BAI Guohua, LU Yilin, LIAN Yuanyuan
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In handwriting identification, when a case involves forged or altered strokes and figures problems the appraiser usually needs to examine the crossing section of the suspected material to confirm whether there is a forgery in the document. In addition, the study on the sequence determination of the crossing line can help appraiser to estimate the thumbprint of the handwriting and the character of the writing sequence. And also, those identification methods have reference value for the sequential identification of crossed writing and seal stamps documents. This paper draws experience from the existing methods with the common features, such as continuity of strokes and convergence phenomenon, and tests several types of black pens by Raman spectroscopy. Through the design of experiment to compare and choose the best parameters of the instrument and software settings, including microscope lens, laser wavelength, laser output power, spectral range, single acquisition time, cumulative acquisition times, scanning step, get the best experimental parameters and acquisition method and comparison principle. The experimental results of Raman spectrum 3D imaging are discussed in classification, analysis whether the application of this method to determine the writing order of cross strokes is useful. When preponderance and unanimous heterochromia phenomenon can be observed between the “hills and valleys”, an accurate conclusion can be drawn. When the heterochromia phenomenon is obvious but not incongruent or the phenomenon is not obvious, it need to combine the characteristics of stroke continuity in the 3D model to get the correct conclusion, but the accuracy is greatly influenced by the data processing and the 3D model imaging effect. At the same time, the undetectable situation is summarized, that is, when the Raman spectrum information is unable to be obtained effectively or the spectral information those are homology cannot be distinguished, the method is invalid. Based on the analysis and summarize of the experimental result, it can be sure that the Raman spectroscopy 3D profilometry techniques can get relatively objective and accurate judgment on the determination of sequence of black pen ink crossings under certain conditions, and the conclusion is affected little by the appraiser’s subjective judgment. It is worth a more thorough and comprehensive study in order to promote the application.
