1. Articles from Maciej Szkulmowski

    1-24 of 61 1 2 3 »
    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. Spatiotemporal optical coherence (STOC) manipulation suppresses coherent cross-talk in full-field swept-source optical coherence tomography

      Spatiotemporal optical coherence (STOC) manipulation suppresses coherent cross-talk in full-field swept-source optical coherence tomography

      Full-field swept-source optical coherence tomography (FF-SS-OCT) provides high-resolution depth-resolved images of the sample by parallel Fourier-domain interferometric detection. Although FF-SS-OCT implements high-speed volumetric imaging, it suffers from the cross-talk-generated noise from spatially coherent lasers. This noise reduces the transversal image resolution, which in turn, limits the wide adaptation of FF-SS-OCT for practical and clinical applications. Here, we introduce the novel spatiotemporal optical coherence (STOC) manipulation. In STOC the time-varying inhomogeneous phase masks are used to modulate the light incident on the sample. By properly adjusting these phase masks, the spatial coherence can be reduced. Consequently, the cross-talk-generated noise is suppressed ...

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    5. Computationally effective 2D and 3D fast phase unwrapping algorithms and their applications to Doppler optical coherence tomography

      Computationally effective 2D and 3D fast phase unwrapping algorithms and their applications to Doppler optical coherence tomography

      We propose a simplification for a robust and easy to implement fast phase unwrapping (FPU) algorithm that is used to solve the phase wrapping problem encountered in various fields of optical imaging and metrology. We show that the number of necessary computations using the algorithm can be reduced compared to its original version. FPU can be easily extended from two to three spatial dimensions. We demonstrate the applicability of the two- and three-dimensional FPU algorithm for Doppler optical coherence tomography (DOCT) in numerical simulations, and in the imaging of a flow phantom and blood flow in the human retina in ...

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    6. 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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    7. 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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    8. 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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    9. 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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    10. Method and apparatus for imaging of semi-transparent matter

      Method and apparatus for imaging of semi-transparent matter

      The invention relates to a method and apparatus for measuring the spatial and velocity distribution of scattering structures of a sample in semi-transparent matter. The acquired spectral data I(k, t) are transformed in two steps to image data I(z, v). A Doppler shift is imposed on the light to a separate real and mirror images in the v space to suppress the complex ambiguity artifact.

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    11. Image capturing apparatus, image capturing method, and storage medium

      Image capturing apparatus, image capturing method, and storage medium

      An image capturing apparatus includes a dividing unit configured to divide light from a light source into reference light and measurement light; a first dichroic mirror arranged in a measurement optical path for guiding the measurement light to an object to be examined; a second dichroic mirror arranged in a reference optical path for guiding the reference light to a reference object; and a light receiving unit configured to receive interference light between the measurement light passing through the first dichroic mirror and the reference light passing through the second dichroic mirror.

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    12. 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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    13. 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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    14. 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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    15. Multimodal instrument for high-sensitivity autofluorescence and spectral optical coherence tomography of the human eye fundus

      Multimodal instrument for high-sensitivity autofluorescence and spectral optical coherence tomography of the human eye fundus

      In this paper we present a multimodal device for imaging fundus of human eye in vivo which combines functionality of autofluorescence by confocal SLO with Fourier domain OCT. Native fluorescence of human fundus was excited by modulated laser beam (λ = 473 nm, 20 MHz) and lock-in detection was applied resulting in improving sensitivity. The setup allows for acquisition of high resolution OCT and high contrast AF images using fluorescence excitation power of 50-65 μW without averaging consecutive images. Successful functioning of constructed device have been demonstrated for 8 healthy volunteers of different age ranging from 24 to 83 years old.

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    16. 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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    17. Quantitative lateral and axial flow imaging with optical coherence microscopy and tomography

      Quantitative lateral and axial flow imaging with optical coherence microscopy and tomography

      Optical coherence tomography (OCT) and optical coherence microscopy (OCM) allow the acquisition of quantitative three-dimensional axial flow by estimating the Doppler shift caused by moving scatterers. Measuring the velocity of red blood cells is currently the principal application of these methods. In many biological tissues, blood flow is often perpendicular to the optical axis, creating the need for a quantitative measurement of lateral flow. Previous work has shown that lateral flow can be measured from the Doppler bandwidth, albeit only for simplified optical systems. In this work, we present a generalized model to analyze the influence of relevant OCT/OCM ...

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    18. Averaging techniques for OCT imaging

      Averaging techniques for OCT imaging

      State-of-the-art Fourier-domain optical coherence tomography (OCT) allows for the acquisition of up to millions of spectral fringes per second. This large amount of data can be used to improve the quality of structural tomograms after effective averaging. Here, we compare three OCT image improvement techniques: magnitude averaging, complex averaging, and spectral and time domain OCT (STdOCT). We evaluate the performance for images on both linear and logarithmic intensity scales and discuss their advantages and disadvantages. We propose the use of the STdOCT approach as it offers the best advantages. Applications to in vivo imaging and speckle reduction are presented.

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    19. Feature Of The Week 11/25/12: Nicolaus Copernicus University Presents Work on Four-Dimensional OCT Imaging Using Graphics Processing Units

      Feature Of The Week 11/25/12: Nicolaus Copernicus University Presents Work on Four-Dimensional OCT Imaging Using Graphics Processing Units

      Nicolaus Copernicus University present the application of graphics processing unit (GPU) programming for real-time three-dimensional (3-D) Fourier domain optical coherence tomography (FdOCT) imaging with implementation of flow visualization algorithms. One of the limitations of FdOCT is data processing time, which is generally longer than data acquisition time. Utilizing additional algorithms, such as Doppler analysis, further increases computation time. The general purpose computing on GPU (GPGPU) has been used successfully for structural OCT imaging, but real-time 3-D imaging of flows has so far not been presented. NCU has developed software for structural and Doppler OCT processing capable of visualization of two-dimensional ...

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    20. Improved measurement of vibration amplitude in dynamic optical coherence elastography

      Improved measurement of vibration amplitude in dynamic optical coherence elastography

      Optical coherence elastography employs optical coherence tomography (OCT) to measure the displacement of tissues under load and, thus, maps the resulting strain into an image, known as an elastogram. We present a new improved method to measure vibration amplitude in dynamic optical coherence elastography. The tissue vibration amplitude caused by sinusoidal loading is measured from the spread of the Doppler spectrum, which is extracted using joint spectral and time domain signal processing. At low OCT signal-to-noise ratio (SNR), the method provides more accurate vibration amplitude measurements than the currently used phase-sensitive method. For measurements performed on a mirror at OCT ...

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    21. Four-dimensional structural and Doppler optical coherence tomography imaging on graphics processing units

      Four-dimensional structural and Doppler optical coherence tomography imaging on graphics processing units

      The authors present the application of graphics processing unit (GPU) programming for real-time three-dimensional (3-D) Fourier domain optical coherence tomography (FdOCT) imaging with implementation of flow visualization algorithms. One of the limitations of FdOCT is data processing time, which is generally longer than data acquisition time. Utilizing additional algorithms, such as Doppler analysis, further increases computation time. The general purpose computing on GPU (GPGPU) has been used successfully for structural OCT imaging, but real-time 3-D imaging of flows has so far not been presented. We have developed software for structural and Doppler OCT processing capable of visualization of two-dimensional (2-D ...

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    22. Optical Coherence Tomography Apparatus And Method With Speckle Suppression

      Optical Coherence Tomography Apparatus And Method With Speckle Suppression

      The invention relates to an optical coherence tomography apparatus and method. It improves speckle suppression by modifying the scanning trajectory (18) of the probing light beam so that groups of A scans close to the imaged segments (22) can be recorded and averaged. The invention facilitates effective speckle suppression combined with high resolution and little dependence of sample motions during the measurement.

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    23. Multi-parametric imaging of murine brain using spectral and time domain optical coherence tomography

      Multi-parametric imaging of murine brain using spectral and time domain optical coherence tomography

      Examination of brain functions in small animal models may help improve the diagnosis and treatment of neurological conditions. Transcranial imaging of small rodents’ brains poses a major challenge for optical microscopy. Another challenge is to reduce the measurement time. We describe methods and algorithms for three-dimensional assessment of blood flow in the brains of small animals, through the intact skull, using spectral and time domain optical coherence tomography. By introducing a resonant scanner to the optical setup of the optical coherence tomography (OCT) system, we have developed and applied a high-speed spectral OCT technique that allows us to vary the ...

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    24. Microfluidics analysis of blood using joint spectral and time domain optical coherence tomography

      Microfluidics analysis of blood using joint spectral and time domain optical coherence tomography

      Although the Doppler Optical Coherence Tomography techniques have already enabled imaging of blood flow in large vessels in biological tissues, the generation of velocity maps of the capillary network is still a challenge. Since several important physiological and pathological phenomena occur in the microcirculation, the possibility of flow imaging and velocity assessment in microcapillaries may be important for medical diagnostics. Understanding of the origin of the Doppler signal in capillary vessels and limitations of such measurements is essential for further development of Doppler OCT methods. In the OCT flow maps of a microcapillary network randomly varying Doppler signals are observed ...

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    1-24 of 61 1 2 3 »
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    1. (58 articles) Maciej Szkulmowski
    2. (54 articles) Nicolaus Copernicus University
    3. (50 articles) Maciej Wojtkowski
    4. (25 articles) Andrzej A. Kowalczyk
    5. (19 articles) Daniel Szlag
    6. (17 articles) Anna Szkulmowska
    7. (14 articles) Tomasz Bajraszewski
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    10. (7 articles) Bartlomiej J. Kaluzny
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    Flow velocity estimation using joint Spectral and Time domain Optical Coherence Tomography Optical Coherence Tomography for Tracking Canvas Deformation Comparison of reflectivity maps and outer retinal topography in retinal disease by 3-D Fourier domain optical coherence tomography Ultra high-speed swept source OCT imaging of the anterior segment of human eye at 200 kHz with adjustable imaging range Real-time imaging for Spectral Optical Coherence Tomography with massively parallel data processing 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 Clinical Usefulness of a Novel Optical Coherence Tomography Procedure, “Low Molecular Weight Dextran Infusion Followed by Catheter PUSH (D-PUSH)” Optical Coherence Tomography to Guide Percutaneous Coronary Intervention of the Left Main Coronary Artery: the LEMON study Impact of optical coherence tomography findings on clinical outcomes in ST-segment elevation myocardial infarction patients: a MATRIX (Minimizing Adverse Hemorrhagic Events by Trans-radial Access Site and angioX) OCT sub-study OCTA Multilayer and Multisector Peripapillary Microvascular Modeling for Diagnosing and Staging of Glaucoma Optical coherence tomography angiography for identifying choroidal neovascular membranes: a masked study in clinical practice Preclinical ocular features in patients with Behçet’s disease detected by optical coherence tomography angiography