| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hidden pattern which can efficiently prevent forgery and which is hardly discriminated by a visual means. <P>SOLUTION: The hidden pattern is provided by the optical diffraction pattern, in which the total region formed by a grating is divided into a plurality of discriminable partial regions. At least one region of the plurality of partial regions is composed of two patterns which cannot be discriminated. Each of the two patterns is composed of fine stripes arranged parallel each other. <P>COPYRIGHT: (C)2004,JPO</p> |
