Disk Holographic Storage Positioning via Guide Groove Markers
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Solution Overview
Problem
Existing disk-type holographic storage systems face challenges in achieving high storage density due to insufficient multiplexing number in spherical wave shift multiplex recording methods, which limits recording and reading speed, especially in directions perpendicular to the plane.
Innovation Solution
A positioning method and device that utilize circular and linear guide grooves with markers to accurately position the recording/reproducing beam, allowing for cross-shift multiplex recording by using a positioning beam to detect and correct position deviations, enabling faster and more efficient random recording and reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cross-shift multiplex recording is performed by rotating the medium, then storage density is improved, but recording/reading speed deteriorates due to lack of random access capability
Solution Approach 1:
The patent applies preliminary action by pre-positioning markers on circular guide grooves and using a positioning beam to detect these markers before actual data recording/reading. This preliminary positioning enables the system to quickly locate target positions on the rotating disk, eliminating the need to wait for rotational alignment and thus improving random access speed while maintaining high storage density through cross-shift multiplexing
2Device complexity
If spherical wave shift multiplex recording is used, then device complexity is reduced, but multiplexing number is insufficient limiting storage density
Solution Approach 1:
The patent applies dimensionality change by introducing a second degree of freedom through angular rotation of the disk medium. Instead of only shifting along a linear path, the system now performs shift multiplexing in both linear displacement and angular rotation dimensions. This cross-shift multiplexing approach records holograms at multiple angular positions, dramatically increasing the multiplexing number and storage density while maintaining relative simplicity of the optical system
3Measurement precision
If markers are detected for beam positioning, then positioning precision is improved, but system complexity increases due to additional positioning beam and detection mechanisms
Solution Approach 1:
The patent applies the intermediary principle by introducing markers as intermediate reference objects on the disk medium. These markers serve as mediators between the positioning beam and the actual data positions. The markers provide detectable reference points that enable precise beam positioning without requiring complex direct measurement systems. The positioning beam detects marker positions, and this information is used to calculate and achieve precise positioning for subsequent data recording/reading operations
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 method improves recording and reading speed by allowing precise beam positioning, enabling higher storage density and efficient multiplex recording/reproducing on a disk-type medium, even when the medium is rotated.
Implementation Method 1
firstly the recording/reproducing beam is preliminarily positioned with positioning-beam detection markers when recording/reproducing is performed
Implementation Method 2
a first optical system for recording/reproducing information and generating the recording/reproducing beam
Implementation Method 3
performing a second coverage shift multiplex recording by rotating the medium on a medium plane
Data Source
AI summary
According to a positioning method for a hologram in a disk-type holographic storage medium, a guide groove is formed in advance in the disk-type storage medium and is scribed with a positioning marker that includes index information, position information and crossing angle information. The positions of a positioning laser beam and a recording/reproducing laser beam are applied to the same medium position. When an optical head accesses a recording/reading position at a high speed, the shift multiplex recording/reading is performed starting from a marker position. A servo system controls the laser beams to move along the guide groove and ensures that a focused beam is focused on the medium. According to the method, the position and angular information can be quickly positioned in process of performing cross-shift multiplex recording/reading, the recording/reading speed of the system is improved, and random access is achieved.