In people with keratoconus, rigid contact lenses improve vision by means of tear fluid filling the gap between the irregular corneal surface and the smooth regular inner surface of the lens, thereby creating the effect of a smoother cornea.
Rockwell Hardness Testing Hardness is a characteristic of a material, not a fundamental physical property. It is defined as the resistance to indentation, and it is determined by measuring the permanent depth of the indentation.lick here to learn more about hardness testing basics. The Rockwell hardness test method, as defined in ASTM E-18, is the most commonly used hardness test method.
Microhardness testing is an indentation method for measuring the hardness of a material on a microscopic scale. A precision diamond indenter is impressed into the material at loads from 15 to 1000 gf. The impression length, measured microscopically, and the test load are used to calculate a hardness value.