1. Articles from Robert Huber

    1-24 of 83 1 2 3 4 »
    1. Differentiation of different stages of brain tumor infiltration using optical coherence tomography: Comparison of two systems and histology

      Differentiation of different stages of brain tumor infiltration using optical coherence tomography: Comparison of two systems and histology

      The discrimination of tumor-infiltrated tissue from non-tumorous brain tissue during neurosurgical tumor excision is a major challenge in neurosurgery. It is critical to achieve full tumor removal since it directly correlates with the survival rate of the patient. Optical coherence tomography (OCT) might be an additional imaging method in the field of neurosurgery that enables the classification of different levels of tumor infiltration and non-tumorous tissue. This work investigated two OCT systems with different imaging wavelengths (930 nm/1310 nm) and different resolutions (axial (air): 4.9 μm/16 μm, lateral: 5.2 μm/22 μm) in their ability to ...

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    2. Towards phase-stabilized Fourier domain mode-locked frequency combs

      Towards phase-stabilized Fourier domain mode-locked frequency combs

      Fourier domain mode-locked (FDML) lasers are some of the fastest wavelength-swept light sources, and used in many applications like optical coherence tomography (OCT), OCT endoscopy, Raman microscopy, light detection and ranging, and two-photon microscopy. For a deeper understanding of the underlying laser physics, it is crucial to investigate the light field evolution of the FDML laser and to clarify whether the FDML laser provides a frequency comb structure. In this case, the FDML would output a coherent sweep in frequency with a stable phase relation between output colours. To get access to the phase of the light field, a beat ...

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    3. Registration of histological brain images onto optical coherence tomography images based on shape information

      Registration of histological brain images onto optical coherence tomography images based on shape information

      Identifying tumour infiltration zones during tumour resection in order to excise as much tumour tissue as possible without damaging healthy brain tissue is still a major challenge in neurosurgery. The detection of tumour infiltrated regions so far requires histological analysis of biopsies taken from at expected tumour boundaries. The gold standard for histological analysis is the staining of thin cut specimen and the evaluation by a neuropathologist. This work presents a way to transfer the histological evaluation of a neuropathologist onto optical coherence tomography (OCT) images. OCT is a method suitable for real time in vivo imaging during neurosurgery however ...

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    4. Method for monitoring time-dependent properties of light during scanning swept-source optical coherence tomography

      Method for monitoring time-dependent properties of light during scanning swept-source optical coherence tomography

      A method comprises: splitting laser light into sample light, reference light, and monitor light; routing the reference light into a reference arm of an OCT interferometer; routing the monitor light into a monitor device, which generates at least one optical monitor signal representing at least one time-dependent property of the monitor light; generating at least one electric monitor signal from the at least one optical monitor signal; illuminating in a point-shaped manner a sample with sample light, wherein the illumination point is guided on the surface of the sample along a predetermined trajectory; superimposing the light scattered by the sample ...

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      Mentions: Optores
    5. OCT-Guided Surgery for Gliomas: Current Concept and Future Perspectives

      OCT-Guided Surgery for Gliomas: Current Concept and Future Perspectives

      Optical coherence tomography (OCT) has been recently suggested as a promising method to obtain in vivo and real-time high-resolution images of tissue structure in brain tumor surgery. This review focuses on the basics of OCT imaging, types of OCT images and currently suggested OCT scanner devices and the results of their application in neurosurgery. OCT can assist in achieving intraoperative precision identification of tumor infiltration within surrounding brain parenchyma by using qualitative or quantitative OCT image analysis of scanned tissue. OCT is able to identify tumorous tissue and blood vessels detection during stereotactic biopsy procedures. The combination of OCT with ...

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    6. Spectroscopic thermo-elastic optical coherence tomography for tissue characterization

      Spectroscopic thermo-elastic optical coherence tomography for tissue characterization

      Optical imaging techniques that provide free space, label free imaging are powerful tools in obtaining structural and biochemical information in biological samples. To date, most of the optical imaging technologies create images with a specific contrast and require multimodality integration to add additional contrast. In this study, we demonstrate spectroscopic Thermo-elastic Optical Coherence Tomography (TE-OCT) as a potential tool in tissue identification. TE-OCT creates images based on two different forms of contrast: optical reflectance and thermo-elastic deformation. TE-OCT uses short laser pulses to induce thermo-elastic tissue deformation and measures the resulting surface displacement using phase-sensitive OCT. In this work we ...

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    7. Continuous spectral zooming for in vivo live 4D-OCT with MHz A-scan rates and long coherence

      Continuous spectral zooming for in vivo live 4D-OCT with MHz A-scan rates and long coherence

      We present continuous three-dimensional spectral zooming in live 4D-OCT using a home-built FDML based OCT system with 3.28 MHz A-scan rate. Improved coherence characteristics of the FDML laser allow for imaging ranges up to 10 cm. For the axial spectral zoom feature, we switch between high resolution and long imaging range by adjusting the sweep range of our laser. We present a new imaging setup allowing for synchronized adjustments of the imaging range and lateral field of view during live OCT imaging. For this, a novel inline recalibration algorithm was implemented that enables numerical k-linearization of the raw OCT ...

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    8. Microscopic optical coherence tomography (mOCT) at 600 kHz for 4D volumetric imaging and dynamic contrast

      Microscopic optical coherence tomography (mOCT) at 600 kHz for 4D volumetric imaging and dynamic contrast

      Volumetric imaging of dynamic processes with microscopic resolution holds a huge potential in biomedical research and clinical diagnosis. Using supercontinuum light sources and high numerical aperture (NA) objectives, optical coherence tomography (OCT) achieves microscopic resolution and is well suited for imaging cellular and subcellular structures of biological tissues. Currently, the imaging speed of microscopic OCT (mOCT) is limited by the line-scan rate of the spectrometer camera and ranges from 30 to 250 kHz. This is not fast enough for volumetric imaging of dynamic processes in vivo and limits endoscopic application. Using a novel CMOS camera, we demonstrate fast 3-dimensional OCT ...

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    9. Imaging Inflammation – From Whole Body Imaging to Cellular Resolution

      Imaging Inflammation – From Whole Body Imaging to Cellular Resolution

      Imaging techniques have evolved impressively lately, allowing whole new concepts like multimodal imaging, personal medicine, theranostic therapies, and molecular imaging to increase general awareness of possiblities of imaging to medicine field. Here, we have collected the selected (3D) imaging modalities and evaluated the recent findings on preclinical and clinical inflammation imaging. The focus has been on the feasibility of imaging to aid in inflammation precision medicine, and the key challenges and opportunities of the imaging modalities are presented. Some examples of the current usage in clinics/close to clinics have been brought out as an example. This review evaluates the ...

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    10. Cavity length control for Fourier domain mode locked (FDML) lasers with µm precision

      Cavity length control for Fourier domain mode locked (FDML) lasers with µm precision

      In highly dispersion compensated Fourier domain mode locked (FDML) lasers, an ultra-low noise operation can only be achieved by extremely precise and stable matching of the filter tuning period and light circulation time in the cavity. We present a robust and high precision closed-loop control algorithm and an actively cavity length controlled FDML laser. The cavity length control achieves a stability of ∼0.18 mHz at a sweep repetition rate of ∼418 kHz which corresponds to a ratio of 4×10 −10 . Furthermore, we prove that the rapid change of the cavity length has no negative impact on the quality ...

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    11. Flexible A-scan rate MHz-OCT: efficient computational downscaling by coherent averaging

      Flexible A-scan rate MHz-OCT: efficient computational downscaling by coherent averaging

      In order to realize adjustable A-scan rates of fast optical coherence tomography (OCT) systems, we investigate averaging of OCT image data acquired with a MHz-OCT system based on a Fourier Domain Mode Locked (FDML) laser. Increased system sensitivity and image quality can be achieved with the same system at the cost of lower imaging speed. Effectively, the A-scan rate can be reduced in software by a freely selectable factor. We demonstrate a detailed technical layout of the strategies necessary to achieve efficient coherent averaging. Since there are many new challenges specific to coherent averaging in swept source MHz-OCT, we analyze ...

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    12. Simultaneous morphological and flow imaging enabled by megahertz intravascular Doppler optical coherence tomography

      Simultaneous morphological and flow imaging enabled by megahertz intravascular Doppler optical coherence tomography

      We demonstrate three-dimensional intravascular flow imaging compatible with routine clinical image acquisition workflow by means of megahertz (MHz) intravascular Doppler Optical Coherence Tomography (OCT). The OCT system relies on a 1.1 mm diameter motorized imaging catheter and a 1.5 MHz Fourier Domain Mode Locked (FDML) laser. Using a post processing method to compensate the drift of the FDML laser output, we can resolve the Doppler phase shift between two adjoining OCT A-line datasets. By interpretation of the velocity field as measured around the zero phase shift, the flow direction at specific angles can be qualitatively estimated. Imaging experiments ...

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    13. Motorized capsule for shadow-free OCT imaging and synchronous beam control

      Motorized capsule for shadow-free OCT imaging and synchronous beam control

      We demonstrate a tethered motorized capsule for unobstructed optical coherence tomography (OCT) imaging of the esophagus. By using a distal reflector design, we avoided the common shadow artifact induced by the motor wires. A synchronous driving technique features three types of beam-scanning modes of the capsule, i.e., circumferential beam scanning, localized beam scanning, and accurate beam positioning. We characterized these three modes and carried out ex vivo imaging experiments using the capsule. The results show that the capsule can potentially be a useful tool for diagnostic OCT imaging and OCT-guided biopsy and therapy of the esophagus.

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    14. Permanent Professor Position available at University of Lubeck

      Permanent Professor Position available at University of Lubeck

      The Institute of Biomedical Optics at the Department of Computer Science/Engineering and Department of Natural Sciences (STEM) at the Universität zu Lübeck invites applications for a permanent University Professorship (W2) in Biomedical Optics and Photonics commencing as soon as possible. Conditions of the appointment are in accordance with the Higher Education Act (Hochschulgesetz) of Schleswig Holstein. Details will be explained on request. The successful candidate will represent the respective field in research and teaching. The overall focus of the professorship lies on novel physics approaches in optics and their development to the point of application in the ...

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    15. High-speed fiber scanning endoscope for volumetric multi-megahertz optical coherence tomography

      High-speed fiber scanning endoscope for volumetric multi-megahertz optical coherence tomography

      We present a forward-viewing fiber scanning endoscope (FSE) for high-speed volumetric optical coherence tomography (OCT). The reduction in size of the probe was achieved by substituting the focusing optics by an all-fiber-based imaging system which consists of a combination of scanning single-mode fibers, a glass spacer, made from a step-index multi-mode fiber, and a gradient-index fiber. A lateral resolution of 11 μm was achieved at a working distance of 1.2 mm. The newly designed piezo-based FSE has an outer diameter of 1.6 mm and a rigid length of 13.5 mm. By moving the whole imaging optic in ...

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    16. Ultra low noise Fourier domain mode locked laser for high quality megahertz optical coherence tomography

      Ultra low noise Fourier domain mode locked laser for high quality megahertz optical coherence tomography

      We investigate the origin of high frequency noise in Fourier domain mode locked (FDML) lasers and present an extremely well dispersion compensated setup which virtually eliminates intensity noise and dramatically improves coherence properties. We show optical coherence tomography (OCT) imaging at 3.2 MHz A-scan rate and demonstrate the positive impact of the described improvements on the image quality. Especially in highly scattering samples, at specular reflections and for strong signals at large depth, the noise in optical coherence tomography images is significantly reduced. We also describe a simple model that suggests a passive physical stabilizing mechanism that leads to ...

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    17. High-resolution retinal swept source optical coherence tomography with an ultra-wideband Fourier-domain mode-locked laser at MHz A-scan rates

      High-resolution retinal swept source optical coherence tomography with an ultra-wideband Fourier-domain mode-locked laser at MHz A-scan rates

      We present a new 1060 nm Fourier domain mode locked laser (FDML laser) with a record 143 nm sweep bandwidth at 2∙ 417 kHz = 834 kHz and 120 nm at 1.67 MHz, respectively. We show that not only the bandwidth alone, but also the shape of the spectrum is critical for the resulting axial resolution, because of the specific wavelength-dependent absorption of the vitreous. The theoretical limit of our setup lies at 5.9 µm axial resolution. In vivo MHz-OCT imaging of human retina is performed and the image quality is compared to the previous results acquired with 70 ...

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    18. Feature Of The Week 09/10/2017: Thermo-elastic Optical Coherence Tomography

      Feature Of The Week 09/10/2017: Thermo-elastic  Optical Coherence Tomography

      The conventional OCT image contrast is derived from elastic scattering, and shows the internal structure of the sample. The determination of the tissue type in OCT images usually depends on the interpretation by the image reader. More accurate tissue type contrast may be achieved by new OCT-based imaging modalities, with sensitivity to other physical parameters than scattering alone. Phase-sensitive OCT can detect tissue motion on nanometer-to- micrometer length scales using the phase of the OCT signal. Depending on the nature of the excitation, different functional images can be reconstructed: a mechanical stimulus yields images of tissue elasticity (optical coherence elastography ...

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    19. Thermo-elastic optical coherence tomography

      Thermo-elastic optical coherence tomography

      The absorption of nanosecond laser pulses induces rapid thermo-elastic deformation in tissue. A sub-micrometer scale displacement occurs within a few microseconds after the pulse arrival. In this Letter, we investigate the laser-induced thermo-elastic deformation using a 1.5 MHz phase-sensitive optical coherence tomography (OCT) system. A displacement image can be reconstructed, which enables a new modality of phase-sensitive OCT, called thermo-elastic OCT. An analysis of the results shows that the optical absorption is a dominating factor for the displacement. Thermo-elastic OCT is capable of visualizing inclusions that do not appear on the structural OCT image, providing additional tissue type information.

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    20. Feature tracking for automated volume of interest stabilization on 4D-OCT images

      Feature tracking for automated volume of interest stabilization on 4D-OCT images

      A common representation of volumetric medical image data is the triplanar view (TV), in which the surgeon manually selects slices showing the anatomical structure of interest. In addition to common medical imaging such as MRI or computed tomography, recent advances in the field of optical coherence tomography (OCT) have enabled live processing and volumetric rendering of four-dimensional images of the human body. Due to the region of interest undergoing motion, it is challenging for the surgeon to simultaneously keep track of an object by continuously adjusting the TV to desired slices. To select these slices in subsequent frames automatically, it ...

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    21. Analysis of FDML lasers with meter range coherence

      Analysis of FDML lasers with meter range coherence

      FDML lasers provide sweep rates in the MHz range at wide optical bandwidths, making them ideal sources for high speed OCT. Recently, at lower speed, ultralong-range swept-source OCT has been demonstrated using a tunable vertical cavity surface emitting laser (VCSEL) and also using a Vernier-tunable laser. These sources provide relatively high sweep rates and meter range coherence lengths. In order to achieve similar coherence, we developed an extremely well dispersion compensated Fourier Domain Mode Locked (FDML) laser, running at 3.2 MHz sweep rate and 120 nm spectral bandwidth. We demonstrate that this laser offers meter range coherence and enables ...

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    22. High-speed OCT light sources and systems [Invited]

      High-speed OCT light sources and systems [Invited]

      Imaging speed is one of the most important parameters that define the performance of optical coherence tomography (OCT) systems. During the last two decades, OCT speed has increased by over three orders of magnitude. New developments in wavelength-swept lasers have repeatedly been crucial for this development. In this review, we discuss the historical evolution and current state of the art of high-speed OCT systems, with focus on wavelength swept light sources and swept source OCT systems.

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    23. Heartbeat OCT and Motion-Free 3D In Vivo Coronary Artery Microscopy

      Heartbeat OCT and Motion-Free 3D In Vivo Coronary Artery Microscopy

      Intravascular optical coherence tomography (IV-OCT) has gained widespread use over the past few years, offering highly detailed images of coronary artery pathologies and interventions (1) . In contrast to the cross-sectional view, longitudinal sections and 3-dimensional (3D) renderings are affected by cardiac motion artifacts and undersampling, complicating interpretation and measurements (2) . We developed Heartbeat OCT, a new OCT method that achieves up to 4,000 frames/s imaging speed for isotropically sampled volume datasets acquired within the diastolic phase of 1 cardiac cycle to restore 3D IV-OCT image fidelity. In this research letter, we present the first in vivo data acquired ...

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    24. Flexible A-scan rate MHz OCT: computational downscaling by coherent averaging

      Flexible A-scan rate MHz OCT: computational downscaling by coherent averaging

      In order to realize fast OCT-systems with adjustable line rate, we investigate averaging of image data from an FDML based MHz-OCT-system. The line rate can be reduced in software and traded in for increased system sensitivity and image quality. We compare coherent and incoherent averaging to effectively scale down the system speed of a 3.2 MHz FDML OCT system to around 100 kHz in postprocessing. We demonstrate that coherent averaging is possible with MHz systems without special interferometer designs or digital phase stabilisation. We show OCT images of a human finger knuckle joint in vivo with very high quality ...

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    1-24 of 83 1 2 3 4 »
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    Ultra high-speed swept source OCT imaging of the anterior segment of human eye at 200 kHz with adjustable imaging range FDML swept source at 1060 nm using a tapered amplifier Multi-Megahertz OCT: High quality 3D imaging at 20 million A-scans and 4.5 GVoxels per second Feature Of The Week 7/6/2015: Ultra-Widefield Retinal MHz-OCT Imaging With up to 100 Degrees Viewing Angle Feature Of The Week 12/06/2015: Heartbeat Optical Coherence Tomography In-hospital heart failure in patients with Takotsubo cardiomyopathy due to coronary artery disease: An artificial intelligence and optical coherence tomography study Risk factors for epiretinal membrane formation and peeling following pars plana vitrectomy for primary rhegmatogenous retinal detachment, an OCT guided analysis In vivo tracking of individual stem cells labeled with nanowire lasers using multimodality imaging Spatial resolution in optical coherence elastography of bounded media Detecting vulnerable carotid plaque and its component characteristics: Progress in related imaging techniques Optical Coherence Tomography Features for Identifying Posttreatment Complete Polypoidal Regression in Polypoidal Choroidal Vasculopathy High-depth-resolution imaging of dispersive samples using quantum optical coherence tomography