Abstract: An optical element including, on a substrate, an anti-reflection layer on multiple small concave protrusions, which have a modal pitch less than or equal to a wavelength of light in an environment where the optical element is to be used, are formed; in which 80% or more of the concave protrusions include one or more steps, and satisfy the following conditions: 0.12d?ws?0.17d and 0.42h?zs?0.52h, in which d is a diameter of the concave protrusions, h is a depth of the concave protrusions, ws is a total width of the steps in any cut surface; and zs is an average depth of the steps.

Abstract: An optical element including, on a substrate, an anti-reflection layer on multiple small concave protrusions, which have a modal pitch less than or equal to a wavelength of light in an environment where the optical element is to be used, are formed; in which 80% or more of the concave protrusions include one or more steps, and satisfy the following conditions: 0.12d?ws?0.17d and 0.42h?zs?0.52h, in which d is a diameter of the concave protrusions, h is a depth of the concave protrusions, ws is a total width of the steps in any cut surface; and zs is an average depth of the steps.

Abstract: By improving sliding durability while ensuring a high SNR, an improvement in reliability and a further increase in recording density are to be achieved.

Abstract: A manufacturing method of a magnetic recording medium provided with a protective layer excellent in corrosion resistance, mechanical durability, adhesion with a lubrication layer, and floating stability of a head even if the film thickness is reduced is provided. This is a manufacturing method of a magnetic recording medium in which at least a magnetic layer, a carbon protective layer, and a lubrication layer are sequentially provided on a substrate, and said carbon protective layer is provided with a lower layer formed on the magnetic layer side and an upper layer formed on the lubrication layer side. The lower layer is formed by a chemical vapor deposition (CVD) method using hydrocarbon gas and then, the upper layer is formed by using mixed gas of hydrocarbon gas and nitrogen gas and then, treatment which nitridizes the surface of the upper layer is applied.

Abstract: By improving sliding durability while ensuring a high SNR, an improvement in reliability and a further increase in recording density are to be achieved.