Laser marking of thin organic films.

The threshold marking response of a laser-irradiated dye-polymer thin film is described by a simple, thermally thresholding model. The apparent loss of thermal reciprocity is related to active reflectance changes during mark formation. It is shown that incorporation of measured differences between physical and optically detected mark lengths are required for the model to accurately replicate the subsequent marking response. A theoretical expression is derived that permits the estimation of media thermal diffusivity from the measured marking response.