Pit formation during laser marking of thin organic films

The governing equations for the transitional fluid motion and pit contour induced by the laser marking and the thermocapillary are derived. The rate of thickness change is controlled by two factors: the surface tension force and the gravitation force; the former is much more important than the latter. The temperature rise in a thin optical layer is calculated based on the Poynting vector theorem. Calculated results indicate that the temperature profile follows a Gaussian distribution, and is in agreement with previous reports. Mathematical modeling shows that the rate of pit formation is strongly related to the surface tension, melt viscosity, layer thickness, and optical properties of the recording layer. The effects of the marking conditions, substrates, and convectional heat transfer on pit contour are also determined. In addition, the limitations of this model are discussed in detail.