Holographic storage medium

Abstract

The present invention relates to a holographic storage medium, and more specifically to a holographic storage medium with an improved servo architecture for precise positioning of a laser beam in radial, axial and tangential direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding the invention shall now be explained in more detail in the following description with reference to the figures. It is understood that the invention is not limited to this exemplary embodiment and that specified features can also expediently be combined and/or modified without departing from the scope of the present invention. In the figures:

FIG. 1 schematically depicts a holographic pickup used in a holographic storage system,

FIG. 2 depicts a holographic storage medium with shift-multiplexed holograms,

FIG. 3 shows a schematic cross sectional view of a digital versatile disk,

FIG. 4 shows a schematic 3-dimensional view of a holographic storage medium according to the invention,

FIG. 5 depicts three different types of servo tracks of a holographic storage medium,

FIG. 6 illustrates a top view of a first type of servo layer of a holographic storage medium,

FIG. 7 illustrates a top view of a second type of servo layer of a holographic storage medium, and

FIG. 8 illustrates a top view of a third type of servo layer of a holographic storage medium.

Claims

1. Holographic storage medium with a holographic layer for storing holograms and a servo layer with a track structure for positioning a light beam for reading and/or recording of a hologram relative to the holographic recording medium, wherein the track structure includes a pack of two or more tracks.

2. Holographic storage medium according to claim 1, wherein the pack of two or more tracks includes two or more grooves separated by lands or two or more lands separated by grooves.

3. Holographic storage medium according to claim 1, wherein the track structure includes spiral or concentric packs of tracks.

4. Holographic storage medium according to claim 1, wherein the pitch of the pack of tracks is adapted to the distance between adjacent holograms.

5. Holographic storage medium according to claim 1, wherein the packs of tracks are separated by mirror areas.

6. Holographic storage medium according to claim 1, wherein servo marks are located in a central track of the pack of tracks.

7. Holographic storage medium according to claim 1, wherein address information is located in a track of the pack of tracks.

8. Holographic storage medium according to claim 1, wherein address information is located in one or more outer tracks of the pack of tracks.

9. Holographic storage medium with a holographic layer for storing holograms and a servo layer with tracks for positioning a light beam for reading and/or recording of a hologram relative to the holographic recording medium, wherein the pitch of the tracks is adapted to the distance between adjacent holograms.

10. Holographic storage medium according to claim 9, wherein the servo layer is arranged above the holographic layer.