High-resolution imaging of magnetic fields of banknote anti-counterfeiting strip using fiber diamond probe

Abstract

Counterfeiting of modern banknotes poses a significant challenge, prompting the use of various preventive measures. One such measure is the magnetic anti-counterfeiting strip. However, due to its inherent weak magnetic properties, visualizing its magnetic distribution has been a longstanding challenge. In this research paper, we introduce an innovative approach using a fiber optic diamond probe, a highly sensitive quantum sensor specifically designed for detecting extremely weak magnetic fields. We employed this probe to achieve high-resolution imaging of the magnetic fields associated with the RMB 50 denomination anti-counterfeiting strip. Additionally, we conducted computer simulations using COMSOL Multiphysics software to deduce the potential geometric characteristics and material composition of the magnetic regions within the anti-counterfeiting strip.<br/>The findings and methodologies presented in this study hold broader significance, extending beyond the RMB 50 denomination to various denominations of the Chinese currency and other items that employ magnetic anti-counterfeiting strips. These advancements have the potential to significantly enhance and advance security measures aimed at preventing the counterfeiting of banknotes.