1. Articles from Jeroen Kalkman

    1-21 of 21
    1. Analysis of attenuation coefficient estimation in Fourier-domain OCT of semi-infinite media

      Analysis of attenuation coefficient estimation in Fourier-domain OCT of semi-infinite media

      The attenuation coefficient (AC) is an optical property of tissue that can be estimated from optical coherence tomography (OCT) data. In this paper, we aim to estimate the AC accurately by compensating for the shape of the focused beam. For this, we propose a method to estimate the axial PSF model parameters and AC by fitting a model for an OCT signal in a homogenous sample to the recorded OCT signal. In addition, we employ numerical analysis to obtain the theoretical optimal precision of the estimated parameters for different experimental setups. Finally, the method is applied to OCT B-scans obtained ...

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    2. Deep-tissue label-free quantitative optical tomography

      Deep-tissue label-free quantitative optical tomography

      In vivo imaging of small animals is of wide interest to the biomedical community studying biological disease and developmental processes. However, optical imaging deep in tissue is severely limited by light scattering, posing restrictions on the imaging depth, image contrast, and spatial resolution. We demonstrate optical coherence projection tomography (OCPT) as a fast three-dimensional optical imaging technique for ballistic, non-scattered light, deep-tissue imaging. OCPT is based on a novel scanning transmission sample arm to rapidly measure ballistic light projections of amplitude and phase through thick biological tissues. We demonstrate the strength of OCPT by imaging an adult zebrafish in a ...

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    3. Quantification of plant morphology and leaf thickness with optical coherence tomography

      Quantification of plant morphology and leaf thickness with optical coherence tomography

      Optical coherence tomography (OCT) can be a valuable imaging tool for in vivo and label-free digital plant phenotyping. However, for imaging leaves, air-filled cavities limit the penetration depth and reduce the image quality. Moreover, up to now quantification of leaf morphology with OCT has been done in one-dimensional or two-dimensional images only, and has often been limited to relative measurements. In this paper, we demonstrate a significant increase in OCT imaging depth and image quality by infiltrating the leaf air spaces with water. In the obtained high-quality OCT images the top and bottom surface of the leaf are digitally segmented ...

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    4. Multi-scale optical coherence tomography imaging and visualization of Vermeer’s Girl with a Pearl Earring

      Multi-scale optical coherence tomography imaging and visualization of Vermeer’s Girl with a Pearl Earring

      We demonstrate multi-scale multi-parameter optical coherence tomography (OCT) imaging and visualization of Johannes Vermeer’s painting Girl with a Pearl Earring . Through automated acquisition, OCT image segmentation, and 3D volume stitching we realize OCT imaging at the scale of an entire painting. This makes it possible to image, with micrometer axial and lateral resolution, an entire painting over more than 5 orders of length scale. From the multi-scale OCT data we quantify multiple parameters in a fully automated way: the surface height, the scattering strength, and the combined glaze and varnish layer thickness. The multi-parameter OCT data of Girl with ...

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    5. Optical coherence computed tomography for quantitative 3D imaging of adult zebrafish

      Optical coherence computed tomography for quantitative 3D imaging of adult zebrafish

      Optical imaging in turbid media like biological tissue is limited by light scattering. We present optical coherence computed tomography (OCCT) as a novel optical imaging modality for ballistic 3D optical imaging of turbid media. In OCCT, coherence and confocal gated measurements from multiple lateral positions and angles are used to reconstruct quantitative 3D images of the optical attenuation and refractive index with tomographic reconstruction algorithms. OCCT allows for high resolution imaging in turbid media by strong suppression of scattered light using a combination of coherence and confocal gating. The time-of-flight information in the transmission measurements allows for quantitative reconstruction of ...

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    6. 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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    7. Model-based sensor-less wavefront aberration correction in optical coherence tomography

      Model-based sensor-less wavefront aberration correction in optical coherence tomography

      Several sensor-less wavefront aberration correction methods that correct nonlinear wavefront aberrations by maximizing the optical coherence tomography (OCT) signal are tested on an OCT setup. A conventional coordinate search method is compared to two model-based optimization methods. The first model-based method takes advantage of the well-known optimization algorithm (NEWUOA) and utilizes a quadratic model. The second model-based method (DONE) is new and utilizes a random multidimensional Fourier-basis expansion. The model-based algorithms achieve lower wavefront errors with up to ten times fewer measurements. Furthermore, the newly proposed DONE method outperforms the NEWUOA method significantly. The DONE algorithm is tested on OCT ...

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    8. 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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    9. Towards model-based adaptive optics optical coherence tomography

      Towards model-based adaptive optics optical coherence tomography

      The transfer function for optical wavefront aberrations in single-mode fiber based optical coherence tomography is determined. The loss in measured OCT signal due to optical wavefront aberrations is quantified using Fresnel propagation and the calculation of overlap integrals. A distinction is made between a model for a mirror and a scattering medium model. The model predictions are validated with measurements on a mirror and a scattering medium obtained with an adaptive optics optical coherence tomography setup. Furthermore, a one-step defocus correction, based on a single A-scan measurement, is derived from the model and verified. Finally, the pseudo-convex structure of the ...

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

      Simultaneous measurement of localized diffusion and flow using optical coherence tomography

      We report on the simultaneous and localized measurements of the diffusion coefficient and flow velocity based on the normalized autocorrelation function using optical coherence tomography (OCT). Our results on a flowing solution 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 show that a smaller beam waist results in an improvement of the velocity sensitivity at cost of the precision and accuracy of the estimation of the diffusion coefficient. Further, we show that the ...

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    11. 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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    12. 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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    13. Job Delft University of Technology - 2 PhDs in Optical Tomography

      Job Delft University of Technology - 2 PhDs in Optical Tomography

      Job description Two PhD positions are available in the Quantitative Imaging Group of the Imaging Science and Technology Department. The main research goal is to develop a novel optical tomographic imaging technique based on low coherence interferometry. The tomographic technique is based on the measurement of a set of low coherence optical transmissions at various angles and offsets. From the set of measurements a three-dimensional image is constructed. This technique is applied to high-throughput, in-vivo 3D imaging of tissue and small animals, e.g. zebrafish. PhD 1: This position focuses on the physical processes in the 3D tomographic optical imaging ...

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    14. Common detector for combined raman spectroscopy-optical coherence tomography

      Common detector for combined raman spectroscopy-optical coherence tomography

      An apparatus includes first and second light sources for respectively generating broadband and monochromatic lights, a beamsplitter optically coupled to the first light source for splitting the broadband light into a reference light and a sample light, a reference arm optically coupled to the beamsplitter for receiving the reference light and returning the received reference light into the beamsplitter, a sample arm optically coupled to the beamsplitter and the second light source for combining the sample and monochromatic lights, delivering the combined light to the target of interest, collecting a backscattering light and a Raman scattering light generated from interaction ...

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    15. 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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    16. Toward Spectral-domain Optical Coherence Tomography on a Chip

      Toward Spectral-domain Optical Coherence Tomography on a Chip
      We present experimental results of a spectraldomain optical coherence tomography system based on an integrated optical spectrometer. A 195-channel arrayedwaveguide- grating (AWG) spectrometer with 0.4-nm channel spacing centered at 1300 nm and a 125-channel AWG with 0.16-nm channel spacing centered at 800 nm have been fabricated in silicon oxynitride waveguide technology. Interferometric distance measurements have been performed by launching light from a broadband source into a free-space Michelson interferometer, with its output coupled into the AWG. A maximum imaging depth of 1 mm and axial resolution of 25 ìm and 20 ìm in air are demonstrated for the ...
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    17. Heartbeat-induced axial motion artifacts in optical coherence tomography measurements of the retina

      Heartbeat-induced axial motion artifacts in optical coherence tomography measurements of the retina
      Purpose: To investigate the cause of axial eye motion artifacts that occur in optical coherence tomography (OCT) imaging of the retina. Understanding the cause of these motions can lead to improved OCT image quality and therefore better diagnosis. Methods: 27 measurements were done on 5 subjects. We collected spectral-domain OCT images at the macula over periods up to 30 seconds. We calculated the axial shift of every average A-scan with respect to the previous average A-scan by calculating the cross-correlation. The frequency spectrum of the calculated shifts versus time was determined. The heart rate was determined from blood pressure measurements ...
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    18. Spectral domain optical coherence tomography imaging with an integrated optics spectrometer

      Spectral domain optical coherence tomography imaging with an integrated optics spectrometer
      We designed and fabricated an arrayed-waveguide grating (AWG) in silicon oxynitride as a spectrometer for spectral domain optical coherence tomography (SD-OCT). The AWG has a footprint of only 3.0 cm×2.5 cm, operates at a center wavelength of 1300 nm, and has 78 nm free spectral range. OCT measurements are performed that demonstrate imaging up to a maximum depth of 1 mm with an axial resolution of 19 μm, both in agreement with the AWG design parameters. Using the AWG spectrometer combined with a fiber-based SD-OCT system, we demonstrate cross-sectional OCT imaging of a multilayered scattering phantom.
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    19. Integrated system for combined Raman spectroscopy–spectral domain optical coherence tomography

      Integrated system for combined Raman spectroscopy–spectral domain optical coherence tomography
      Raman spectroscopy (RS) and optical coherence tomography (OCT) are powerful tools for optical analysis of tissues with mutually complementary strengths and limitations. OCT excels at visualizing tissue microstructure but lacks molecular specificity, while RS can relay tissue biochemical composition but typically cannot relate microstructure. Previous implementations of combined RS-OCT have utilized a common sample arm while maintaining independent RS and OCT detection arms. We present the design and application of an integrated RS-OCT instrument with a common detection arm for both RS and OCT. The detector is a spectrograph capable of sequential detection of the 855-nm OCT signal and the ...
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    20. SiON Integrated Optics Elliptic Couplers for Fizeau-Based Optical Coherence Tomography

      SiON Integrated Optics Elliptic Couplers for Fizeau-Based Optical Coherence Tomography
      Integrated optics potentially can offer significant cost reductions and new applications to Optical Coherence Tomography (OCT). We design, fabricate, and characterize Silicon oxynitride (SiON) elliptic couplers, which can be used to focus light from a chip into the off-chip environment. Fizeau-based OCT measurements are performed with elliptic couplers and a moveable mirror. The optical fields at the output of the elliptic coupler are simulated and measured. Good agreement is observed between the measured OCT signal as a function of depth and calculations based on the optical field at the end of the elliptic coupler.
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    21. Structural and biochemical characterization of the rat retina with combined Raman spectroscopy-optical coherence tomography (RS-SDOCT)

      Structural and biochemical characterization of the rat retina with combined Raman spectroscopy-optical coherence tomography (RS-SDOCT)

      Raman spectroscopy (RS) and Optical Coherence Tomography (OCT) are powerful tools for optical analysis of tissues with complimentary strengths. OCT excels and visualizing tissue microstructure while RS can relay tissue biochemical composition. Both instruments have significant potential to serve as valuable tools in non-invasive characterization of the rodent models of retinal disease. In this abstract we present the design and application of a common detector combined RS-OCT instrument for evaluating the morphological and biochemical differences in a rat model for oxygen induced retinopathy. Rat pups that have undergone a variable oxygen treatment are compared to rats raised in room air ...

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    1-21 of 21
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  2. Topics in the News

    1. (21 articles) Jeroen Kalkman
    2. (12 articles) Ton G. van Leeuwen
    3. (11 articles) Delft University of Technology
    4. (10 articles) Academic Medical Center at the University of Amsterdam
    5. (5 articles) University of Twente
    6. (3 articles) Vanderbilt University
    7. (3 articles) Anita Mahadevan-Jansen
    8. (3 articles) Kerstin Wörhoff
    9. (3 articles) Dirk J. Faber
    10. (3 articles) Van Duc Nguyen
    11. (1 articles) Technical University of Munich
    12. (1 articles) Johns Hopkins University
    13. (1 articles) Michalina J. Góra
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    Structural and biochemical characterization of the rat retina with combined Raman spectroscopy-optical coherence tomography (RS-SDOCT) SiON Integrated Optics Elliptic Couplers for Fizeau-Based Optical Coherence Tomography Integrated system for combined Raman spectroscopy–spectral domain optical coherence tomography Spectral domain optical coherence tomography imaging with an integrated optics spectrometer Heartbeat-induced axial motion artifacts in optical coherence tomography measurements of the retina Toward Spectral-domain Optical Coherence Tomography on a Chip Doppler-based lateral motion tracking for optical coherence tomography Job Delft University of Technology - 2 PhDs in Optical 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 Real-time tool to layer distance estimation for robotic subretinal injection using intraoperative 4D OCT Diabetic maculopathy: multicolour and SD-OCT versus fundus photography