| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the problem that according to a conventional interference method, diffraction efficiency is low, it is difficult to increase the depth of ruggedness and deep ruggedness is hardly obtained in a copying stage even if a prototype of deep ruggedness can be obtained and to eliminate the conventional problem that the rugged surface of a hologram is hardly adhered closely to the rear side surface of a light transmitting type display element and a light reflective layer along the ruggedness of the surface of the hologram is hardly formed while the thickness is kept constant. SOLUTION: Ruggedness (=blaze) having a tooth-shaped sectional plane is formed on the rear side surface of a transparent plate having high refractive index in such a manner that d=λ/2n is satisfied, when the wavelength of standard light, the refractive index of light of the transparent plate and the depth of the ruggedness are defined as λ, n and d, respectively, or d=λ(N-1)/2nN is satisfied, when the sectional plane is formed as a ruggedness having the tooth-shape and steps having the number of steps of N. |
