| 摘要 |
The invention provides a fabrication process for a computer-generated hologram (CGH) 1 wherein amplitude information and phase information are recorded on a given recording surface by means of computation by a computer. The computer-generated hologram (1) is characterized by having a first direction X and a second direction Y orthogonal to X, and parallax in the first direction X alone. The hologram has a fixed parallax in one direction and this may also be known as a rainbow hologram or as a Benton hologram. The hologram 1 comprises unit areas B: 1 - M, each one having a given width in the second direction Y. In each unit area B: 1 - M, there is a diffraction pattern with a spatial frequency Cm: 1 - T that varies in the second direction. The spatial frequency may vary gradually in the orthogonal direction. The object light source may be a one dimensional point light source or a two dimensional line light source. The primary field of use of the invention is in verification of authenticity, anti-counterfeit labelling or water marking. |
