Method and apparatus for reading and verifying holograms

Image analysis – Pattern recognition – Template matching

Reexamination Certificate

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Reexamination Certificate

active

06263104

ABSTRACT:

TECHNICAL FIELD
This invention relates to holography, and, more particularly, to a hologram reader/verifier.
BACKGROUND OF THE INVENTION
Prior art hologram readers have depended on the use of holograms having a special format or special characteristics. Examples of prior art hologram readers are illustrated in
FIGS. 1
a
and
1
b
. In the hologram reader of
FIG. 1
a
, a holographic bar code is illuminated by a laser beam
520
that is generated by a laser
525
. A pattern of spots
505
is then reconstructed onto a set of photodetectors
500
positioned specifically to detect spots at particular positions.
In the hologram reader of
FIG. 1
b
, a hologram
510
containing a non-focused image recording is illuminated by a laser beam
520
that is generated by a laser
525
. The laser beam
520
is incident at its reference (or conjugate reference) angle to reconstruct an image
555
onto a ground glass screen
550
, where it can be seen by a human observer
560
.
Another type of prior art hologram reader (not shown) does not actually read a hologram but instead compares a wavefront recorded in a hologram to a reference wavefront. Yet another type of prior art hologram reader (not shown) simply compares a single 2-D view of the hologram to a stored 2-D reference image.
U.S. Pat. No. 4,641,017 to Lopata, entitled Fraud Resistant Credit Card System
U.S. Pat. No. 5,331,443 to Stanisci, entitled Laser Engraved Verification Hologram And Associated Methods
U.S. Pat. No. 4,761,543 to Hayden et al., entitled, Holographic Security Devices And Systems
U.S. Pat. No. 4,108,367 to Hannan, entitled Token And Reader For Vending Machines
U.S. Pat. No. 5,712,731 to Drinkwater et al., entitled Security Device For Security Documents Such As Bank Notes And Credit Cards
U.S. Pat. No. 5,306,899 to Marom, et al., entitled Authentication System For An Item Having A Holographic Display Using A Holographic Record
U.S. Pat. No. 4,131,337 to Moraw, et al., entitled Comparison Reader For Holographic Identification Cards
U.S. Pat. No. 3,905,019 to Aoki, et al., entitled Pattern Recognizing Optical Apparatus
U.S. Pat. No. 5,666,417 to Liang, et al., entitled Fluorescence Authentication Reader With Coaxial Optics
U.S. Pat. No. 5,465,243 to Boardman, et al., entitled Optical Recorder And Reader Of Data On Light Sensitive Media
U.S. Pat. No. RE 035,117 to Rando, et al., entitled Scanner With Coupon Validation.
The prior art hologram readers described above and in the above-listed patents are capable of reading holograms only if the holograms are specially adapted for the reader. There is therefore a need for a hologram reader that is capable of reading all kinds of holograms without the need for the holograms to be specially adapted for the reader and is capable of reading variable information from holograms.


REFERENCES:
patent: 4543660 (1985-09-01), Maeda
patent: 4641017 (1987-02-01), Lopata
patent: 5339305 (1994-08-01), Curtis et al.
patent: 5756981 (1998-05-01), Roustaci et al.
patent: 5933823 (1999-08-01), Cullen et al.
patent: 0 549 990 A1 (1993-07-01), None
patent: 0 878 780 A2 (1998-11-01), None
patent: 07302338 (1995-11-01), None

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