Laser surface cleaning is the removal of contaminants or impurities on the surface of a material by physically removing the upper layer of the substrate using laser irradiation.
An extremely brief laser pulse at high power is aimed at the surface to be cleaned. The laser energy applied ablates the surface. While part of the removed material is vaporised, some remains as particulate dust and may be collected in a filtration system. This process is repeated until the required depth and area has been reached.
There are two distinctly different laser cleaning processes. The first, coating removal, is characterised by the removal of a layer on the surface of a substrate. In this case, the chemical and physical composition of the layer to be removed differs significantly from that of the substrate. Examples include paint, rubber coatings and insulation. The laser light is absorbed by the organic material and the non-organic substrate is not affected. There is no mechanical, thermal or chemical strain on the substrate. The second cleaning process, laser surface decontamination, refers to the removal of impurities or contaminants deeply embedded within the surface of a material by physically removing the entire upper layer. Examples include the removal of radioactive concrete layers by laser 'scabbling'.
Laser surface cleaning is a non-contact/non-abrasive process that can replace the use of chemicals or abrasive cleaning. No chemicals are used and there is no secondary waste produced. The cleaning process can be conducted remotely by optical fibre beam delivery, and the laser head can be manipulated by robots, thus avoiding exposing workers to a potentially radioactive area. It also has advantages over other processes in terms of automation and safety.
Laser surface cleaning can be used for micro-scale or large-scale cleaning of a number of materials. Contaminants ranging from radioactive elements to paint or dust particles can be effectively removed using lasers. Potential applications range in size from large commercial aircraft to microchips. Typical applications include cleaning the contact areas of plugs and pads and removal of the insulation layer in cables for the electronics industry; surface cleaning of moulds in the rubber and tyre manufacturing industries; and large area stripping of paints from buildings, bridges, aircraft or ships where the use of chemical solvents is restricted.