Patent ID: 8335045

Claim:
An optical element for use in below 300 nm photolithography consisting of: a crystal optic having two faces and an edge surface formed by said faces, a base coating of a thermally deposited, plasma-modified AlF 3 deposited on at least portion of said edge surface; a base coating of thermally deposited AlF 3 on the faces of the optic; and one of a plurality of periods consisting of (1) a selected thermally co-deposited, n binary fluoride coating layer and (2) a thermally deposited, metal fluoride layer deposited on the faces base coating, the selected binary fluoride layer being the first deposited period layer and the selected metal fluoride layer being second deposited period layer; wherein: said fluoride coating materials are transmissive to UV curing radiation and transmit less than 5% of any below 300 nm radiation striking said selected coating materials, the co-deposited binary metal fluoride coating is an A/B coating where A is selected from the group consisting of MgF 2 and AlF 3 and B is a lanthanide series metal fluoride; and an UV-curable adhesive applied to at least part of said edge AlF 3 coating for mounting said optic into a holder.