Cylindrical master mold assembly for casting cylindrical masks

A method for forming a cylindrical mask configured to have one or more features formed on a surface with a cylindrical master mold assembly, wherein the master mold assembly comprises a cylindrical patterned component having a first radius and a sacrificial casting component having a second radius, wherein the second radius is different from the first radius, wherein a surface of the patterned component facing the sacrificial casting component has one or more patterned features, the method comprising:

• a) co-axially inserting the component with the smaller radius into the component with the larger radius;
• b) filling a space between the cylindrical patterned component and the sacrificial casting component with a liquid precursor;
• c) curing the liquid precursor to form the elastomeric material;
• and
• d) removing the sacrificial casting component.

A cylindrical mask comprising:

• a cylindrical elastomer component with an inner radius, the elastomer component having a major surface with a nanopattern formed in the major surface;
• and
• a rigid transparent cylindrical component having an outer radius, wherein the outer radius is sized to fit within the cylindrical elastomer component;
• a gas retainer configured to retain a volume of gas between an inner surface of the elastomer component and an outer surface of the rigid transparent cylindrical component.