1. Articles from Ben O’Shaughnessy

    1-3 of 3
    1. Convective Nozaki-Bekki holes in a long cavity OCT laser

      Convective Nozaki-Bekki holes in a long cavity OCT laser

      We show, both experimentally and theoretically, that the loss of coherence of a long cavity optical coherence tomography (OCT) laser can be described as a transition from laminar to turbulent flows. We demonstrate that in this strongly dissipative system, the transition happens either via an absolute or a convective instability depending on the laser parameters. In the latter case, the transition occurs via formation of localised structures in the laminar regime, which trigger the formation of growing and drifting puffs of turbulence. Experimentally, we demonstrate that these turbulent bursts are seeded by appearance of Nozaki-Bekki holes, characterised by the zero ...

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    2. Coherence properties of fast frequency swept lasers revealed via full electric field reconstruction

      Coherence properties of fast frequency swept lasers revealed via full electric field reconstruction

      A novel, time-resolved interferometric technique is presented allowing the reconstruction of the complex electric field output of a fast frequency swept laser in a single-shot measurement. The power of the technique is demonstrated by examining a short cavity swept source designed for optical coherence tomography applications, with a spectral bandwidth of 18 THz. This novel analysis of the complete electric field reveals the modal structure and modal evolution of the device as well as providing a time-resolved real-time characterization of the optical spectrum, linewidth and coherence properties of a dynamic rapidly swept laser.

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    3. Feature Of The Week 11/9/14: Dynamics of a Short Cavity Swept Source OCT Laser

      Feature Of The Week 11/9/14: Dynamics of a Short Cavity Swept Source OCT Laser

      Great advances in OCT speed and sensitivity have been possible due to the introduction of fast frequency swept laser sources. One of the most commonly used swept source devices is a short (~5 cm) cavity Fabry-Perot laser. We present both experimental characterisation and numerical modelling of such an OCT swept source and also analyse the underlying physics to better understand how such sources may be optimised. For the experimental characterisation we use a high-speed digital oscilloscope for real time analysis of the fast temporal intensity and frequency evolution. For the theoretical analysis we use a set of delay differential equations ...

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    1-3 of 3
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  2. Topics in the News

    1. (5 articles) National Institutes of Health
    2. (2 articles) Nicolaus Copernicus University
    3. (2 articles) Bryan Kelleher
    4. (2 articles) Maciej Wojtkowski
    5. (2 articles) Karol Karnowski
    6. (1 articles) University College Cork
    7. (1 articles) University of Houston
    8. (1 articles) University of Minnesota
    9. (1 articles) Indiana University
    10. (1 articles) Yale University
    11. (1 articles) Massachusetts Institute of Technology
    12. (1 articles) James G. Fujimoto
    13. (1 articles) Taner Akkin
    14. (1 articles) Donald T. Miller
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    Feature Of The Week 11/9/14: Dynamics of a Short Cavity Swept Source OCT Laser Coherence properties of fast frequency swept lasers revealed via full electric field reconstruction Convective Nozaki-Bekki holes in a long cavity OCT laser Indiana University Receives NIH Grant for Imaging Spatial and Temporal Dynamics of Retinal Ganglion Cells University of Houston Receives NIH Grant for Structural and Molecular Phenotyping of Embryonic Development Through Multi-Modal Optical Imaging. Massachusetts Institute of Technology Receives NIH Grant for Novel Optical Diagnostics with Optical Coherence Tomography Yale University Receives a NIH Grant for Xenopus As A Model System for Hydrocephaly and Ependymal Ciliogenesis University of Minnesota Receives NIH Grant for Optical Imaging of Neural Activity Based on Lorentz Effect Skin Imaging to Inform Laser Treatments Diabetes and Fundus OCT: 1st Edition (Textbook) Wavelength-encoded multi-channel spectral-domain optical coherence tomography (SD-OCT) for spatiotemporally resolved imaging Optical Coherence Tomography-Angiography of a large retinal microaneurysm