1. Articles from Michael Maria

    1-11 of 11
    1. Noise of supercontinuum sources in spectral domain optical coherence tomography

      Noise of supercontinuum sources in spectral domain optical coherence tomography

      In this paper, we investigate the effect of pulse-to-pulse fluctuations of supercontinuum sources on the noise in spectral domain optical coherence tomography (OCT) images. The commonly quoted theoretical expression for the OCT noise is derived for a thermal light source, which is not suitable if a supercontinuum light source is used. We therefore propose a new, measurement-based OCT noise model that predicts the noise without any assumptions on the type of light source. We show that the predicted noise values are in excellent agreement with the measured values. The spectral correlation evaluated for the photodetected signal when using a supercontinuum ...

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    2. Recovering distance information in spectral domain interferometry

      Recovering distance information in spectral domain interferometry

      This work evaluates the performance of the Complex Master Slave (CMS) method, that processes the spectra at the interferometer output of a spectral domain interferometry device without involving Fourier transforms (FT) after data acquisition. Reliability and performance of CMS are compared side by side with the conventional method based on FT, phase calibration with dispersion compensation (PCDC). We demonstrate that both methods provide similar results in terms of resolution and sensitivity drop-off. The mathematical operations required to produce CMS results are highly parallelizable, allowing real-time, simultaneous delivery of data from several points of different optical path differences in the interferometer ...

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    3. Q-switched based supercontinuum source towards low-cost ultra-high resolution optical coherence tomography

      Q-switched based supercontinuum source towards low-cost ultra-high resolution optical coherence tomography

      Supercontinuum (SC) light source is certainly one of the best option for ultra-high resolution optical coherence tomography (UHR-OCT). Over the last few years several demonstrations have been done for each commonly used wavelength range [1-2-3]. Nowadays, SC dedicated to UHR-OCT is a mature technology with turn-key commercially available system [4]. The new challenge to answer for SC source is the cost reduction one. In this study, we demonstrate that a Q-switched based SC (QS-SC) could be an alternative to the current state of the art SC based on a Mode-Locked laser (ML-SC). This QS-SC, whose cost is less than 15 ...

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    4. Two optical coherence tomography systems detect topical gold nanoshells in hair follicles, sweat ducts and measure epidermis

      Two optical coherence tomography systems detect topical gold nanoshells in hair follicles, sweat ducts and measure epidermis

      Optical coherence tomography (OCT) is an optical imaging technology that enables real time, high‐resolution, cross‐sectional and en face investigation of skin by detecting reflected broad‐spectrum near‐infrared light from tissue. OCT provides micron‐scale spatial resolution and millimeter‐scale depth of penetration [1]. Several commercial OCT systems with handheld probes targeted for Dermatology are now available [2].

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    5. In-vivo detection of the skin dermo-epidermal junction by ultrahigh resolution optical coherence tomography

      In-vivo detection of the skin dermo-epidermal junction by ultrahigh resolution optical coherence tomography

      The human skin is comprised by two layers; epidermis and dermis, separated by the dermo-epidermal junction (DEJ). The relevance of depicting DEJ and measurement of the epidermal thickness (ET) is e.g. seen for superficial skin cancers where delineation of DEJ is of prime prognostic importance. Another example is diagnosis of psoriasis where a thickened epidermis and a ridged DEJ is a hallmark. Histopathological examination of biopsied tissue is traditionally performed to trace DEJ and measure ET. An efficient and precise method to locate DEJ and measure ET is optical coherence tomography (OCT) which is an in vivo and non-invasive ...

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    6. Two Optical Coherence Tomography Systems detect Topical Gold Nanoparticles in Hair follicles, Sweat Ducts and Measure Epidermis

      Two Optical Coherence Tomography Systems detect Topical Gold Nanoparticles in Hair follicles, Sweat Ducts and Measure Epidermis

      Optical coherence tomography (OCT) is an optical imaging technology that enables real time, highresolution, cross-sectional and en face investigation of skin by detecting reflected broad-spectrum near-infrared light from tissue. OCT provides micron-scale spatial resolution and millimeter-scale depth of penetration [1]. Several commercial OCT systems with handheld probes targeted for Dermatology are now available [2]. The ability of OCT to achieve high diagnostic accuracy in skin diseases is hampered by the fact that not all diseases show sufficient contrast to be discriminated from normal skin. The challenge in realizing contrast enhancement in OCT imaging is to achieve signal from exogenous contrast ...

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    7. All-depth dispersion cancellation in spectral domain optical coherence tomography using numerical intensity correlations

      All-depth dispersion cancellation in spectral domain optical coherence tomography using numerical intensity correlations

      In ultra-high resolution (UHR-) optical coherence tomography (OCT) group velocity dispersion (GVD) must be corrected for in order to approach the theoretical resolution limit. One approach promises not only compensation, but complete annihilation of even order dispersion effects, and that at all sample depths. This approach has hitherto been demonstrated with an experimentally demanding ’balanced detection’ configuration based on using two detectors. We demonstrate intensity correlation (IC) OCT using a conventional spectral domain (SD) UHR-OCT system with a single detector. IC-SD-OCT configurations exhibit cross term ghost images and a reduced axial range, half of that of conventional SD-OCT. We demonstrate ...

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    8. Q-switch-pumped supercontinuum for ultra-high resolution optical coherence tomography

      Q-switch-pumped supercontinuum for ultra-high resolution optical coherence tomography

      In this Letter, we investigate the possibility of using a commercially available Q-switch-pumped supercontinuum (QS-SC) source, operating in the kilohertz regime, for ultra-high resolution optical coherence tomography (UHR-OCT) in the 1300 nm region. The QS-SC source proves to be more intrinsically stable from pulse to pulse than a mode-locked-based SC (ML-SC) source while, at the same time, is less expensive. However, its pumping rate is lower than that used in ML-SC sources. Therefore, we investigate here specific conditions to make such a source usable for OCT. We compare images acquired with the QS-SC source and with a current state-of-the-art ...

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    9. Feature of the Week 05/08/2016: Complex Master Slave Interferometry

      Feature of the Week 05/08/2016: Complex Master Slave Interferometry

      A general theoretical model is developed to improve the novel Spectral Domain Interferometry method denoted as Master/Slave (MS) Interferometry. In this model, two functions, g and h are introduced to describe the modulation chirp of the channeled spectrum signal due to nonlinearities in the decoding process from wavenumber to time and due to dispersion in the interferometer. The utilization of these two functions brings two major improvements to previous implementations of the MS method. A first improvement consists in reducing the number of channeled spectra necessary to be collected at Master stage. In previous MSI implementation, the number of ...

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    10. Complex master slave interferometry

      Complex master slave interferometry

      A general theoretical model is developed to improve the novel Spectral Domain Interferometry method denoted as Master/Slave (MS) Interferometry. In this model, two functions, g and h are introduced to describe the modulation chirp of the channeled spectrum signal due to nonlinearities in the decoding process from wavenumber to time and due to dispersion in the interferometer. The utilization of these two functions brings two major improvements to previous implementations of the MS method. A first improvement consists in reducing the number of channeled spectra necessary to be collected at Master stage. In previous MSI implementation, the number of ...

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    11. Demonstration of tolerance to dispersion of master/slave interferometry

      Demonstration of tolerance to dispersion of master/slave interferometry

      A theoretical model is developed for the Master/Slave interferometry (MSI) that is used to demonstrate its tolerance to dispersion left uncompensated in the interferometer when evaluating distances and thicknesses. In order to prove experimentally its tolerance to dispersion, different lengths of optical fiber are inserted into the interferometer to introduce dispersion. It is demonstrated that the sensitivity profile versus optical path difference is not affected by the length of fiber left uncompensated. It is also demonstrated that the axial resolution is constant within the axial range, close to the expected theoretical resolution determined by the optical source bandwidth. Then ...

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    1-11 of 11
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    1. (11 articles) University of Kent
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    Demonstration of tolerance to dispersion of master/slave interferometry Complex master slave interferometry Feature of the Week 05/08/2016: Complex Master Slave Interferometry Q-switch-pumped supercontinuum for ultra-high resolution optical coherence tomography All-depth dispersion cancellation in spectral domain optical coherence tomography using numerical intensity correlations Two Optical Coherence Tomography Systems detect Topical Gold Nanoparticles in Hair follicles, Sweat Ducts and Measure Epidermis In-vivo detection of the skin dermo-epidermal junction by ultrahigh resolution optical coherence tomography Two optical coherence tomography systems detect topical gold nanoshells in hair follicles, sweat ducts and measure epidermis Recovering distance information in spectral domain interferometry Noise of supercontinuum sources in spectral domain optical coherence tomography Postdoctoral Associate Position at Duke Vision and Image Processing Laborator Anterior segment optical coherence tomography angiography