Patent ID: 7245406

Claim:
A method for copying an optical diffraction structure including the steps of: laminating an optical diffraction structure master-hologram having an object region to be copied having optical interference fringes in a concavo-convex form on a fusion layer formed on a base substrate, irradiating the optical diffraction structure master-hologram and the fusion layer which are laminated mutually with an energy beam in such a manner than an irradiation range is limited to a portion of the object region to be copied to fuse the fusion layer in the irradiation range by heat based on the energy beam, and transferring the interference fringes successively to the fusion layer by shifting the irradiation range in the object region to be copied, wherein the step for transferring comprises: a first transfer process of successively transferring the interference fringes to the fusion layer by shifting the irradiation range of the energy beam in a predetermined direction so as to draw scanning lines, and a second transfer process of successively transferring the interference fringes in a boundary part of each of the scanning lines drawn in the object region to be copied to the fusion layer by irradiating the boundary parts with the energy beam and shifting the irradiation range of the energy beam in such a manner of moving along the scanning lines.