光学相干层析技术在打印文书朱墨时序判别中的实验研究

Experiment of Optical Coherence Tomography in Determining the Sequence of Intersecting Lines of Printed Documents

打印文书与印章交线先后顺序的判断是鉴定文件真伪和相对制成时间的关键内容。利用中心波长为900 nm的谱域光学相干层析(OCT)系统对激光打印机和喷墨打印机与油性和水性两种印油印章制成的若干相交线样本进行检测,通过获取的交线区域二维断层成像和三维立体图像,比较两类打印机制成的样本在OCT检验下的成像特征,进而判断朱墨时序。对120个样品,包括30组激光打印机与印油的朱墨时序样品和30组喷墨打印机与印油的朱墨时序样品进行了比较研究,每组样品均选取了多个区域重复测试。实验结果表明,激光打印机和喷墨打印机形成的相同朱墨时序样本的OCT图像在透射光亮度分布上形成的反差是不一致的,这可为判别打印文书和印章的交线顺序提供参考。

The intersection of a printed document and stamp-seal determined in a sequence is one important method for confirming the authenticity and relative manufacturing time of document components. The spectral domain optical coherence tomography(OCT) system having a wavelength of 900 nm is used to examine several intersecting line samples made using laser and inkjet printers with oil-based and water-based stamp seals, thus obtaining 2D tomographic and 3D stereo images of the intersection line region to compare the imaging characteristics presented using two types of printers and determine the intersecting line sequence. This study investigated 120 intersecting line samples, including 30 groups made by laser printers and stamp seals and 30 groups obtained using inkjet printers and stamp seals. Each group of samples was repeated multiple times, and multiple areas were selected to repeat the test.The experimental results show that the contrast in the luminance distribution of the transmitted light reflected in the OCT images of the same intersecting line sequence formed by laser and inkjet printers differed. This can provide a reference for discriminating the intersection line sequence of printed documents and stamp seals.