Hybrid gradient-interference hardcoatings

An article comprising:

• a substrate;
• and
• an optical coating disposed over at least a portion of the substrate, the optical coating comprising:
• a first major surface in contact with the substrate,
• a second major surface opposite the first major surface,
• a thickness in a direction normal to the second major surface,
• a first gradient portion,
• a high hardness portion, and
• a second gradient portion disposed between the high hardness portion and the substrate,
• wherein:
• a refractive index of the optical coating varies along a thickness of the optical coating between the first major surface and the second major surface;
• the difference between the maximum refractive index of the first gradient portion and the minimum refractive index of the first gradient portion is 0.1 or greater;
• the absolute value of the slope of the refractive index of the first gradient portion is 0.1/nm or less everywhere along the thickness of the first gradient portion;
• wherein the article exhibits:
• a single side photopic average light reflectance of 3% or less, measured at the second major surface, and
• a maximum hardness in the range from about 10 GPa to about 30 GPa, wherein maximum hardness is measured on the second major surface by indenting the second major surface with a Berkovich indenter to form an indent comprising an indentation depth of about 100 nm or more from the surface of the second major surface;
• wherein slope is measured along the thickness over a refractive index change of 0.04.