Browsing by Author "Tatam, Ralph P."

Browsing by Author "Tatam, Ralph P."

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  • Multiplexing a serial array of tapered optical fibre sensors using coherent optical frequency domain reflectometry 
    Jarzebinska, Renata; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P. (Iop Publishing Ltd, 2012-08-01)
    The use of high spatial resolution optical frequency domain reflectometry (OFDR) to facilitate the multiplexing of a serial array of tapered optical fibre sensors is presented. Changes in the attenuation of the Rayleigh ...
  • Multiplexing curvature sensors using fibre segment interferometry for lateral vibration measurements 
    Kissinger, Thomas; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P. (SPIE - International Society for Optics and Photonics, 2017-04-23)
    Dynamic fibre-optic curvature sensing is demonstrated by interrogating chains of fibre segments, separated by broadband Bragg grating reflectors, using range-resolved interferometry (RRI). Four fibre strings, containing ...
  • Multiplexing of Fibre optic long period Grating based interferometric sensors 
    Murphy, Richard P.; James, Stephen W.; Tatam, Ralph P. (IEEE Institute of Electrical and Electronics, 2007-03-01)
    Two long-period gratings (LPGs) fabricated in series in an optical fiber form a Mach-Zehnder interferometer, producing a sinusoidal channelled spectrum within the characteristic LPG attenuation bands, which has the ...
  • Multipoint gas detection using range resolved interferometry 
    Bremner, James (2021-07)
    The ability to detect and quantify gas in multiple locations is important in environmental and safety monitoring situations. This thesis describes the first application of Range Resolved Interferometry to the problem of ...
  • NDIR instrumentation design for Carbon Dioxide gas sensing 
    Zakaria, Ryadh Abdullah (Cranfield University, 2010-03)
    In this thesis the development of a single pass non-dispersive infrared (NDIR) CO2 gas sensor with a path length of 30mm and with a lowest level CO2 detectivity of 20 ppm is described. A single pass NDIR CO2 sensor was ...
  • Nested long period grating interferometers 
    Murphy, Richard P.; James, Stephen W.; Tatam, Ralph P. (International Society for Optical Engineering; 1999, 2007-12-31)
    The concept of nested fibre optic long period grating (LPG) based interferometers is introduced. A number of in-series, identical LPGs may be used to form a set of nested, multiplexed Mach-Zehnder interferometers that ...
  • Noise analysis for CCD-based ultraviolet and visible spectrophotometry 
    Davenport, John; Hodgkinson, Jane; Saffell, John R.; Tatam, Ralph P. (Optical Society of America, 2015-08-17)
    We present the results of a detailed analysis of the noise behavior of two CCD spectrometers in common use, an AvaSpec-3648 CCD UV spectrometer and an Ocean Optics S2000 Vis spectrometer. Light sources used include a ...
  • A non-contact laser speckle sensor for the measurement of robotic tool speed 
    Charrett, Thomas O. H.; Bandari, Yashwanth K.; Michel, Florent; Ding, Jialuo; Williams, Stewart W.; Tatam, Ralph P. (Elsevier, 2018-04-23)
    A non-contact speckle correlation sensor for the measurement of robotic tool speed is described that is capable of measuring the in-plane relative velocities between a robot end-effector and the workplace or other surface. ...
  • Non-dispersive infra-red (NDIR) measurement of carbon dioxide at 4.2μm in a compact and optically efficient sensor 
    Hodgkinson, Jane; Smith, Richard; Ho, Wah On; Saffell, John R.; Tatam, Ralph P. (Elsevier Science B.V., Amsterdam., 2013-09-30)
    Non-dispersive infra-red (NDIR) gas detection has enjoyed widespread uptake as a result of development of devices in the standard miniature format for gas sensors, consisting of a cylinder with external dimensions of 20mm ...
  • Non-dispersive ultra-violet spectroscopic detection of formaldehyde gas for indoor environments 
    Davenport, J. J.; Hodgkinson, Jane; Saffell, J. R.; Tatam, Ralph P. (IEEE, 2018-01-25)
    We describe a simple method for detecting formaldehyde using low resolution non-dispersive UV absorption spectroscopy. A two channel sensor was developed, making use of a strong absorption peak at 339 nm and a neighbouring ...
  • Novel applications and stabilisation for widely wavelength modulated laser interferometry for precision dimensional metrology. 
    Wiseman, Kieran (Cranfield UniversitySATM, 2021-11)
    The need for precision dimensional metrological techniques is always increasing, including high precision displacement measuring metrology used to precisely and accurately position stages, components and machines. Laser ...
  • Novel highly sensitive protein sensors based on tapered optical fibres modified with Au-based nanocoatings 
    Urrutia, Aitor; Bojan, Kartheka; Marques, L.; Mullaney, Kevin; Goicoechea, Javier; James, Stephen W.; Clark, M.; Tatam, Ralph P.; Korposh, Sergiy (Hindawi Publishing Corporation, 2016-08-08)
    In this work, novel protein sensors based on tapered optical fibres modified with Au coatings deposited using two different procedures are proposed. Au based coatings are deposited onto a non-adiabatic tapered optical fibre ...
  • A novel laser diode wavelength stabilisation technique for use in high resolution spectroscopy 
    Asmari, Abdullah Shah (Cranfield University, 2015)
    Tuneable diode laser absorption spectroscopy (TDLAS) based gas sensors are widely used for trace gas detection for their high selectivity and sensitivity. The laser source used in TDLAS requires a narrow line width in ...
  • 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 ...