Optical sheet with structured surface

An optical sheet comprises;

• a substrate and a light-collecting layer having a structured surface formed with a plurality of optical three-dimensional patterns and including a curable resin,
• wherein the optical sheet has a damage resistance load of 20 g or more, the damage resistance load being measured in a way such that a polyethyleneterephthalate film including a coating layer containing particles with a surface roughness of 0.5˜15 μm and a hardness ranging from 2B to 2H is disposed on the structured surface of the optical sheet so that the coating layer of the polyethyleneterephthalate film is in contact with the structured surface of the optical sheet, the optical sheet is pulled at a rate of 300 mm/min while applying a varying load to the polyethyleneterephthalate film, and a maximum value of the varying load is defined as the damage resistance load when the structured surface of the optical sheet has no substantial damage, wherein the ‘no substantial damage’ means that no scratches occur upon observation with naked eyes and neither cracks nor height changes of the three-dimensional patterns occur upon observation using a scanning electron microscope in which a magnification falls in a range of from ×50 to ×500.