In laser thermal transfer printing using a dye sublimation type medium, a high definition and continuous tone image can be easily obtained because a laser light focuses on a small spot, and its heat energy can be controlled by pulse width modulation. On the other hand, the physical phenomena occurring at an ink donor sheet during or just after the laser heating are unknown. In this report, the surface of the ink layer consisting of sublimation color dye heated by microseconds laser pulse irradiation was observed using time-resolved optical microscopy. The ink layer was deformed during and after laser pulse irradiation. The diameter of the hole formed by laser heating at the ink layer increased rapidly after the threshold time during the laser pulse, and its increasing rate became slowly according as approach to the pulse end. The Gaussian distribution of laser light intensity and the diffusion of the heat energy by thermal conduction seem to be important factors to explain the thermal response of the ink layer in microseconds order.
Masaru Kinoshita, Katsuyoshi Hoshino, Takashi Kitamura, "Time-Resolved Microscopy of the Surface of Ink Layer in Laser Dye Thermal Transfer" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP15), 1999, pp 239 - 242, https://doi.org/10.2352/ISSN.2169-4451.1999.15.1.art00062_1