title: Identifying diagonal cutter marks on thin wires using 3D imaging.
abstract: We present work on matching 2-mm-thick wires using optical 3D imaging methods. Marks on such small surfaces are difficult to match using a comparison microscope as this 2D imaging method does not provide height data about the sample surface. Moreover, these 2D microscopy images may be affected by illumination. Hence, the reference and investigated sample should be present at the same time. We employed scanning white light interferometry and confocal microscopy to provide quantitative 3D profiles for reliable comparison of samples that are unavailable for simultaneous analysis. We show that 3D profiling offers a solution by allowing illumination-independent sample comparison. We correctly identified 74 of 80 profiles using consecutive matching striae (CMS) criteria, and we were able to match samples based on profiles measured using different 3D imaging devices. The results suggest that the used methods allow matching cutter marks on thin wires, which has been difficult previously.
authors.affiliation: Department of Physics, University of Helsinki, P. O. Box 64, FIN-00014, Helsinki, Finland.
authors.forename: Ville Vili
authors.initials: VV
authors.lastname: Heikkinen
authors.forename: Ivan
authors.initials: I
authors.lastname: Kassamakov
authors.forename: Claude
authors.initials: C
authors.lastname: Barbeau
authors.forename: Sami
authors.initials: S
authors.lastname: Lehto
authors.forename: Tapani
authors.initials: T
authors.lastname: Reinikainen
authors.forename: Edward
authors.initials: E
authors.lastname: Haeggström
keywords: 3D imaging; confocal microscopy; diagonal cutters; forensic science; scanning white light interferometry; toolmarks