Abstract
Laser removal of particles from solid surfaces was investigated both theoretically and experimentally. A cleaning model was established for laser-induced removal of particles from solid surfaces by taking van der Waals force, capillary force and cleaning force into account. Laser cleaning forces are induced by fast thermal expansion of particles and/or solid surfaces irradiated by laser for dry laser cleaning and by evaporating liquid film heated by laser irradiation for steam laser cleaning. It was found that cleaning efficiency depended on laser fluence, pulse number, wavelength, incident direction, and liquid properties. Cleaning thresholds can be obtained by comparing cleaning force and adhesion force. Near-field light focusing underneath microparticles due to the optical resonance effect plays a very important role in laser removal of particles from a solid surface. Due to laser-induced optical resonance in the particles on a surface, nanometer-scale damages can be created on a solid surface which have a dimension much smaller than the particle size or the incident laser wavelength. Calculation results are also presented by solving the electromagnetic boundary problem.