Engineered fluoride-coated elements for laser systems

Abstract

The invention is directed to elements having fluoride coated surfaces having multiple layers of fluoride material coatings for use in laser systems, and in particular in laser systems operating at wavelength <200 nm. In a particular embodiment the invention is directed to highly reflective mirrors for use in wavelengths <200 nm laser systems. The invention describes the mirrors and a method of making them that utilizes a plurality of periods of fluoride coatings, each period comprising one layer a high refractive index fluoride material and one layer low refractive index fluoride material, and additionally at least one layer of an amorphous silica material. The silica material can be inserted between each period, inserted between a stack consisting of a plurality of periods, and, optionally, can also be applied as the final layer of the finished element to protect the element.

1 . A method for making a fluoride coated element suitable for use <200 nm laser systems, said method comprising the steps of:
 providing a substrate;   coating, using an energetic deposition technique, the substrate with one or a plurality of periods of fluoride coating materials using an energetic deposition technique, and   further coating, using an energetic deposition technique, with an amorphous SiO 2  material to thereby form a fluoride coated element suitable for use in <200 nm laser systems;   wherein coating the substrate with one or a plurality of periods of fluoride coating materials means coating such that each period comprises a layer of a high refractive index fluoride coating material and a layer of a low refractive index coating material.   
     
     
         2 . The method according to  claim 1 , wherein said method further comprises coating said substrate with a layer of an amorphous SiO 2  material prior to the application of the first period of fluoride coating materials. 
     
     
         3 . The method according to  claim 1 , wherein coating using an energetic deposition technique comprises coating using deposition techniques selected form the group consisting of plasma ion-assisted deposition, ion-assisted deposition and ion beam sputtering. 
     
     
         4 . The method according to  claim 1 , wherein the method further comprises coating said element with a final layer of an amorphous silica after the coating with a plurality of fluoride materials is completed. 
     
     
         5 . The method according to  claim 1 , wherein coating with said amorphous silica material means coating with a silica material selected from the group consisting of silica, F-doped SiO 2 , N-doped SiO 2  and Al 2 O 3 -doped SiO 2 .