Wu Xiang, Fang Fang, Li Biao
Department of Document Examination, Criminal Investigation Police University of China, No. 83 Tawan Street, Shenyang, 110854, China.
Zhejiang Han Bo Research Institute of Forensic Science, No. 9 Hangda Road, Hangzhou, 310012, China.
J Forensic Sci. 2019 Nov;64(6):1761-1768. doi: 10.1111/1556-4029.14097. Epub 2019 May 31.
Fluorescence microscope is considered to be one of the most effective ways to examine the sequence of intersecting seal and toner lines of questioned documents. In reality, however, the toner (mainly divided into compact and noncompact toners) and seal of a questioned document have such a complex morphology and sequence of crossing lines that current methods cannot meet the requirement of practical document identification. In view of the challenges of document examination, a laser fluorescence microscope and method are developed in this study. The developed microscope provides additional functionality to traditional fluorescence microscopes of transmitted light modality, laser excitation, selectable excitation wavelength, and selectable fluorescence filters. The results obtained from the method of comparisons between transmitted light and fluorescence modalities were positive under most conditions, particularly for noncompact toner examination for which a 100% accuracy rate and 90% detection rate were achieved in blind testing.
