John Walker

Contact

• workRoom 608 School of Electrical and Electronic Engineering
  University Park
  Nottingham
  NG7 2RD
  UK
• work0115 951 5595
• fax0115 951 5616
• john.walker@nottingham.ac.uk

Biography

After a BSc and a PhD in Physics from Imperial College, London I worked at the Royal signals and Radar Establishment, Malvern and as a Lecturer in the Physics department at King's College, London. I am currently Reader in Signal Processing with the Electrical and Electronic Engineering School of the University of Nottingham. I was Chair of the Optical Group of the Institute of Physics from 1998 to 2001.

Expertise Summary

Optical systems, signal processing

Research Summary

• Optical particle characterization techniques

• Signal Processing

• Imaging through Turbulence

• Light Scattering techniques

• Phase Retrieval

• Superresolution for Microscopy and Metrology

Current Teaching

• Introduction to Electronic Engineering (H61IIC) Level 1

• Digital Communications (H63DCM) Level 3

• Communication Systems (H63CMS) Level 3

Recent Publications

• WALKER, J.G., HUYNH, N.T. and CHEN, R., 2012. Image vector histogram approach to nanoparticle sizing Applied Optics. 51(5), 651-658
• WALKER, J.G., 2012. Improved nano-particle tracking analysis Measurement Science and Technology. 23, 065605
• HUYNH, N.T., HE, D., HAYES-GILL, B.R., CROWE, J.A., WALKER, J.G., MATHER, M.L., ROSE, F.R.A.J., PARKER, N.G., POVEY, M.J.W. and MORGAN, S.P., 2012. Application of a maximum likelihood algorithm to ultrasound modulated optical tomography Journal of Biomedical Optics. 17(2), 026014
• JIANG, S. and WALKER, J., 2010. Differential high-speed digtal micromirror device based fluorescence speckle confocal microscopy Applied Optics. 49(3), 497-504

• View all publications

• WALKER, J.G., HUYNH, N.T. and CHEN, R., 2012. Image vector histogram approach to nanoparticle sizing Applied Optics. 51(5), 651-658
• WALKER, J.G., 2012. Improved nano-particle tracking analysis Measurement Science and Technology. 23, 065605
• HUYNH, N.T., HE, D., HAYES-GILL, B.R., CROWE, J.A., WALKER, J.G., MATHER, M.L., ROSE, F.R.A.J., PARKER, N.G., POVEY, M.J.W. and MORGAN, S.P., 2012. Application of a maximum likelihood algorithm to ultrasound modulated optical tomography Journal of Biomedical Optics. 17(2), 026014
• JIANG, S. and WALKER, J., 2010. Differential high-speed digtal micromirror device based fluorescence speckle confocal microscopy Applied Optics. 49(3), 497-504
• SHI-HONG JIANG AND J G WALKER, 2009. Speckle-illuminated fluorescence confocal microscopy, using a digital micro-mirror Measurement Science and Technology. 6, 065501
• JIAO, Y and WALKER, J., 2008. A maximum livelihood approach to wavefront sensing Journal of Optical Communications. 281(5), 906-912
• SUN, Y. and WALKER, J.G., 2008. Maximum likelihood data inversion for photon correlation spectroscopy Measurement Science and Technology. 19(11), 115302
• CROWE, J.A., MORRIS, D.E., WOOLFSON, M.S., RODMELL, P.I. and WALKER, J.G., 2007. Quantitative spectrophotometry of scattering media via frequency-domain and constant-intensity measurements Journal of the Optical Society of America A, Optics, image science, and vision. 24(7), 1969-1974
• CHANG, P.C.Y., WALKER, J.G. and HOPCRAFT, K.I., 2005. Ray tracing in absorbing media Journal of Quantitative Spectroscopy and Radiative Transfer. VOL 96(NUMBER 3-4), 327-341
• JIANG, S.H. and WALKER, J.G., 2005. Non-scanning fluorescence confocal microscopy using speckle illumination and optical data processing Optics Communications. 256(1-3), 35-45
• WALKER, J. G., CHANG, P. C. Y., HOPCRAFT, K. I. and MOZAFFARI, E., 2004. Independent particle size and shape estimation from polarization fluctuation spectroscopy Measurement Science and Technology. VOL 15(PART 5), 771-776
• STOCKFORD, I.M., MORGAN, S.P., CROWE, J.A. and WALKER, J.G., 2004. A polarized light imaging instrument for characterising skin lesions In: Optical Biopsy V, Proceedings of SPIE 5826. 82-91
• HOPCRAFT, K.I., CHANG, P.C.Y., JAKEMAN, E. and WALKER, J.G., 2004. Polarization fluctuation spectroscopy Photopolarimetry in Remote Sensing. 161, 137-174
• BAKER, S. F., WALKER, J. G. and HOPCRAFT, K. I., 2004. A dual thickness spatial system for determining optical coefficients from scattering media Measurement Science and Technology. VOL 15(PART 3), 501-508
• JIANG, S.H. and WALKER, J.G., 2004. Experimental confirmation of non-scanning fluorescence confocal microscopy using speckle illumination Optics Communications. 238(1-3), 1-12
• CHANG, P.C.Y., FLITTON, J.C., HOPCRAFT, K.I., JAKEMAN, E., JORDAN, D.L. and WALKER, J.G., 2003. Improving visibility depth in passive underwater imaging by use of polarization Applied Optics. 42(15), 2794-2803
• CHANG,P.C., HOPCRAFT,K.I., JAKEMAN,E. and WALKER,J.G., 2002. Optimal configurations for polarization correlation spectroscopy Measurement Science and Technology. 13, 341-48
• CHANG, P.C.Y., FLITTON, J.C., HOPCRAFT, K.I., JAKEMAN, E. and WALKER, J.G., 2002. Importance of shadowing and multiple reflections in emission polarization Waves in Random Media. 12(1), 1-19
• STOCKFORD, I.M., MORGAN, S.P., CHANG, P.C.Y. and WALKER, J.G., 2002. Analysis of the spatial distribution of polarized light backscattered from layered scattering media Journal of Biomedical Optics. 7(3), 313-320
• WALKER, J.G., 2002. Iterative correction for ''pile-up'' in single-photon lifetime measurement Optics Communications. 201(4-6), 271-277
• BAKER, S. F., WALKER, J. G. and HOPCRAFT, K. I., 2001. Optimal extraction of optical coefficients from scattering media Optics Communications. VOL 187(NUMBER 1-3), 17-27
• WALKER, J.G., 2001. Non-scanning confocal fluorescence microscopy using speckle illumination Optics Communications. 189(4-6), 221-226
• STOCKFORD, I.M., MORGAN, S.P., CHANG, P.C.Y. and WALKER, J.G., 2001. Characterisation of layered scattering media using the spatial distribution of polarized light In: HYBRID AND NOVEL IMAGING AND NEW OPTICAL INSTRUMENTATION FOR BIOMEDICAL APPLICATIONS. 37-47
• BAKER, S.F., WALKER, J.G. and HOPCRAFT, K.I., 2001. Comparison of optical arrangements for determining the optical coefficients of a scattering medium In: Optical Tomography and Spectroscopy of Tissue IV. 239-250
• WALKER, J. G., CHANG, P. C. Y. and HOPCRAFT, K. I., 2000. Visibility depth improvement in active polarization imaging in scattering media Applied Optics. VOL 39(PART 27), 4933-4941
• WALKER, J.G., CHANG, P.C.Y. and HOPCRAFT, K.I., 2000. Visibility depth improvement in active polarization imaging in scattering media Applied Optics. 39(27), 4933-4941
• BARMAN, S. A., WALKER, J. G., NUNN, J. W., TURNER, N. P. and DOWNS, M. J., 2000. Phase effects in double-focus and double-aperture interference microscopy Applied Optics. VOL 39(PART 13), 2159-2166
• CHANG, P. C. Y., WALKER, J. G., HOPCRAFT, K. I., ABLITT, B. and JAKEMAN, E., 1999. Polarization discrimination for active imaging in scattering media Optics Communications. VOL 159(ISSUE 1-3), 1-6
• TURPIN, K., WALKER, J.G., CHANG, P.C.Y., HOPCRAFT, K.I., ABLITT, B. and JAKEMAN, E., 1999. The influence of particle size in active polarization imaging in scattering media Optics Communications. VOL 168(NUMBER 5-6), 325-335
• ABLITT, B. P., HOPCRAFT, K. I., TURPIN, K. D., CHANG, P. C. Y., WALKER, J. G. and JAKEMAN, E., 1999. Imaging and multiple scattering through media containing optically active particles Waves in Random Media. VOL 9(NUMBER 4), 561-572
• CHANG, P. C. Y., WALKER, J. G., JAKEMAN, E. and HOPCRAFT, K. I., 1999. Polarization properties of light multiply scattered by non-spherical Rayleigh particles Waves in Random Media. VOL 9(NUMBER 3), 415-426
• PITTER, M.C., HOPCRAFT, K.I., JAKEMAN, E. and WALKER, J.G., 1999. Structure of polarization fluctuations and their relation to particle shape Journal of Quantitative Spectroscopy and Radiative Transfer. VOL 63(NUMBER 2-6), 433-444
• PITTER, M.C., HOPCRAFT, K.I., JAKEMAN, E. and WALKER, J.G., 1999. Measurement of polarization fluctuations in polydispersions of small spheroids In: POLARIZATION: MEASUREMENT, ANALYSIS, AND REMOTE SENSING II. 55-64
• MORGAN, S.P., PITTER, M.C. and WALKER, J.G., 1998. Frequency domain imaging through heavily scattering media - a comparison of diffusion and Monte Carlo simulations In: PHOTON PROPAGATION IN TISSUES III, PROCEEDINGS OF. 311-322
• CHANG, P.C.Y., WALKER, J.G., JAKEMAN, E., HOPCRAFT, K.I., JORDAN, D.L. and LEWIS, G.D., 1998. Propagation of polarized light in scattering media. In: APPLIED OPTICS AND OPTOELECTRONICS 1998. 281-281
• WOOD, C. and WALKER, J.G., 1998. Asymmetric spectral lineshape recovery using higher order photon-correlation spectroscopy Optics Communications. 152(4-6), 412-420
• HUNTER, A.D., CROWE, J.A. and WALKER, J.G., 1998. Measurement of in-vivo hemoglobin concentration using diffuse reflectance. In: PHOTON PROPAGATION IN TISSUES IV, PROCEEDINGS. 88-96
• PITTER, M. C. and WALKER, J., 1997. The effect of spatial filtering on the performance of TOF imaging systems Bioimaging. VOL 5(NUMBER 2), 71-81
• PITTER, M.C. and WALKER, J.G., 1996. A comparison of the performance of spatial-filtering and time-of-flight imaging systems. In: APPLIED OPTICS AND OPTOELECTRONICS 1996. 131-135
• WOOD, C. and WALKER, J.G., 1996. Detecting intermittency in scattered light fields In: APPLIED OPTICS AND OPTOELECTRONICS 1996. 120-125
• FISH, D.A., BRINICOMBE, A.M., PIKE, E.R. and WALKER, J.G., 1995. BLIND DECONVOLUTION BY MEANS OF THE RICHARDSON-LUCY ALGORITHM Optical Society of America Journal Part A. 12(1), 58-65