1. Articles from Christian Hart

    1-6 of 6
    1. Spatially deconvolved optical coherence tomography

      Spatially deconvolved optical coherence tomography
      In this paper we present spatially mapped point-spread function (PSF) measurements of an optical coherence tomography (OCT) instrument and subsequent spatial deconvolution. The OCT B-scan image plane was divided into 2400 subimages, for which PSFs were determined from OCT measurements of a specially designed phantom. Each PSF was deconvolved from its corresponding subimage of the phantom using the Lucy-Richardson algorithm. Following deconvolution, all of the subimages were reassembled to form a final deconvolved image, from which the resolution improvement was quantitatively assessed. The lateral resolution was found to improve by 3.1 μm compared to an axial resolution enhancement of ...
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    2. Report on Optical Tissue Phantoms from National Physical Laboratory in UK

      Report on Optical Tissue Phantoms from National Physical Laboratory in UK
      The key figures of merit for Optical Coherence Tomography (OCT) systems are sensitivity and resolution. These parameters can be used to determine the suitability of instruments for purpose and to gauge the practical improvements to instruments afforded by modifications to the design. Therefore, NPL is developing reproducible and stable phantoms for depth resolved sensitivity and three-dimensional resolution or point-spread-function (PSF
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    3. Point-spread function phantoms for optical coherence tomography

      Point-spread function phantoms for optical coherence tomography
      Recently scientists at the Uk's National Physical Laboratory completed an initial study into the development of robust point-spread function (PSF) phantoms, that are potentially suitable as OCT calibration standards. The findings have been published in a publicly available NPL report, available freely from the NPL website or upon request to Pete Tomlins (pete.tomlins@npl.co.uk).
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    4. Refractive index mapping of layered samples using optical coherence refractometry

      In this paper a novel method for determining refractive indices of a multi-layered samples using low coherence interferometry (LCI), developed at the National Physical Laboratory, UK, is introduced. Conventional Optical Coherence Tomography (OCT) utilises a lateral scanning optical probe beam to construct a depth resolved image of the sample under investigation. All interfaces are detected in optical path length, resulting in an image depending on the refractive index of all prior layers. This inherent ambiguity in optical and geometric path length reduces OCT images to purely qualitative ones. We have demonstrated that by optically probing the sample at multiple angles ...
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    5. Optical coherence refractometry

      Peter H. Tomlins, Peter Woolliams, Christian Hart, Andrew Beaumont, Matthew Tedaldi We introduce a novel approach to refractometry using a low coherence interferometer at multiple angles of incidence. We show that for plane parallel samples it is possible to measure their phase refractive index rather than the group index that is usually measured by interferometric methods. This ... [Opt. Lett. 33, 2272-2274 (2008)]
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    6. Measurement of the three-dimensional point-spread function in an optical coherence tomography imaging system

      Peter H. Tomlins, Peter Woolliams, Matthew Tedaldi et al. Two significant figures of merit for optical coherence tomography (OCT) systems are the axial and transverse resolutions. Transverse resolution has been defined using the Rayleigh Criterion or from Gaussian beam optics. The axial resolution is generally defined in terms of the coherence length of a ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 68472Q (2008)] published Mon Feb 18, 2008.
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    1-6 of 6
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  2. Topics in the News

    1. (6 articles) Pete H. Tomlins
    2. (6 articles) Peter D. Woolliams
    3. (5 articles) UK National Physical Laboratory
    4. (3 articles) Matthew Tedaldi
    5. (1 articles) Alex Grimwood
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