Capped blocking coating for laser optics

A method, comprising:

• applying a protective coating for protecting an optically transmissive substrate from at least ultraviolet laser energy to a first surface of the optically transmissive substrate;
• applying an adhesion layer over a portion of a second surface of the optically transmissive substrate that is opposite the first surface, wherein the adhesion layer has a first thickness;
• applying a blocking coating over the adhesion layer, wherein the blocking coating has a second thickness that is between about 60 nanometers and about 280 nanometers;
• and
• applying a capping layer over the blocking coating, wherein the capping layer has a third thickness that is less than the second thickness of the blocking coating.

An apparatus, comprising:

• a substrate that is optically transmissive to ultraviolet light;
• a protective layer applied to a first surface of the substrate, wherein the protective layer is configured to protect the substrate from at least ultraviolet laser energy;
• a metallic adhesion layer applied to a subset of a second surface of the substrate that is opposite the first surface;
• an annular blocking layer applied over the metallic adhesion layer, wherein the annular blocking layer has a first thickness between about 60 nanometers and about 120 nanometers and is configured to block the ultraviolet light;
• and
• an annular silicate layer applied over the annular blocking layer, wherein the annular silicate layer has a second thickness between about 10 nanometers and about 20 nanometers.