Toolmarks identification using SEM images in an optoelectronic correlator device

The forensic problem of identifying toolmarks is analysed and a method based on utilizing an optoelectronic correlator device as a possible solution is proposed. The method includes: acquiring striation patterns as digital files by using an environmental scanning electron microscope (SEM), selecting and extracting features from the striation patterns and identifying tools by calculating the correlation measures. Our approach relies on transforming the two-dimensional striation patterns to one-dimensional bar-code information, by which the starting information is well preserved and the obtained information is robust to deformations and noise. The effectiveness of the proposed approach is demonstrated by the results of the identification of the toolmarks impressed by lap joint pliers in a test wire. Since the optoelectronic device combines fast optical processing and digital image information, the proposed method can be automatised.