3D effects in dry laser cleaning

Abstract

For 10 previous years dry laser cleaning has been analyzed in the frame of 1D model with homogeneous surface heating. This model gave qualitative description of the process and was sufficient for initial studies. Nevertheless further examinations show that 1D model is in one-two order magnitudes discrepancy with experiment. The problem is that the particle on the surface produces non-homogeneous distribution of laser intensity. For example, a small transparent particle can work as a near-field lens. This produces nonstationary 3D distribution of temperature and nonstationary 3D thermal deformations of the surface. 3D model is qualitatively different from the 1D model (the latest does not permit the inward motion of the surface). In some region of parameters 3D model predicts a result close to the experimental one (for small particles, typically smaller 1 μm). With higher particle size intensity under the surface becomes so strong that the particle is removed by the flux of evaporated material.