AFTE Store - Examination Techniques: The Beam Splitter and Reverse Lighting

A task commonly encountered in the field of Toolmark Examination is physical matching. In a physical match, often it is necessary to examine the break or fracture surface for common characteristics. Two problems exist with such direct examinations: first, that each surface is a reversed or mirror image of the other; and second, that each surface is a topographic negative of the other. To overcome these difficulties, examinations of this nature are usually done either by a system of photographic overlays or by taking a surface mold. Both techniques result in a loss of detail either in the reduction to two demensions or the introduction of an intermediate transfer material. Application of the techniques outlined herein allows direct optical examination of both surfaces permitting a direct comparison, since the required reversals are accomplished optically.