Laser fluorescence inspection method for recognizing sequence of crossed writing and seal stamp

Abstract

The invention discloses a laser fluorescence inspection method for recognizing a sequence of a crossed writing and seal stamp. The specific implementation scheme is that blue laser is used as a light source and the laser is irradiated to a crossing position, which needs to be recognized, of a seal stamp and writing stokes. A cut-off long-wave-pass color filter with wave length longer than laser wave length is added at the front of a light sensor, and the light sensor transmits an image acquired through a microscope lens and the color filter to a computer through a data line for observation and photographing. By distinguishing the printing ink which emits fluorescence from the writing stokes which do not emit fluorescence through a method that the blue laser can excite printing ink fluorescence, the goal of recognizing the sequence of forming the seal stamp and the handwriting and typewriting is achieved, and the laser fluorescence inspection method has the characteristics of simplicity, feasibility and small equipment investment.

Description

technical field [0001] The invention relates to a laser fluorescence inspection method for identifying the timing sequence of ink and ink, and belongs to the field of identifying the timing of ink and ink. Background technique [0002] The time sequence of ink and ink refers to the order in which the seals (hereinafter referred to as Zhu) and characters (hereinafter referred to as ink) on documents are formed. At present, in the field of forensic document inspection, direct microscope observation is usually used to inspect the time sequence of ink and ink, that is, under an 80-200 magnification stereo microscope, the color of the intersection of the printed text and the handwriting and strokes is observed with the naked eye to judge the formation sequence. This traditional method is unreliable, prone to misjudgment, and cannot perform image fixation on the observed phenomenon. Another common inspection method is the peeling method, that is, use a blade to lightly scrape the...

AI Technical Summary

Problems solved by technology

At present, in the field of forensic document inspection, direct microscope observation is usually used to inspect the time sequence of ink and ink, that is, under an 80-200 magnification stereo microscope, the color of the intersection of the printed text and the handwriting and strokes is observed with the naked eye to judge the formation sequence. This traditional method is unreliable, prone to misjudgment, and cannot perform image fixation on the observed phenomenon

Another common inspection method is the stripping method, that is, lightly scrape the intersection with a blade to observe the color of the lower layer of the scraped surface, but this method not only destroys the inspection material, but in most cases it is not only invalid but also prone to misjudgment

[0003] The inventor also retrieved the literature on the use of laser Raman spectroscopy to test the time sequence of ink and ink, but laser Raman spectroscopy is a qualitative and quantitative method for testing substances, and it is mainly used in the inspection of ink and ink timing by laser Raman spectroscopy. The material composition of the part is expressed in the form of a spectral curve, which cannot provide intuitive images for identification, and requires professionals with relevant knowledge to identify, which is not conducive to the promotion and application of this method

[0004] In recent years, there have been reports on the use of fluorescence microscopy. However, since the excitation light source of the fluorescence microscope is an ordinary xenon lamp or LED light source with a color filter, the lack of monochromaticity will cause the background light to be too strong and affect the judgment; the intensity of the light is not enough to cause the excited fluorescence. Not strong; coupled with insufficient magnification of the microscope or insufficient sensitivity of the photoreceptor, under darker observation conditions, only part of the ink stamped by the printing ink can be observed. Therefore, although this kind of fluorescence microscope inspection method has existed for a long time, it only stays in the research stage and has not been applied.

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