Structural and optical characterization of banknotes using spectral-domain optical coherence tomography

Area of Science:

• Optics
• Forensic Science
• Materials Science

Background:

• Banknote counterfeiting poses significant economic and social risks.
• Current methods rely on surface security features, which are vulnerable to forgery and offer limited source information.
• A need exists for advanced techniques to authenticate banknotes and identify counterfeit origins.

Purpose of the Study:

• To introduce spectral-domain optical coherence tomography (SD-OCT) as a novel approach for banknote characterization.
• To evaluate the efficacy of SD-OCT in distinguishing authentic from counterfeit banknotes.
• To explore the potential of SD-OCT for tracing counterfeit banknotes to their sources.

Main Methods:

• Spectral-domain optical coherence tomography (SD-OCT) was employed for non-destructive imaging of banknotes.
• Three groups of counterfeit Chinese 100 Yuan banknotes and one group of authentic banknotes were analyzed.
• High-resolution tomographic and 3D volumetric images were acquired from four distinct areas per note without sample preparation.

Main Results:

• SD-OCT successfully generated detailed structural and optical features of banknotes.
• Distinct imaging characteristics were identified for authentic and counterfeit banknotes.
• The technique demonstrated effectiveness in classifying different types of counterfeit notes based on their internal structures.

Conclusions:

• SD-OCT provides a powerful, non-destructive tool for banknote authentication.
• The method can reliably detect and classify counterfeit banknotes.
• SD-OCT shows promise for linking counterfeit notes to their manufacturing sources efficiently.