Browsing by Author "Tatam, Ralph P."

Browsing by Author "Tatam, Ralph P."

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  • Charrett, Thomas O. H.; Tatam, Ralph P. (SPIE, 2015)
    This paper describes an extended theory of the displacement of the objective speckle pattern resulting from displacement and/or deformation of a coherently illuminated diffuse object where the influence of the surface shape ...
  • Charrett, Thomas O. H.; Tatam, Ralph P. (Optical Society of America, 2014-10-10)
    This paper describes an extended and improved theory of the displacement of the objective speckle pattern resulting from displacement and/or deformation of a coherently illuminated diffuse object. Using the theory developed ...
  • Francis, Daniel; Charrett, Thomas O. H.; Waugh, L.; Tatam, Ralph P. (Osa Optical Society of America, 2012-05-31)
    Speckle velocimetry is investigated as a means of determining odometry data with potential for application on autonomous robotic vehicles. The technique described here relies on the integration of translation measurements ...
  • Chehura, Edmon; Dell'Anno, Giuseppe; Huet, Tristan; Staines, Stephen E.; James, Stephen W.; Partridge, Ivana K.; Tatam, Ralph P. (Institute of Physics, 2014-05-20)
    Dynamic loadings induced on a tufting needle during the tufting of dry carbon fibre preform via a commercial robot-controlled tufting head were investigated in situ and in real-time using optical fibre Bragg grating (FBG) ...
  • 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 ...
  • Chowdhury, Sahar A.; Correia, Ricardo N.; Francis, Daniel; Brooks, Simon J.; Jones, Benjamin J. S.; Thompson, Alexander W. J.; Hodgkinson, Jane; Tatam, Ralph P. (Institute of Electrical and Electronics Engineers, 2015-06-15)
    A self-referenced optical fiber refractometer using a ball lens as a sensor head has been developed and characterized. A 350-μm ball lens created at the tip of a single mode fiber has been coated with a 40-nm optically ...
  • Gagliardi, G.; Salza, M.; Ferraro, P.; Chehura, Edmon; Tatam, Ralph P.; Gangopadhyay, T. K.; Ballard, N.; Paz-Soldan, D.; Barnes, J. A.; Loock, H-P; Lam, TT-Y; Chow, J. H.; De Natale, P. (MDPI AG, 2010-03-05)
    An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs) and FBG resonators built in fibers of different types are used ...
  • 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 ...
  • Buggy, Stephen J.; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P. (Institute of Physics, 2007-06-01)
    The use of fibre grating refractometers as a means of monitoring the cure of a UVcured epoxy resin is presented. The wavelength shift of the attenuation bands of a long period grating and the spectral response of a tilted ...
  • Topliss, Stephen M.; James, Stephen W.; Davis, Frank; Higson, Seamus P. J.; Tatam, Ralph P. (Elsevier Science B.V., Amsterdam., 2010-01-07)
    The chemical sensing capabilities of an optical fibre long period grating (LPG) coated with a functional material are explored. The LPG period and coating thickness are chosen such that the mode transition region, ...
  • Hromadka, Jiri; Tokay, Begum; James, Stephen W.; Tatam, Ralph P.; Korposh, Sergiy (Elsevier, 2015-07-09)
    An optical fibre long period grating (LPG) modified with a thin film of ZIF-8, a zeolitic immidazol framework material and a subgroup of metal organic framework family, was employed for the detection of organic vapours. ...
  • Topliss, Stephen M. (Cranfield University, 2011-06)
    The dual resonant response of long period fibre gratings (LPG) operating near the phase matching turning point to the deposition of nanostructured coatings is explored. A broad range of LPGs have been fabricated with grating ...
  • Ford, Helen. Diana (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 ...
  • Khan, Omer Shahab (Cranfield University, 1994-02)
    A fibre optic frequency shifter has been developed which generates a heterodyne frequency that is used to facilitate electronic demodulation of optical information. The operation of this device is analogous to an ...
  • Hodgkinson, Jane; Tatam, Ralph P. (Iop Publishing Ltd, 2013-01-31)
    The detection and measurement of gas concentrations using the characteristic optical absorption of the gas species is important for both understanding and monitoring a variety of phenomena from industrial processes to ...
  • Jarzebinska, Renata; Korposh, Sergiy; James, Stephen W.; Batty, William J.; Tatam, Ralph P.; Lee, Seung-Woo (Taylor & Francis, 2012-07-31)
    Tapered optical fibers with nano-assembled coatings of thicknesses of order tens of nanometres were used for the detection of ammonia gas. The film coating was composed of alternate layers of tetrakis-(4-sulfophenyl) ...
  • Mullaney, Kevin; Staines, Stephen; James, Stephen; Tatam, Ralph P. (SPIE, 2017-04-23)
    The process of fabricating tapered long period gratings (TLPGs) using a CO2 laser is described. TLPGs with a period spacing of 378 μm, were fabricated by optimization of the taper waist diameter and careful control of the ...
  • Mullaney, Kevin; Staines, Stephen E.; James, Stephen W.; Tatam, Ralph P. (IEEE, 2017-11-03)
    The CO2 laser based fabrication of tapered long period gratings (TLPGs) is optimized so that their transmission spectra are comparable with those made using the arc-discharge technique, which typically exhibits transmission ...
  • Partridge, Matthew; James, Stephen W.; Barrington, James; Tatam, Ralph P. (Optical Society of America: Open Access Journals / Optical Society of America (OSA), 2016-09-19)
    The central wavelengths of the resonance bands are critical aspect of the performance of long period gratings (LPGs) as sensors, particularly for devices designed to operate near the phase matching turning point (PMTP), ...
  • 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, ...