Method and apparatus for copying holographic disks
AssigneeInternational Business Machines Corporation
InventorLeRoy D. Dickson
Life of this patent
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Abstract
A multi-faceted holographic disk can be copied in a one-step process by using a source disk, actually a sandwich of two thin film layers of photosensitive material. The first thin film layer is capable of producing multiple reference beams simultaneously. The second thin film layers is a "master" copy of the disk to be copied. Both layers are produced using known off-axis holographic techniques. A target disk, having an unexposed film of photosensitive material is located ajacent the second thin film layer. The source disk is illuminated with coherent light, preferably in the form of a conical beam with an apparent point of origin on an axis through the common centers of the source and target disks. Several optical elements capable of producing the conical beam are illustrated.
Claims9
Apparatus for replicating a multi-faceted holographic disk comprising:
- a source disk having a first layer of light-transmitting, developed photosensitive material capable of producing multiple, collimated reference beams simultaneously, and a second adjacent layer of light-transmitting developed photosensitive material, said second layer being the multi-faceted holographic disk to be replicated;
- a coherent light source positioned on a normal from the center of the source disk, said light source being capable of illuminating a predetermined portion of the first layer in said source disk with coherent light at a predetermined angle relative to the normal;
- and
- means for positioning a third layer of unexposed photosensitive material adjacent the second layer of the source disk.
A method of copying a multi-faceted holographic disk comprising the steps of:
- placing a source disk in a predetermined position on an axis extending along a normal through the center of the disk, said disk having a first layer of light transmitting material capable for producing multiple collimated reference beams simultaneously and a second, adjacent layer of light transmitting material, said second layer being the multi-faceted holographic disk to be copied;
- placing a third layer of unexposed photosensitive material adjacent the second layer of the copying disk;
- and
- illuminating a predetermined portion of the first layer of the source disk with a coherent light pattern having an annular cross section.
A method as defined in claim 10 including the further step of expanding the collimated, coherent beam before the beam impinges on the conical element.
Dependencies are inferred from the claim text.