Patent Number: 
Section: claims

1. A multilayer mirror comprising:a substrate;a multilayer coating on the substrate; anda capping layer on the multilayer coating, the capping layer comprisingan outermost layer comprising Nb2O5 or TiO2, anda multilayer structure positioned between the outermost layer and the multilayer coating, the multilayer structure comprising a plurality of bilayers, each of the bilayers comprising a spacer layer comprising a first material and an absorber layer comprising a second material different from the first material, one of the first material and the second material comprising ZrN. 2. The multilayer mirror as claimed in claim 1 wherein the other of the first material and the second material comprises B4C. 3. A multilayer mirror comprising:a substrate;a multilayer coating on the substrate; anda capping layer on the multilayer coating, the capping layer comprising:an outermost layer comprising Ta2O5 anda multilayer structure positioned between the outermost layer and the multilayer coating, the multilayer structure comprising a plurality of bilayers, each of said bilayers comprising a spacer layer comprising a spacer layer nitride material resistant to hydrogen diffusion and blistering and an absorber layer comprising an oxide material resistant to ion penetration. 4. A multilayer mirror comprising:a substrate;a multilayer coating on the substrate; anda capping layer on the multilayer coating, the capping layer comprisingan outermost layer comprising ZrN, anda multilayer structure positioned between the outermost layer and the multilayer coating, the multilayer structure comprising a plurality of bilayers, each of the bilayers comprising a spacer layer comprising a first material and an absorber layer comprising a second material different from the first material, at least one of the bilayers comprising ZrN. 5. A multilayer mirror comprising:a substrate;a multilayer coating on the substrate; anda capping layer on the multilayer coating, the capping layer comprisingan outermost layer comprising Nb2O5 or TiO2, anda multilayer structure positioned between the outermost layer and the multilayer coating, the multilayer structure comprising a plurality of bilayers, each of the bilayers comprising a spacer layer comprising a first material and an absorber layer comprising a second material different from the first material, one of the first material and the second material comprising ZrO2 and the other of the first material and the second material comprising ZrN.