| XIE Dong-bai,LI Xin-ting,SHAN Guo,CHEN Yu.Improving Imaging Quality of Criminal Photography Photomicrograph by Corrosion of Metals[J],46(1):200-205 |
| Improving Imaging Quality of Criminal Photography Photomicrograph by Corrosion of Metals |
| Received:August 25, 2016 Revised:January 20, 2017 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2017.01.032 |
| KeyWord:metallic trace carrier etching solution optical microscope dispersion imaging quality |
| Author | Institution |
| XIE Dong-bai |
Key Laboratory of Impression Evidence Examination and Identification Technology, National Police University of China, Shenyang , China |
| LI Xin-ting |
Department of Forensic Science, Xinjiang Police College, Urumqi , China |
| SHAN Guo |
Department of Forensic Science, Xinjiang Police College, Urumqi , China |
| CHEN Yu |
Foreign Exchange Department of Liaoning Police Association, Liaoning Provincial Public Security Department, Shenyang , China |
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| Abstract: |
| To improve the image quality of criminal photography through surface treatment on the metallic trace carrier to upgrade the imaging quality in ordinary environment of visible light sources. The imaging characteristics of traces with shapes of line and concave formed on the surface of Al and Pb boards were investigated by an optical microscope with different light sources. The dispersion phenomena under high magnification were analyzed in order to validate their effects on the imaging quality. After pre-processing of traces on the metal surface with mixed solution of absolute ethyl alcohol and 50% (mass fraction) acetone, the imaging quality was tested and the causes of changes were discussed. Tiny lines in the traces on the metal surface could lead to optical interference, which resulted in the formation of light and dark stripes with different colors in the optical microscope photomicrograph. Proper treatment of traces on metallic trace carrier with special etching solution can eliminate interference of trace carrier in the optical imaging system. Pretreatment of traces on metal surface with this method can improve the imaging quality of tiny trances in photomicrography. |
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