Holographic Memory Using Single Laser Diode and Beam Steering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current holographic memory systems face limitations in storage density, transfer rate, and radiation resistance, failing to meet the high demands of applications such as NASA missions, which require non-volatile, high-density, and high-speed data storage with low power consumption and mass.
Innovation Solution
A multilevel hologram recording and readout system utilizing a digital micromirror device (DMD) spatial light modulator and high-speed beam steering with a photorefractive crystal, enabling increased storage density and transfer rate without significant increases in system volume, mass, or power consumption, by using a single laser diode for writing and reading multibit data and employing liquid crystal or MEMS mirrors for beam steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional optical storage methods (CDs, DVDs) are used, then data storage is achieved, but transfer rate and capacity are limited
Solution Approach 1:
The patent transitions from surface-level optical storage (2D) to volume-based holographic storage (3D). By recording holograms throughout the bulk of the photorefractive crystal and using angular multiplexing to store multiple holograms at different angles in the same volume, the system achieves terabyte-scale capacity while maintaining high transfer rates through parallel readout of multiple pages.
Solution Approach 2:
The patent divides the storage medium into multiple angularly-multiplexed holographic pages. Each page can be independently addressed and read out through beam steering, enabling parallel data access. This segmentation allows simultaneous retrieval of multiple data pages, dramatically increasing the effective transfer rate.
2Quantity of substance
If holographic memory is used to increase capacity, then storage density improves, but recording and reading speed is limited
Solution Approach 1:
The patent employs continuous-wave laser operation with rapid beam steering to achieve continuous data writing and reading. The photorefractive crystal's inherent fast response time combined with high-speed angular multiplexing allows uninterrupted data transfer at terabit rates, eliminating the speed limitations of sequential access methods.
Solution Approach 2:
The system uses dynamic beam steering with movable mirrors to rapidly change the angle of the reference beam, enabling fast switching between different holographic pages. This dynamic angular multiplexing allows the system to access any stored page in microseconds, achieving high-speed random access despite high storage density.
3Quantity of substance
If flash memory is used for non-volatile storage, then capacity increases, but endurance and radiation resistance deteriorate
Solution Approach 1:
The patent changes the fundamental storage mechanism from electronic charge trapping in flash memory to optical interference pattern recording in photorefractive crystals. This parameter change from electrical to optical storage provides inherent radiation hardness and unlimited write endurance, as the holographic gratings are formed by light-induced refractive index changes that are not degraded by repeated cycling or radiation exposure.
4Productivity
If beam steering with multiple lasers is used to increase transfer rate, then bandwidth improves, but system complexity and power consumption increase
Solution Approach 1:
The patent uses a single laser source that serves dual functions: writing holograms during recording mode and reading holograms during playback mode. The same laser beam is modulated and steered to access different stored pages, eliminating the need for separate write and read laser systems. This universal laser approach reduces component count, system complexity, and power consumption while maintaining high bandwidth through rapid angular multiplexing.
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 system achieves ultrahigh density (up to 256 terabytes) and ultrahigh bandwidth (Gigabits/sec) holographic memory, supporting massive data storage needs with improved radiation resistance and reduced power consumption, suitable for applications like NASA missions.
Implementation Method 1
holographic memory stores information beneath the surface of the recording medium and uses the volume of the recording medium for storage
Implementation Method 2
A multilevel hologram is stored in a photorefractive crystal
Implementation Method 3
employing liquid crystal or MEMS mirrors for beam steering
Implementation Method 4
utilizing a digital micromirror device (DMD) spatial light modulator
Implementation Method 5
high-speed beam steering with a photorefractive crystal
Implementation Method 6
employing liquid crystal or MEMS mirrors for beam steering
Implementation Method 7
A first imaging relay lens pair positioned between the multilevel spatial light modulator and the photorefractive crystal
Implementation Method 8
using a single laser diode for writing and reading multibit data
Implementation Method 9
A multilevel hologram is stored in a photorefractive crystal using a single laser diode
Data Source
AI summary
A holographic memory system and apparatus, and a method provide the ability to store multibit holograms in a photorefractive crystal. A single laser diode is configured to emit a collimated laser beam to both write a page of multibit data to and read the page of multibit data from the photorefractive crystal. A multilevel spatial light modulator (DMDSLM) is configured to encode the page of multibit data on an input beam split from the collimated laser beam. A first imaging relay lens pair is positioned between the multilevel spatial light modulator and the photorefractive crystal to image a multibit spatial light modulator image on a plane behind the photorefractive crystal. One or more mirrors are configured to steer a reference beam, split from the collimated laser beam, at high speed to the photorefractive crystal to read or write a page of the multi-bit data.