High-damage-threshold fluoride UV mirrors made by ion-beam sputtering

The demonstration of the technical feasibility of very high damage threshold mirrors deposited by an ion beam sputtering process is made. The two chosen materials are Yttrium fluoride for the high index and Lithium fluoride for the low index. The threshold of these two materials at 355nm 3ns is higher than 20J/cm2. High reflection stacks have been deposited with a reflection level of 98.5 percent and a threshold which meets the laser megajoule requirements.