1. Articles from Sebastian Marschall

    1-11 of 11
    1. Semiconductor Lasers and Diode-based Light Sources for Biophotonics (Textbook)

      Semiconductor Lasers and Diode-based Light Sources for Biophotonics (Textbook)

      Semiconductor lasers are small, reliable, low cost, high-performance and user-friendly optical devices which make them highly suitable for a variety of biomedical applications. This edited book gathers experts in the field to cover the fundamentals and technology advances of semiconductor lasers and diode-based lasers with a focus on their applications in medical optics and biophotonics including edge-emitting semiconductor lasers and light emitting diodes, Q-switched and mode-locked lasers, quantum cascade lasers, semiconductor disk lasers, near-infrared spectroscopy systems for biomedical applications, bio-medical Raman spectroscopy, nonlinear imaging and optical coherence tomography.

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    2. Skin Cancer A Practical Approach (Textbook)

      Skin Cancer A Practical Approach (Textbook)

      Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described as the optical analogue to ultrasound. The inherent safety of the technology allows for in vivo use of OCT in patients. The main strength of OCT is the depth resolution. In dermatology, most OCT research has turned on non-melanoma skin cancer (NMSC) and non-invasive monitoring of morphological changes in a number of skin diseases based on pattern recognition ...

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    3. Retinal polarization-sensitive optical coherence tomography at 1060 nm with 350 kHz A-scan rate using an Fourier domain mode locked laser

      Retinal polarization-sensitive optical coherence tomography at 1060 nm with 350 kHz A-scan rate using an Fourier domain mode locked laser

      We present a novel, high-speed, polarization-sensitive, optical coherence tomography set-up for retinal imaging operating at a central wavelength of 1060 nm which was tested for in vivo imaging in healthy human volunteers. We use the system in combination with a Fourier domain mode locked laser with active spectral shaping which enables the use of forward and backward sweep in order to double the imaging speed without a buffering stage. With this approach and with a custom designed data acquisition system, we show polarization-sensitive imaging with an A-scan rate of 350 kHz. The acquired three-dimensional data sets of healthy human volunteers ...

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    4. Feature Of The Week 1/13/13: Technical University of Denmark Publishes Detailed Quantitative Analysis of 1060nm Window for Optimal OCT Retinal Imaging

      Feature Of The Week 1/13/13: Technical University of Denmark Publishes Detailed Quantitative Analysis of 1060nm Window for Optimal OCT Retinal Imaging

      During the past decade, the wavelength range around the local water absorption minimum at 1060 nm has found increasing interest in the OCT community, as it allows imaging of the human posterior eye segment with improved penetration depth into the choroid and the sclera. However, the neighboring water absorption bands narrow the bandwidth of probing light, and reduce thus the achievable axial resolution. A detailed quantitative analysis of this effect has been missing until now, but has become increasingly relevant due to the availability of new light sources (SLDs, swept sources) with bandwidths in excess of 100 nm. For light ...

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    5. Investigation of the impact of water absorption on retinal OCT imaging in the 1060 nm range

      Investigation of the impact of water absorption on retinal OCT imaging in the 1060 nm range

      Recently, the wavelength range around 1060 nm has become attractive for retinal imaging with optical coherence tomography (OCT), promising deep penetration into the retina and the choroid. The adjacent water absorption bands limit the useful bandwidth of broadband light sources, but until now, the actual limitation has not been quantified in detail. We have numerically investigated the impact of water absorption on the axial resolution and signal amplitude for a wide range of light source bandwidths and center wavelengths. Furthermore, we have calculated the sensitivity penalty for maintaining the optimal resolution by spectral shaping. As our results show, with currently ...

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    6. High-speed polarization-sensitive OCT at 1060 nm using a Fourier domain mode-locked swept source

      High-speed polarization-sensitive OCT at 1060 nm using a Fourier domain mode-locked swept source

      Optical coherence tomography (OCT) in the 1060nm range is interesting for in vivo imaging of the human posterior eye segment (retina, choroid, sclera), as it permits a long penetration depth. Complementary to structural images, polarization-sensitive OCT (PS-OCT) images visualize birefringent, polarization-maintaining or depolarizing areas within the sample. This information can be used to distinguish retinal layers and structures with different polarization properties. High imaging speed is crucial for imaging ocular structures in vivo in order to minimize motion artifacts while acquiring sufficiently large datasets. Here, we demonstrate PS-OCT imaging at 350 kHz A-scan rate using a two-channel PS-OCT system in ...

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    7. Broadband Fourier domain mode-locked laser for optical coherence tomography at 1060 nm

      Broadband Fourier domain mode-locked laser for optical coherence tomography at 1060 nm

      Optical coherence tomography (OCT) in the 1060nm range is interesting for in vivo imaging of the human posterior eye segment (retina, choroid, sclera) due to low absorption in water and deep penetration into the tissue. Rapidly tunable light sources, such as Fourier domain mode-locked (FDML) lasers, enable acquisition of densely sampled three-dimensional datasets covering a wide field of view. However, semiconductor optical amplifiers (SOAs)-the typical laser gain media for swept sources-for the 1060nm band could until recently only provide relatively low output power and bandwidth. We have implemented an FDML laser using a new SOA featuring broad gain bandwidth ...

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    8. Optical coherence tomography-current technology and applications in clinical and biomedical research

      Optical coherence tomography-current technology and applications in clinical and biomedical research
      Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. By mapping the local reflectivity, OCT visualizes the morphology of the sample. In addition, functional properties such as birefringence, motion, or the distributions of certain substances can be detected with high spatial resolution. Its main field of application is biomedical imaging and diagnostics. In ophthalmology, OCT is accepted as a clinical standard for diagnosing and monitoring the treatment of a number of retinal diseases, and OCT is becoming an important instrument for clinical cardiology. New applications are emerging ...
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    9. Fourier domain mode-locked swept source
 at 1050 nm based on a tapered amplifier

      Fourier domain mode-locked swept source
 at 1050 nm based on a tapered amplifier

      While swept source optical coherence tomography (OCT) in the 1050 nm range is promising for retinal imaging, there are certain challenges. Conventional semiconductor gain media have limited output power, and the performance of high-speed Fourier domain mode-locked (FDML) lasers suffers from chromatic dispersion in standard optical fiber. We developed a novel light source with a tapered amplifier as gain medium, and investigated the FDML performance comparing two fiber delay lines with different dispersion properties. We introduced an additional gain element into the resonator, and thereby achieved stable FDML operation, exploiting the full bandwidth of the tapered amplifier despite high dispersion ...

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    10. FDML swept source at 1060 nm using a tapered amplifier

      FDML swept source at 1060 nm using a tapered amplifier

      We present a novel frequency-swept light source working at 1060nm that utilizes a tapered amplifier as gain medium. These devices feature significantly higher saturation power than conventional semiconductor optical amplifiers and can thus improve the limited output power of swept sources in this wavelength range. We demonstrate that a tapered amplifier can be integrated into a fiber-based swept source and allows for high-speed FDML operation. The developed light source operates at a sweep rate of 116kHz with an effective average output power in excess of 30mW. With a total sweep range of 70 nm an axial resolution of 15 µm ...

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    11. Frequency-swept laser light source at 1050 nm with higher bandwidth due to multiple semiconductor optical amplifiers in series

      We report on the development of an all-fiber frequency-swept laser light source in the 1050 nm range based on semiconductor optical amplifiers (SOA) with improved bandwidth due to multiple gain media. It is demonstrated that even two SOAs with nearly equal gain spectra can improve the performance of ... [Proc. SPIE 7168, 716824 (2009)] published Fri Feb 20, 2009.

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    1-11 of 11
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  2. Topics in the News

    1. (11 articles) Technical University of Denmark (DTU)
    2. (11 articles) Peter E. Andersen
    3. (11 articles) Sebastian Marschall
    4. (7 articles) Christian R. Petersen
    5. (5 articles) Ludwig Maximilian University of Munich
    6. (5 articles) Robert A. Huber
    7. (5 articles) Thomas Klein
    8. (5 articles) Benjamin R. Biedermann
    9. (5 articles) Wolfgang Wieser
    10. (3 articles) Micron Optics
    11. (2 articles) Medical University of Vienna
    12. (1 articles) Nara Medical University
    13. (1 articles) K. U. Leuven
    14. (1 articles) University of Alabama
    15. (1 articles) Singapore Eye Research Institute
    16. (1 articles) Michael Pircher
    17. (1 articles) Taishi Yonetsu
    18. (1 articles) Ursula Schmidt-Erfurth
    19. (1 articles) Tsunekazu Kakuta
    20. (1 articles) Dalip Singh Mehta
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    FDML swept source at 1060 nm using a tapered amplifier Fourier domain mode-locked swept source
 at 1050 nm based on a tapered amplifier Optical coherence tomography-current technology and applications in clinical and biomedical research Broadband Fourier domain mode-locked laser for optical coherence tomography at 1060 nm High-speed polarization-sensitive OCT at 1060 nm using a Fourier domain mode-locked swept source Investigation of the impact of water absorption on retinal OCT imaging in the 1060 nm range Feature Of The Week 1/13/13: Technical University of Denmark Publishes Detailed Quantitative Analysis of 1060nm Window for Optimal OCT Retinal Imaging Retinal polarization-sensitive optical coherence tomography at 1060 nm with 350 kHz A-scan rate using an Fourier domain mode locked laser Skin Cancer A Practical Approach (Textbook) High space-bandwidth in quantitative phase imaging using partially spatially coherent optical coherence microscopy and deep neural network Optical coherence tomography assessment of macrophages accumulation in non-ST-segment elevation acute coronary syndromes Early disability in ambulatory patients with multiple sclerosis: optical coherence tomography versus visual evoked potentials, a comparative study