Laser photothermal diagnostics of genuine and counterfeit British and United States banknotes
Andreas Othonos · Optical Engineering · 1997
Laser-induced, frequency-scanned IR photothermal radiom- etry was used to investigate the thermophysical properties of the paper on which several genuine and counterfeit British (£10) and U.S. ($50, $100) currency bills were printed. The radiometric photothermal ampli- tudes and phases were further compared with a theoretical model, which yielded simultaneous quantitative measurements of the thermal diffusivi- ties and conductivities of the bills. Both statistical and single-specimen results demonstrated the excellent thermophysical resolution of the tech- nique with prospects for its use in the nonintrusive, on-line identification of counterfeit banknotes. © 1997 Society of Photo-Optical Instrumentation Engi- neers.