Feature Of The Week 3/27/11: Feasibility of Full-Field Optical Coherence Tomography for Detection of Counterfeit Paper Money
Feature Of The Week 3/27/11: This week’s featured work is from Gwangju Institute of Science and Technology (GIST) where researchers reported on an exciting application of full-field optical coherence tomography (FF-OCT) for identifying counterfeit bank notes. Recent application of the FF-OCT has been expanded to medical biology, clinical pathology, cell biology, material industry and even biometric-based forensic science. In this study, they have demonstrated new approach of the OCT technique for counterfeit science. Money counterfeiting is mostly prevalently forged item worldwide with advance of printing technology and computer system, leading to deep concerns for the risk of massive circulation of the fake notes. Although newly anti-counterfeiting measures on the bill have been utilized on the issued notes, identification on the security features just depended on superficial observation, which can be easily fooled and tampered by mimicking these ones. To overcome existing limit, they introduced FF-OCT scheme for internal structural imaging of the banknote. Their time-domain FF-OCT system achieved ultrahigh spatial resolution down to 1 micron with high sensitivity over 80 dB and provided scan-free en-face OCT imaging at the speed of 0.2s/frame. The depth-resolved imaging capability of the scheme enabled tomographic identification of superficially-identical objects. With the system, OCT imaging of a cash hologram on the original banknote was demonstrated, revealing that the hologram consisted of micron scale multi-coated layers with intrinsic thicknesses including an air gap. Therefore it is expected that FF-OCT has potential as a new non-invasive tool to discern imitation of currency, and furthermore, applications in identifying certificates, credit cards, and also various other security documents.
For more information see recent Article. Courtesy Woo June Choi.