue optics, Optical testing, Therapeutics

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Proceedings Article | 2 April 2020 Presentation

Assessing corneal biomechanics without external excitation: heartbeat optical coherence elastography (Conference Presentation)

Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

Proceedings Volume 11363, 113630O (2020) https://doi.org/10.1117/12.2555000

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Proceedings Article | 25 February 2020 Presentation + Paper

Mechanical changes of the crystalline lens in oxidative cataractogenesis assessed with optical coherence elastography

Hongqiu Zhang, Achuth Nair, Salavat Aglyamov, Kirill Larin

Proceedings Volume 11242, 112420W (2020) https://doi.org/10.1117/12.2548202

KEYWORDS: Crystals, Elastography, Coherence (optics), Optical coherence tomography, Tissue optics, Hydrogen, Wave propagation, Biomedical optics, Proteins, Eye

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Proceedings Article | 25 February 2020 Paper

Characterization of biomechanical properties of crystalline lens using Brillouin microscopy and optical coherence elastography

Yogeshwari S. Ambekar, Manmohan Singh, Jitao Zhang, Achuth Nair, Salavat Aglyamov, Giuliano Scarcelli, Kirill Larin

Proceedings Volume 11218, 112180T (2020) https://doi.org/10.1117/12.2546759

KEYWORDS: Microscopy, Elastography, Coherence (optics), Tissues, Optical microscopy, Tissue optics, Phased array optics, Calibration

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Proceedings Article | 13 February 2020 Paper

Heartbeat OCE: Corneal biomechanical response to simulated heartbeat pulsation

Achuth Nair, Manmohan Singh, Salavat Aglyamov, Kirill Larin

Proceedings Volume 11242, 1124205 (2020) https://doi.org/10.1117/12.2546196

KEYWORDS: Cornea, Tissues, Elastography, Optical coherence tomography, Eye, Tissue optics, Ultrasonography, Control systems, Coherence (optics), Collagen

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SPIE Journal Paper | 12 March 2019 Open Access

Optical coherence elastography of cold cataract in porcine lens

Hongqiu Zhang, Chen Wu, Manmohan Singh, Achuth Nair, Salavat Aglyamov, Kirill Larin

JBO, Vol. 24, Issue 03, 036004, (March 2019) https://doi.org/10.1117/12.10.1117/1.JBO.24.3.036004

KEYWORDS: Temperature metrology, Elastography, Optical coherence tomography, Coherence (optics), Crystals, Opacity, Tissue optics, Control systems, Wave propagation, Error analysis

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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 | 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 | 8 March 2018 Paper

Ultra-high speed OCT allows measurement of intraocular pressure, corneal geometry, and corneal stiffness using a single instrument

Manmohan Singh, Zhaolong Han, Achuth Nair, Alexander Schill, Michael Twa, Kirill Larin

Proceedings Volume 10483, 1048319 (2018) https://doi.org/10.1117/12.2288450

KEYWORDS: Cornea, Optical coherence tomography, Elastography, Wave propagation, Tissue optics, Coherence (optics), Tissues, Biomedical engineering, In situ metrology, Ultrafast imaging

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Proceedings Article | 19 February 2018 Presentation + Paper

Evaluation of posterior porcine sclera elasticity in situ as a function of IOP

Achuth Nair, Chen Wu, Manmohan Singh, Chih Hao Liu, Raksha Raghunathan, Jennifer Nguyen, Megan Goh, Salavat Aglyamov, Kirill Larin

Proceedings Volume 10474, 1047418 (2018) https://doi.org/10.1117/12.2289233

KEYWORDS: Sclera, Tissues, Elastography, Eye, Ultrasonography, Optical coherence tomography, Acoustics, Wave propagation, Transducers, Tissue optics

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Proceedings Article | 21 February 2017 Paper

Assessing the changes in the spatial stiffness of the posterior sclera as a function of IOP with air-pulse OCE

Manmohan Singh, Achuth Nair, Salavat Aglyamov, Chen Wu, Zhaolong Han, Ericka Lafon, Kirill Larin

Proceedings Volume 10067, 100670F (2017) https://doi.org/10.1117/12.2251550

KEYWORDS: Sclera, Optic nerve, Tissues, Tissue optics, Elastography, Coherence (optics), Eye, Information visualization, In situ metrology, Eye models, Optical coherence tomography, Kinematics

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Proceedings Article | 21 February 2017 Paper

Quantifying the effects of UV-A/riboflavin crosslinking on the elastic anisotropy and hysteresis of the porcine cornea by noncontact optical coherence elastography

Manmohan Singh, Jiasong Li, Raksha Raghunathan, Zhaolong Han, Achuth Nair, Chih-Hao Liu, Salavat Aglyamov, Michael Twa, Kirill Larin

Proceedings Volume 10067, 100670D (2017) https://doi.org/10.1117/12.2251680

KEYWORDS: Cornea, Anisotropy, Elastography, Tissue optics, Coherence (optics), Collagen, UV optics, Tissues, Wave propagation, Biomedical engineering

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SPIE Journal Paper | 20 February 2017 Open Access

Applanation optical coherence elastography: noncontact measurement of intraocular pressure, corneal biomechanical properties, and corneal geometry with a single instrument

Manmohan Singh, Zhaolong Han, Achuth Nair, Alexander Schill, Michael Twa, Kirill Larin

JBO, Vol. 22, Issue 02, 020502, (February 2017) https://doi.org/10.1117/12.10.1117/1.JBO.22.2.020502

KEYWORDS: Cornea, Optical coherence tomography, Elastography, Coherence (optics), Tissues, Wave propagation, Video, Control systems, Biomedical optics, Tissue optics

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Proceedings Article | 8 February 2017 Paper

Noncontact optical coherence elastography of the posterior porcine sclera in situ as a function of IOP

Manmohan Singh, Achuth Nair, Salavat Aglyamov, Chen Wu, Zhaolong Han, Ericka Lafon, Kirill Larin

Proceedings Volume 10045, 1004524 (2017) https://doi.org/10.1117/12.2253445

KEYWORDS: Tissues, Sclera, Optic nerve, Tissue optics, Coherence (optics), Elastography, Eye, Eye models, Model-based design, Optical coherence tomography, Kinematics, Atomic force microscopy

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Proceedings Article | 8 February 2017 Paper

Assessing the mechanical anisotropy and hysteresis while cycling IOP of porcine eyes before and after CXL by noncontact optical coherence elastography

Manmohan Singh, Jiasong Li, Raksha Raghunathan, Zhaolong Han, Achuth Nair, Chih-Hao Liu, Salavt Aglyamov, Michael Twa, Kirill Larin

Proceedings Volume 10045, 1004504 (2017) https://doi.org/10.1117/12.2253433

KEYWORDS: Anisotropy, Cornea, Coherence (optics), Elastography, Collagen, Tissue optics, Coherence imaging, Tissues, Optical imaging, Biomedical engineering, Eye

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SPIE Journal Paper | 20 September 2016 Open Access

Quantifying tissue viscoelasticity using optical coherence elastography and the Rayleigh wave model

Zhaolong Han, Manmohan Singh, Salavat Aglyamov, Chih-Hao Liu, Achuth Nair, Raksha Raghunathan, Chen Wu, Jiasong Li, Kirill Larin

JBO, Vol. 21, Issue 09, 090504, (September 2016) https://doi.org/10.1117/12.10.1117/1.JBO.21.9.090504

KEYWORDS: Tissue optics, Tissues, Liver, Elastography, Soft tissue optics, Coherence (optics), Phase velocity, Geometrical optics, Protactinium, Optical coherence tomography

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Proceedings Article | 9 March 2016 Presentation + Paper

Dynamic phase-sensitive optical coherence elastography at a true kilohertz frame-rate

Manmohan Singh, Chen Wu, Chih-Hao Liu, Jiasong Li, Alexander Schill, Achuth Nair, Kirill Larin

Proceedings Volume 9710, 97100A (2016) https://doi.org/10.1117/12.2208596

KEYWORDS: Elastography, Tissues, Tissue optics, Coherence (optics), Acoustics, Mode locking, Finite element methods, Optical coherence tomography, Ultrafast phenomena, Laser sources, Cornea, Wave propagation, Imaging systems, Laser safety

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Proceedings Article | 9 March 2016 Presentation + Paper

Revealing anisotropic properties of cornea at different intraocular pressures using optical coherence elastography

Jiasong Li, Manmohan Singh, Zhaolong Han, Chen Wu, Achuth Nair, Salavat Aglyamov, Michael Twa, Kirill Larin

Proceedings Volume 9710, 97100T (2016) https://doi.org/10.1117/12.2213317

KEYWORDS: Cornea, Anisotropy, Elastography, Coherence (optics), Optical coherence tomography, Collagen, Mercury, In vivo imaging, Tissues, Wave propagation, Imaging systems, Control systems

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Proceedings Article | 8 March 2016 Presentation + Paper

Noncontact phase-sensitive dynamic optical coherence elastography at megahertz rate

Manmohan Singh, Chen Wu, Chih-Hao Liu, Jiasong Li, Alexander Schill, Achuth Nair, Yury Kistenev, Kirill Larin

Proceedings Volume 9697, 96970P (2016) https://doi.org/10.1117/12.2208404

KEYWORDS: Tissue optics, Optical coherence tomography, Coherence (optics), Elastography, Cornea, Mode locking, Tissues, Laser safety, Imaging systems, Molecular spectroscopy, Wave propagation

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Proceedings Article | 8 March 2016 Presentation + Paper

Corneal elastic anisotropy and hysteresis as a function of IOP assessed by optical coherence elastography

Jiasong Li, Manmohan Singh, Zhaolong Han, Chen Wu, Raksha Raghunathan, Chih-Hao Liu, Achuth Nair, Shezaan Noorani, Salavat Aglyamov, Michael Twa, Kirill Larin

Proceedings Volume 9697, 96971N (2016) https://doi.org/10.1117/12.2213226

KEYWORDS: Anisotropy, Cornea, Coherence (optics), Elastography, Optical coherence tomography, Wave propagation, In vivo imaging, Tissues, Biomedical optics, Tissue optics, Collagen, Imaging systems

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Proceedings Article | 8 March 2016 Presentation + Paper

Single shot line-field optical coherence elastography

Chih-Hao Liu, Alexander Schill, Manmohan Singh, Chen Wu, Jiasong Li, Zhaolong Han, Raksha Raghunathan, Tina Kazemi, Achuth Nair, Thomas Hsu, Kirill Larin

Proceedings Volume 9697, 96971R (2016) https://doi.org/10.1117/12.2213413

KEYWORDS: Tissue optics, Coherence (optics), Elastography, Optical coherence tomography, Tissues, Wave propagation, Singular optics, Natural surfaces, Coherence imaging, Molecular spectroscopy, Breast, Ferroelectric materials

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Proceedings Article | 10 March 2015 Paper

Comparison of optical projection tomography and optical coherence tomography for assessment of murine embryonic development

Manmohan Singh, Achuth Nair, Tegy Vadakkan, Victor Piazza, Ryan Udan, Michael Frazier, Trevor Janecek, Mary Dickinson, Kirill Larin

Proceedings Volume 9334, 93340J (2015) https://doi.org/10.1117/12.2078319

KEYWORDS: Optical coherence tomography, Projection systems, Tomography, Spatial resolution, Tissues, Image resolution, Imaging systems, Optical filters, Magnetism, Mirrors

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Showing 5 of 38 publications

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