1. Articles from Sven Meissner

    1-24 of 28 1 2 »
    1. Visualization of dynamic boiling processes using high-speed optical coherence tomography

      Visualization of dynamic boiling processes using high-speed optical coherence tomography

      Investigating microscale nucleate boiling processes with high heat flux requires experimental visualization and quantification with high spatial resolution in the micrometer range as well as a sufficient temporal resolution. Numerous measurement techniques are employed for providing comprehensive experimental data on microscale boiling processes and other multiphase flows. In this context, optical coherence tomography (OCT) has been introduced recently for the visualization of quasistatic growing vapor bubbles in turbid fluids with a high spatial resolution. Since OCT detects backscattered light, only one optical access is necessary and OCT is feasible for measurements in turbid media, where other imaging techniques fail. Within ...

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    2. Total liquid ventilation: a new approach to improve 3D OCT image quality of alveolar structures in lung tissue

      Total liquid ventilation: a new approach to improve 3D OCT image quality of alveolar structures in lung tissue

      Little is known about mechanical processes of alveolar tissue during mechanical ventilation. Optical coherence tomography (OCT) as a three-dimensional and high-resolution imaging modality can be used to visualize subpleural alveoli during artificial ventilation. The quality of OCT images can be increased by matching the refractive index inside the alveoli to the one of tissue via liquid-filling. Thereby, scattering loss can be decreased and higher penetration depth and tissue contrast can be achieved. We show the liquid-filling of alveolar structures verified by optical coherence tomography and intravital microscopy (IVM) and the advantages of index matching for OCT imaging of subpleural alveoli ...

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    3. Method And Arrangement For Checking Fingerprints For Authenticity

      Method And Arrangement For Checking Fingerprints For Authenticity

      The invention relates to a method and an arrangement (60) for checking fingerprints (2) for authenticity by means of optical coherence tomography, wherein the method has at least the following steps: real fingerprints (1) are scanned by means of a scanning unit (4) for the optical coherence tomography; three-dimensional maps in the form of volume data records (7) are created; the volume data records (7) of the real fingerprints (1) are broken down at least into a large number of single parameters in the form of technical electrical signal trains that are equivalent to individual authenticity parameters; the volume data ...

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    4. Defense of fake fingerprint attacks using a swept source laser optical coherence tomography setup

      Defense of fake fingerprint attacks using a swept source laser optical coherence tomography setup

      The most established technique for the identification at biometric access control systems is the human fingerprint. While every human fingerprint is unique, fingerprints can be faked very easily by using thin layer fakes. Because commercial fingerprint scanners use only a two-dimensional image acquisition of the finger surface, they can only hardly differentiate between real fingerprints and fingerprint fakes applied on thin layer materials. A Swept Source OCT system with an A-line rate of 20 kHz and a lateral and axial resolution of approximately 13 μm, a centre wavelength of 1320 nm and a band width of 120 nm (FWHM) was ...

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    5. A new small-package super-continuum light source for optical coherence tomography

      A new small-package super-continuum light source for optical coherence tomography

      Broadband light sources provide a significant benefit for optical coherence tomography (OCT) imaging concerning the axial resolution. Light sources with bandwidths over 200 nm result in an axial resolution up to 2 microns. Such broad band OCT imaging can be achieved utilizing super continuum (SC) light sources. The main important disadvantage of commercial SC light sources is the overall size and the high costs. Therefore, the use of SC light sources in small OCT setups and applications is limited. We present a new small housing and costeffective light source, which is suitable for OCT imaging. The used light source has ...

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    6. Feature Of The Week 8/5/12: Dresden University of Technology Uses OCT As a Tool for Microscope Investigation of Nucleated Boiling on Headed Surfaces

      Feature Of The Week 8/5/12: Dresden University of Technology Uses OCT As a Tool for Microscope Investigation of Nucleated Boiling on Headed Surfaces

      Dresden University of Technology has been very active publishing interesting articles across a wide range of technologies and applications for Optical Coherence Tomography (see Link). Recently researchers their showed an interesting non-biological non-medical applications for OCT, namely the application of OCT ininvestigating boiling phenomena. Below is a summary of their work. -Eric Swanson Boiling phenomena are an important aspect in security and efficiency for technical applications with high heat flux like nuclear reactors. This study presents optical coherence tomography (OCT) as a novel modality for three-dimensional and two-dimensional time resolved imaging of nucleate boiling on heated surfaces on a microscopic ...

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    7. Feature Of The Week 7/15/12: 3D Simultaneous Optical Coherence Tomography and Confocal Fluorescence Microscopy for Investigation of Lung Tissue

      Feature Of The Week 7/15/12: 3D Simultaneous Optical Coherence Tomography and Confocal Fluorescence Microscopy for Investigation of Lung Tissue

      The acute respiratory distress syndrome (ARDS) is a life-threatening condition of the lung leading to a state of decreased lung compliance and blood oxygenation efficiency. The treatment of patients utilizes artificial ventilation, which has a tremendous impact on the lung’s sensitive microenvironment and can even lead to further damage in the form of ventilator induced lung injury (VILI). As a basis for the understanding of physiological processes occurring on the microscale of lung tissue, the alveolar tissue, contact free imaging can elucidate dynamic changes during artificial ventilation. The main interest focuses here on the rearrangement of alveolar geometry and ...

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    8. 3D optical coherence tomography as new tool for microscopic investigations of nucleate boiling on heated surfaces

      3D optical coherence tomography as new tool for microscopic investigations of nucleate boiling on heated surfaces

      Boiling phenomena are an important aspect in security and efficiency for technical applications with high heat flux like nuclear reactors. This study presents optical coherence tomography (OCT) as a novel modality for three-dimensional and two-dimensional time resolved imaging of nucleate boiling on heated surfaces on a microscopic scale with high spatial (<10 μm) and temporal (>25 frames per second) resolution. Within this study, a borosilicate glass plate coated with an optically transparent and electrically conductive indium tin oxide (ITO) layer with a thickness of approximately 100 nm was used as heating surface. The combination of these two properties allows optical ...

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    9. Three-dimensional simultaneous optical coherence tomography and confocal fluorescence microscopy for investigation of lung tissue

      Three-dimensional simultaneous optical coherence tomography and confocal fluorescence microscopy for investigation of lung tissue

      Although several strategies exist for a minimal-invasive treatment of patients with lung failure, the mortality rate of acute respiratory distress syndrome still reaches 30% at minimum. This striking number indicates the necessity of understanding lung dynamics on an alveolar level. To investigate the dynamical behavior on a microscale, we used three-dimensional geometrical and functional imaging to observe tissue parameters including alveolar size and length of embedded elastic fibers during ventilation. We established a combined optical coherence tomography (OCT) and confocal fluorescence microscopy system that is able to monitor the distension of alveolar tissue and elastin fibers simultaneously within three dimensions ...

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    10. Feature Of The Week 5/20/12: Dresden University of Technology Investigates Precision Lung Dynamics Using Four-Dimensional OCT

      Feature Of The Week 5/20/12: Dresden University of Technology Investigates Precision Lung Dynamics Using Four-Dimensional OCT

      The treatment of urgent lung diseases, such as the acute respiratory distress syndrome and the acute lung injury, requires the development of protective ventilation strategies with the help of numerical simulations. For this purpose, information about the structure of lung tissue and its dynamics is required on an alveolar level. Optical coherence tomography (OCT) can obtain high resolution cross-sectional and volumetric data of lung tissue using rodent models. Access to the lung tissue is obtained by preparing a transparent thorax window. In previous studies, OCT imaging was limited by the depth scan rate and three-dimensional information has been obtained by ...

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    11. Four-dimensional imaging of murine subpleural alveoli using high-speed optical coherence tomography

      Four-dimensional imaging of murine subpleural alveoli using high-speed optical coherence tomography

      The investigation of lung dynamics on alveolar scale is crucial for the understanding and treatment of lung diseases, such as acute lung injury and ventilator induced lung injury, and to promote the development of protective ventilation strategies. One approach to this is the establishment of numerical simulations of lung tissue mechanics where detailed knowledge about three-dimensional alveolar structure changes during the ventilation cycle is required. We suggest four-dimensional optical coherence tomography (OCT) imaging as a promising modality for visualizing the structural dynamics of single alveoli in subpleural lung tissue with high temporal resolution using a mouse model. A high-speed OCT ...

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    12. Multimodal imaging of lung tissue using optical coherence tomography and two photon microscopy

      Multimodal imaging of lung tissue using optical coherence tomography and two photon microscopy

      In the context of protective artificial ventilation strategies for patients with severe lung diseases, the contribution of ventilator settings to tissue changes on the alveolar level of the lung is still a question under debate. To understand the impact of respiratory settings as well as the dynamic process of respiration, high-resolution monitoring and visualization of the dynamics of lung alveoli are essential. An instrument allowing 3D imaging of lung tissue as well as imaging of functional constituents, such as elastin fibers, in in situ experimental conditions is presented in this study using a combination of Fourier domain optical coherence tomography ...

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    13. Quantitative investigation of alveolar structures with OCT using total liquid ventilation during mechanical ventilation

      Quantitative investigation of alveolar structures with OCT using total liquid ventilation during mechanical ventilation

      To develop new treatment possibilities for patients with severe lung diseases it is crucial to understand the lung function on an alveolar level. Optical coherence tomography (OCT) in combination with intravital microscopy (IVM) are used for imaging subpleural alveoli in animal models to gain information about dynamic and morphological changes of lung tissue during mechanical ventilation. The image content suitable for further analysis is influenced by image artifacts caused by scattering, refraction, reflection, and absorbance. Because the refractive index varies with each air-tissue interface in lung tissue, these effects decrease OCT image quality exceedingly. The quality of OCT images can ...

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    14. Investigation of alveolar tissue deformations using OCT combined with fluorescence microscopy

      Investigation of alveolar tissue deformations using OCT combined with fluorescence microscopy

      In critical care medicine, artificial ventilation is a life saving tool providing sufficient blood oxygenation to patients suffering from respiratory failure. Essential for their survival is the use of protective ventilation strategies to prevent further lung damage due to ventilator induced lung injury (VILI). Since there is only little known about implications of lung tissue overdistension on the alveolar level, especially in the case of diseased lungs, this research deals with the investigation of lung tissue deformation on a microscale. A combined setup utilizing optical coherence tomography (OCT) and confocal fluorescence microscopy, is used to study the elastic behavior of ...

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    15. Improved OCT imaging of lung tissue using a prototype for total liquid ventilation

      Improved OCT imaging of lung tissue using a prototype for total liquid ventilation
      Optical coherence tomography (OCT) is used for imaging subpleural alveoli in animal models to gain information about dynamic and morphological changes of lung tissue during mechanical ventilation. The quality of OCT images can be increased if the refraction index inside the alveoli is matched to the one of tissue via liquid-filling. Thereby, scattering loss can be decreased and higher penetration depth and tissue contrast can be achieved. Until now, images of liquid-filled lungs were acquired in isolated and fixated lungs only, so that an in vivo measurement situation is not present. To use the advantages of liquid-filling for in vivo ...
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    16. Optical coherence tomography for imaging of subpleural alveolar structure using a Fourier domain mode locked laser

      Optical coherence tomography for imaging of subpleural alveolar structure using a Fourier domain mode locked laser

      Optical coherence tomography (OCT) is a noninvasive imaging modality generating cross sectional and volumetric images of translucent samples. In Fourier domain OCT (FD OCT), the depth profile is calculated by a fast Fourier transformation of the interference spectrum, providing speed and SNR advantage and thus making FD OCT well suitable in biomedical applications. The interference spectrum can be acquired spectrally resolved in spectral domain OCT or time-resolved in optical frequency domain imaging (OFDI). Since OCT images still suffer from motion artifacts, especially under in vivo conditions, increased depth scan rates are required. Therefor, the principle of Fourier domain mode locking ...

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    17. Optical coherence tomography in biomedical research

      Optical coherence tomography in biomedical research
      Optical coherence tomography (OCT) is a noninvasive, high-resolution, interferometric imaging modality using near-infrared light to acquire cross-sections and three-dimensional images of the subsurface microstructure of biological specimens. Because of rapid improvement of the acquisition speed and axial resolution of OCT over recent years, OCT is becoming increasingly attractive for applications in biomedical research. Therefore, OCT is no longer used solely for structural investigations of biological samples but also for functional examination, making it potentially useful in bioanalytical science. The combination of in vivo structural and functional findings makes it possible to obtain thorough knowledge on basic physiological and pathological processes ...
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    18. Intravital microscopy of subpleural alveoli via transthoracic endoscopy

      Intravital microscopy of subpleural alveoli via transthoracic endoscopy
      Transfer of too high mechanical energy from the ventilator to the lung's alveolar tissue is the main cause for ventilator-induced lung injury (VILI). To investigate the effects of cyclic energy transfer to the alveoli, we introduce a new method of transthoracic endoscopy that provides morphological as well as functional information about alveolar geometry and mechanics. We evaluate the new endoscopic method to continuously record images of focused subpleural alveoli. The method is evaluated by using finite element modeling techniques and by direct observation of subpleural alveoli both in isolated rat lungs as well as in intact animals (rats). The ...
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    19. Three-dimensional functional imaging of lung parenchyma using optical coherence tomography combined with confocal fluorescence microscopy

      Three-dimensional functional imaging of lung parenchyma using optical coherence tomography combined with confocal fluorescence microscopy

      Optical coherence tomography (OCT), as a non-invasive technique for studying tissue morphology, is widely used in in vivo studies, requiring high resolution and fast three-dimensional imaging. Based on light scattering it reveals micrometer sized substructures of the samples due to changes in their optical properties and therefore allows quantification of the specimen's geometry. Utilizing fluorescence microscopy further information can be obtained from molecular compositions embedded in the investigated object. Fluorescent markers, specifically binding to the substance of interest, reveal the sample's chemical structure and give rise to functional studies. This research presents the application of a combined OCT ...

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    20. Virtual four-dimensional imaging of lung parenchyma by optical coherence tomography in mice

      Virtual four-dimensional imaging of lung parenchyma by optical coherence tomography in mice
      In this feasibility study, we present a method for virtual 4-D imaging of healthy and injured subpleural lung tissue in the ventilated mouse. We use triggered swept source optical coherence tomography (OCT) with an A-scan frequency of 20 kHz to image murine subpleural alveoli during the inspiratory phase. The data acquisition is gated to the ventilation pressure to take single B-scans in each respiration cycle for different pressure levels. The acquired B-scans are combined off-line into one volume scan for each pressure level. The air fraction in healthy lungs and injured lungs is measured using 2-D OCT en-face images. Upon ...
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    21. Combining optical coherence tomography with fluorescence microscopy: a closer look into tissue

      Combining optical coherence tomography with fluorescence microscopy: a closer look into tissue

      Optical coherence tomography (OCT) is a technique, capable of high resolution and non-invasive 3D imaging in vivo by detection of backscattered light from cellular and sub cellular structures. Due to visualization of micrometer sized tissue constituents and high penetration depths of up to 2 mm, it is already well established in medical fields like ophthalmology and dermatology. Laser scanning confocal microscopy (LSCM), on the contrary, gives further information on structural tissue components stained with suitable dyes. In combination, these two methods yield three dimensional and high resolution data providing geometrical and structural details of tissue. In this study, we present ...

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    22. Three-dimensional Fourier domain optical coherence tomography in vivo imaging of alveolar tissue in the intact thorax using the parietal pleura as a window

      Three-dimensional Fourier domain optical coherence tomography in vivo imaging of alveolar tissue in the intact thorax using the parietal pleura as a window
      In vivo determination of 3-D and dynamic geometries of alveolar structures with adequate resolution is essential for developing numerical models of the lung. A thorax window is prepared in anesthetized rabbits by removal of muscle tissue between the third and fourth rib without harming the parietal pleura. The transparent parietal pleura allows contact-free imaging by intravital microscopy IVM and 3-D optical coherence tomography 3-D OCT. We demonstrate that dislocation of the lung surface is small enough to observe identical regions in the expiratory and inspiratory plateau phase, and that OCT in this animal model is suitable for generating 3-D geometry ...
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    23. Improved three-dimensional Fourier domain optical coherence tomography by index matching in alveolar structures

      Three-dimensional Fourier domain optical coherence tomography (3-D FDOCT) is used to demonstrate that perfusion fixation with a mixture of glutaraldehyde and paraformaldehyde does not alter the geometry of subpleural lung parenchyma in isolated and perfused rabbit lungs. This is confirmed by simultaneous imaging of lung parenchyma with intravital microscopy. To eliminate the diffraction index interfaces between alveolar pockets and walls, we fill the fixed lungs with ethanol by perfusing with gradually increasing concentrations. This bottom-up filling process leaves no remaining air bubbles in the alveolar structures, thus drastically improving the resolution and penetration depth of 3-D FDOCT imaging. We observe ...
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    1-24 of 28 1 2 »
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    1. (28 articles) Dresden University of Technology
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    Combining optical coherence tomography with fluorescence microscopy: a closer look into tissue Virtual four-dimensional imaging of lung parenchyma by optical coherence tomography in mice Intravital microscopy of subpleural alveoli via transthoracic endoscopy Optical coherence tomography in biomedical research Investigation of alveolar tissue deformations using OCT combined with fluorescence microscopy Three-dimensional simultaneous optical coherence tomography and confocal fluorescence microscopy for investigation of lung tissue Feature Of The Week 7/15/12: 3D Simultaneous Optical Coherence Tomography and Confocal Fluorescence Microscopy for Investigation of Lung Tissue Optical imaging techniques could offer non-invasive method to measure swelling within the brain, new study finds Using Optical Coherence Tomography as a Surrogate of Measurements of Intracranial Pressure in Idiopathic Intracranial Hypertension Endoscopic imaging in inflammatory bowel disease: current developments and emerging strategies 2D Ultrasonic Array-based Optical Coherence Elastography Optical coherence tomography angiography in diabetic retinopathy: an updated review