Security diffraction devices difficult to exactly duplicate

Details Security diffraction devices difficult to exactly duplicate Security diffraction devices difficult to exactly duplicate

1986-05-16

1989-05-23

Arnold, Bruce Y.

Printed matter

Maps

283 86, 283 91, 283904, 350 369, 35016219, G02B 518, G03H 120

Patent

active

048324450

ABSTRACT:
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.

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