A theoretical model for laser cleaning of microparticles in a thin liquid layer

A theoretical model for removal of tiny particles from solid surface by laser cleaning with a thin liquid layer is established by taking adhesion force and cleaning force into account. When pulsed laser irradiates on the solid surface coated with a thin liquid film, a sheet of liquid near the liquid/substrate interface can be superheated through thermal diffusion. The rapid growth of vapor bubbles inside the superheated liquid can generate transient stress wave with high pressure, large enough to expel micron and sub-micron particles from the contaminated surface. Through calculating adhesion force and cleaning force, the cleaning threshold of laser fluence can be predicted from this theoretical model and the difference between cleaning force and adhesion force increases with increasing of laser fluence, leading to higher cleaning efficiency.