All Articles from Branislav Grajciar -Optical Coherence Tomography News

Articles from Branislav Grajciar

1-17 of 17
1. Line-field parallel swept source interferometric imaging at up to 1 MHz
  
  Explore OSA | OSA Publishing Oct 18 2015
  
  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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  Mentions: Rainer A. Leitgeb Wolfgang Drexler Medical University of Vienna
2. Line-field parallel swept source MHz OCT for structural and functional retinal imaging
  
  Explore opticsinfobase.org Feb 19 2015
  
  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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  Mentions: Rainer A. Leitgeb Wolfgang Drexler Medical University of Vienna
3. Line-field parallel swept source interferometric imaging at up to 1MHz
  
  Explore opticsinfobase.org Sep 5 2014
  
  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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  Mentions: Rainer A. Leitgeb Wolfgang Drexler Medical University of Vienna
4. Line field off axis swept source OCT utilizing digital refocusing
  
  Explore Conference Proceedings May 13 2014
  
  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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  Mentions: Rainer A. Leitgeb Wolfgang Drexler Medical University of Vienna
5. Angle independent flow assessment with bidirectional Doppler optical coherence tomography
  
  Explore opticsinfobase.org Oct 28 2013
  
  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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  Mentions: Rainer A. Leitgeb Medical University of Vienna Branislav Grajciar
6. Dove prism based rotating dual beam bidirectional Doppler OCT
  
  Explore opticsinfobase.org Jun 30 2013
  
  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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  Mentions: Rainer A. Leitgeb Medical University of Vienna Branislav Grajciar
7. Intrasweep phase-sensitive optical coherence tomography for noncontact optical photoacoustic imaging
  
  Explore opticsinfobase.org Oct 16 2012 Tunable Sources
  
  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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  Mentions: Rainer A. Leitgeb Medical University of Vienna Branislav Grajciar
8. In situ structural and microangiographic assessment of human skin lesions with high-speed OCT
  
  Explore opticsinfobase.org Oct 2 2012 Dermatology
  
  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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  Mentions: Rainer A. Leitgeb Wolfgang Drexler Medical University of Vienna
9. Ultrahigh-speed non-invasive widefield angiography
  
  Explore Linking to Scitation Content Jun 29 2012 Ophthalmology
  
  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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  Mentions: Rainer A. Leitgeb Medical University of Vienna Branislav Grajciar
10. High-resolution phase mapping with parallel Fourier domain optical coherence microscopy for dispersion contrast imaging
  
  Explore Photonics Society of Poland Dec 29 2011 Microscopy
  
  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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  Mentions: Adolf F. Fercher Rainer A. Leitgeb Medical University of Vienna
11. Extended focus high-speed swept source OCT with self-reconstructive illumination
  
  Explore opticsinfobase.org Jun 8 2011
  
  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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  Mentions: Rainer A. Leitgeb Branislav Grajciar Robert A. Huber
12. High-speed functional OCT with self-reconstructive Bessel illumination at 1300nm
  
  Explore SPIE Digital Library Jun 1 2011 Dermatology
  
  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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  Mentions: Rainer A. Leitgeb Medical University of Vienna Branislav Grajciar
13. Structural and functional imaging with extended focus dark-field OCT at 1300nm
  
  Explore SPIE Digital Library Feb 10 2011 Tunable Sources
  
  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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  Mentions: Rainer A. Leitgeb Branislav Grajciar Robert A. Huber
14. Dual-band refractive low coherence interferometry in the spectral domain for dispersion measurements
  
  Explore SPIE Digital Library Feb 10 2011 Broadband Sources
  
  $Dual-band refractive low coherence interferometry in the spectral domain for dispersion measurements$
  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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  Mentions: Adolf F. Fercher Medical University of Vienna Branislav Grajciar
15. High sensitivity phase mapping with parallel Fourier domain optical coherence tomography at 512 000 A-scan/s
  
  Explore opticsinfobase.org Sep 29 2010
  
  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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  Mentions: Adolf F. Fercher Rainer A. Leitgeb Medical University of Vienna
16. Improved sensitivity measurement of the human eye length in vivo with Fourier domain optical coherence tomography
  
  Explore SPIE Digital Library Feb 11 2008 Ophthalmology
  
  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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  Mentions: Christoph K. Hitzenberger Michael Pircher Medical University of Vienna
17. High sensitive measurement of the human axial eye length in vivo with Fourier domain low-coherence interferometry
  
  Explore opticsinfobase.org Feb 5 2008 Ophthalmology
  
  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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  Mentions: Adolf F. Fercher Christoph K. Hitzenberger Michael Pircher
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