1. Articles from Branislav Grajciar

    1-17 of 17
    1. Line-field parallel swept source interferometric imaging at up to 1  MHz

      Line-field parallel swept source interferometric imaging at up to 1  MHz

      We present a novel medical imaging modality based on optical coherence tomography (OCT) that enables in vivo 3D tomography at acquisition rates up to 1 MHz. Line field parallel swept source interferometric imaging (LPSI) combines line-field swept source OCT with modulation of the interferometric signal in spatial direction for full range imaging. This method enables high speed imaging with cost-effective and commercially available technology. We explain the realization of the LPSI setup, acquisition, and postprocessing and finally demonstrate 3D in vivo imaging of human nail fold. To the best of our knowledge, sensitivity and depth penetration are competitive with respective ...

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    2. Line-field parallel swept source MHz OCT for structural and functional retinal imaging

      Line-field parallel swept source MHz OCT for structural and functional retinal imaging

      We demonstrate three-dimensional structural and functional retinal imaging with line-field parallel swept source imaging (LPSI) at acquisition speeds of up to 1 MHz equivalent A-scan rate with sensitivity better than 93.5 dB at a central wavelength of 840 nm. The results demonstrate competitive sensitivity, speed, image contrast and penetration depth when compared to conventional point scanning OCT. LPSI allows high-speed retinal imaging of function and morphology with commercially available components. We further demonstrate a method that mitigates the effect of the lateral Gaussian intensity distribution across the line focus and demonstrate and discuss the feasibility of high-speed optical angiography ...

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    3. Line-field parallel swept source interferometric imaging at up to 1MHz

      Line-field parallel swept source interferometric imaging at up to 1MHz

      We present a novel medical imaging modality based on optical coherence tomography (OCT) that enables in vivo 3D tomography at acquisition rates up to 1 MHz. Line field parallel swept source interferometric imaging (LPSI) combines line-field swept source OCT with modulation of the interferometric signal in spatial direction for full range imaging. This method enables high speed imaging with cost-effective and commercially available technology. We explain the realization of the LPSI setup, acquisition, and postprocessing and finally demonstrate 3D in vivo imaging of human nail fold. To the best of our knowledge, sensitivity and depth penetration are competitive with respective ...

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    4. Line field off axis swept source OCT utilizing digital refocusing

      Line field off axis swept source OCT utilizing digital refocusing

      OCT is a promising tool for performing fast and cheap noninvasive biopsies. High speed imaging helps to reduce motion artifacts that cause decreased sensitivity and resolution. Using a point scanning configuration one is ultimately limited in sensitivity. Therefore parallel configurations are a potentially attractive solution to further enhance the speed capabilities of future OCT systems. Even more, if full field configurations are employed one can exploit the intrinsic phase correlation over the field of view for digital wavefront correction techniques. Full field OCT has nevertheless limitations concerning the missing confocal gating. The sensitivity is decreased in the presence of specular ...

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    5. Angle independent flow assessment with bidirectional Doppler optical coherence tomography

      Angle independent flow assessment with bidirectional Doppler optical coherence tomography

      Bidirectional Doppler optical coherence tomography is a stable and accurate method to extract the absolute velocity of vessels close to perpendicular to the optical axis by illuminating the sample under two different angles. However it requires knowledge of the vessel angle in the en face plane. In this Letter, we demonstrate that a direct calculation of the flow out of bidirectional Doppler cross sections perpendicular to the illumination plane is independent of that angle and of the Doppler angle, thereby improving the accuracy and flexibility of that technique. We validate our approach with an in vitro experiment and in vivo ...

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    6. Dove prism based rotating dual beam bidirectional Doppler OCT

      Dove prism based rotating dual beam bidirectional Doppler OCT

      Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its accuracy in clinical practice. To overcome this limitation, we use a bidirectional dual beam technique equipped with a novel rotating scanning scheme employing a Dove prism. The volume is probed from two distinct illumination directions with variable controlled incidence plane, allowing for reconstruction of the true flow velocity at arbitrary vessel orientations. The principle is implemented with Swept Source OCT at 1060nm with 100,000 A-Scans/s. We apply the system to resolve pulsatile retinal absolute blood velocity by performing ...

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    7. Intrasweep phase-sensitive optical coherence tomography for noncontact optical photoacoustic imaging

      Intrasweep phase-sensitive optical coherence tomography for noncontact optical photoacoustic imaging

      We introduce a method to extract the photoacoustic (PA) signal from the phase time evolution of an optical coherence tomography (OCT) swept source spectral sweep. This all-optical detection is achieved in a noncontact fashion directly on the sample surface by using its specular reflection. High-speed measurement and referencing allow for close to shot noise limited phase-sensitive detection. It offers a simple way to perform OCT and PA imaging by sharing the same system components.

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    8. In situ structural and microangiographic assessment of human skin lesions with high-speed OCT

      In situ structural and microangiographic assessment of human skin lesions with high-speed OCT

      We demonstrate noninvasive structural and microvascular contrast imaging of different human skin diseases in vivo using an intensity difference analysis of OCT tomograms. The high-speed swept source OCT system operates at 1310 nm with 220 kHz A-scan rate. It provides an extended focus by employing a Bessel beam. The studied lesions were two cases of dermatitis and two cases of basal cell carcinoma. The lesions show characteristic vascular patterns that are significantly different from healthy skin. In case of inflammation, vessels are dilated and perfusion is increased. In case of basal cell carcinoma, the angiogram shows a denser network of ...

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    9. Ultrahigh-speed non-invasive widefield angiography

      Ultrahigh-speed non-invasive widefield angiography

      tinal and choroidal vascular imaging is an important diagnostic benefit for ocular diseases such as age-related macular degeneration. The current gold standard for vessel visualization is fluorescence angiography. We present a potential non-invasive alternative to image blood vessels based on functional Fourier domain optical coherence tomography (OCT). For OCT to compete with the field of view and resolution of angiography while maintaining motion artifacts to a minimum, ultrahigh-speed imaging has to be introduced. We employ Fourier domain mode locking swept source technology that offers high quality imaging at an A-scan rate of up to 1.68 MHz. We present retinal ...

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    10. High-resolution phase mapping with parallel Fourier domain optical coherence microscopy for dispersion contrast imaging

      High-resolution phase mapping with parallel Fourier domain optical coherence microscopy for dispersion contrast imaging

      We demonstrate a high-speed parallel line field optical coherence microscopy (OCM) system that exhibits intrinsically high phase stability even with lateral scanning. The presented Fourier domain (FD) OCM system employs a high speed CMOS detector and achieves up to 512 000 equivalent A-scans per second. The microscopy system is shown to resolve the smallest elements of the USAF resolution test target (Group 7, Element 6), indicating the transverse (Y- non-scanning parallel direction)) resolution and resolution in X (scanning) direction less than 2.2 µm. The capability of imaging biological samples is demonstrated on human red blood cells (RBC). The high ...

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    11. Extended focus high-speed swept source OCT with self-reconstructive illumination

      Extended focus high-speed swept source OCT with self-reconstructive illumination

      We present a Bessel beam illumination FDOCT setup using a FDML Swept Source at 1300nm with up to 440kHz A-scan rate, and discuss its advantages for structural and functional imaging of highly scattering samples. An extended focus is achieved due to the Bessel beam that preserves its lateral extend over a large depth range. Furthermore, Bessel beams exhibit a self-reconstruction property that allows imaging even behind obstacles such as hairs on skin. Decoupling the illumination from the Gaussian detection increases the global sensitivity and enables dark field imaging. Dark field imaging is useful to avoid strong reflexes from the sample ...

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    12. High-speed functional OCT with self-reconstructive Bessel illumination at 1300nm

      High-speed functional OCT with self-reconstructive Bessel illumination at 1300nm

      Cedric Blatter, Branislav Grajciar, and Christoph M. Eigenwillig et al. We present a Bessel beam illumination FDOCT setup with FDML buffered swept source at 1300nm. An extended focus is achieved due to the Bessel beam that preserves its lateral extend over a large depth range. Decoupling the illumination from the Gaussian detection improves the sensitivity as compared t ... [Proc. SPIE 8091, 809104 (2011)] published Thu Jun 09, 2011.

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    13. Structural and functional imaging with extended focus dark-field OCT at 1300nm

      Structural and functional imaging with extended focus dark-field OCT at 1300nm

      We present an extended focus FDOCT setup with FDML swept source centered at 1310nm. The illumination, preserving its lateral extend over a large depth range thanks to the use of a Bessel beam, is decoupled from the Gaussian detection in order to increase the global sensitivity. The efficient spatial separation enables dark-field imaging. In-vivo measurements in the skin were performed to demonstrate the gain in lateral resolution while preserving the imaging depth. More, the calculation of the speckle variance between B-Scans allows a clear visualization of the microvasculature.

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    14. Dual-band refractive low coherence interferometry in the spectral domain for dispersion measurements

      Dual-band refractive low coherence interferometry in the spectral domain for dispersion measurements

      We present a spectral domain refractive low coherence interferometry technique (SD-rLCI) using a novel extreme broadband Super Continuum laser source equipped with a dual spectrometer system which is able to measure the dispersion in the visual and near infrared range simultaneously. The setup was verified obtaining the second order dispersion of distilled water. We will use this system for measuring the dispersion sensitivities of important tissue substances in order to determine analyte concentrations within mixtures.

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    15. High sensitivity phase mapping with parallel Fourier domain optical coherence tomography at 512 000 A-scan/s

      High sensitivity phase mapping with parallel Fourier domain optical coherence tomography at 512 000 A-scan/s

      In this paper we present an ultra high speed and highly phase sensitive line-field FD-OCT system for quantitative phase mapping. The system works with a maximum speed of 512 000 A-scan/s (1000 fps) in real time mode. Along the parallel recorded direction excellent phase stability corresponding to a path length variation of only 510 pm was measured. We demonstrate how to exploit this phase accuracy for fast chemical analysis of glucose mixture processes. The system has particular potential for studying micro-fluidic processes.

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    16. Improved sensitivity measurement of the human eye length in vivo with Fourier domain optical coherence tomography

      Branislav Grajciar, Michael Pircher, Christoph K. Hitzenberger et al. We present a system for intraocular distance measurement of the human eye in vivo with high sensitivity. The instrument is based on Fourier domain low coherence interferometry (FD-LCI). State-of-the-art FD-LCI systems are capable to image a depth range of only a few mm, because the depth range is de ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68440L (2008)] published Mon Feb 11, 2008.

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    17. High sensitive measurement of the human axial eye length in vivo with Fourier domain low-coherence interferometry

      In this paper we present a system for intraocular distance measurement of the human eye in vivo with high sensitivity. The instrument is based on Fourier domain low coherence interferometry (FD-LCI). Stateof-the-art FD-LCI systems are limited to a depth range of only a few mm, because the depth range is determined by the spectral resolution of the spectrometer. To measure larger distances (e.g. human eye length) we implemented two separate reference arms with different arm lengths into the interferometer. Each reference arm length corresponds to a different depth position within the sample (e.g. cornea and retina). Therefore two ...

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    1-17 of 17
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  2. Topics in the News

    1. (17 articles) Branislav Grajciar
    2. (15 articles) Medical University of Vienna
    3. (14 articles) Rainer A. Leitgeb
    4. (10 articles) Cedric Blatter
    5. (6 articles) Robert A. Huber
    6. (5 articles) Ludwig Maximilian University of Munich
    7. (5 articles) Wolfgang Drexler
    8. (5 articles) Wolfgang Wieser
    9. (4 articles) Tilman Schmoll
    10. (4 articles) Adolf F. Fercher
    11. (1 articles) Medical University of Vienna
    12. (1 articles) Angelika Unterhuber
    13. (1 articles) Perimeter Medical Imaging
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    High sensitivity phase mapping with parallel Fourier domain optical coherence tomography at 512 000 A-scan/s Structural and functional imaging with extended focus dark-field OCT at 1300nm Dual-band refractive low coherence interferometry in the spectral domain for dispersion measurements High-speed functional OCT with self-reconstructive Bessel illumination at 1300nm Extended focus high-speed swept source OCT with self-reconstructive illumination High-resolution phase mapping with parallel Fourier domain optical coherence microscopy for dispersion contrast imaging Ultrahigh-speed non-invasive widefield angiography Intrasweep phase-sensitive optical coherence tomography for noncontact optical photoacoustic imaging Diagnostic Performance of Deep Learning for Angle Closre Wide-field Optical Coherence Tomography Imaging of Excised Breast Tissue. PhD, Doctoral Student Opening in Multimodal Optical Imaging at the Medical University of Vienna Progression in Glaucoma (Thesis)