Mold for manufacturing optical element and production method for same, and optical element
A mold for manufacturing an optical element is provided with a base material, and a recessing and protruding layer formed on a surface of the base material. The recessing and protruding structure of the recessing and protruding layer having a plurality of areas continuously arranged in a positional relationship in which the central point of seven adjacent protrusions is an intersection point of diagonal lines of six vertices of a regular hexagon, and the areas, shapes, and crystal orientations of the plurality of areas are random.
1. A mold for manufacturing an optical element, comprising:
a base material; and
a recessing and protruding layer formed on a surface of the base material, having a recessing and protruding structure;
the recessing and protruding structure having a plurality of areas continuously arranged in a positional relationship in which a central point of seven adjacent protrusions is an intersection point of diagonal lines of six vertices of a regular hexagon, and when an atomic force microscope (AFM) image is obtained for a square region whose edge length is from 30 to 40 times a modal pitch P of the protrusions on the recessing and protruding structures, an ellipse of the maximum area circumscribed by a boundary line of one area is drawn, wherein the ellipse is represented by formula (α) below:
X 2 /a 2 +Y 2 /b 2 =1 (α)
and the mold fulfills requirements (i) to (iii) below:
(i) when the modal pitch P of the recessing and protruding structure is less than 500 nm, the standard deviation of πab in the above formula (α) (of a plurality of areas) within a 10 mm×10 mm AFM image measurement range is not less than 0.08 μm 2 , when the modal pitch P of the recessing and protruding structure is from not less than 500 nm to less than 1,000 nm, the standard deviation of πab in the above formula (α) (of a plurality of areas) within a 10 mm×10 mm AFM image measurement range is not less than 1.95 μm 2 , and when the modal pitch P of the recessing and protruding structure is not less than 1,000 nm, the standard deviation of πab in the above formula (α) (of a plurality of areas) within a 50 mm×50 mm AFM image measurement range is not less than 8.58 μm 2 ;
(ii) the standard deviation of the ratio of a to b (a/b) in the above formula (α) (of a plurality of areas) is not less than 0.1; and
(iii) when a straight line K 0 is drawn connecting the central points of any two adjacent protrusions in any area (I), and one area (II) adjacent to the area (I) is chosen, and six straight lines K 1 to K 6 are drawn connecting any protrusion in area (II) and the central points of six protrusions adjacent to that protrusion, when all of lines K 1 to K 6 are at an angle of not less than 3 degrees with respect to line K 0 , the crystal orientations of area (I) and area (ii) are different.
2. The mold for manufacturing an optical element according to claim 1 , wherein
the recessing and protruding layer is formed by a material containing at least one kind selected from the group consisting of (A1) and (B) to (D), wherein (A1) is a metal containing Si, Cr, Mo, W, Ta, Ti, or an alloy containing at least two of Si, Cr, Mo, W, Ta, Ni, and Ti, (B) is a metal oxide of at least one element selected from the group consisting of Si, Cr, Mo, W, Ta, Ni, and Ti, (C) is a metal nitride of at least one element selected from the group consisting of Si, Cr, Mo, W, Ta, Ni, and Ti, and (D) is a metal carbide of at least one element selected from the group consisting of Si, Cr, Mo, W, Ta, Ni, and Ti.
3. The mold for manufacturing an optical element according to claim 1 , wherein the surface of the base material is flat.
4. The mold for manufacturing an optical element according to claim 1 , wherein
the surface of the base material has one of a concave curved face and a convex curved face.