Product Code: JLA_15_4_294

Authors:
R. Stewart
L. Li
Department of Mechanical, Aerospace and Manufacturing Engineering, Laser Processing Research Centre, University of Manchester Institute of Science and Technology (UMIST), P.O. Box 88, Manchester M60 1QD, United Kingdom

Inks consisting of two and three pigments as well as an infrared absorber were printed onto plain paper and treated using a Q-switched Nd:yttrium–aluminum–garnet laser. It has been shown that the color of these inks can be altered through selective pigment decay: a red, green and blue ink decayed red first, then green, leaving a blue mark or a purple one, selectively. The process is related to the thermal decomposition temperature of the pigments used which is dependent upon the incident laser intensity. © 2003 Laser Institute of America.