| CPC G02B 6/0053 (2013.01) [G02B 6/0051 (2013.01)] | 10 Claims |

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1. An optical film, comprising a light incident side and a light emitting side opposite to the light incident side, wherein a plurality of light incident microstructures are formed on the light incident side and dispersed on one plane, and each of the light incident microstructures is a tapered structure, wherein the extension direction of the optical film is defined as a first axis and a second axis perpendicular to the first axis, the cross-sectional shape of each of the light incident microstructure in the first axis is different from the cross-sectional shape in the second axis, and each of the light incident microstructures has a first optical surface and a second optical surface with the different slope and asymmetrical arrangement in the direction of the first axis as well as has a third optical surface and a fourth optical surface with the same slope and symmetrical arrangement in the direction of the second axis, thereby a brightness distribution emitted from the light emitting side of the optical film is non-symmetrical and deflects light to a specific direction with higher brightness as long as suppresses light to another different direction with lower brightness.
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