Browsing by Author "Tatam, Ralph P."

Browsing by Author "Tatam, Ralph P."

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  • Objective speckle displacement resulting from the deformation of shaped objects 
    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 ...
  • Objective speckle displacement: an extended theory for the small deformation of shaped objects 
    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 ...
  • Objective speckle velocimetry for autonomous vehicle odometry 
    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 ...
  • On-line monitoring of multi-component strain development in a tufting needle using optical fibre Bragg grating sensors 
    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) ...
  • 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 ...
  • An optical fiber hydrogen sensor using a palladium-coated ball lens 
    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 ...
  • Optical fiber sensing based on reflection laser spectroscopy 
    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 ...
  • 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 Grating Refractometers for Resin Cure Monitoring. 
    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 ...
  • Optical fibre long period grating based selective vapour sensing of volatile organic compounds 
    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, ...
  • Optical fibre long period grating gas sensor modified with metal organic framework thin films 
    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. ...
  • Optical fibre long period grating sensors with nanostructured coatings 
    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 ...
  • Optical fibre pressure sensing using a frequency modulated laser-based signal processing technique 
    Barrington, James; James, Stephen; Kissinger, Thomas; Staines, Stephen; Prince, Simon; Alcusa Saez, Erica; Lawson, Nicholas J.; Tatam, Ralph P. (IOP Publishing, 2023-04-21)
    Range resolved interferometry (RRI) applied to the interrogation of an extrinsic Fabry–Perot based pressure sensor in laboratory and wind tunnel environments is presented. A simple, compact sensor head design was fabricated ...
  • 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 ...
  • Optical fibre-coupled displacement and angle measurements using range-resolved interferometry 
    Wiseman, Kieran B.; Kissinger, Thomas; Tatam, Ralph P. (euspen, 2021-07-10)
    A novel approach to displacement and angle measurements that uses range-resolved interferometry to interrogate multiple interferometers is presented. Spatially offset beams are multiplexed onto the same delivery fibre ...
  • Optical frequency shifter using stimulated Brillouin scattering in fibre optic ring resonators. 
    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 ...
  • Optical gas sensing: a review 
    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 ...
  • Optical Gas Sensor Fabrication Based on Porphyrin-Anchored Electrostatic Self-Assembly onto Tapered Optical Fibers 
    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) ...
  • Optimised process for fabricating tapered long period gratings 
    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 ...
  • Optoelectronic speckle shearing interferometry 
    Huang, Jen-Rong (1996-04)
    This thesis describes the implementation of enhanced signal processing techniques in electronic speckle shearing interferometry, including two-wavelength slope measurement, phase stepping, and heterodyning and stroboscopic ...