OPTICAL PROFILOMETRY AS A METHOD FOR DETECTING INDENTED WRITING

The current methodology for indented writing detection involves electrostatic detection apparatus (ESDA) processing and oblique light. While commonly used in forensics analysis, ESDA has several drawbacks, including its unsuitability for documents of certain shapes and densities, the damage it occasionally causes to evidence, its need for prior humidification in order to process documents, and the ozone it creates. In this study we evaluated optical profilometry as an alternative to ESDA. We tested several optical profilometer brands and showed their capacity for detecting very slight indentations, even to the magnitude of 8µm. We also obtained the clear resolution of a 3D image of this writing.