Holographic storage using shift multiplexing

A method of recording successive holograms in a recording medium, comprising:

• providing at least a fan of M amount of waves along at least a first axis with a separation angle between adjacent waves and directing said fan of M waves as a reference beam along a reference beam path onto said recording medium;
• successively modulating a wave with a succession of images to produce a succession of signal beams along a signal beam path lying at a propagation angle relative to said reference beam path so that said signal and reference beams intersect at a beam intersection lying within said medium, said beam intersection having a size corresponding to beam areas of said reference and signal beams;
• producing a succession of relative displacements a direction parallel to said first axis between said recording medium and said beam intersection of said signal and reference beam paths in synchronism with said succession of signal beams, each of said displacements being less than said size of said intersection whereby to record successive holograms partially overlapped along a direction of said displacements;
• and
• wherein said signal beam and said M amount of waves of said reference beam have a wavelength and each of said relative displacements is of a length at least approximately equal to ##EQU18## wherein .lambda. is the wavelength and .theta. is the separation angle.

A method of recording successive holograms in a recording medium, comprising:

• providing at least a fan of M amount of waves along at least a first axis with a separation angle between adjacent waves and directing said fan of M waves as a reference beam along reference beam path onto said recording medium;
• successively modulating a wave with a succession of images to produce a succession of signal beams along a signal beam path lying at a propagation angle relative to said reference beam path so that said signal and reference beams intersect at a beam intersection lying within said medium, said beam intersection having a size corresponding to beam areas of said reference and signal beams;
• producing a succession of relative displacements a direction parallel to said first axis between said recording medium and said beam intersection of said signal and reference beam paths in synchronism with said succession of signal beams, each of said displacements being less than said size of said intersection whereby to record successive holograms partially overlapped along a direction of said displacements;
• and
• further comprising temporarily halting said succession of signal beams after a predetermined number of said relative displacements have been produced and moving said recording medium and said beam intersection relative to one another until said beam intersection does not intersect the first one of said holograms recorded with said succession of relative displacements, and then resuming the producing of a succession of signal beams and the producing of a succession of relative displacements.

A method of recording successive holograms in a recording medium, comprising:

• providing at least a fan of M amount of waves along at least a first axis with a separation angle between adjacent waves and directing said fan of M waves as a reference beam along a reference beam path onto said recording medium;
• successively modulating a wave with a succession of images to produce a succession of signal beams along a signal beam path lying at a propagation angle relative to said reference beam path so that said signal and reference beams intersect at a beam intersection lying within said medium, said beam intersection having a size corresponding to beam areas of said reference and signal beams;
• producing a succession of relative displacements a direction parallel to said first axis between said recording medium and said beam intersection of said signal and reference beam paths in synchronism with said succession of signal beams, each of said displacements being less than said size of said intersection whereby to record successive holograms partially overlapped along a direction of said displacements;
• wherein said providing comprises providing a two-dimensional fan of waves, said fan of M waves being comprised within said two-dimensional fan of waves, said two dimensional array comprising M waves along said first axis and N waves along a second axis, said M waves of said first axis being separated by said separation angle and said N waves of said second axis being separated by an other separation angle, said method further comprising producing an other relative displacement between said recording media and said beam intersection in a direction parallel to said second axis, said other relative displacement being less than said size of said beam intersection;
• and
• wherein said signal beam and said M amount of waves of said reference beam have a wavelength, said signal beam has a bandwidth and said second axis and said signal beam path are approximately normal to one another and said other separation angle is approximately equal to
• .sqroot..lambda./L,
• wherein .lambda. is the wavelength and L is the thickness.

A method of recording successive holograms in a recording medium, comprising:

• providing at least a fan of M amount of waves along at least a first axis with a separation angle between adjacent waves and directing said fan of M waves as a reference beam along a reference beam path onto said recording medium;
• successively modulating a wave with a succession of images to produce a succession of signal beams along a signal beam path lying at a propagation angle relative to said reference beam path so that said signal and reference beams intersect at a beam intersection lying within said medium, said beam intersection having a size corresponding to beam areas of said reference and signal beams;
• producing a succession of relative displacements a direction parallel to said first axis between said recording medium and said beam intersection of said signal and reference beam paths in synchronism with said succession of signal beams, each of said displacements being less than said size of said intersection whereby to record successive holograms partially overlapped along a direction of said displacements;
• wherein said providing comprises providing a two-dimensional fan of waves, said fan of M waves being comprised within said two-dimensional fan of waves, said two dimensional array comprising M waves along said first axis and N waves along a second axis, said M waves of said first axis being separated by said separation angle and said N waves of said second axis being separated by an other separation angle, said method further comprising producing an other relative displacement between said recording media and said beam intersection in a direction parallel to said second axis, said other relative displacement being less than said size of said beam intersection;
• and
• wherein said signal beam and said M amount of waves of said reference beam have a wavelength and said other relative displacement is approximately equal to ##EQU21## wherein .lambda. is the wavelength and .theta.' is the other separation angle of the second axis.

A method of reconstructing at a detection plane successive holograms previously recorded in a recording medium by interfering a succession of signal beams with a reference beam including a fan of M amount of waves, said fan being parallel to the path of said signal beams and having a separation angle between adjacent waves of the fan, while successively displacing said medium relative to said signal and reference beams in a direction parallel to said first axis by a distance less than the intersection of said reference and signal beams in said recording medium in synchronism with said succession of signal beams, said method of reconstructing comprising:

• providing at least a fan of M amount of waves along at least a first axis corresponding to the direction of the reference beam with which said holograms were previously recorded with a separation angle between adjacent waves and directing said fan of M waves as a reference beam along a reference beam path onto said recording medium;
• producing a succession of relative displacements a direction parallel to said first axis between said recording medium and said beam intersection of said signal and reference beam paths in synchronism with said succession of signal beams, each of said displacements being equal to the distance of said displacements with which said holograms were previously recorded;
• detecting at said detection plane light diffracted from said reference beam by a succession of said previously recorded holograms;
• and
• wherein said first axis and said signal beam path are parallel and said signal beam and said M amount of waves of said reference beam have a wavelength, said recording medium has a thickness and said separation angle of said fan of M waves is at least approximately equal to ##EQU22## wherein .lambda. is the wavelength, L is the thickness, and .theta..sub.S is the propagation angle.

A method of reconstructing at a detection plane successive holograms previously recorded in a recording medium by interfering a succession of signal beams with a reference beam including a fan of M amount of waves, said fan being parallel to the path of said signal beams and having a separation angle between adjacent waves of the fan, while successively displacing said medium relative to said signal and reference beams in a direction parallel to said first axis by a distance less than the intersection of said reference and signal beams in said recording medium in synchronism with said succession of signal beams, said method of reconstructing comprising:

• providing at least a fan of M amount of waves along at least a first axis corresponding to the direction of the reference beam with which said holograms were previously recorded with a separation angle between adjacent waves and directing said fan of M waves as a reference beam along a reference beam path onto said recording medium;
• producing a succession of relative displacements a direction parallel to said first axis between said recording medium and said beam intersection of said signal and reference beam paths in synchronism with said succession of signal beams, each of said displacements being equal to the distance of said displacements with which said holograms were previously recorded;
• detecting at said detection plane light diffracted from said reference beam by a succession of said previously recorded holograms;
• and
• wherein said signal beam and said M amount of waves of said reference beam have a wavelength and each of said relative displacements is of a length at least approximately equal to ##EQU23## wherein .lambda. is the wavelength and .theta. is the separation angle.

A method of reconstructing at a detection plane successive holograms previously recorded in a recording medium by diffracting a succession of signal beams with a reference beam including a fan of M amount of waves, said fan being parallel to the path of said signal beams and having a separation angle between adjacent waves of the fan, while successively displacing said medium relative to said signal and reference beams in a direction parallel to said first axis by a distance less than the intersection of said reference and signal beams in said recording medium in synchronism with said succession of signal beams, said method of reconstructing comprising:

• providing at least a fan of M amount of waves along at least a first axis corresponding to the direction of the reference beam with which said holograms were previously recorded with a separation angle between adjacent waves and directing said fan of M waves as a reference beam along a reference beam path onto said recording medium;
• producing a succession of relative displacements a direction parallel to said first axis between said recording medium and said beam intersection of said signal and reference beam paths in synchronism with said succession of signal beams, each of said displacements being equal to the distance of said displacements with which said holograms were previously recorded;
• detecting at said detection plane light diffracted from said reference beam by a succession of said previously recorded holograms;
• and
• further comprising temporarily halting said succession of signal beams after a predetermined number of said relative displacements have been produced and moving said recording medium and said beam intersection relative to one another until said beam intersection does not intersect the first one of said holograms recorded with said succession of relative displacements, and then resuming the producing of a succession of signal beams and the producing of a succession of relative displacements.

A method of reconstructing at a detection plane successive holograms previously recorded in a recording medium by diffracting a succession of signal beams with a reference beam including a fan of M amount of waves, said fan being parallel to the path of said signal beams and having a separation angle between adjacent waves of the fan, while successively displacing said medium relative to said signal and reference beams in a direction parallel to said first axis by a distance less than the intersection of said reference and signal beams in said recording medium in synchronism with said succession of signal beams, said method of reconstructing comprising:

• providing at least a fan of M amount of waves along at least a first axis corresponding to the direction of the reference beam with which said holograms were previously recorded with a separation angle between adjacent waves and directing said fan of M waves as a reference beam along a reference beam path onto said recording medium;
• producing a succession of relative displacements a direction parallel to said first axis between said recording medium and said beam intersection of said signal and reference beam paths in synchronism with said succession of signal beams, each of said displacements being equal to the distance of said displacements with which said holograms were previously recorded;
• detecting at said detection plane light diffracted from said reference beam by a succession of said previously recorded holograms;
• wherein said providing comprises providing a two-dimensional fan of waves, said fan of M waves being comprised within said two-dimensional fan of waves, said two dimensional array comprising M waves along said first axis and N waves along a second axis, said M waves of said first axis being separated by said separation angle and said N waves of said second axis being separated by an other separation angle, said method further comprising producing an other relative displacement between said recording media and said beam intersection in a direction parallel to said second axis, said other relative displacement being less than said size of said beam intersection;
• and
• wherein said signal beam and said M amount of waves of said reference beam have a wavelength, said signal beam has a bandwidth and said second axis and said signal beam path are approximately normal to one another and said other separation angle is approximately equal to
• .sqroot..lambda./L,
• wherein .lambda. is the wavelength and L is the thickness.

A method of reconstructing at a detection plane successive holograms previously recorded in a recording medium by diffracting a succession of signal beams with a reference beam including a fan of M amount of waves, said fan being parallel to the path of said signal beams and having a separation angle between adjacent waves of the fan, while successively displacing said medium relative to said signal and reference beams in a direction parallel to said first axis by a distance less than the intersection of said reference and signal beams in said recording medium in synchronism with said succession of signal beams, said method of reconstructing comprising:

• providing at least a fan of M amount of waves along at least a first axis corresponding to the direction of the reference beam with which said holograms were previously recorded with a separation angle between adjacent waves and directing said fan of M waves as a reference beam along a reference beam path onto said recording medium;
• producing a succession of relative displacements a direction parallel to said first axis between said recording medium and said beam intersection of said signal and reference beam paths in synchronism with said succession of signal beams, each of said displacements being equal to the distance of said displacements with which said holograms were previously recorded;
• detecting at said detection plane light diffracted from said reference beam by a succession of said previously recorded holograms;
• wherein said providing comprises providing a two-dimensional fan of waves, said fan of M waves being comprised within said two-dimensional fan of waves, said two dimensional array comprising M waves along said first axis and N waves along a second axis, said M waves of said first axis being separated by said separation angle and said N waves of said second axis being separated by an other separation angle, said method further comprising producing an other relative displacement between said recording media and said beam intersection in a direction parallel to said second axis, said other relative displacement being less than said size of said beam intersection;
• and
• wherein said signal beam and said M amount of waves of said reference beam have a wavelength and said other relative displacement is approximately ##EQU26## wherein .lambda. is the wavelength and .theta.' is the other separation angle of the second axis.