Laser cleaning is an efficient and environmentally-friendly non-contact method for removing paint and unwanted surface contamination from manmade structures to improve longevity, performance and appearance without the need for chemicals, water or abrasive mechanical tools. Owing to their power scaling advantages, pulsed fibre lasers and solid-state lasers based on ytterbium or neodymium have become the lasers of choice for laser cleaning and there are now a number of commercial products serving this market. However, these lasers suffer from the shortcoming that the maximum permissible exposure (MPE) limit before the onset of eye damage is relatively low and, as a consequence, laser cleaning operations are restricted to enclosed environments.

This project will investigate a new strategy for scaling fibre lasers to meet the needs for laser cleaning, but in a wavelength band (~1.55 -1.6 um) where the MPE limit is well over an order-of-magnitude higher than for ~1 um lasers. This will allow deployment in outdoor scenarios, without the need for an enclosure, allowing laser cleaning to be used in a much wider range of situations. If successful, this will revolutionise laser cleaning and open up the prospect of even more applications made possible due to the greatly relaxed safety considerations. In terms of laser performance, the goal will be to develop a laser power scaling technology that can deliver pulsed output with energy in the range ~10-100 mJ, duration <50 ns and average powers in the few hundred-watt to kilowatt regime, as required for the intended applications.