Liu Shuo, Yang Yaqi, Zhang Yi, Li Bing
Institute of Evidence Law and Forensic Science, China University of Political Science and Law, Beijing, China.
Procuratorial Technology Information Research Centre of the Supreme People's Procuratorate of China, Beijing, China.
J Forensic Sci. 2024 Nov;69(6):2148-2158. doi: 10.1111/1556-4029.15632. Epub 2024 Sep 24.
In the field of questioned document examination, determining the sequence of intersecting lines is still a technical challenge. This study aims to validate whether confocal Raman spectroscopy can determine the sequence of intersecting lines created by laser prints toner and seal ink through empirical research. The study collected 110 varieties of seal ink and 1074 test pages from 66 models of laser printers available in the Chinese market. Based on the Raman spectral characteristics of the seal ink and the microscopic morphology of the toner, 13 types of seal ink and three types of laser printers were selected for further analysis, producing 78 representative samples of intersecting lines. Confocal Raman spectroscopy was applied to the examination of these samples using a point-scanning mode for enhanced accuracy and efficiency. The experimental results demonstrate that confocal Raman spectroscopy can non-destructively and quickly examine the sequence of intersecting lines produced by laser printer toner and seal ink. Variations in toner forms result in differing levels of difficulty in resolving intersection problems, with the sequence of intersecting lines from toner-dense laser printers being the easiest to ascertain. In contrast, those from printers with porous and dispersed toner present a more significant challenge in examination. This study can be corroborated with other methods proposed, and more significantly, it lays the groundwork for addressing intersection problems related to other printing or writing instruments.
在文件检验领域，确定交叉线条的先后顺序仍然是一项技术挑战。本研究旨在通过实证研究验证共聚焦拉曼光谱法能否确定激光打印碳粉和印章油墨形成的交叉线条的先后顺序。该研究收集了中国市场上66种型号激光打印机的110种印章油墨和1074份测试页面。基于印章油墨的拉曼光谱特征和碳粉的微观形态，选择了13种印章油墨和三种激光打印机进行进一步分析，制作了78个具有代表性的交叉线条样本。采用点扫描模式将共聚焦拉曼光谱法应用于这些样本的检验，以提高准确性和效率。实验结果表明，共聚焦拉曼光谱法能够无损且快速地检验激光打印机碳粉和印章油墨产生的交叉线条的先后顺序。碳粉形态的差异导致解决交叉问题的难度不同，碳粉密集的激光打印机产生的交叉线条顺序最容易确定。相比之下，碳粉多孔且分散的打印机产生的交叉线条在检验中面临更大挑战。本研究可与其他提出的方法相互印证，更重要的是，它为解决与其他打印或书写工具相关的交叉问题奠定了基础。
