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铜、银在真空金属镀膜显现指纹技术中的应用研究

Detection of Latent Fingerprints on Non-Porous/Semi-Porous Surfaces with Cu/Ag Coatings:A Forensic Science Study

  • 摘要: 真空金属镀膜(VMD)对于显现非渗透性及半渗透性客体表面的潜在指纹具有极高的灵敏度,但由于其通常采用金、锌两种金属的联用对潜在指纹进行显现,成本过高且操作繁琐,因此未能在实践中得到广泛运用。为解决这一问题,本文选用铜、银代替金对常见塑料客体上的潜在指纹进行显现,在优化金属用量的基础上,将铜、银、铜锌、银锌VMD与传统金锌VMD进行比较,以探究更为便宜、简单、高效的VMD显现方案。实验结果表明,铜、银可以作为传统金锌的有效补充,铜锌VMD在塑料客体表面的显现效果优于传统金锌VMD,银VMD在深色塑料表面具有极大优势。

     

    Abstract: The latent fingerprint,left on non-porous and semi-porous surfaces,was imaged with vacuum evaporated metal-coatings.The influence of the type and thickness of coatings,including Ag/Cu/Au/Zn metals and CuZn/AgZn/AuZn alloys,on the image quality of fingerprint was investigated for cost-efficiency optimization.The results show that depending on specific situations,a proper coating works better for a proper fingerprint.For instance,the optimized thickness of metal coating should be greater than that of alloy coating;when it comes to image quality of fingerprint on plastic surfaces,a descending order existed:CuZn>AuZn>AgZn;Cu and Ag coatings work well for fresh fingerprints on plastic surface,and in imaging fingerprint on dark colored PE membrane,especially fingerprint with retention time of 30-days,Ag-coating outperforms AuZn-coating because of higher resolution and greater contrast.

     

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