Photoacoustic (PA) imaging for the examination of altered documents in forensic science has been investigated by an innovative system with a nanosecond pulsed laser, a microphone, and a handmade sample holder. The PA signals from lines written by black pens on paper were successfully detected without coupling media such as gels, and the signal amplitude was found to depend on the type of writing pen. The original contents of the document changed by the addition of a line and of the obliterated document were clearly observed by the PA imaging. The nondestructive PA measurement and imaging have been demonstrated to be a high-potential technique to discriminate writing inks and to examine altered documents.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither SPIE nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the SPIE website.