| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a diffraction grating recording medium which has high forgery prevention properties and high reliability in terms of security. <P>SOLUTION: A diffraction grating recording medium 3 has a first recording section 31 including unit cells 11a, 12a, and 13a for observation image which have light diffracting structures, and a second recording section 32 including unit cells 2R, 2G, and 2B for hidden image which have light diffracting structures. The unit cells for observation image of the first recording section 31 have a grating pitch equal to or larger than a wavelength of visible light, and the unit cells for hidden image of the second recording section 32 has a grating pitch equal to or less than the wavelength of the visible light and include curved diffraction gratings. <P>COPYRIGHT: (C)2013,JPO&INPIT |
