Temperature distribution in multilayers covered by liquid layer and processed by focused laser beam

As the experimental determination of surface temperatures on micrometer scale can only be carried out in very special cases, the estimation of spatial temperature distributions requires numerical model calculations. In the present contribution experimental results obtained by scanning a focused beam of an Ar-ion laser over a tungsten covered glass slide immersed in water, are compared with the results of temperature calculations. The steady-state temperature distribution is calculated by solving numerically the three-dimensional heat diffusion equation using the second-order finite difference method. During the discretization procedure the upwind scheme is applied to ensure the stability of the equation system at scanning speeds as high as few tens of meter per second. The temperature dependence of the thermophysical properties of the materials is explicitly included. The effects of processing parameters, in particular laser power, focus diameter and scanning speed, are described and found to be consistent with the experimental results.