US Patent 7268795 Labeling methods and apparatus using electromagnetic radiation

A method and apparatus are provided for visually marking a recording medium by inducing a phase change in a light-sensitive surface by heat absorption from laser radiation. The method includes applying the laser radiation to a desired portion of the light-sensitive surface according to a first power profile for a first period sufficient to substantially obtain a color change at the desired portion, and applying the laser radiation to the desired portion of the light-sensitive surface according to a second power profile for a second period sufficient to complete the color change at the desired portion.