1. Articles from Anna Szkulmowska

    1-24 of 24
    1. Professor Andrzej Kowalczyk Celebration Gala

      Professor Andrzej Kowalczyk Celebration Gala

      On September 15 th 2018, the Institute of Physics at Nicolaus Copernicus University in Toruń, Poland, held a special event to celebrate the academic achievements of Professor Andrzej Kowalczyk, on the occasion of his retirement. Professor Kowalczyk has been a great mentor, teacher, scholar and ambassador of science over his lengthy career. At the conclusion of his PhD thesis viva voce on spectroscopy, the great Jabłoński, the grandfather of fluorescence, said “Too much Chemistry, Dr Kowalczyk!” A great part of his scientific work has, indeed, been devoted to the development of spectral domain optical coherence tomography – pure optics, and his ...

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    2. 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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    3. Differentiation of morphotic elements in human blood using optical coherence tomography and a microfluidic setup

      Differentiation of morphotic elements in human blood using optical coherence tomography and a microfluidic setup

      We demonstrate a novel optical method for the detection and differentiation between erythrocytes and leukocytes that uses amplitude and phase information provided by optical coherence tomography (OCT). Biological cells can introduce significant phase modulation with substantial scattering anisotropy and dominant forward-scattered light. Such physical properties may favor the use of a trans-illumination imaging technique. However, an epi-illumination mode may be more practical and robust in many applications. This study describes a new way of measuring the phase modulation introduced by flowing microobjects. The novel part of this invention is that it uses the backscattered signal from the substrate located below ...

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    4. Detection of small biological objects by phase-sensitive optical coherence tomography

      Detection of small biological objects by phase-sensitive optical coherence tomography

      We demonstrate a novel label-free OCT method allowing optical detection and differentiation of moving micro-objects, such as blood cells. In this study we use phase-sensitive Fd-OCT/OCM system with broadband light source (axial resolution: 3 μm in tissue and lateral resolution 4−8 μm) and fluidic sample setup. The novel part of this method is that the optical identification is based on optical signal coming from optically uniform scattering media localized beneath the flowing/moving objects and not from the objects itself. This signal reveals as an enhancement in speckle pattern on intensity images and non-zero phase change on phase ...

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    5. Apparatus for optical frequency domain tomography with adjusting system

      Apparatus for optical frequency domain tomography with adjusting system

      In an apparatus for imaging of objects by applying optical frequency domain tomography and provided with an adjusting system for setting a relative position of photosensitive elements (174) and a spectrum image (273), the adjusting system is an automatically controlled device causing a relative displacement of at least one photosensitive element (174) of the detection device (173) of the spectrum and the spectrum image (273) between each other. The adjusting system comprises at least one actuator (14, 16) acting on the dispersion device (171) and/or the set of optical elements (172) and/or the detection device (173) and movement ...

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    6. High-speed optical coherence imaging: towards the structure and the physiology of living tissue

      High-speed optical coherence imaging: towards the structure and the physiology of living tissue
      Recently rapid development of ultrahigh speed optical coherence tomography (OCT) instruments have been observed. This imaging modality enables performing cross-sectional in vivo imaging of biological samples with speeds of more than 100,000,000 axial scans per second. This progress has been achieved by the introduction of Fourier domain detection techniques to OCT instruments. High-speed imaging capabilities lifts the primary limitation of early OCT technology by giving access to in vivo 3-D volumetric reconstructions in large scales within reasonable time constraints. New perspectives for existing OCT applications has been added by creating new instrumentation including the functional imaging. The latter ...
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    7. Real-time bulk motion insensitive flow segmentation algorithm for doppler spectral optical coherence tomography

      Real-time bulk motion insensitive flow segmentation algorithm for doppler spectral optical coherence tomography
      We present a simple and efficient numerical technique for segmentation retinal and choroidal blood vasculature with bulk motion correction in functional Doppler Spectral Optical Coherence Tomography (Doppler SOCT). The technique uses local variance of velocity tomogram which is higher in the areas of the tomogram with internal flow. The resulting variance map reveals the position of vessels. This can be used either for vessel segmentation purposes or for masking the vessels on velocity tomograms. The remaining velocity information is connected only with static structure velocity offset. As only Fourier transformations are used in calculations the algorithm removes the bulk motion ...
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    8. Scanning protocols dedicated to smart velocity ranging in Spectral OCT

      Scanning protocols dedicated to smart velocity ranging in Spectral OCT
      We introduce a new type of scanning protocols, called segmented protocols, which enable extracting multi-range flow velocity information from a single Spectral OCT data set. The protocols are evaluated using a well defined flow in a glass capillary. As an example of in vivo studies, we demonstrate two- and three-dimensional imaging of the retinal vascular system in the eyes of healthy volunteers. The flow velocity detection is performed using a method of Joint Spectral and Time domain OCT. Velocity ranging is demonstrated in imaging of retinal vasculature in the macular region and in the optic disk area characterized by different ...
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    9. Flow velocity estimation by complex ambiguity free joint Spectral and Time domain Optical Coherence Tomography

      Flow velocity estimation by complex ambiguity free joint Spectral and Time domain Optical Coherence Tomography
      We show that recently introduced joint Spectral and Time domain Optical Coherence Tomography (STdOCT) can be used for simultaneous complex ambiguity removal and functional Spectral OCT images. This permits to take advantage of higher sensitivity achievable near the zero-path delay. The technique can be used with all Spectral OCT systems that are equipped with an optical delay line (ODL) and provide oversampled scanning patterns. High sensitivity provided by STdOCT allows this technique to be used in Spectral OCT setups with acquisition speed of 100 000 lines/s. We show that different imaging ranges and velocity ranges can be achieved by ...
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    10. 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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    11. Three-dimensional quantitative imaging
of retinal and choroidal blood flow velocity using joint Spectral and Time domain Optical Coherence Tomography

      Three-dimensional quantitative imaging
of retinal and choroidal blood flow velocity using joint Spectral and Time domain Optical Coherence Tomography
      Recently, joint Spectral and Time domain Optical Coherence Tomography (joint STdOCT) has been proposed to measure ocular blood flow velocity. Limitations of CCD technology allowed only for two-dimensional imaging at that time. In this paper we demonstrate fast three-dimensional STdOCT based on ultrahigh speed CMOS camera. Proposed method is straightforward, fully automatic and does not require any advanced image processing techniques. Three-dimensional distributions of axial velocity components of the blood in human eye vasculature are presented: in retinal and, for the first time, in choroidal layer. Different factors that affect quality of velocity images are discussed. Additionally, the quantitative measurement ...
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    12. Simultaneous complex ambiguity removal and quantitative flow velocity estimation with joint spectral and time domain OCT

      , , et al. We show that recently developed joint Spectral and Time Optical Coherence Tomography data analysis scheme combined with oscillatory change of optical path difference allows for simultaneous complex ambiguity removal and quantitative flow velocity estimation. Full range structural tomograms as well a ... [Proc. SPIE 7168, 71681K (2009)] published Thu Feb 19, 2009.
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    13. Segmentation of flowing particles using joint spectral and time domain optical coherence tomography

      We propose a modified method of acquisition and analysis of Spectral Optical Coherence Tomography (SOCT) data to provide information about flow velocities in three dimensions. Joint Spectral and Time domain Optical Coherence Tomography (joint STdOCT) enables flow velocity assessment and segmentation ... [Proc. SPIE 7168, 71680C (2009)] published Thu Feb 19, 2009.
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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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    15. Fuchs’ Endothelial Dystrophy in 830-nm Spectral Domain Optical Coherence Tomography

      This article presents for the first time the potential of 830-nm spectral domain optical coherence tomography (SD-OCT) in the evaluation of Fuchs’ endothelial dystrophy. SD-OCT is an imaging technique that can be used for in vivo cross-sectional corneal visualization. The important features of SD-OCT instruments include improved sensitivity and short acquisition time, which improves the quality of the tomograms compared with conventional time domain OCT. Tomograms of the corneas of three patients in different stages of Fuchs’ endothelial dystrophy are presented. The authors conclude that 830-nm SDOCT provides clinically valuable cross-sectional assessment of pathomorphological changes in Fuchs’ endothelial dystrophy in ...
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    16. Analysis of the Outer Retina Reconstructed by High-resolution, Three-dimensional Spectral Domain Optical Coherence Tomography

      BACKGROUND AND OBJECTIVE A retrospective cross-sectional study was conducted to demonstrate an analysis of an outer retinal layer reconstructed by the three-dimensional and high-speed spectral domain optical coherence tomography (SD-OCT) instrument. PATIENTS AND METHODS New measurement protocols for SD-OCT and methods of analysis and visualization of the individual segmented retinal layer reconstructed by SD-OCT were proposed. Three contour maps representing mutual distances between the basal part of the retinal pigment epithelium, the junction between the inner and outer segments of photoreceptors, and a reference contour representing the shape of a healthy retina were introduced. RESULTS The analysis of the outer ...
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    17. Phase-resolved Doppler optical coherence tomography—limitations and improvements

      Anna Szkulmowska, Maciej Szkulmowski, Andrzej Kowalczyk, Maciej WojtkowskiWe describe how the simple phase difference averaging causes a systematic bias in the velocity estimation obtained by phase-resolved Fourier domain optical coherence tomography (FdOCT). The magnitude of this bias depends on the signal-to-noise ratio as well as proximity of the measured velocity to ... [Opt. Lett. 33, 1425-1427 (2008)]
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    18. Flow velocity estimation using joint Spectral and Time domain Optical Coherence Tomography

      Flow velocity estimation using joint Spectral and Time domain Optical Coherence Tomography
      Maciej Szkulmowski, Anna Szkulmowska, Tomasz Bajraszewski, Andrzej Kowalczyk, Maciej Wojtkowski We propose a modified method of acquisition and analysis of Spectral Optical Coherence Tomography (SOCT) data to provide information about flow velocities. The idea behind this method is to acquire a set of SOCT spectral fringes dependent on time followed by a numerical analysis using two ... [Opt. Express 16, 6008-6025 (2008)]
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    19. Improved spectral optical coherence tomography using optical frequency comb

      Tomasz Bajraszewski, Maciej Wojtkowski, Maciej Szkulmowski, Anna Szkulmowska, Robert Huber, Andrzej Kowalczyk. We identify and analyze factors influencing sensitivity drop-off in Spectral OCT and propose a system employing an Optical Frequency Comb (OFC) to verify this analysis. Spectral Optical Coherence Tomography using a method based on an optical frequency comb is demonstrated. Since the spectrum ... [Opt. Express 16, 4163-4176 (2008)]
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    20. Simultaneous analysis of extinction and flow velocity with joint spectral and time domain OCT

      Maciej Wojtkowski, Maciej Szkulmowski, Tomasz Bajraszewski et al. In this contribution we propose a new method of acquisition and analysis of Spectral Optical Coherence Tomography data to obtain information about depth dependent extinction in the scattering media. In joint Spectral and Time domain OCT a set of Spectral Optical Coherence Tomography fringes is acqui ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 68471M (2008)] published Mon Feb 18, 2008.
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    21. Flow velocity analysis with joint spectral and time domain OCT

      Maciej Szkulmowski, Maciej Wojtkowski, Anna Szkulmowska et al. We propose a new method of acquisition and analysis of Spectral Optical Coherence Tomography data. The method acquires a set of SOCT spectral fringes as a function of time. The Fourier analysis of such data allows for investigation of various functional aspects of analyzed tissue. We show that Doppl ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 68471K (2008)] published Mon Feb 18, 2008.
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    22. Spectral Optical Coherence Tomography in Video-Rate and 3D Imaging of Contact Lens Wear

      Optometry & Vision Science. 84(12):E1104-E1109, December 2007. KALUZNY, BARTLOMIEJ J. MD, PhD; FOJT, WOJCIECH Dipl Ing; SZKULMOWSKA, ANNA MSc; BAJRASZEWSKI, TOMASZ MSc; WOJTKOWSKI, MACIEJ PhD; KOWALCZYK, ANDRZEJ PhD Abstract: Purpose. To present the applicability of spectral optical coherence tomography (SOCT) for video-rate and three-dimensional imaging of a contact lens on the eye surface. Methods. The SOCT prototype instrument constructed at Nicolaus Copernicus University (Torun, Poland) is b
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    23. Retinal blood flow analysis using joint spectral and time domain optical coherence tomography

      Anna Szkulmowska, Maciej Szkulmowski, Tomasz Bajraszewski et al. We propose a new technique of measuring and analysis of OCT signals: joint Spectral and Time domain Optical Coherence Tomography (STdOCT). This technique is based on a multiple spectral interferogram registration in time increments. The analysis of a single spectral interferogram provides an axial s ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68440K (2008)] published Mon Feb 11, 2008.
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    1-24 of 24
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    1. (23 articles) Anna Szkulmowska
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