Browsing by Author "Ford, Helen D."

Browsing by Author "Ford, Helen D."

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  • 3D planar velocity measurements, using Mach-Zehnder interferometric-filter-based planar Doppler velocimetry (MZI-PDV) and imaging fibre bundles 
    Lu, Z. H.; Charrett, Thomas O. H.; Ford, Helen D.; Tatam, Ralph P. (2008-12-31)
    Three component planar flow-field measurements are made using imaging fibre bundles to port different views of the measurement plane, defined by a laser light sheet, to a single imaging head. The Doppler frequency shifts ...
  • Acousto-optic frequency switching for single-camera planar Doppler velocimetry 
    Ford, Helen D.; Nobes, David S.; Tatam, Ralph P. (International Society for Optical Engineering; 1999, 2001-12-31)
    A single-camera Planar Doppler velocimetry system has been demonstrated, in which illumination beams at two closely-spaced optical frequencies are derived from a single Argon-ion laser. The frequency of one beam lies on ...
  • Characterization of optical fiber imaging bundles for swept-source optical coherence tomography 
    Ford, Helen D.; Tatam, Ralph P. (Osa Optical Society of America, 2011-02-03)
    Fiber imaging bundles have been investigated for use in endoscopic optical coherence tomography (OCT) systems, to obviate the requirement for scanning components within the endoscope probe section. Images have been ...
  • Coherent fibre bundles in full-field swept-source OCT 
    Ford, Helen D.; Tatam, Ralph P. (2009-02-20)
    Endoscopic OCT probes deliver light to the measurement region via a single optical fibre mounted in a probe head. The output beam is focused onto the sample, providing a single point measurement. The beam is translated, ...
  • Comparative signal-to-noise analysis of fibre-optic based optical coherence tomography systems 
    Ford, Helen D.; Beddows, R.; Casaubieilh, P.; Tatam, Ralph P. (Taylor & Francis, 2005-09-20)
    Several optical coherence tomography ( OCT) systems are proposed using optical. fibre components and based around Fizeau sensing interferometers. The theoretical signal- to- noise ratio ( SNR) is calculated for each of ...
  • Dual beam swept source optical coherence tomography for microfluidic velocity measurements 
    Rigas, Evangelos (2018-11)
    Microfluidic flows are an increasing area of interest used for “lab-on-a-chip” bioanalytical techniques, drug discovery, and chemical processing. This requires optical, non-invasive flow-visualization techniques for ...
  • Dual Illumination Planar Doppler Velocimetry using a Single Camera 
    Charrett, Thomas O. H.; Ford, Helen D.; Nobes, David S.; Tatam, Ralph P. (International Society for Optical Engineering; 1999, 2003-12-31)
    A Planar Doppler Velocimetry (PDV) illumination system has been designed which is able to generate two beams, separated in frequency by about 600 MHz. This allows a common-path imaging head to be constructed, using a ...
  • Dual-channel OCT for velocity measurement in microfluidic channels. 
    Rigas, Evangelos; Hallam, Jonathan M.; Ford, Helen D.; Charrett, Thomas O. H.; Tatam, Ralph P. (OSA, 2018-09-28)
    A dual-beam Optical Coherence Tomography system has been developed, using a bespoke dual optical fibre, to simultaneously image microfluidic channel structures and measure high velocity flows (presently 250μm/s) from a ...
  • Fibre imaging bundles for full-field optical coherence tomography 
    Ford, Helen D.; Tatam, Ralph P. (Iop Publishing Ltd, 2007-01-01)
    An imaging fibre bundle is incorporated into a full-field imaging OCT system, with the aim of eliminating the mechanical scanning currently required at the probe tip in endoscopic systems. Each fibre within the imaging ...
  • Full-field optical coherence tomography 
    Ford, Helen D.; Tatam, Ralph P. (International Society for Optical Engineering; 1999, 2005-12-31)
    To eliminate mechanical scanning in the probe head of an endoscopic OCT system, we propose the use of an imaging fibre bundle for probe beam delivery. Each fibre in the bundle addresses a Fizeau interferometer formed ...
  • Full-field optical coherence tomography using a fibre imaging bundle 
    Ford, Helen D.; Tatam, Ralph P. (2006-12-31)
    An imaging fibre bundle is demonstrated for spatially-multiplexed probe beam delivery in OCT, with the aim of eliminating the mechanical scanning currently required at the probe tip in endoscopic systems. Each fibre in ...
  • Imaging fibre bundles for Fizeau-based optical coherence tomography 
    Sarantavgas, G. F.; Ford, Helen D.; Tatam, Ralph P. (2008-03-05)
    An OCT system incorporating a coherent fibre imaging bundle is described. Fibres are accessed sequentially by a beam focused onto the input face of the bundle, allowing 2D or 3D images to be acquired using point detection. ...
  • Influence of aberrations on confocal-based remote refractive index measurements 
    Ford, Helen D.; Francis, Daniel; Hallam, Jonathan M.; Tatam, Ralph P. (Optical Society of America, 2019-08-13)
    Confocal scanning combined with low-coherence interferometry is used to provide remote refractive index and thickness measurements of transparent materials. The influence of lens aberrations in the confocal measurement is ...
  • Instantaneous, three-component planar Doppler velocimetry using imaging fibre bundles 
    Nobes, David S.; Ford, Helen D.; Tatam, Ralph P. (Springer Science Business Media, 2004-01-01)
    Abstract This paper describes a planar Doppler velocimetry (PDV) technique that is capable of measuring the three, instantaneous and time average components of velocity over two spatial dimensions using a single pair of ...
  • Low-coherence optical fibre speckle interferometry 
    Balboa, Itziar; Ford, Helen D.; Tatam, Ralph P. (Iop Publishing Ltd, 2006-02-10)
    This paper describes the development of optical fibre low-coherence speckle interferometers capable of three-dimensional surface profiling with a resolution of 10–20 µm and a depth range of typically tens of centimetres. ...
  • Mach-Zehnder interferometric filter based planar Doppler velocimetry (MZI-PDV) 
    Lu, Zenghai H.; Charrett, Thomas O. H.; Ford, Helen D.; Tatam, Ralph P. (Springer, 2008)
    This paper describes the development of a Mach-Zehnder interferometric filter based planar Doppler velocimetry (MZI-PDV) flow measurement technique. The technique uses an unbalanced Mach-Zehnder interferometer (MZI) to ...
  • Optical coherence tomography with a Fizeau interferometer configuration 
    Casaubieilh, P.; Ford, Helen D.; James, Stephen W.; Tatam, Ralph P. (International Society for Optical Engineering; 1999, 2005-12-31)
    We report the investigation of a Fizeau interferometer-based OCT system. A secondary processing interferometer is necessary in this configuration, to compensate the optical path difference formed in the Fizeau ...
  • Optical fibre Fizeau-based OCT 
    Casaubieilh, P.; Ford, Helen D.; Tatam, Ralph P. (SPIE - International Society for Optics and Photonics, 2004-06-09)
    An optical fibre, Fizeau configuration Optical Coherence Tomography (OCT) system is presented in this paper. The interferometer is formed between the distal end of the sample-arm fibre and the sample itself. This ensures ...
  • Optical fibre wavelength filters and multiplexers 
    Ford, Helen D. (Cranfield University, 1994-03)
    Polarisation-based wavelength-division multi-/demulti-plexers (WDMs) and filters have been designed, constructed and evaluated. These are compact devices made from single-mode optical fibre possessing high linear ...
  • Passive OCT probe head for 3D duct inspection 
    Ford, Helen D.; Tatam, Ralph P. (Iop Publishing Ltd, 2013-07-24)
    A passive, endoscopic optical coherence tomography (OCT) probe has been demonstrated, incorporating an imaging fibre bundle and 45° conical mirror, and with no electromechanical components at the probe tip. Circular scanning, ...