1. Articles from Nicolás Weiss

    1-7 of 7
    1. On-chip Mach-Zehnder interferometer for OCT systems

      On-chip Mach-Zehnder interferometer for OCT systems

      By using integrated optics, it is possible to reduce the size and cost of a bulky optical coherence tomography (OCT) system. One of the OCT components that can be implemented on-chip is the interferometer. In this work, we present the design and characterization of a Mach-Zehnder interferometer consisting of the wavelength-independent splitters and an on-chip reference arm. The Si 3 N 4 was chosen as the material platform as it can provide low losses while keeping the device size small. The device was characterized by using a home-built swept source OCT system. A sensitivity value of 83 dB, an axial ...

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    2. Measurement of biofilm growth and local hydrodynamics using optical coherence tomography

      Measurement of biofilm growth and local hydrodynamics using optical coherence tomography

      We report on localized and simultaneous measurement of biofilm growth and local hydrodynamics in a microfluidic channel using optical coherence tomography. We measure independently with high spatio-temporal resolution the longitudinal flow velocity component parallel to the imaging beam and the transverse flow velocity component perpendicular to the imaging beam. Based on the measured velocities we calculate the shear-rates in the flow channel. We show the relation between the measured biofilm structure and flow velocities as biofilm growth progresses over the course of 48 hours.

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    3. Chip based common-path optical coherence tomography system with an on-chip microlens and multi-reference suppression algorithm

      Chip based common-path optical coherence tomography system with an on-chip microlens and multi-reference suppression algorithm

      We demonstrate an integrated optical probe including an on-chip microlens for a common-path swept-source optical coherence tomography system. This common-path design uses the end facet of the silicon oxynitride waveguide as the reference plane, thus eliminating the need of a space-consuming and dispersive on-chip loop reference arm, thereby obviating the need for dispersion compensation. The on-chip micro-ball lens eliminates the need of external optical elements for coupling the light between the chip and the sample. The use of this lens leads to a signal enhancement up to 37 dB compared to the chip without a lens. The light source, the ...

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    4. Simultaneous and localized measurement of diffusion and flow using optical coherence tomography

      Simultaneous and localized measurement of diffusion and flow using optical coherence tomography

      We report on the simultaneous and localized measurement of the diffusion coefficient and flow velocity based on the normalized autocorrelation function using optical coherence tomography (OCT). Our results on a flowing suspension of polystyrene spheres show that the flow velocity and the diffusion coefficient can be reliably estimated in a regime determined by the sample diffusivity, the local flow velocity, and the Gaussian beam waist. We experimentally demonstrate that a smaller beam waist results in an improvement of the velocity sensitivity at the expense of the precision and accuracy of the estimation of the diffusion coefficient. Further, we show that ...

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    5. Ultra-compact silicon photonic integrated interferometer for swept-source optical coherence tomography

      Ultra-compact silicon photonic integrated interferometer for swept-source optical coherence tomography

      We demonstrate an ultra-compact silicon integrated photonic interferometer for swept-source optical coherence tomography (SS-OCT). The footprint of the integrated interferometer is only 0.75 × 5     mm 2 . The design consists of three 2 × 2 splitters, a 13 cm physical length (50.4 cm optical length) reference arm, and grating couplers. The photonic integrated circuit was used as the interferometer of an SS-OCT system. The sensitivity of the system was measured to be − 62     dB with 115 μW power delivered to the sample. Using the system, we demonstrate cross-sectional OCT imaging of a layered tissue phantom. We also discuss potential improvements ...

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    6. Localized measurement of longitudinal and transverse flow velocities in colloidal suspensions using optical coherence tomography

      Localized measurement of longitudinal and transverse flow velocities in colloidal suspensions using optical coherence tomography

      We report on localized measurement of the longitudinal and transverse flow velocities in a colloidal suspension using optical coherence tomography. We present a model for the path-length resolved autocorrelation function including diffusion and flow, which we experimentally verify. For flow that is not perpendicular to the incident beam, the longitudinal velocity gradient over the coherence gate causes additional decorrelation, which is described by our model. We demonstrate simultaneous imaging of sample morphology and longitudinal and transverse flow at micrometer scale in a single measurement.

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    7. Doppler-based lateral motion tracking for optical coherence tomography

      Doppler-based lateral motion tracking for optical coherence tomography

      Nonuniform lateral scanning of the probe beam in optical coherence tomography produces imaging artifacts and leads to a morphologically inaccurate representation of the sample. Here, we demonstrate a solution to this problem, which is based on the Doppler shift carried by the complex-valued depth-resolved scattering amplitude. Furthermore, we demonstrate the feasibility of Doppler flow velocity measurements in underlying flow channels while laterally scanning the imaging probe over large surfaces with arbitrary and varying velocity. Finally, we performed centimeters-long hand-held B-mode imaging of skin in vivo.

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    1-7 of 7
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  2. Topics in the News

    1. (7 articles) Ton G. van Leeuwen
    2. (5 articles) Academic Medical Center at the University of Amsterdam
    3. (5 articles) Jeroen Kalkman
    4. (3 articles) Delft University of Technology
    5. (1 articles) University of Twente
    6. (1 articles) Markus Pollnau
    7. (1 articles) Kerstin Wörhoff
    8. (1 articles) B. Imran Akca
    9. (1 articles) René M. de Ridder
    10. (1 articles) Harvard University
    11. (1 articles) Massachusetts General Hospital
    12. (1 articles) University of North Carolina
    13. (1 articles) Baylor College of Medicine
    14. (1 articles) Masamichi Takano
    15. (1 articles) Joel S. Schuman
    16. (1 articles) Ik-Kyung Jang
    17. (1 articles) Yoshiyasu Minami
    18. (1 articles) Donald L. Budenz
    19. (1 articles) Gadi Wollstein
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    Doppler-based lateral motion tracking for optical coherence tomography Localized measurement of longitudinal and transverse flow velocities in colloidal suspensions using optical coherence tomography Ultra-compact silicon photonic integrated interferometer for swept-source optical coherence tomography Simultaneous and localized measurement of diffusion and flow using optical coherence tomography Chip based common-path optical coherence tomography system with an on-chip microlens and multi-reference suppression algorithm Measurement of biofilm growth and local hydrodynamics using optical coherence tomography On-chip Mach-Zehnder interferometer for OCT systems 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 Dueling Deep Q-Network for Unsupervised Inter-frame Eye Movement Correction in Optical Coherence Tomography Volumes Atlas of Optical Coherence Tomography for Glaucoma (Textbook)