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Title: Objective criteria for matching textile fibres using visible MSP
Author: Chaud, Aurelie
Awarding Body: The University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2008
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Although the analysis of fibres is not essential in all criminal cases, fibres can provide useful evidence in the reconstruction of criminal events. With this evidence, one of the most difficult issues for the forensic scientist is to assess whether two fibres could have come from the same source or not. For this purpose, microspectrophotometry is a technique to be considered, because it can be used to obtain visible absorbance spectra allowing discrimination of macroscopically indistinguishable fibres. Although MSP (microspectrophotometer) records colour objectively (unlike humans), the spectra it produces (although objective) are being compared subjectively, therefore another system of comparison, based on objective criteria, must be determined. This research focuses on colour discrimination and considers several systems of comparison that can be used in order to determine some objective criteria of matching spectra. For this purpose, two approaches are envisaged: a colorimetric and a mathematical approach, and more than 230 fibres were studied by microspectrophotometry in order to determine some criteria of matching and non-matching. Firstly, the influence of some parameters was studied in order to establish a correct method of analysis. This study shows that the most important parameter to have good repeatability and good reproducibility is the light intensity because when the level of light intensity is raised, the ratio signal/noise follows the same pattern. experiments made, some criteria for matching and non-matching textile fibres were determined. A first discrimination can be made by the visible colour and the direct comparison of spectra, however this discrimination must be realised cautiously because they are not objective criteria. The calculation of the HQI values (Hit Quality Indices) then provides an objective criterion for the discrimination.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available