Simple description of how cd and dvd are recorded.

2. Definition of optical storage
Optical storage is a term from engineering
referring to the storage of data on an
optically readable medium. That sort of
mediums are:
DVD (Digital Versatile Others like:
CD (Compact disc) Disc or Digital Video Disc)

3. Optical disc drive (ODD)
An optical disc drive is a disc drive that
uses laser light or electromagnetic waves
near the light spectrum as part of the
process of reading or writing data to or
from optical discs.

4. Laser and optics
In an ODD there is an optical path,
placed in a pickup head consisting of
semiconductor laser, a lens for guiding
the beam, and photodiodes detecting
the light reflection from disc's surface.
Laser assembly in a CD burner:

5. How do we read data?
CDs store information in series of 0s and 1s.
These 1s and 0s are represented by millions of
tiny bumps and flat areas on the disc's
reflective surface.

6. How do we encode data?
A recorder encodes (or burns) data onto a
recordable CD-R, DVD-+R, or BD-R disc
(called a blank) by selectively heating
parts of an organic dye layer with a laser.
It changes the reflectivity of the dye by
making marks.

7. Types of media
1. Read Only Media (ROM)
2. Rewritable media - CD-RW, DVD-RW,
DVD+RW, DVD-RAM and BD-RE
3. Double-sided media
4. Double layer (DL) media

8. Rotational mechanism
The CD player spins the disc while
moving the laser assembly outward from
the middle. To keep the laser scanning
the data track at a constant speed, the
player must slow the disc as the
assembly moves outward.

9. Loading mechanisms
Tray-loading mechanism:
Slot-loading mechanism:
Top-loading mechanism:

10. Recording performance
Optical recorder drives are often marked
with three different speed ratings. In
these cases, the first speed is for write-
once (R) operations, second for re-write
(RW or RE) operations, and one for
read-only (ROM) operations.
The Z-CLV recording strategy:

11. Example:
For example a 12x/10x/32x CD drive is capable
of writing to CD-R discs at 12x speed (1.76
MB/s), write to CD-RW discs at 10x speed
(1.46 MB/s), and read from any CD discs at
32x speed (4.69 MB/s).

12. New technology
Blu-ray Disc (also known as Blu-ray or BD) is
an optical disc storage medium designed to
supersede the standard DVD format. Its
main uses are for storing high-definition
video, PlayStation 3 games, and other data,
with up to 25 GB per single layered.

13. Recorder Unique Identifier
Owing to pressure from the music
industry, as represented by the IFPI and
RIAA, Philips developed the Recorder
Identification Code (RID) to allow
media to be uniquely associated with
the recorder that has written it.
Example:
Security Identification Code - 12345678
Recorder Identification Code - 87654321 PHI (for Phillips)

14. Contents
1. Definition of optical storage
2. Optical disc drive (ODD)
3. Laser and optics
4. How do we read data?
5. How do we encode data?
6. Types of media
7. Rotational mechanism
8. Loading mechanisms
9. Recording performance
10. New technology
11. Recorder Unique Identifier

15. That was all!
Thank You for Your patience and attention.
Author of the presentation:
Georgi Mirchev 1b Group