Efficient laser cleaning of small particulates using pulsed laser irradiation synchronized with liquid-film deposition

Pulsed laser heating of a surface is shown to be a promising new approach for effective cleaning of small particulate contaminations. Various versions of such a technique of laser cleaning is possible, depending on where the laser irradiation is absorbed and whether a thin film is deposited on the surface to enhance the cleaning. We have observed that laser cleaning with the highest efficiency can be achieved by choosing a laser wavelength (typically ultraviolet) that is strongly absorbed by the surface, and by pulse-depositing a water film of thickness on the order of microns on the surface momentarily before the pulse laser irradiation. This permits the effective removal of particles smaller than ≈ 20 μm, down to as small as 0.1 μm, from a solid surface, using a modest ultraviolet laser fluence of ≈ 0.1 J/cm2.