Method for generating microstructure on a film by a roller

A method of manufacturing a spherical microstructure mold module to be incorporated into a calendering roller for manufacturing a microstructure on a planar surface, comprising:

• a) determining a location of the microstructure on the planar surface by:
• i) calculating a first curvature on a cross-sectional planar surface for a first microstructure point of the spherical microstructure mold module;
• ii) calculating a second curvature of a spherical surface of the spherical microstructure mold module;
• u
• iii) measuring a radius of the spherical surface, the radius being from the center of the spherical surface to the first microstructure point;
• said location being derived from the first curvature, the second curvature, and the radius;
• wherein the first curvature is between a first line and a second line on the cross-sectional planar surface, the first curvature being a longitude of the first microstructure point on the spherical microstructure mold module;
• and
• b) manufacturing the spherical microstructure mold module, wherein the manufacturing is based on the determined location of the microstructure.