LIMA in Damage Diagnostics

Abstract

LIMA (laser induced mass analysis) has been used as a damage testing facility incorporating damage detection and analysis of all ionic species generated by breakdown and plasma formation on a surface. The laser radiation is frequency quadrupled Nd-YAG at 266 nm, enabling studies in the UV near to the most important KrF emission. Preliminary qualitative results give an insight into damage mechanisms and coating weaknesses. Two prototype coatings, an A.R. and an H.R., have been studied above and below the 50% damage fluence. The state of coating cleanliness is immediately obvious and it is possible to conclude the sources of sub-threshold damage and the extent of coating disruption. The ready availability of this information should led to forthcoming improvements from coating manufacturers.