A comparative study of the effects of laser wavelength on laser removal ofchlorinated rubber

This paper compares the use of different lasers fur the removal of Chlorina ted Rubber (CR) coatings from concrete surfaces. The work involves the inve stigation of basic phenomena and reactions of CR to various laser wavelengt hs, including CO2 (10.6 mu m), diode (810 nm) and ArF excimer (193 nm) lase r radiation. Characteristics of beam absorption, residues and the thermal e ffects on the materials are analysed by optical microscopy. SEM and EDX. By calculating the thermal loading (gamma) of the materials for the different lasers it has been revealed that the diode and excimer laser removal proce sses have very similar thermal loading with a gamma value of 1.2, kJ/cm(3) for the excimer laser and 1.5 kJ/cm(3) for the diode laser. The similarity of the two arises from the fact that this thermal loading is of the same or der of magnitude as the dissociation energy of the primary bonds. The therm al loading for the CO2 laser process is around 100 J/cm(3), an order of mag nitude smaller than the other two systems (C) 1999 Elsevier Science B.V. Al l rights reserved.