1. Articles mentioning both Grigory V. Gelikonov and Pavel A. Shilyagin

    1-24 of 29 1 2 »
    1. Elimination of Artifacts Caused by the Nonidentity of Parallel Signal-Reception Channels in Spectral Domain Optical Coherence Tomography

      Elimination of Artifacts Caused by the Nonidentity of Parallel Signal-Reception Channels in Spectral Domain Optical Coherence Tomography
      We study the causes of artifact appearance in the images obtained by the method of spectral domain optical coherence tomography with parallel reception of the optical-spectrum components, which are manifested in repetition and overlay of the structural elements of the images of the studied medium with a shift in depth. It is shown that nonidentity of the transfer characteristics of the channels of the multichannel photoreceiving elements is one of ...
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    2. Compensation for the Influence of Fluctuations in the Distance to the Object During Noncontact Probing in Spectral Domain Optical Coherence Tomography

      Compensation for the Influence of Fluctuations in the Distance to the Object During Noncontact Probing in Spectral Domain Optical Coherence Tomography
      We propose and experimentally test a numerical method for correction of the influence of fluctuations in the distance to objects during noncontact probing in optical coherence tomography. The method is based on the analysis of phase shifts of the neighboring scans, which are due to microscale displacements, and further compensation for these displacements by using phasefrequency correction in the spectral domain. Unlike the known correlation methods, the proposed method does ...
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    3. Improving the Transverse Resolution of Optical Coherence Tomography with a Finite Impulse Response Filter and a Series of Numerically Refocused Images

      Improving the Transverse Resolution of Optical Coherence Tomography with a Finite Impulse Response Filter and a Series of Numerically Refocused Images
      Among the numerous methods for improving the informative value of the optical coherence tomography (OCT), a special place is taken by the methods for increasing the spatial resolution of the resulting images. Increasing the resolution allows one to identify more clinically significant structures in OCT images and thus improve the diagnostic value of OCT. Since the transverse resolution of OCT images is determined by the physical principles different from those ...
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    4. Cross-polarization optical coherence tomography for brain tumor imaging

      Cross-polarization optical coherence tomography for brain tumor imaging
      This paper considers valuable visual assessment criteria for distinguishing between tumorous and non-tumorous tissues, intraoperatively, using cross-polarization OCT (CP OCT) OCT with a functional extension, that enables detection of the polarization properties of the tissues in addition to their conventional light scattering. Materials and methods. The study was performed on 176 ex vivo human specimens obtained from 30 glioma patients. To measure the degree to which the typical parameters of ...
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    5. Digital refocusing in optical coherence tomography using finite impulse response filters

      Digital refocusing in optical coherence tomography using finite impulse response filters
      A finite impulse response filter, which shifts the focal plane in optical coherence tomography (OCT) images, is proposed. Since several OCT images with the focal plane in various positions can be fused into one image with increased lateral resolution, such a filter facilitates the creation of an OCT system with numerically increased lateral resolution, operating in real-time, i.e. showing one OCT B-scan with increased lateral resolution while collecting data ...
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    6. Time domain optical coherence tomography is a useful tool for diagnosing otitis media with effusion

      Time domain optical coherence tomography is a useful tool for diagnosing otitis media with effusion
      The usability of time-domain optical coherence tomography equipped with a flexible endoscopic probe for detecting effusion in the tympanic cavity is shown in the clinical environment. The possibility of assessing the dynamic properties of effusion, particularly its contained scatterers' mobility, is shown in real clinical cases. A method of comparative assessment of scatterers' mobility is proposed.
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    7. Cross-Polarization Optical Coherence Tomography with Active Maintenance of the Circular Polarization of a Sounding Wave in a Common Path System

      Cross-Polarization Optical Coherence Tomography with Active Maintenance of the Circular Polarization of a Sounding Wave in a Common Path System
      We consider a cross-polarization optical coherence tomography system with a common path for the sounding and reference waves and active maintenance of the circular polarization of a sounding wave. The system is based on the formation of birefringent characteristics of the total optical path, which are equivalent to a quarter-wave plate with a 45 orientation of its optical axes with respect to the linearly polarized reference wave. Conditions under which ...
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    8. Equidistant Recording of the Spectral Components in Ultra-Wideband Spectral-Domain Optical Coherence Tomography

      Equidistant Recording of the Spectral Components in Ultra-Wideband Spectral-Domain Optical Coherence Tomography
      We develop an effective method for reducing nonequidistance when recording the spectral components of an interference signal in ultra-wideband spectral-domain optical coherence tomography. For this purpose, a corrector consisting of two identical prisms is used in a diffraction-grating spectrometer. The corrector rotation with respect to the diffraction-grating plane and a variation in the angle between the corrector elements allow one to adjust the equidistant spatial distribution of the spectral components ...
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    9. A data-acquisition and control system for spectral-domain optical coherence tomography with a speed of 91 912 A-scans/s based on a USB 3.0 interface

      A data-acquisition and control system for spectral-domain optical coherence tomography with a speed of 91 912 A-scans/s based on a USB 3.0 interface
      We describe a system of optical spectrum registration at the output of an interferometer with controlled phase shifts for an experimental device intended for visualizing the internal structure of an optically turbid specimen, using the method of spectral domain optical coherence tomography. A device for spectral domain optical coherence tomography based on a common-path optical scheme with a USB 3.0 interface for inputting data into a computer has been ...
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    10. Medium chromatic dispersion calculation and correction in spectral-domain optical coherence tomography

      Medium chromatic dispersion calculation and correction in spectral-domain optical coherence tomography
      A method for determining and correcting distortions in spectral-domain optical coherence tomography images caused by medium dispersion was developed. The method is based on analysis of the phase distribution of the interference signal recorded by an optical coherence tomography device using an iterative approach to find and compensate for the effect of a mediums chromatic dispersion on point-spread function broadening in optical coherence tomography. This enables compensation of the impact ...
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    11. Correction of aberrations in digital holography using the phase gradient autofocus technique

      Correction of aberrations in digital holography using the phase gradient autofocus technique
      We propose a method for correcting aberrations in digital holography based on the principles of computational adaptive optics using the phase gradient autofocus technique that demands no reference measurements. The method requires a priori information on the relative positions of the elements of the optical setup. It is applicable for sufficiently smooth optical aberrations. This technique does not impose any restrictions on the magnitude of the scattered optical field phase ...
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    12. Improvement of lateral resolution of spectral domain optical coherence tomography images inout-of-focus regions with holographic data processing techniques

      Improvement of lateral resolution of spectral domain optical coherence tomography images inout-of-focus regions with holographic data processing techniques
      An analogy between spectral-domain optical coherence tomography (SD OCT) data and broadband digital holography data is considered. Based on this analogy, a method for processing SD OCT data, which makes it possible to construct images with a lateral resolution in the whole investigated volume equal to the resolution in the in-focus region, is developed. Several issues concerning practical application of the proposed method are discussed.
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    13. Achromatic registration of quadrature components of the optical spectrum in spectral domain opticalcoherence tomography

      Achromatic registration of quadrature components of the optical spectrum in spectral domain opticalcoherence tomography
      We have thoroughly investigated the method of simultaneous reception of spectral components with the achromatised quadrature phase shift between two portions of a reference wave, designed for the effective suppression of the 'mirror' artefact in the resulting image obtained by means of spectral domain optical coherence tomography (SD OCT). We have developed and experimentally tested a phase-shifting element consisting of a beam divider, which splits the reference optical beam into ...
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    14. Noniterative method of reconstruction optical coherence tomography images with improved lateralresolution in semitransparent media

      Noniterative method of reconstruction optical coherence tomography images with improved lateralresolution in semitransparent media
      A method of OCT imaging with a resolution throughout the investigated volume equal to the resolution in the best-focused region is described. It is based on summation of three-dimensional scattered field distributions at the wavelengths determined by OCT source spectral decomposition. A method of finding parameters needed for algorithmic realization of the summation is also proposed. The proposed approaches are tested on several model media, including biological ones.
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    15. Spectral reflectometry method and device

      Spectral reflectometry method and device
      An optical low-coherence reflectometry with spectral reception for obtaining images without coherent noise caused by self-interference of the radiation scattered from the studied object and by spurious reflections in the optical path of the system is disclosed. Two or more consecutive measurements of the interference spectrum are made. During at least one measurement of the interference spectrum by means of the interference control unit the phase between the interfering parts ...
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    16. Digital refocusing for transverse resolution improvement in optical coherence tomography

      Digital refocusing for transverse resolution improvement in optical coherence tomography
      Based on the fact that spectral domain (SD) optical coherence tomography (OCT) data can be treated as digital holography (DH) data acquired pointwise, we develop a spectral refocusing algorithm and show its ability to shift the focal region of OCT images obtained from SD OCT data acquired with a tightly focused scanning beam. Although refocusing itself depends on the refractive index of the studied media, we propose a procedure capable ...
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    17. Suppression of image autocorrelation artefacts in spectral domain optical coherence tomography and multiwave digital holography

      Suppression of image autocorrelation artefacts in spectral domain optical coherence tomography and multiwave digital holography
      An improved method for suppressing image artefacts in spectral domain optical coherence tomography (SD OCT) and multiwave digital holography, caused by the influence of coherent noise in the course of successive registration of an autocorrelation component and informative signal is reported. The method allows complete suppression of all types of coherent noises, provided that the sample of values used to record the autocorrelation component satisfies the conditions of Kotelnikov's ...
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    18. Feature Of The Week 4/1/12: Russian Institute of Applied Physics Investigates Digital Refocusing in Optical Coherence Tomography Systems

      Feature Of The Week 4/1/12: Russian Institute of Applied Physics Investigates Digital Refocusing in Optical Coherence Tomography Systems
      Over the past few years using electronic post optical detection processing to create a synthetic receiver field-of-view has become a very promising technique for offering improved performance in biomedical optical imaging systems. Various approaches around this basic theme have been used in OCT and non-OCT systems such as synthetic aperture radar, digital holography, and other microscopy techniques.  The approach not only allows for improving the classic depth-of-focus vs lateral resolution ...
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    19. Single-shot full complex spectrum spectrometer-based OCT with a single-line photodiode array

      Single-shot full complex spectrum spectrometer-based OCT with a single-line photodiode array
      An efficient technique of simultaneous obtaining of quadrature spectral components of interference signal in spectrometer-based OCT using a single-line linear photodiode array is proposed. The components are obtained in air-spaced non-polarization interferometer by partition of reference beam onto two parts and using an achromatic phase shifter. Several setups are described and compared.
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    20. Digital refocusing in optical coherence tomography

      Digital refocusing in optical coherence tomography
      The problem of restoration Optical Coherence Tomography (OCT) images, acquired with tightly focused probing beam, in out-of-focus region for improving lateral resolution of the OCT has been considered. Phase stability issue has been discussed and phase equalization algorithm has been proposed. After phase equalization, the algorithm of digital refocusing, based on some methods from the DH, have been applied to the simulated as well as to experimental OCT data, acquired ...
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    21. Feature Of The Week 3/13/11: Russian Scientists Investigate Cross Polarization OCT for Early Bladder Cancer Detection

      Feature Of The Week 3/13/11: Russian Scientists Investigate Cross Polarization OCT for Early Bladder Cancer Detection
      ...arly bladder-cancer detection: statistical study, Journal of Biophotonics, 1-14 (2010). V. M. Gelikonov and G. V. Gelikonov, New approach to cross-polarized optical coherence tomography based on orthogonal arbitrarily ...
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    22. Cross-polarization optical coherence tomography for early bladder-cancer detection: statistical study

      Cross-polarization optical coherence tomography for early bladder-cancer detection: statistical study
      The capabilities of cross-polarization optical coherence tomography (CP OCT) for early bladder-cancer detection are assessed in statistical study and compared with the traditional OCT. Unlike the traditional OCT that demonstrates images only in copolarization, CP OCT acquires images in cross-polarization and copolarization simultaneously. 116 patients with localized flat suspicious lesions in the bladder were enrolled, 360 CP OCT images were obtained and analyzed. CP OCT demonstrated sensitivity 93.7% (vs ...
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    23. 1-24 of 29 1 2 »
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  2. Organizations in the News

    1. (27 articles) Institute of Applied Physics
    2. (4 articles) Nizhny Novgorod State Medical Academy
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  3. People in the News

    1. (28 articles) Valentin M. Gelikonov
    2. (17 articles) Dmitry A. Terpelov
    3. (3 articles) Elena V. Zagaynova
    4. (3 articles) Natalia D. Gladkova
    5. (3 articles) Elena B. Kiseleva
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    10. (1 articles) Natalia M. Shakhova
    11. (1 articles) Andrew M. Rollins
    12. (1 articles) I. Alex Vitkin