Laser removal of particulates from solid surfaces was achieved using an energy transfer medium which preferentially adsorbs in the capillary spaces under and around the particulates on the contaminated surface. Subsequent laser irradiation causes explosive evaporation of the energy transfer medium and propels the particles off the substrate much like a small rocket engine. In our experiments, a TEA CO2(10.6 and 9.6 mgr;m) laser was used to remove 9.5 mgr;m Al2O3, 5 mgr;m Al2O3, and 1 mgr;m polystyrene particles from Si surfaces using water as the energy transfer medium. At these wavelengths the laser energy is absorbed predominantly in the water not in the substrate. The threshold fluence for particle removal was found to follow a degenerate threshold model with measured thresholds significantly below the substrate damage threshold. The temperature rise in the energy transfer medium was estimated using energy conservation, suggesting that superheating of the adsorbed water is a reasonable mechanism for water assisted laser particle removal.
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