Peter D. Woolliams

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A technique for generating contrast in two-dimensional shear strain elastograms from a localized stress is presented. The technique involves generating a non-uniform, localized stress via a magnetically actuated implant. Its effectiveness is demonstrated using finite-element simulations and a phantom study provides experimental verification of this. The(More)
Point spread function (PSF) phantoms based on unstructured distributions of sub-resolution particles in a transparent matrix have been demonstrated as a useful tool for evaluating resolution and its spatial variation across image volumes in optical coherence tomography (OCT) systems. Measurements based on PSF phantoms have the potential to become a standard(More)
We introduce a novel approach to refractometry using a low coherence interferometer at multiple angles of incidence. We show that for plane parallel samples it is possible to measure their phase refractive index rather than the group index that is usually measured by interferometric methods. This is a significant development because it enables bulk(More)
Improvements to the NPL time domain measurement facility for the calibration of fast oscilloscope risetime are described. Particular emphasis is placed on characterising a coplanar waveguide to coaxial connector transition between a photoconductive pulse generator and the input of an oscilloscope sampling head. Two methods of measuring the transition are(More)
In this paper we describe measurements of the contrast transfer function, modulation transfer function and point-spread function of an optical coherence tomography (OCT) imaging system through scattering layers having a dimension-less scattering depth over the range 0.2-6.9. The results were found to be insensitive to scattering density, indicating that(More)
The definition, measurement, and traceability of aberrations in pulse waveform metrology is discussed. The use of reference waveforms and masks allows the definition of aberrations within specific regions relative to the transition point of a pulse generator, as desired by manufacturers and users. Of particular importance is the definition of aberrations(More)
Optical coherence tomography (OCT) systems are becoming more commonly used in biomedical imaging and, to enable continued uptake, a reliable method of characterizing their performance and validating their operation is required. This paper outlines the use of femtosecond laser subsurface micro-inscription techniques to fabricate an OCT test artifact for(More)
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