Στο καινούργιο τευχος του Forensic Science International (Volume 177, Issues 2-3, 20 May 2008, Pages 97-104), οι Luke Yaraskavitch, Matthew Graydon, Tobin Tanaka και Lay-Keow Ng παρουσιάζουν μια εργασία με τίτλο: "Controlled electrostatic methodology for imaging indentations in documents".
In the new Issue of Forensic Science International (Volume 177, Issues 2-3, 20 May 2008, Pages 97-104), Luke Yaraskavitch, Matthew Graydon, Tobin Tanaka and Lay-Keow Ng present a paper titled: "Controlled electrostatic methodology for imaging indentations in documents".
Περίληψη/Abstract: The electrostatic process for imaging indentations on documents using the ESDA device is investigated under controlled experimental settings. An in-house modified commercial xerographic developer housing is used to control the uniformity and volume of toner deposition, allowing for reproducible image development. Along with this novel development tool, an electrostatic voltmeter and fixed environmental conditions facilitate an optimization process. Sample documents are preconditioned in a humidity cabinet with microprocessor control, and the significant benefit of humidification above 70% RH on image quality is verified. Improving on the subjective methods of previous studies, image quality analysis is carried out in an objective and reproducible manner using the PIAS-II. For the seven commercial paper types tested, the optimum ESDA operating point is found to be at an electric potential near −400 V at the Mylar surface; however, for most paper types, the optimum operating regime is found to be quite broad, spanning relatively small electric potentials between −200 and −550 V. At −400 V, the film right above an indented area generally carries a voltage which is 30–50 V less negative than the non-indented background. In contrast with Seward's findings [G.H. Seward, Model for electrostatic imaging of forensic evidence via discharge through Mylar–paper path, J. Appl. Phys. 83 (3) (1998) 1450–1456; G.H. Seward, Practical implications of the charge transport model for electrostatic detection apparatus (ESDA), J. Forensic Sci. 44 (4) (1999) 832–836], a period of charge decay before image development is not required when operating in this optimal regime. A brief investigation of the role played by paper-to-paper friction during the indentation process is conducted using our optimized development method.
http://dx.doi.org/10.1016/j.forsciint.2007.11.004
In the new Issue of Forensic Science International (Volume 177, Issues 2-3, 20 May 2008, Pages 97-104), Luke Yaraskavitch, Matthew Graydon, Tobin Tanaka and Lay-Keow Ng present a paper titled: "Controlled electrostatic methodology for imaging indentations in documents".
Περίληψη/Abstract: The electrostatic process for imaging indentations on documents using the ESDA device is investigated under controlled experimental settings. An in-house modified commercial xerographic developer housing is used to control the uniformity and volume of toner deposition, allowing for reproducible image development. Along with this novel development tool, an electrostatic voltmeter and fixed environmental conditions facilitate an optimization process. Sample documents are preconditioned in a humidity cabinet with microprocessor control, and the significant benefit of humidification above 70% RH on image quality is verified. Improving on the subjective methods of previous studies, image quality analysis is carried out in an objective and reproducible manner using the PIAS-II. For the seven commercial paper types tested, the optimum ESDA operating point is found to be at an electric potential near −400 V at the Mylar surface; however, for most paper types, the optimum operating regime is found to be quite broad, spanning relatively small electric potentials between −200 and −550 V. At −400 V, the film right above an indented area generally carries a voltage which is 30–50 V less negative than the non-indented background. In contrast with Seward's findings [G.H. Seward, Model for electrostatic imaging of forensic evidence via discharge through Mylar–paper path, J. Appl. Phys. 83 (3) (1998) 1450–1456; G.H. Seward, Practical implications of the charge transport model for electrostatic detection apparatus (ESDA), J. Forensic Sci. 44 (4) (1999) 832–836], a period of charge decay before image development is not required when operating in this optimal regime. A brief investigation of the role played by paper-to-paper friction during the indentation process is conducted using our optimized development method.
http://dx.doi.org/10.1016/j.forsciint.2007.11.004
