| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a diffraction grating recording medium which has higher anti-counterfeiting effect than conventional techniques and has higher reliability with respect to security. <P>SOLUTION: The diffraction grating recording medium is produced on the basis of data where a diffraction grating pattern including a first unit cell having a first optical diffraction structure and a second unit cell having a second optical diffraction structure and machine-read information having a first block and a second block are superposed one over the other. The diffraction grating recording medium includes: a first unit region which is produced in a portion where the first block and the first unit cell are superposed one over the other, and has the first optical diffraction structure; a second unit region which is produced in a portion where the first block and the second unit cell are superposed one over the other, and has a second optical diffraction structure; a first conversion unit region which is produced in a portion where the second block and the first unit cell are superposed one over the other, and has a third optical diffraction structure different from the first optical diffraction structure; and a second conversion unit region which is produced in a portion where the second block and the second unit cell are superposed one over the other, and has a fourth optical diffraction structure different from the second optical diffraction structure. <P>COPYRIGHT: (C)2012,JPO&INPIT |
