Abstract: An optical element includes a plurality of optical surfaces. At least one of the plurality of optical surfaces includes a main surface extending in a longitudinal direction and a short-side direction, and a mark including a recess portion or a protrusion portion, the mark extending in the longitudinal direction of the main surface.

Abstract: A product includes a first concave portion and a second concave portion on a curved surface and a third concave portion on an opposite side of the second concave portion from the first concave portion. A first direction from a bottommost point of the first concave portion to a midpoint between the first and second opening ends of the first concave portion is different from a third direction from a bottommost point of the third concave portion to a midpoint between the first and second opening ends of the third concave portion. A second direction from a bottommost point of the second concave portion to a midpoint between the first and second opening ends of the second concave portion is a direction between the first and third directions. A reference line passing through the first and second opening ends of the third concave portion is orthogonal to the third direction.

Abstract: A product includes a first concave portion and a second concave portion on a curved surface and a third concave portion on an opposite side of the second concave portion from the first concave portion. A first direction from a bottommost point of the first concave portion to a midpoint between the first and second opening ends of the first concave portion is different from a third direction from a bottommost point of the third concave portion to a midpoint between the first and second opening ends of the third concave portion. A second direction from a bottommost point of the second concave portion to a midpoint between the first and second opening ends of the second concave portion is a direction between the first and third directions. A reference line passing through the first and second opening ends of the third concave portion is orthogonal to the third direction.

Abstract: A product includes a fine periodic structure having a plurality of projection portions extending parallel to each other in a first direction in each of a first region and a second region adjacent in the first direction on a surface of a substrate. The fine periodic structure formed in an inner portion of the first region and the fine periodic structure formed in an inner portion of the second region are substantially the same periodic structures. End portions of the plurality of projection portions formed in the first region and end portions of the plurality of projection portions formed in the second region are formed in a boundary portion between the first region and the second region.

Abstract: An optical member having a concentric diffraction surface facing the outside, wherein the projection having a inclined surface concentric to the diffraction surface having an angle of inclination ? smaller than the angle of inclination ? is provided outside the diffraction surface having the largest ?, so that an interference of a cutting tool is avoided, and simultaneously, deterioration of a surface roughness may be restrained.

Abstract: An optical member having a concentric diffraction surface facing the outside, wherein the projection having a inclined surface concentric to the diffraction surface having an angle of inclination ? smaller than the angle of inclination ? is provided outside the diffraction surface having the largest ?, so that an interference of a cutting tool is avoided, and simultaneously, deterioration of a surface roughness may be restrained.

Abstract: An optical member having a concentric diffraction surface facing the outside, wherein the projection having a inclined surface concentric to the diffraction surface having an angle of inclination ? smaller than the angle of inclination ? is provided outside the diffraction surface having the largest ?, so that an interference of a cutting tool is avoided, and simultaneously, deterioration of a surface roughness may be restrained.

Abstract: An optical member having a concentric diffraction surface facing the outside, wherein the projection having a inclined surface concentric to the diffraction surface having an angle of inclination ? smaller than the angle of inclination ? is provided outside the diffraction surface having the largest ?, so that an interference of a cutting tool is avoided, and simultaneously, deterioration of a surface roughness may be restrained.