利用红外显微镜无损检测圆珠笔油墨色痕的研究

在这个研究中,红外显微镜聚焦功能得到了充分验证。该研究采用的检测方法是通过红外显微镜将红外光斑直接聚焦在样品表面,采集其红外光谱。根据样品红外吸收峰的个数、位置、强度及形状进行定性分析,以达到区分相同颜色不同品牌的圆珠笔油墨色痕的研究目的。研究结果表明,采用的检测方法可有效区分相同颜色不同品牌的圆珠笔油墨色痕。而且该检测方法具有无损检测特点,保持了物证的原样性。     

Photoshop软件在印章印文比对检验中的应用

利用Photoshop软件的图像处理功能,对印章印文进行重叠比对,旨在为伪造印章印丈的简单比对以及检验鉴定提供一种思路。文中方法具有操作简便,精确性高的特点,可为检验鉴定工作做出初步判断。     

Effect of electron beam irradiation on forensic evidence. 2. Analysis of writing inks on porous surfaces

The effect of electron beam irradiation on a series of different writing inks is described. As the anthrax-tainted letters were discovered in October 2001, the U.S. government began to experiment with the use of the electron beam irradiation process for destroying such biological agents. Plans initially considered a large-scale countrywide use of this technology. However, over time the scope of this plan as well as the radiation dosage were reduced, especially when some adverse consequences to mailed items subjected to this process were observed. Little data existed at the time to characterize what level of damage might be expected to occur with common items sent through the mail. This was especially important to museums and other institutions that routinely ship valuable and historic items through the mail. Although the Smithsonian Institution initiated some studies of the effect of electron beam irradiation on archived materials, little data existed on the effect that this process would have on forensic evidence. Approximately 97 different black, blue, red, green, and yellow writing inks were selected. Writing ink types included ballpoint, gel, plastic/felt tip, and rollerball. All noncontrol samples were subjected to standard mail irradiation conditions used by the U.S. Postal Service at the time this experiment was performed. A video spectral comparator and thin-layer chromatography (TLC) analysis were used to evaluate both the control and the irradiated samples. Some published studies reported changes in the presence/absence of dye bands in the chromatograms of irradiated writing inks. Some of these studies report the formation of additional dye bands on the chromatogram while others report missing dye bands. However, using standard testing guidelines and procedures, none of the 97 irradiated inks tested were found to show any significant optical or chemical differences from the control samples. In addition, random testing of some of the ink samples using a second solvent system did not reveal any changes. However, one control ink did show some minor changes in optical properties and dye characteristics over time (but not TLC) while the irradiated sample remained stable. Significant changes in the ultraviolet fluorescence characteristics of the irradiated paper samples themselves (not inks) were also observed.     

显微共焦激光拉曼光谱仪分析激光打印黑色墨粉字迹

激光打印机是常用办公设备,案件中经常会涉及到激光打印文件的检验,运用显微共焦激光拉曼光谱仪检验激光打印黑色墨粉字迹是一种快速、无损、灵敏度高的检验方法,可以对墨粉成分进行定性分析,在司法实践中,此种方法对激光打印黑色墨粉具有较好的检验效果,应用前景广阔。     

一起通过利用Photoshop辨别印章真伪的检验

随着社会的迅猛发展,Photoshop等图像处理软件的运用普及程度越来越广泛。对基层公安机关而言,Photoshop功能的运用,不仅符合"科技强警"的要求,也为公安技术工作中解决文检的一些实际问题提供了新思路和新方法,特别是针对文检中印章印文检验,具有广泛的应用前景。     

Determination of the Sequence of Intersecting Lines Between Toners and Seals by Laser Fluorescence Microscope

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.     

Application of Raman Spectroscopy and Surface‐Enhanced Raman Scattering to the Analysis of Synthetic Dyes Found in Ballpoint Pen Inks*

Abstract: The applicability of Raman spectroscopy and surface‐enhanced Raman scattering (SERS) to the analysis of synthetic dyes commonly found in ballpoint inks was investigated in a comparative study. Spectra of 10 dyes were obtained using a dispersive system (633 nm, 785 nm lasers) and a Fourier transform system (1064 nm laser) under different analytical conditions (e.g., powdered pigments, solutions, thin layer chromatography [TLC] spots). While high fluorescence background and poor spectral quality often characterized the normal Raman spectra of the dyes studied, SERS was found to be generally helpful. Additionally, dye standards and a single ballpoint ink were developed on a TLC plate following a typical ink analysis procedure. SERS spectra were successfully collected directly from the TLC plate, thus demonstrating a possible forensic application for the technique.     

蓝色圆珠笔字迹色痕FT-IR光谱经时变化的研究

笔者曾用FT-IR光谱法对108种不同蓝色圆珠笔油墨进行了系统分析,确定了油墨组成成份,实现了种类认定.在此基础上,选取了二种不同种类的蓝色圆珠笔油墨字迹色痕,在紫外光下定时照射,根据各自光谱特征峰校正峰高的计算,确定相关峰的相对峰高比.根据相对峰高比值随时间变化的规律,进行了曲线拟合和计算机编程.同时,探讨了油墨组份之间随光照时间的变化,其目的是为了推断字迹色痕的“年龄”.     

万用表测量字迹电阻方法的初步研究

目的介绍一种鉴定添加变造黑色笔迹的新方法—万用表测量字迹电阻法。方法用万用表的探针测量字迹笔画的电阻值数值,根据数值的大小范围来判断字迹是否存在添加变造。结果该方法简便快速,不破坏原件,不受检测条件及环境的限制,成本低,效率高,便于广泛推广应用。结论凡是可测出电阻值数值的,证明书写色料中的成份是以碳黑为主,凡电阻值为正无穷大时,证明书写色料中不含碳黑,而是由多种色料拼色而成的,从而可分析判断字迹是否被添加变造。     

光敏印章盖印印文的检验

光敏印章盖印印文是司法鉴定中涉及真伪鉴别的一类新型印文。课题组以调研、实验研究、个案鉴定的积累为基础,对这类印章印文的特点和检验要点进行了操作层面的探讨。