Patent ID: 7674031

Claim:
An optical film, comprising: an entrance surface, for receiving an incident light where it is refracted inside the optical film to form a refracted optical field; and an exit surface, having a plurality of microstructures formed thereon, each microstructure being configured with a first curved surface and a second curved surface, for collecting the refracted optical field to a frontal and normalized view angle of the exit surface where it is emitted; wherein, the incident light is composed of a first sub-field and a second sub-field while enabling a specific included angle, ranged between −50 degrees to −80 degrees, to be formed between the normal of the energy peak of the first sub-field and the normal of the entrance surface, and another specific included angle, ranged between 50 degree and 80 degree, to be formed between the normal of the energy peak of the second sub-field and the normal of the entrance surface.