optical media storage-multimedia

1. Presentation
On
CD Write-Once
And
CD Magneto Capital
By
SUNIL KAFLE

2. Compact Disk Write Once
 Cross-section through disc in direction of spiral track
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3. Principle
 Pre-grooven track.
 Absorption layer between substrate and reflective layer.
 CD-WO can be played in CD-DA players.
 Irreversible change of the reflection characterisitics by :
Heating up the absorption layer
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4. Sessions
 CD player needs table of contents
 Serveral session each with :
1. lead in part
2. Data part
3. lead out part
 New sessions can be added
 Maximum 99 of sessions
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5. Disc layout with serveral session
 CD players before 1992 can only read first session.
 Regular CD-WO: only one session.
 Hybrid CD-WO: several sessions.
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6. Compact Disc Magneto Optical
 Write, read, erase, and rewrite data.
 High capacity (double-sided): about 650 M Byte.
 Data transfer rate: about 1.2 Mbit/s
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7. 19-Sep-17
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8. Principles of magneto optical technique:
 Write
• Heating up of blocks
• Apply about 10 x earth magnetic field
• Polarization of single elements
 Discard
• Use constant magnetic field
• Simultaneous heating up of block
 Read
• Polarization of light is influenced by magnetic characteristics
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9. CD-MO: Premastered and Rewriteable
 Optional premastered area
• Read-only
• Readable on any CD-player
• Using Red, Yellow and Green Book specifications
 Rewriteable area
• Use of different magneto-optical encoding techniques
➪ incompatible to other CDs
• Cannot be read by standard CD-players
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10. Compact Disc Technologies:
 Features of Compact Disc Technology
• Can be used for all kind of storage with large storage capacity.
• Wide application area.
• Base is CD-DA technology (except CD-MO).
• Sequential specification of the different CD technologies.
 Disadvantages
• Long average access time.
• Incompatibility of CD-MO.
 Future
• CD with enhanced storage space and data retrieval rate
• Smaller optical disc with similar capacity
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11. THANK
YOU
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