Patent Number: 6,252,685

Title: Optical recording medium and apparatus of judging fake thereof

Abstract: A phase watermark hologram "W" is composed of a blaze having binary phase difference of 2.pi..times.n, where "n" is a natural number of more than 1. An watermark appears in response to phase difference, which changes by a faked blaze. A phase watermark hologram "W" and a phase hologram "D" indicating data are formed on a same surface of a substrate mixed in arbitrary locations and arbitrary ratio of both holograms.

Inventors: Yokochi; Yoshinari (Tokyo, JP)

Assignee: Victor Company of Japan, Ltd.

International Classification: G06K 9/74 (20060101); G03H 1/26 (20060101); G06K 9/76 (20060101); G11B 7/24 (20060101); G11B 23/28 (20060101); G03H 001/00 (); G03H 001/30 (); B42D 015/00 (); G06K 009/76 (); G01B 009/021 ()

Expiration Date: 06/26/2018