Excimer laser interaction with dielectric thin films

Utilizing thermal Mirage technique, UV laser damage resistivity studies on electron beam evaporeted LaF3/MgF2 and Al2O3/SiO2 reflecting multilayer stacks have been performed at lambda = 248 nm, tau = 20 ns. Investigating these stacks by changing the number of (H, L) pairs, different coating properties were shown to be responsible to UV single-shot laser damage. The high damage resistivity of the Al2O3/SiO2 multilayers is caused by low defect density, whereas the damage of LaF3/MgF2 stacks origins from defects which are incorporated in the layers during the deposition process.