1. Articles from Andrzej Kowalczyk

    1-24 of 36 1 2 »
    1. 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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    2. 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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    3. Fourier domain OCT imaging of American cockroach nervous system

      Fourier domain OCT imaging of American cockroach nervous system

      In this pilot study we demonstrate results of structural Fourier domain OCT imaging of the nervous system of Periplaneta americana L. (American cockroach). The purpose of this research is to develop an OCT apparatus enabling structural imaging of insect neural system. Secondary purpose of the presented research is to develop methods of the sample preparation and handling during the OCT imaging experiments. We have performed imaging in the abdominal nerve cord excised from the American cockroach. For this purpose we have developed a Fourier domain / spectral OCT system operating at 820 nm wavelength range.

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    4. 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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    5. Efficient reduction of speckle noise in Optical Coherence Tomography

      Efficient reduction of speckle noise in Optical Coherence Tomography
      Speckle pattern, which is inherent in coherence imaging, influences significantly axial and transversal resolution of Optical Coherence Tomography (OCT) instruments. The well known speckle removal techniques are either sensitive to sample motion, require sophisticated and expensive sample tracking systems, or involve sophisticated numerical procedures. As a result, their applicability to in vivo real-time imaging is limited. In this work, we propose to average multiple A-scans collected in a fully controlled way to reduce the speckle contrast. This procedure involves non-coherent averaging of OCT A-scans acquired from adjacent locations on the sample. The technique exploits scanning protocol with fast beam deflection ...
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    6. Feature Of The Week 11/6/11: Nicolaus Copernicus University Researchers Develop Technique to Study Biomechanical Properties of The Cornea Using OCT

      Feature Of The Week 11/6/11: Nicolaus Copernicus University Researchers Develop Technique to Study Biomechanical Properties of The Cornea Using OCT
      Researchers from Nicolaus Copernicus University have a long history of development of OCT in general and ophthalmology in particular. Recently NCU developed a technique to study the mechanical dynamics of the cornea using high speed OCT combined with an air puff system. Below is a summary of their work.We present a novel method and instrument for in vivo imaging and measurement of the human corneal dynamics during an air puff. The instrument is based on high-speed swept source optical coherence tomography (ssOCT) combined with a custom adapted air puff chamber from a non-contact tonometer, which uses an air stream ...
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    7. Assessment of corneal dynamics with high-speed swept source Optical Coherence Tomography combined with an air puff system

      Assessment of corneal dynamics with high-speed swept source Optical Coherence Tomography combined with an air puff system
      We present a novel method and instrument for in vivo imaging and measurement of the human corneal dynamics during an air puff. The instrument is based on high-speed swept source optical coherence tomography (ssOCT) combined with a custom adapted air puff chamber from a non-contact tonometer, which uses an air stream to deform the cornea in a non-invasive manner. During the short period of time that the deformation takes place, the ssOCT acquires multiple A-scans in time (M-scan) at the center of the air puff, allowing observation of the dynamics of the anterior and posterior corneal surfaces as well as ...
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    8. Segmented scanning protocols for speckle contrast reduction in Spectral OCT images

      Segmented scanning protocols for speckle contrast reduction in Spectral OCT images

      Recently introduced smart scanning protocols called segmented protocols offer possibility to create Spectral Optical Coherence Tomography images with strongly reduced speckle contrast. The algorithm is fast, robust and gives cross-sectional images with preserved high lateral resolution. To obtain efficient speckle reduction only slight modification to the optical setup is required. Cross-sectional images of anterior and posterior parts of the human eye with reduced speckle noise are presented.

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    9. 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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    10. Imaging of the lens capsule with an ultrahigh-resolution spectral optical coherence tomography prototype based on a femtosecond laser

      Aim To demonstrate the applicability of ultrahigh-speed, ultrahigh-resolution spectral optical coherence tomography (SOCT) to cross-sectional imaging of the capsular bag in vivo. Methods The ultrahigh-speed and ultrahigh-resolution SOCT prototype was designed and constructed at Nicolaus Copernicus University (Torun, Poland). To obtain an ultrahigh speed up to 100 000 lines/s a new spectrometer with fast CMOS line-scan camera was built. A femtosecond laser with a central wavelength of 780 nm and =160 nm enabled imaging with an axial resolution of 2.3 µm and lateral resolution of 10 µm in tissue. Lens capsules of two healthy eyes were examined with ...
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    11. 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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    12. 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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    13. 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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    14. Ultra high-speed swept source OCT imaging of the anterior segment of human eye at 200 kHz with adjustable imaging range

      Ultra high-speed swept source OCT imaging of the anterior segment of human eye at 200 kHz with adjustable imaging range
      We present an application of in vivo anterior segment imaging of the human eye with an ultrahigh speed swept source OCT instrument. For this purpose, a dedicated OCT system was designed and constructed. This instrument enables axial zooming by automatic reconfiguration of spectral sweep range; an enhanced imaging range mode enables imaging of the entire anterior segment while a high axial resolution mode provides detailed morphological information of the chamber angle and the cornea. The speed of 200,000 lines/s enables high sampling density in three-dimensional imaging of the entire cornea in 250 ms promising future applications of OCT ...
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    15. 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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    16. 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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    17. 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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    18. Anterior segment imaging with Spectral OCT system using a high-speed CMOS camera

      Anterior segment imaging with Spectral OCT system using a high-speed CMOS camera
      We describe a new ultrahigh speed Spectral OCT instrument making use of a CMOS camera and demonstrate high quality in vivo imaging of the anterior segment of the human eye. The high flexibility of the designed imaging system allows a wide range of imaging protocols. Two- and three-dimensional high ... [Opt. Express 17, 4842-4858 (2009)]
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    19. Comparison of reflectivity maps and outer retinal topography in retinal disease by 3-D Fourier domain optical coherence tomography

      Comparison of reflectivity maps and outer retinal topography in retinal disease by 3-D Fourier domain optical coherence tomography
      We demonstrate and compare two image processing methods for visualization and analysis of three-dimensional optical coherence tomography (OCT) data acquired in eyes with different retinal pathologies. A method of retinal layer segmentation based on a multiple intensity thresholding algorithm was ... [Opt. Express 17, 4189-4207 (2009)]
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    20. 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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    21. 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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    22. 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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    23. Swept source OCT imaging of human anterior segment at 200 kHz

      Karol Karnowski, Michalina Gora, Bartlomiej Kaluzny et al. We present applicability of the high speed swept-source optical coherence tomography for in vivo imaging of the anterior segment of the human eye. Three dimensional imaging of the cornea with reduced motion artifacts is possible by using swept source with Fourier domain mode locking operating at 200 ... [Proc. SPIE 7163, 716308 (2009)] published Wed Feb 18, 2009.
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    24. 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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    1-24 of 36 1 2 »
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  2. Topics in the News

    1. (33 articles) Andrzej A. Kowalczyk
    2. (32 articles) Maciej Wojtkowski
    3. (31 articles) Nicolaus Copernicus University
    4. (27 articles) Maciej Szkulmowski
    5. (19 articles) Anna Szkulmowska
    6. (11 articles) Daniel Szlag
    7. (10 articles) Ireneusz Grulkowski
    8. (9 articles) Bartlomiej J. Kaluzny
    9. (9 articles) Tomasz Bajraszewski
    10. (9 articles) Iwona Gorczynska
    11. (1 articles) UC Davis
    12. (1 articles) Robert J. Zawadzki
    13. (1 articles) Mehdi Azimipour
    14. (1 articles) John S. Werner
    15. (1 articles) Ravi S. Jonnal
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    Flow velocity estimation using joint Spectral and Time domain Optical Coherence Tomography Comparison of reflectivity maps and outer retinal topography in retinal disease by 3-D Fourier domain optical coherence tomography Anterior segment imaging with Spectral OCT system using a high-speed CMOS camera Ultra high-speed swept source OCT imaging of the anterior segment of human eye at 200 kHz with adjustable imaging range Optoretinography: optical measurements of human cone and rod photoreceptor responses to light Nodular skin lesions: correlation of reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) features OCT and Ophthalmology in the Age of Artificial Intelligence, Tuesday Oct 8, 2019 1:00P EDT Compensation for the Influence of Fluctuations in the Distance to the Object During Noncontact Probing in Spectral Domain Optical Coherence Tomography Pattern electroretinogram changes in patients with primary open-angle glaucoma in correlation with visual field and optical coherence tomography changes Objective evaluation of proliferative diabetic retinopathy using optical coherence tomography Repeatability of Cornea and Sublayer Thickness Measurements Using Optical Coherence Tomography in Corneas of Anomalous Refractive Status Endoscopic Optical Coherence Tomography for Assessing Inhalation Airway Injury: A Technical Review