1. Articles from Sebastian Karpf

    1-6 of 6
    1. Frequency-doubled FDML-MOPA laser in the visible

      Frequency-doubled FDML-MOPA laser in the visible

      Wavelength-swept lasers enable high-speed measurements in absorption spectroscopy, Raman spectroscopy, nonlinear Raman hyperspectral microscopy, rapid confocal microscopy, short impulse generation, and most importantly for high-speed optical coherence tomography, with speeds up to video-rate volumetric imaging. Recently, we introduced a pulsed wavelength-swept laser based on the Fourier domain mode-locked (FDML) laser principle combined with a master-oscillator power amplifier (MOPA) architecture. The high peak powers reached with this laser enabled rapid two-photon microscopy and two-photon fluorescence lifetime microscopy and high-speed light detection and ranging measurements. Here, we present the extension of this laser into the visible wavelength range by frequency doubling the ...

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    2. Fourier-domain mode-locked laser combined with a master-oscillator power amplifier architecture

      Fourier-domain mode-locked laser combined with a master-oscillator power amplifier architecture

      Originally introduced in 2005 for high-speed optical coherence tomography, the rapidly wavelength-swept Fourier-domain mode-locked (FDML) laser still, to this day, enables highest imaging speeds through a very high-speed spectral tuning capability. The FDML laser achieves a tuning bandwidth of over 1/10th of its center wavelength and can sweep this entire bandwidth in less than a microsecond. Interestingly, even though it covers a very broad spectral range, instantaneously it has a narrow spectral linewidth that puts it in a unique space compared to other high-speed broadband laser sources, e.g., mode-locked lasers or supercontinuum sources. Although it has been applied ...

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      Mentions: Bahram Jalali UCLA
    3. A Time-Encoded Technique for fibre-based hyperspectral broadband stimulated Raman microscopy

      A Time-Encoded Technique for fibre-based hyperspectral broadband stimulated Raman microscopy

      Raman sensing and microscopy are among the most specific optical technologies to identify the chemical compounds of unknown samples, and to enable label-free biomedical imaging. Here we present a method for stimulated Raman scattering spectroscopy and imaging with a time-encoded (TICO) Raman concept. We use continuous wave, rapidly wavelength-swept probe lasers and combine them with a short-duty-cycle actively modulated pump laser. Hence, we achieve high stimulated Raman gain signal levels, while still benefitting from the narrow linewidth and low noise of continuous wave operation. Our all-fibre TICO-Raman setup uses a Fourier domain mode-locked laser source to achieve a unique combination ...

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    4. A 4-D OCT Engine with 1 GVoxel/s

      A 4-D OCT Engine with 1 GVoxel/s

      Optical coherence tomography (OCT) is a depth-resolved imaging modality that provides micrometer-scale cross-sectional and 3-D information on the scattering properties of biological samples. 1 Video rate real-time 3-D volumetric OCT (4-D-OCT) could generate a new class of optical tools in clinical practice, like surgical guidance. 2 This challenge requires us to combine a high-speed OCT imaging setup, ultrafast data acquisition and adequate real-time data processing to process and visualize the vast amount of data. Although 4-D-OCT has long been a dream for researchers, only a few groups have successfully implemented 4-D volumetric OCT imaging with real-time visualization—usually with low ...

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    5. High definition live 3D-OCT in vivo: design and evaluation of a 4D OCT engine with 1 GVoxel/s

      High definition live 3D-OCT in vivo: design and evaluation of a 4D OCT engine with 1 GVoxel/s

      We present a 1300 nm OCT system for volumetric real-time live OCT acquisition and visualization at 1 billion volume elements per second. All technological challenges and problems associated with such high scanning speed are discussed in detail as well as the solutions. In one configuration, the system acquires, processes and visualizes 26 volumes per second where each volume consists of 320 x 320 depth scans and each depth scan has 400 usable pixels. This is the fastest real-time OCT to date in terms of voxel rate. A 51 Hz volume rate is realized with half the frame number. In both ...

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    6. Extended coherence length megahertz FDML and its application for anterior segment imaging

      Extended coherence length megahertz FDML and its application for anterior segment imaging
      We present a 1300 nm Fourier domain mode locked (FDML) laser for optical coherence tomography (OCT) that combines both, a high 1.6 MHz wavelength sweep rate and an ultra-long instantaneous coherence length for rapid volumetric deep field imaging. By reducing the dispersion in the fiber delay line of the FDML laser, the instantaneous coherence length and hence the available imaging range is approximately quadrupled compared to previously published MHz-FDML setups, the imaging speed is increased by a factor of 16 compared to previous extended coherence length results. We present a detailed characterization of the FDML laser performance. We demonstrate ...
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    1-6 of 6
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  2. Topics in the News

    1. (4 articles) University of Lübeck
    2. (4 articles) Thomas Klein
    3. (4 articles) Wolfgang Wieser
    4. (3 articles) Ludwig Maximilian University of Munich
    5. (3 articles) Robert A. Huber
    6. (2 articles) UCLA
    7. (2 articles) Tom Pfeiffer
    8. (1 articles) Desmond C. Adler
    9. (1 articles) Joseph M. Schmitt
    10. (1 articles) Abbot
    11. (1 articles) Institute of Applied Physics
    12. (1 articles) Medical University of Vienna
    13. (1 articles) Kyungpook National University
    14. (1 articles) Singapore Eye Research Institute
    15. (1 articles) University of Western Australia
    16. (1 articles) Stefan G. Sacu
    17. (1 articles) Brendan F. Kennedy
    18. (1 articles) Yongyang Huang
    19. (1 articles) Jeehyun Kim
    20. (1 articles) Ursula Schmidt-Erfurth
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    Extended coherence length megahertz FDML and its application for anterior segment imaging High definition live 3D-OCT in vivo: design and evaluation of a 4D OCT engine with 1 GVoxel/s A 4-D OCT Engine with 1 GVoxel/s A Time-Encoded Technique for fibre-based hyperspectral broadband stimulated Raman microscopy Fourier-domain mode-locked laser combined with a master-oscillator power amplifier architecture Frequency-doubled FDML-MOPA laser in the visible Full-range space-division multiplexing optical coherence tomography angiography Measuring 3D Optic Nerve Head Deformations using Digital Volume Correlation of in vivo Optical Coherence Tomography Data (Thesis) Optical coherence tomography for characterization of nanocomposite materials (Thesis) In Vivo Corneal Microstructural Changes in Herpetic Stromal Keratitis: A Spectral-Domain Optical Coherence Tomography Analysis Non-invasive optical screening of Streptococcus Pneumonia based inflammatory changes of the tympanic membrane and mastoid mucosa in guinea pig otitis media using optical coherence tomography Visual function tests including the role of optical coherence tomography in neurofibromatosis