1. Articles from ole bang

    1-13 of 13
    1. Potential of contrast agents to enhance in vivo confocal microscopy and optical coherence tomography in dermatology: A review

      Potential of contrast agents to enhance in vivo confocal microscopy and optical coherence tomography in dermatology: A review

      Distinction between normal skin and pathology can be a diagnostic challenge. This systematic review summarizes how various contrast agents, either topically delivered, or injected into the skin affect distinction between skin disease and normal skin when imaged by optical coherence tomography (OCT) and confocal microscopy (CM). A systematic review of in vivo OCT and CM studies using exogenous contrast agents on healthy human skin or skin disease was performed. In total, 9 CM studies and 1 OCT study were eligible. Four contrast agents aluminum chloride (AlCl) n=2, indocyanin green (ICG) n=3, sodium fluorescein n=3 and acetic acid ...

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    2. 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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    3. Real-time high-resolution mid-infrared optical coherence tomography

      Real-time high-resolution mid-infrared optical coherence tomography

      The potential for improving the penetration depth of optical coherence tomography systems by using light sources with longer wavelengths has been known since the inception of the technique in the early 1990s. Nevertheless, the development of mid-infrared optical coherence tomography has long been challenged by the maturity and fidelity of optical components in this spectral region, resulting in slow acquisition, low sensitivity, and poor axial resolution. In this work, a mid-infrared spectral-domain optical coherence tomography system operating at a central wavelength of 4 µm and an axial resolution of 8.6 µm is demonstrated. The system produces two-dimensional cross-sectional images ...

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    4. 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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    5. Real‐time High‐Resolution Mid‐infrared Optical Coherence Tomography

      Real‐time High‐Resolution Mid‐infrared Optical Coherence Tomography

      The potential for improving the penetration depth of optical coherence tomography systems by using increasingly longer wavelength light sources has been known since the inception of the technique in the early 1990s. Nevertheless, the development of mid‐infrared optical coherence tomography has long been challenged by the maturity and fidelity of optical components in this spectral region, resulting in slow acquisition, low sensitivity, and poor axial resolution. In this work, a mid‐infrared spectral‐domain optical coherence tomography system operating at 4 µm central wavelength with an axial resolution of 8.6 µm is demonstrated. The system produces 2D cross ...

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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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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    12. Gabor fusion master slave optical coherence tomography

      Gabor fusion master slave optical coherence tomography

      This paper describes the application of the Gabor filtering protocol to a Master/Slave (MS) swept source optical coherence tomography (SS)-OCT system at 1300 nm. The MS-OCT system delivers information from selected depths, a property that allows operation similar to that of a time domain OCT system, where dynamic focusing is possible. The Gabor filtering processing following collection of multiple data from different focus positions is different from that utilized by a conventional swept source OCT system using a Fast Fourier transform (FFT) to produce an A-scan. Instead of selecting the bright parts of A-scans for each focus position ...

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    13. Back-seeding of higher order gain processes in picosecond supercontinuum generation

      Peter M. Moselund, Michael H. Frosz, Carsten L. Thomsen, Ole BangIn photonic crystal fibers with closely spaced zero dispersion wavelengths it is possible to have two pairs of four-wave mixing (FWM) gain peaks. Here, we demonstrate both numerically and experimentally how the outer four-wave mixing gain peaks can be used to produce a strong amplification peak in ... [Opt. Express 16, 11954-11968 (2008)]
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    1-13 of 13
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    1. (11 articles) University of Kent
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    Gabor fusion master slave optical coherence tomography 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 Q-switched based supercontinuum source towards low-cost ultra-high resolution optical coherence tomography Recovering distance information in spectral domain interferometry Real-time high-resolution mid-infrared optical coherence tomography Real-time detection of circulating tumor cells in living animals using functionalized large gold nanorods Macular OCT-angiography parameters to predict the clinical stage of nonproliferative diabetic retinopathy: an exploratory analysis Central perpendicular line in macular spectral-domain optical coherence tomography in five eyes