1. An optical film for use on a display device or a light source for photolithography, comprising a substrate on which an array of structures is formed, wherein a material having a different refractive index, absorbency or reflectivity from that of a surface of the structures is partially coated on the surface of the structures, and a period, selected from a distance from a trough to a next trough and a distance from a crest to a next crest, of the array of structures provides a change in brightness, image, or light strength according to the viewing angle or the direction in which light passes through, or for representing a three-dimensional image.