发明名称 |
Security diffraction devices difficult to exactly duplicate. |
摘要 |
<p>Holograms, including diffraction gratings, and methods of making them, that reconstruct an image which changes as the hologram is tilted with respect to the viewer and in a manner that images reconstructed from copies made of the hologram in monochromatic light do not have that motion. The hologram is a valuable security device for authenticating documents or objects to which it is attached since it is extremely difficult to duplicate.</p> |
申请公布号 |
EP0247471(A2) |
申请公布日期 |
1987.12.02 |
申请号 |
EP19870107146 |
申请日期 |
1987.05.18 |
申请人 |
AMERICAN BANK NOTE HOLOGRAPHICS, INC. |
发明人 |
HAINES, KENNETH A.;WELLER, ROBERT H. |
分类号 |
G02B5/32;G02B5/18;G02B27/42;G03H1/00;G03H1/04;G03H1/18;G06K19/16;G07D7/12;G07F7/08 |
主分类号 |
G02B5/32 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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