Application of ultraviolet, visible, infrared and X-ray electromagnetic waves in the investigation of fake and suspicious documents

Forensic experts use a variety of physical, optical, and chemical methods to determine the authenticity of a document. The emphasis of the present study is to investigate the use of ultraviolet, visible , infrared and X-ray electromagnetic waves in the study of fake and suspicious documents.

In terms of methodology, the research is of qualitative-exploratory type and in terms of type of supervision and degree of control, this research is among the field research and the research is exploratory. The statistical population in the qualitative research is the official experts and the experts' association. In selecting the research experts, the method of targeted snowball sampling was used. A statistical sample of a quantitative section of 100 people was selected. The results of the experts' interviews were distributed as a questionnaire based on the Likert scale to the statistical sample. Data analysis method was analyzed in the qualitative part by interview and in the quantitative part by exploratory factor analysis method after confirmation by Kaiser-Mayer-Oaklin test.

Applications of ultraviolet electromagnetic waves: detection of the presence and use of cleaning and chemical liquids, examination of burned documents with special filters, etc. infrared: detecting differences between ink and paper, reading the contents of burned documents, etc. visible: recognizing the difference of material, color, special properties of ink and ink used in documents, identifying the type, material and difference of paper, etc. Applications of light microscope: Recognition of rewrites, abrasions, scratches, etc., and finally other electromagnetic waves are: X-ray, spot light, etc.

The results obtained from factor analysis showed that 1- visible electromagnetic waves 2- ultraviolet electromagnetic waves, 3- infrared electromagnetic waves, 4- light microscope, 5- other electromagnetic waves are effective in examining fake documents.