Wide-field time-resolved luminescence imaging and spectroscopy to decipher obliterated documents in forensic science

Mototsugu Suzuki; Norimitsu Akiba; Kenji Kurosawa; Kenro Kuroki; Yoshinori Akao; Yoshiyasu Higashikawa

doi:10.1117/1.OE.55.1.014101

13 January 2016 Wide-field time-resolved luminescence imaging and spectroscopy to decipher obliterated documents in forensic science

Mototsugu Suzuki, Norimitsu Akiba, Kenji Kurosawa, Kenro Kuroki, Yoshinori Akao, Yoshiyasu Higashikawa

Author Affiliations +

Optical Engineering, Vol. 55, Issue 1, 014101 (January 2016). https://doi.org/10.1117/1.OE.55.1.014101

Abstract

We applied a wide-field time-resolved luminescence (TRL) method with a pulsed laser and a gated intensified charge coupled device (ICCD) for deciphering obliterated documents for use in forensic science. The TRL method can nondestructively measure the dynamics of luminescence, including fluorescence and phosphorescence lifetimes, which prove to be useful parameters for image detection. First, we measured the TRL spectra of four brands of black porous-tip pen inks on paper to estimate their luminescence lifetimes. Next, we acquired the TRL images of 12 obliterated documents at various delay times and gate times of the ICCD. The obliterated contents were revealed in the TRL images because of the difference in the luminescence lifetimes of the inks. This method requires no pretreatment, is nondestructive, and has the advantage of wide-field imaging, which makes it is easy to control the gate timing. This demonstration proves that TRL imaging and spectroscopy are powerful tools for forensic document examination.

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Mototsugu Suzuki, Norimitsu Akiba, Kenji Kurosawa, Kenro Kuroki, Yoshinori Akao, and Yoshiyasu Higashikawa "Wide-field time-resolved luminescence imaging and spectroscopy to decipher obliterated documents in forensic science," Optical Engineering 55(1), 014101 (13 January 2016). https://doi.org/10.1117/1.OE.55.1.014101

Published: 13 January 2016

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