| 摘要 |
PURPOSE:To permit formation of a large-diameter FZP by dividing diffraction rings to plural groups successively from the inner side and setting the positions of two light sources at the time of exposing in such a manner that the ring radii applying prescribed condensing characteristics at the use wavelengths of the representative diffraction rings and the radii of the interference ring is of the same sequence from the center at the time of exposing coincide with each other for each of the respective groups. CONSTITUTION:The Fresnel zone plate (FZP) patterns are divided to the diffraction ring groups on the inside L1, middle side L2, outside L3, etc. The representative rings are respectively selected with the respective groups. The ring radii are calculated from the conditions for using the FZP and the positions of the two light sources which give the same diffraction ring radii as the radii calculated with the diffraction rings of the same number at the time of exposing are counted back and determined. The interference pattern at the time of exposing and the diffraction ring pattern required at the time of use can be made identical with each other respectively at sufficient approximations for each of the respective groups, so that the FZP corrected in aberration is obtd. Since the aberrations are thereby removed in the prepn. of the FZP by a holographic exposing method, the formation of the larger-diameter FZP is permitted. |
