@article{3038100, title = "Laser photothermal diagnostics of genuine and counterfeit British and United States banknotes", author = "Othonos, A. and Mandelis, A. and Nestoros, M. and Christofides, C.", journal = "Optical Engineering", year = "1997", volume = "36", number = "2", pages = "400-407", publisher = "SPIE/International Society of Optical Engineering", issn = "0091-3286, 1560-2303", doi = "10.1117/1.601212", abstract = "Laser-induced, frequency-scanned IR photothermal radiometry 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 amplitudes and phases were further compared with a theoretical model, which yielded simultaneous quantitative measurements of the thermal diffusivities and conductivities of the bills. Both statistical and single-specimen results demonstrated the excellent thermophysical resolution of the technique with prospects for its use in the nonintrusive, on-line identification of counterfeit banknotes. © 1997 Society of Photo-Optical Instrumentation Engineers." }