Holographic Storage via Angle-Shift Multiplexing
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Solution Overview
Problem
Existing holographic storage methods using angle multiplexing face limitations in storage capacity due to cross-write noise and restricted angle variation, which hinder the increase of multiplex times, and shift multiplexing does not effectively address these issues.
Innovation Solution
The proposed method employs angle-shift multiplexing, where the incident angle of the reference light is in one-to-one correspondence with its position on the storage medium, combining angle and shift multiplexing techniques to improve storage capacity and stability by controlling the incident angle and wavelength of the reference light, and using a dual galvanometer mirror for precise illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If angle multiplex recording is used to increase storage capacity, then multiplex times can be increased, but cross-write noise accumulates and signal-to-noise ratio decreases
Solution Approach 1:
The patent combines angle multiplexing with shift multiplexing, adding a spatial dimension (shift distance) to the traditional angle multiplexing approach. By recording holograms at different positions (shifts) on the medium in addition to different angles, the system increases storage capacity while maintaining signal quality, as each hologram is recorded at a unique combination of angle and position rather than reusing the same spatial location.
2Quantity of substance
If angle multiplex recording is used to increase storage capacity, then multiplex times can be increased, but the variation range of incident angle is limited
Solution Approach 1:
The patent introduces shift distance as an additional controllable parameter alongside incident angle. By varying both the incident angle and the shift distance (position on medium), the system overcomes the limitation of limited angle variation range. The shift multiplexing component allows holograms to be recorded at different positions, effectively expanding the parameter space available for multiplexing beyond just angular variation.
3Quantity of substance
If incident angle is changed by 0.1 degree to record new hologram, then multiplexing can be achieved, but reproduction light intensity is greatly reduced
Solution Approach 1:
The patent segments the storage medium into multiple spatial locations and assigns different holograms to different segments through shift multiplexing. Instead of relying solely on small angular changes (0.1 degree) that cause intensity reduction, the system divides the storage space and records holograms at different positions, thereby maintaining reproduction light intensity while achieving multiplexing through spatial segmentation combined with angular diversity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances storage capacity and stability by preventing cross-write noise accumulation and allowing for a higher number of multiplexing, while correcting the Bragg condition caused by medium contraction and expansion, resulting in a large-capacity recording device with improved signal quality.
Implementation Method 1
the reference light and the signal light interfere with each other on a storage medium to form holographic image information
Implementation Method 2
the holographic image information is stored in a storage medium in the form of unit
Data Source
AI summary
The invention discloses a holographic multiplex recording method, which combines technical advantages of angle multiplexing and shift multiplexing, and improves capacity and stability of a system. A medium contracts and expands due to environmental temperature fluctuations, which causes broken Bragg condition. However, the angle multiplexing has the advantages that the broken Bragg condition caused by contraction and expansion of the medium can be corrected by controlling an incident angle of a reference beam and an emitting wavelength of a laser, and the problem of a weak reproduction signal caused by the environmental temperature fluctuations is solved. On the other hand, the advantages of shift multiplex recording are that cross-write noise is not accumulated and that a multiplexing number can be improved by using a cross-shift multiplex method. According to the present invention, a large-capacity recording device with high stability is realized by combining the two technologies.