Double facing double storage capacity

Abstract

A first holographic data storage device has a first set of holograms stored thereon. A second holographic data storage device has a second set of holograms stored thereon. An opaque layer is disposed between and attached to one side of the first and the second holographic data storage devices. In the case of double reflective diffractive recording, the opaque layer is not necessary.

1 . An apparatus for reading a double-sided diffractive holographic data storage device having first and second reflective holograms stored on first and second sides respectively, comprising: 
 a first multi-scanning device for directing a first read beam incident on the first side at a first predetermined angle; and    a first detecting device for detecting the first read beam reflected from the storage device.    
   
   
       2 . The apparatus according to  claim 1  further comprising a rotating unit for rotating the double-sided diffractive holographic data storage device into first and second positions.  
   
   
       3 . The apparatus according to  claim 2  wherein the rotating unit is in the first position when the read beam is incident upon the first side and the detecting device detects a first diffractive data output packets produced by reflective diffraction from the first side.  
   
   
       4 . The apparatus according to  claim 2  wherein the rotating unit is in the second position when the first read beam is incident upon the second side and the detecting device detects a second data packet output produced by reflective diffraction from the second side.  
   
   
       5 . The apparatus according to  claim 1  wherein the first and second reflective holograms are angularly multiplexed holograms.  
   
   
       6 . The apparatus according to  claim 1  wherein the double-sided device includes an organic material.  
   
   
       7 . The apparatus according to  claim 6  wherein the organic material is a polypeptide.  
   
   
       8 . The apparatus according to  claim 1  wherein the first read beam is coherent or incoherent.  
   
   
       9 . The apparatus according to  claim 8  further comprising: 
 a second multi-scanning device for directing a second read beam incident upon a second side of the diffractive device at a second predetermined angle; and    a second detecting device for detecting a second diffractive holographic image formed by the second reflectively diffractive read beam reflected from the second side.    
   
   
       10 . The apparatus according to  claim 9  wherein the first read beam is generated from a coherent or non-coherent light having a same wavelength as a recording light.  
   
   
       11 . The apparatus according to  claim 9  wherein the second read beam is coming from a laser or a portion of the first read beam is coming through a beam splitter.  
   
   
       12 . The apparatus according to  claim 9  wherein the dual layer located on double-faced plate is an angularly multiplexed hologram.  
   
   
       13 . The apparatus according to  claim 9  wherein the second read beam is coherent or incoherent.  
   
   
       14 . A method for reading a double-sided holographic data storage device having first and second reflective holograms stored on first and second sides respectively, comprising: 
 directing a first read beam incident on first side at a predetermined angle; and    detecting the first read beam reflectively diffracted from the storage device.    
   
   
       15 . The method according to  claim 14  further comprising rotating the double-sided diffractive holographic data storage device into first and second positions.  
   
   
       16 . The method according to  claim 15  wherein the rotating is in the first position when the first beam is incident on the first side and the detecting device detects a first output data packet produced by reflective diffraction from the first side.  
   
   
       17 . The method according to  claim 15  wherein the rotating unit is in the second position when the first beam is incident upon the second side and the detecting device detects a second holographic image reflectively diffracted from the second side of the holographic storage device.  
   
   
       18 . The method according to  claim 14  wherein the first and second reflective holograms are angularly multiplexed holograms.  
   
   
       19 . The method according to  claim 14  wherein the double-sided device includes an organic material.  
   
   
       20 . The method according to  claim 14  wherein the organic material is a polypeptide.  
   
   
       21 . The method according to  claim 14  wherein the first read beam is coherent or incoherent light beam.  
   
   
       22 . A method according  14  further comprising: 
 directing a second read beam incident upon a second side of the diffractive device at a second predetermined angle; and    detecting a second diffractive holographic image formed by the second reflectively diffractive read beam reflected from the second side.    
   
   
       23 . The method according to  claim 22  wherein the first read beam is generated from a coherent or non-coherent light having a same wavelength as a recording light.  
   
   
       24 . The method according to  claim 22  wherein the second read beam is coming from a laser or a portion of the first read beam is coming through a beam splitter.  
   
   
       25 . The apparatus according to  claim 22  wherein the dual layer located on double-faced plate is an angularly multiplexed hologram.