Dynamic Phase Mask for Holographic Data Storage
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Solution Overview
Problem
Holographic data storage systems face challenges due to the design and performance of the signal-beam optical path, particularly the Fourier-plane DC bright-spot problem, which limits data recording and reconstruction fidelity and reduces the number of holograms that can be stored per unit media volume.
Innovation Solution
A spatial light modulator with an integrated phase mask that can change its phase pattern over time, allowing for varying phase modulation to reduce intensity peaks and achieve more even exposure of the recording media, thereby increasing data density and storage capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a fixed phase mask is used to reduce the DC bright spot, then the intensity peaks are reduced, but the number of holograms that can be stored per unit media volume is limited
Solution Approach 1:
The phase mask is made dynamically changeable over time, allowing it to adopt different phase patterns for different hologram recordings. This dynamic capability enables the system to overcome the limitations of fixed phase masks and store more holograms per unit volume by varying the phase modulation to optimize each recording.
Solution Approach 2:
The phase mask changes its optical phase parameters over time, transitioning between different phase patterns. This parameter change allows the system to reduce intensity peaks for each hologram while maintaining the ability to store multiple holograms by adjusting the phase characteristics between recordings.
2Reliability
If a fixed phase mask is used, then the media dynamic range demand is reduced, but the data density and storage capacity are limited
Solution Approach 1:
The dynamically changeable phase mask allows the system to optimize phase modulation for each hologram recording, reducing the demand on media dynamic range while enabling higher data density through multiple holograms per unit volume.
Solution Approach 2:
By changing the phase parameters of the mask over time, the system can achieve more efficient use of media dynamic range, allowing higher data density and storage capacity without compromising reliability.
3Productivity
If the phase mask pattern is changed over time, then more holograms can be recorded per unit volume, but the device complexity increases
Solution Approach 1:
The phase mask functionality is integrated with the spatial light modulator, combining multiple functions into a single device. This integration reduces overall system complexity while enabling dynamic phase pattern changes for increased hologram storage capacity.
Solution Approach 2:
The spatial light modulator is designed to perform both spatial modulation and phase mask functions, making it a multi-functional device. This universality eliminates the need for separate phase mask components, reducing device complexity while maintaining the ability to store multiple holograms.
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
The solution enables more efficient data storage by reducing the demand on media dynamic range and allowing for a greater number of holograms to be recorded per unit volume, improving data density and storage capacity while avoiding the limitations of fixed phase masks.
Implementation Method 1
a phase mask that can change its phase pattern over time, allowing for varying phase modulation
Implementation Method 2
The SLM converts input electronic data to a two-dimensional image of bright and dark pixels... Light modulated by the SLM passes through the optical system
Implementation Method 3
When the beams are coherent, coming for example from the same laser, standing waves in the beam's interference pattern create changes in the photosensitive material's index of refraction, thus forming a hologram
Implementation Method 4
standing waves in the beam's interference pattern create changes in the photosensitive material's index of refraction
Implementation Method 5
the hologram diffracts light from the reference beam to create a copy of the original information-bearing beam
Data Source
AI summary
A holographic data storage system that includes a write head that includes a pixellated spatial light modulator and a separate or integral phase mask that varies the phase depending on the location in the phase mask that light passes through. The phase variation can be changed over time in a random, pseudo-random, or predetermined fashion. The spatial light modulator and phase mask can be implemented in a liquid crystal SLM (nematic, ferroeleletric, or other), in a DMD SLM, in a magneto-optical SLM, or in any other suitable manner.