Method for producing a security mark on an optical data carrier

摘要

A device for producing a security mark on an optical data carrier includes directing means for directing a first and a second light beam onto a hologram area of the optical data carrier, wherein the first and second light beams are coherent light beams. The directing means are adapted to direct the first light beam onto the hologram area along a first direction, and the second light beam onto the hologram area along a second direction. Tilting means are provided for tilting the second direction by a predefined tilt angle with respect to the first direction.

主权项

1. A method for generating a security mark on an optical data carrier, the method comprising the steps of:
directing a first and a second light beam onto a hologram area of the optical data carrier, wherein the first and second light beams are coherent light beams, the first light beam being directed onto the hologram area along a first direction and the second light beam being directed onto the hologram area along a second direction; tilting the second direction by a tilt angle with respect to the first direction, wherein an information bit is encoded by at least one of a sign and a value of the tilt angle; and generating the security mark by performing the steps of:
recording a first security hologram in the hologram area as an interference pattern obtained through interference of the first and the second light beam,shifting said first and second light beams in a third direction relative to the first and second direction,recording a further security hologram in the hologram area as said interference pattern obtained through interference of the first and the second light beam, said further security hologram being identical to said first security hologram, andrepeating said steps of shifting said first and second light beams and recording a further security hologram such that a line of overlapping identical security holograms is formed perpendicular to a scanning direction for reading the information stored in the hologram area,wherein said interference pattern is the same for all security holograms within the line of overlapping security holograms.