Three-dimensional effects in dry laser cleaning

Abstract

Dry laser cleaning has usually been analyzed within the framework of a one-dimensional (1D) model with homogeneous surface heating. This model gives a qualitative description of the process and is sufficient for understanding the main mechanisms. More detailed studies show that the 1D model disagrees with experiments by one to two orders of magnitude. A particle on the surface produces an inhomogeneous intensity distribution in its vicinity due to scattering and diffraction. For example, a small transparent particle can work as a lens, even in the near-field. Consequently, a non-stationary 3D distribution of the temperature and non-stationary 3D thermal deformations of the surface are produced. The 3D model developed here is qualitatively different from the 1D model (the latter does not permit the inward motion of the surface). In some region of parameter space, the 3D model predicts results close to those of experiment.