13-12-2010, 10:57 PM
Holographic versatile disc
JUBIN MATHEW
S7-A
Overview
Introduction
Holography
HVD System
Conclusion
References
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Introduction
Optical Storage
Storage of data on an optically readable medium. Data is recorded by making marks in a pattern that can be read back with the aid of light.
Existing Optical Storage Media
CD
DVD
HD-DVD
BLU-RAY
Features
Holography
Process of storing information as optical interference pattern on a photo sensitive material.
Two coherent laser beams needed.
The beams intersect within the recording medium.
Interference pattern is stored as physical or chemical change.
Stored grating pattern diffracts incident light.
1. Two axis holography
2. Collinear holography
Two Axis Holography
Off-axially aligned coherent reference beam and information beam.
Recording Reconstruction
Disadvantages
Wavelength margin is very small (1nm).
Recording disc of transmission type.
Disc tilt margin ≈ 0°.
System is complex.
Collinear Holography
Co-axially aligned information beam and reference beam.
Information pattern in the centre surrounded by reference pattern.
Outer reference pattern is usually circular .
Recording Hologram
Read the Hologram
Read the Hologram
Advantages of Collinear Holography
Reference wavelength margin 3 times conventional holography .
Low coherent laser diode can be used.
Higher tilt margin.
Reflective disc.
HVD System
2-D page data patterns are recorded as volume holograms.
Uses 2 laser beams. 1. Green or Blue – Reading / writing 2. Red – Positioning / addressing
Laser diodes are flashed synchronously.
HVD Structure
Focusing And Tracking
Focus and Track Servo Mechanism
HVD Drive Optical Configuration
HVD Advantages
Higher storage capacity.
Selectable capacity recording format.
Good read / write performance.
Data security.
Present Status
HVD storage capacity : 100gb.
Structure similar to CD/DVD.
Data transfer rate : 125mbps.
Expensive
In The Future
Storage capacity : 3.9 TB
Data transfer rate: 1gb/s
Backward compatible drives.
Holographic Versatile Cards.
Conclusion
HVD is the next generation ultra high speed and ultra high density optical storage media.
Collinear holography solves practical issues of conventional holography.
System margins are wide enough to produce practical low cost HVD system.
References
Hideyoshi Horimai and Xiaodi Tan “Holographic Information Storage System :Today and Future.” IEEE Transactions on Magnetics Vol.43,No:2,Feb.2007.
Y. Kaneko “Holographic Versatile Disc System” Media-Tech Conference, October 11, 2006.
Gregory J. Steckman, Allen Pu, and Demetri Psaltis “Storage density of shift-multiplexed holographic memory” 10 July 2001 Vol. 40, No. 20 Applied Optics.
J.Ashly, H.Coufal, B.Marcus, H.Guenther, M.P Bernal, R.M Shelby and C.M Jefferson “Holographic Data Storage” IBM . Research and Development. Vol. 44 No. 3 May 2000.
