An examination of 56 inks with an argon-ion laser revealed the laser will sometimes stimulate infrared luminescence in inks which did not produce infrared luminescence under the video spectral comparator (VSC-1). This infrared luminescence was always at a higher range (usually 830 to 900 nm) than that found under the VSC-1. This indicates that laser-induced infrared luminescence may be a useful tool in differentiating between inks which otherwise appear similar.

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