Patent ID: 8179944

Claim:
An shaped optical element having faces for the entry and exit of laser light and an edge defined by the faces, said element consisting of a substrate and a thin film deposited on at least a portion of the edge, said thin film consisting of at least one layer of at least one index matching material deposited on top of the substrate and a blocking layer material deposited on top of said at least one matching layer; wherein: the thin film consists of 1-7 layers of at least one index matching and a blocking layer, each of said index layers having a thickness in the range of 5 nm to 50 nm, and said blocking layer having a thickness in the range of 20 nm to 400 nm, and the index matching material consists of alternating index matching materials selected from the group consisting of Nb 2 O 5 , Al 2 O 3 , HfO 2 , SiO 2 , Y 2 O 3 , MgF 2 , LaF 3 , GdF 3 , AlF 3 , Ta 2 O 5 and TiO 2 , and mixtures thereof.