Theoretical description of dry laser cleaning

Dry laser cleaning (DLC) is considered as an escape from an adhesion potential under the forces induced by thermal expansion. Important temporal and spatial scales are: period of small oscillations To, and equilibrium deformation h(0). Possible cleaning regimes are discussed. With laser pulse duration tau < tau(0) (large particles) removal is due to elastic energy. With tau > tau(0) (small particles) cleaning proceeds in the inefficient inertial force regime. If the fronts of the laser pulse are steep enough, t(f) much less than tau(0), cleaning occurs when kinetic energy of the particle exceeds that of adhesion. Utilization of resonance effects by modulation of laser pulse or employing the train of pulses and influence of damping on these regimes are discussed. Effects of the near field focusing by dielectric spheres and decrease in cleaning threshold due to three-dimensional (3D) effects are analyzed and compared with the experimental results for SiO2 particles on Si surface. (C) 2002 Elsevier Science BX All rights reserved.