Browsing College of Science by Author "Alexandrov, Sergey"
Now showing items 1-20 of 28
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Accessing depth-resolved high spatial frequency content from the optical coherence tomography signal
Alexandrov, Sergey; Arangath, Anand; Zhou, Yi; Murphy, Mary; Duffy, Niamh; Neuhaus, Kai; Shaw, Georgina; McAuley, Ryan; Leahy, Martin (Nature Research, 2021-08-24)Optical coherence tomography (OCT) is a rapidly evolving technology with a broad range of applications, including biomedical imaging and diagnosis. Conventional intensity-based OCT provides depth-resolved imaging with a ... -
Audio frequency in vivo optical coherence elastography
Adie, Steven G.; Kennedy, Brendan F.; Armstrong, Julian J.; Alexandrov, Sergey; Sampson, David (IOP Publishing, 2009-05-06)We present a new approach to optical coherence elastography (OCE), which probes the local elastic properties of tissue by using optical coherence tomography to measure the effect of an applied stimulus in the audio frequency ... -
Characterization of an amplified piezoelectric actuator for multiple reference optical coherence tomography
O'Gorman, Sean; Neuhaus, Kai; Alexandrov, Sergey; Hogan, Josh; Wilson, Carol; McNamara, Paul M.; Leahy, Martin (Optica, 2018-08-30)The characterization of an amplified piezoelectric actuator (APA) as a new axial scanning method for multiple-reference optical coherence tomography (MR-OCT) is described. MR-OCT is a compact optical imaging device based ... -
Characterization of nanosensitive multifractality in submicron scale tissue morphology and its alteration in tumor progression
Das, Nandan; Alexandrov, Sergey; Gilligan, Katie E.; Dwyer, Róisín M.; Saager, Rolf B.; Ghosh, Nirmalya; Leahy, Martin (Society of Photo-optical Instrumentation Engineers, 2021-01-11)Significance: Assessment of disease using optical coherence tomography is an actively investigated problem, owing to many unresolved challenges in early disease detection, diagnosis, and treatment response monitoring. The ... -
Feasibility of correlation mapping optical coherence tomography angiographic technique using a 200 kHz vertical-cavity surface-emitting laser source for in vivo microcirculation imaging applications
Lal, Cerine; Subhash, Hrebesh M.; Alexandrov, Sergey; Leahy, Martin J. (Optica, 2018-08-01)Optical coherence tomography (OCT) angiography is a well-established in vivo imaging technique to assess the overall vascular morphology of tissues and is an emerging field of research for the assessment of blood flow ... -
Functional imaging for regenerative medicine
Leahy, Martin; Thompson, Kerry; Zafar, Haroon; Alexandrov, Sergey; Foley, Mark; O’Flatharta, Cathal; Dockery, Peter (BMC, 2016-04-19)In vivo imaging is a platform technology with the power to put function in its natural structural context. With the drive to translate stem cell therapies into pre-clinical and clinical trials, early selection of the right ... -
High-resolution, wide-field object reconstruction with synthetic aperture Fourier holographic optical microscopy
Hillman, Timothy R.; Gutzler, Thomas; Alexandrov, Sergey; Sampson, David (Optica, 2009)We utilize synthetic-aperture Fourier holographic microscopy to resolve micrometer-scale microstructure over millimeter-scale fields of view. Multiple holograms are recorded, each registering a different, limited region ... -
In vivo correlation mapping microscopy
McGrath, James; Alexandrov, Sergey; Owens, Peter; Subhash, Hrebesh; Leahy, Martin (Society of Photo-optical Instrumentation Engineers (SPIE), 2016-03)To facilitate regular assessment of the microcirculation in vivo, noninvasive imaging techniques such as nailfold capillaroscopy are required in clinics. Recently, a correlation mapping technique has been applied to optical ... -
Interference method for determination of the refractive index and thickness
Alexandrov, Sergey; Chernyh, Igor V. (Society of Photo-optical Instrumentation Engineers, 2000-09-01)The interference method for simultaneous measurement of the absolute refractive index and the thickness of plane parallel samples is developed. This method enables us to test solid (including optical glasses, crystals, ... -
Investigation of depth-resolved nanoscale structural changes in regulated cell proliferation and chromatin decondensation
Uttam, Shikhar; Bista, Rajan K.; Staton, Kevin; Alexandrov, Sergey; Choi, Serah; Bakkenist, Christopher J.; Hartman, Douglas J.; Brand, Randall E.; Liu, Yang (2013)We present depth-resolved spatial-domain low-coherence quantitative phase microscopy, a simple approach that utilizes coherence gating to construct a depth-resolved structural feature vector quantifying sub-resolution axial ... -
Investigation of nanoscale structural alterations of cell nucleus as an early sign of cancer
Alexandrov, Sergey (BioMed Central, 2014)Background: The cell and tissue structural properties assessed with a conventional bright-field light microscope play a key role in cancer diagnosis, but they sometimes have limited accuracy in detecting early-stage cancers ... -
Label free ultra-sensitive imaging with sub-diffraction spatial resolution
Alexandrov, Sergey; Das, Nandan; McGrath, James; Owens, Peter; Sheppard, Colin J. R.; Boccafoschi, Francesca; Giannini, Cinzia; Sibillano, Teresa; Subhash, Hrebesh; Leahy, Martin (IEEE, 2019-07-09)In this paper, we show a new way to break the resolution limit and dramatically improve sensitivity to structural changes. To realize it we developed a novel label free contrast mechanism, based on the spectral encoding ... -
Label-free ultra-sensitive visualization of structure below the diffraction resolution limit
Alexandrov, Sergey; McGrath, James; Sheppard, Colin J. R.; Boccafoschi, Francesca; Giannini, Cinzia; Sibillano, Teresa; Subhash, Hrebesh; Hogan, Josh; Leahy, Martin (Wiley, 2018-03-23)For both fundamental study of biological processes and early diagnosis of diseases, information about nanoscale changes in tissue and cell structure is crucial. Nowadays, almost all currently known nanoscopy methods rely ... -
Microscopic particle discrimination using spatially-resolved Fourier-holographic light scattering angular spectroscopy
Hillman, Timothy R.; Alexandrov, Sergey; Gutzler, Thomas; Sampson, David D. (Optica, 2006-11-13)We utilize Fourier-holographic light scattering angular spectroscopy to record the spatially resolved complex angular scattering spectra of samples over wide fields of view in a single or few image captures. Without resolving ... -
Nano-sensitive optical coherence tomography
Alexandrov, Sergey; Subhash, Hrebesh M.; Zam, Azhar; Leahy, Martin (Royal Society of Chemistry, 2014)Depth resolved label-free detection of structural changes with nanoscale sensitivity is an outstanding problem in the biological and physical sciences and has significant applications in both the fundamental research and ... -
Nanosensitive optical coherence tomography for the study of changes in static and dynamic structures
Subhash, Hrebesh M.; Leahy, Martin; Alexandrov, Sergey (IOP Science, 2014-03-06)We briefly discuss the principle of image formation in Fourier domain optical coherence tomography (OCT). The theory of a new approach to improve dramatically the sensitivity of conventional OCT is described. The approach ... -
Nanosensitive optical coherence tomography to assess wound healing within the cornea
Lal, Cerine; Alexandrov, Sergey; Rani, Sweta; Zhou, Yi; Ritter, Thomas; Leahy, Martin (Optical Society of America, 2020-05-01)Optical coherence tomography (OCT) is a non-invasive depth resolved optical imaging modality, that enables high resolution, cross-sectional imaging in biological tissues and materials at clinically relevant depths. Though ... -
Noninvasive detection of nanoscale structural changes in cornea associated with cross-linking treatment
Zhou, Yi; Alexandrov, Sergey; Nolan, Andrew; Das, Nandan; Dey, Rajib; Leahy, Martin (Wiley, 2020-02-17)Corneal cross-linking (CXL) using ultraviolet-A (UVA) irradiation with a riboflavin photosensitizer has grown from an interesting concept to a practical clinical treatment for corneal ectatic diseases globally, such as ... -
Novel approach for label free super-resolution imaging in far field
Alexandrov, Sergey; McGrath, James; Hrebesh, Subhash; Leahy, Martin (Nature Publishing Group, 2015)Progress in the emerging areas of science and technology, such as bio- and nano-technologies, depends on development of corresponding techniques for imaging and probing the structures with high resolution. Recently, the ... -
Performance review of multiple reference versus time domain optical coherence tomography
Neuhaus, Kai; McNamara, Paul M.; Alexandrov, Sergey; O'Gorman, Seán; Hogan, Josh; Wilson, Carol; Leahy, Martin J. (IEEE, 2018-04-19)We present a detailed characterization of noise sources in multiple reference optical coherence tomography (MR-OCT) compared to time-domain OCT (TD-OCT). The noise characteristics were modeled based on the TD-OCT noise ...