1. Articles from Szymon Tamborski

    1-14 of 14
    1. Spectral and time domain optical coherence spectroscopy

      Spectral and time domain optical coherence spectroscopy

      We propose a novel method for spectroscopic optical coherence tomography (OCT). This method uses the dependence of the Doppler frequency spectrum on the wavenumber. Controlled modulation of the light in the spectral OCT interferometer allows for an instantaneous depth-resolved reconstruction of the backscattered light spectrum from all depths. The feasibility of the spectroscopic analysis using the proposed scheme was confirmed experimentally.

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    2. Blood flow rate estimation in optic disc capillaries and vessels using Doppler optical coherence tomography with 3D fast phase unwrapping

      Blood flow rate estimation in optic disc capillaries and vessels using Doppler optical coherence tomography with 3D fast phase unwrapping

      The retinal volumetric flow rate contains useful information not only for ophthalmo-logy but also for the diagnosis of common civilization diseases such as diabetes, Alzheimer's disease, or cerebrovascular diseases. Non-invasive optical methods for quantitative flow assessment, such as Doppler optical coherence tomography (OCT), have certain limitations. One is the phase wrapping that makes simultaneous calculations of the flow in all human retinal vessels impossible due to a very large span of flow velocities. We demonstrate that three-dimensional Doppler OCT combined with three-dimensional four Fourier transform fast phase unwrapping (3D 4FT FPU) allows for the calculation of the volumetric blood ...

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    3. In vivo brain imaging with multimodal optical coherence microscopy in a mouse model of thromboembolic photochemical stroke

      In vivo brain imaging with multimodal optical coherence microscopy in a mouse model of thromboembolic photochemical stroke

      We used a new multimodal imaging system that combines optical coherence microscopy and brightfield microscopy. Using this in vivo brain monitoring approach and cranial window implantation, we three-dimensionally visualized the vascular network during thrombosis, with high temporal (18 s) and spatial (axial, 2.5  μm; lateral, 2.2  μm) resolution. We used a modified mouse model of photochemical thromboembolic stroke in order to more accurately parallel human stroke. Specifically, we applied green laser illumination to focally occlude a branch of the middle cerebral artery. Despite the recanalization of the superficial arteries at 24 h after stroke, no blood flow was ...

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    4. Feature Of The Week 10/08/2017: Optical Coherence Microscopy as a Novel, Non-Invasive Method for the 4D Live Imaging of Early Mammalian Embryos

      Feature Of The Week 10/08/2017: Optical Coherence Microscopy as a Novel, Non-Invasive Method for the 4D Live Imaging of Early Mammalian Embryos

      Imaging of living cells based on traditional fluorescence and confocal laser scanning microscopy has delivered an enormous amount of information critical for understanding biological processes in single cells. However, the requirement for a high numerical aperture and fluorescent markers still limits researchers’ ability to visualize the cellular architecture without causing short- and long-term photodamage. Optical coherence microscopy (OCM) is a promising alternative that circumvents the technical limitations of fluorescence imaging techniques and provides unique access to fundamental aspects of early embryonic development, without the requirement for sample pre-processing or labeling. In the present paper, we utilized the internal motion of ...

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    5. Optical coherence microscopy as a novel, non-invasive method for the 4D live imaging of early mammalian embryos

      Optical coherence microscopy as a novel, non-invasive method for the 4D live imaging of early mammalian embryos

      Imaging of living cells based on traditional fluorescence and confocal laser scanning microscopy has delivered an enormous amount of information critical for understanding biological processes in single cells. However, the requirement for a high numerical aperture and fluorescent markers still limits researchers’ ability to visualize the cellular architecture without causing short- and long-term photodamage. Optical coherence microscopy (OCM) is a promising alternative that circumvents the technical limitations of fluorescence imaging techniques and provides unique access to fundamental aspects of early embryonic development, without the requirement for sample pre-processing or labeling. In the present paper, we utilized the internal motion of ...

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    6. Spectrometer calibration for spectroscopic Fourier domain optical coherence tomography

      Spectrometer calibration for spectroscopic Fourier domain optical coherence tomography

      We propose a simple and robust procedure for Fourier domain optical coherence tomography (FdOCT) that allows to linearize the detected FdOCT spectra to wavenumber domain and, at the same time, to determine the wavelength of light for each point of detected spectrum. We show that in this approach it is possible to use any measurable physical quantity that has linear dependency on wavenumber and can be extracted from spectral fringes. The actual values of the measured quantity have no importance for the algorithm and do not need to be known at any stage of the procedure. As example we calibrate ...

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    7. Extended-focus optical coherence microscopy for high-resolution imaging of the murine brain

      Extended-focus optical coherence microscopy for high-resolution imaging of the murine brain

      We propose a new method and optical instrumentation for mouse brain imaging based on extended-focus optical coherence microscopy. This in vivo imaging technique allows the evaluation of the cytoarchitecture at cellular level and the circulation system dynamics in three dimensions. This minimally invasive and non-contact approach is performed without the application of contrasting agents. The optical design achieved a resolution of 2.2 μm over a distance of 800 μm, which was sufficient to obtain a detailed three-dimensional image of a wild-type mouse’s brain down to the layer III of the cortex. Intrinsically contrasted microvessels and structures similar to ...

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    8. Imaging of the stroke-related changes in the vascular system of the mouse brain with the use of extended focus Optical Coherence Microscopy

      Imaging of the stroke-related changes in the vascular system of the mouse brain with the use of extended focus Optical Coherence Microscopy

      We used Optical Coherence Microscopy (OCM) to monitor structural and functional changes due to ischemic stroke in small animals brains in vivo. To obtain lateral resolution of 2.2 μm over the range of 600 μm we used extended focus configuration of OCM instrument involving Bessel beam. It provided access to detailed 3D information about the changes in brain vascular system up to the level of capillaries across I and II/III layers of neocortex. We used photothrombotic stroke model involving photoactive application of rose bengal to assure minimal invasiveness of the procedure and precise localization of the clot distribution ...

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    9. Spectroscopy by joint spectral and time domain optical coherence tomography

      Spectroscopy by joint spectral and time domain optical coherence tomography

      We present the methodology for spectroscopic examination of absorbing media being the combination of Spectral Optical Coherence Tomography and Fourier Transform Spectroscopy. The method bases on the joint Spectral and Time OCT computational scheme and simplifies data analysis procedure as compared to the mostly used windowing-based Spectroscopic OCT methods. The proposed experimental setup is self-calibrating in terms of wavelength-pixel assignment. The performance of the method in measuring absorption spectrum was checked with the use of the reflecting phantom filled with the absorbing agent (indocyanine green). The results show quantitative accordance with the controlled exact results provided by the reference method.

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    10. Wavelength to pixel calibration for FdOCT

      Wavelength to pixel calibration for FdOCT

      We show that in Fourier domain Optical Coherence Tomography (FdOCT) it is possible to determine the wavelength of light for each point of the detected spectrum using any measurable physical quantity that has linear dependency on wavenumber. The presented approach is robust as the actual values of the measured quantity have no importance for the algorithm. As example we calibrate a SOCT spectrometer using Doppler frequency induced in time-dependent spectral fringes by a mirror moving in one of the arm of the interferometer. The results of calibration are validated using narrow spectral lines generated by optical parametric oscillator

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    11. Assessment of the flow velocity of blood cells in a microfluidic device using joint spectral and time domain optical coherence tomography

      Assessment of the flow velocity of blood cells in a microfluidic device using joint spectral and time domain optical coherence tomography

      Although Doppler optical coherence tomography techniques have enabled the imaging of blood flow in mid-sized vessels in biological tissues, the generation of velocity maps of capillary networks remains a challenge. To better understand the origin and information content of the Doppler signal from small vessels and limitations of such measurements, we used joint spectral and time domain optical coherence tomography to monitor the flow in a model, semitransparent microchannel device. The results obtained for Intralipid, whole blood, as well as separated red blood cells indicate that the technique is suitable to record velocity profiles in vitro , in a range of ...

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    12. True velocity mapping using joint spectral and time domain optical coherence tomography

      True velocity mapping using joint spectral and time domain optical coherence tomography
      We present both axial and transverse components estimation using joint Spectral and Time domain Optical Coherence Tomography (STdOCT) method. Whereas axial component of velocity vector can be determined from the time-dependent Doppler beating frequency, the transverse component can be assessed by the analysis of the broadening of flow velocity profiles (Doppler bandwidth). This enables us to quantitatively determine the absolute value of the velocity vector. The accurate analyses are performed using well-defined flow of Intralipid solution in the glass capillary. This enables performing in vivo imaging and allows to calculate velocity maps of the retinal vasculature
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    13. Simultaneous analysis of flow velocity and spectroscopic properties of scattering media with the use of joint Spectral and Time domain OCT

      In this paper we describe how to simultaneously retrieve spectroscopic and flow velocity information of scattering media such as biological tissues with the use of Optical Coherence Tomography (OCT). The main problem which must be overcome during spectral information recovery is random speckle noise. It cannot be effectively removed if the medium is stationary. However, if during the measurement time there is a continuous change of locations of scattering particles causing the phase change, an efficient averaging of speckle-affected spectra takes place. In order to implement this idea we propose to make use of the measurement protocol of joined Spectral ...
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    14. Three-dimensional retinal blood flow analysis using joint spectral and time domain optical coherence tomography

      In this submission we demonstrate a new application of the joint Spectral and Time domain Optical Coherence Tomography (STdOCT) technique for segmenting and measuring the retinal blood flow velocity in three dimensions. The method is based on direct detection of Doppler shift that arises in time dur ... [Proc. SPIE 7163, 71630Q (2009)] published Wed Feb 18, 2009.
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    1-14 of 14
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  2. Topics in the News

    1. (14 articles) Nicolaus Copernicus University
    2. (14 articles) Maciej Szkulmowski
    3. (12 articles) Maciej Wojtkowski
    4. (3 articles) Daniel Szlag
    5. (3 articles) Andrzej A. Kowalczyk
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    True velocity mapping using joint spectral and time domain optical coherence tomography Assessment of the flow velocity of blood cells in a microfluidic device using joint spectral and time domain optical coherence tomography Wavelength to pixel calibration for FdOCT Imaging of the stroke-related changes in the vascular system of the mouse brain with the use of extended focus Optical Coherence Microscopy Extended-focus optical coherence microscopy for high-resolution imaging of the murine brain Spectrometer calibration for spectroscopic Fourier domain optical coherence tomography Optical coherence microscopy as a novel, non-invasive method for the 4D live imaging of early mammalian embryos Feature Of The Week 10/08/2017: Optical Coherence Microscopy as a Novel, Non-Invasive Method for the 4D Live Imaging of Early Mammalian Embryos Optical coherence tomography features of neovascularization in proliferative diabetic retinopathy: a systematic review Retinal microvascular metrics in untreated essential hypertensives using optical coherence tomography angiography Optical coherence tomography angiography findings of fellow eye of proliferative macular telangiectasia type 2: Long term study Reorganization of the perifoveal microvasculature after macular hole closure assessed via optical coherence tomography angiography