SLIDE 1
Optical Recording Technology
MAE 268
- Prof. Frank E. Talke
2
Optical Recording Technology MAE 268 Prof. Frank E. Talke June - - PowerPoint PPT Presentation
Optical Recording Technology MAE 268 Prof. Frank E. Talke June - - PowerPoint PPT Presentation
Optical Recording Technology MAE 268 Prof. Frank E. Talke June 2008 Outline Introduction Basics of optical recording Evolution of optical recording systems Holographic Atomic level Conclusion 2 Storage Pyramide 4
SLIDE 2
SLIDE 3
Storage Pyramide
SLIDE 4
4
SLIDE 5
5
Optical Recording
Data is stored on a reflective surface
so it can be read by a beam of laser light.
David Paul Gregg developed an
analog optical disk for recording video and patented it in 1961 and 1969 (U.S. patent 3,430,966).
It encompasses systems such as CD,
DVD and Blu-ray Disc
SLIDE 6
6
Optical Recording
- The historical advantage of optical over magnetic
technology was the potential recording density
– Red laser -- spot size ~0.4μ
diameter ~5 Gbits/inch2
- Many high end products - but never gave real
competition to magnetic products
– performance, cost – niche market for write-once applications
- magnetic disk has exceeded optical recording
densities
- BUT magnetic disks see competition from
low-end mass market products: CD-R, DVD-R and DVD-RAM
SLIDE 7
7
Three types of optical storage
CD (Compact Disk) DVD (Digital Video Disk or Digital
Versatile Disk)
BD (Blu-ray Disk)
SLIDE 8
8
Evolution of optical recording systems
SLIDE 9
9
?
SLIDE 10
10
How Optical Storage Works
SLIDE 11
11
Optical Storage Devices
An optical disk is a high-capacity storage medium.
An optical drive uses reflected light to read data.
To store data, the disk's metal surface is covered with
tiny dents (pits) and flat spots (lands), which cause light to be reflected differently.
When an optical drive shines light into a pit, the light
cannot be reflected back. This represents a bit value of 0 (off). A land reflects light back to its source, representing a bit value of 1 (on).
SLIDE 12
12
Principle of Traditional Optical Storage
PDI C Laser track
disc
lens
track
pit
spiral
land
eye-pattern
010010110111011000 001101110001001110 101111001011011000
user data Signal Processing
SLIDE 13
13
Assembly of a CD player
SLIDE 14
14
Laser head
SLIDE 15
15
1
SLIDE 16
16
Structure diagram of an optical drive
SLIDE 17
17
SLIDE 18
18
SLIDE 19
19
Solid state laser pulsed and focused on spinning disk surface Laser produces momentarily raised temperature along a track Thermally driven reflectivity change
SLIDE 20
20
SLIDE 21
21
CD disk layout
graphic - SONY
SLIDE 22
22
SLIDE 23
23
Compact Disk (CD)
Storage capacity ranges from 650
MB to 700 MB
SLIDE 24
24
Optical Storage Devices – CD-ROM Speeds and Uses
- Early CD-ROM drives were called single speed,
and read data at a rate of 150 KBps. (Hard disks transfer data at rates of 5 – 15 MBps).
- CD-ROM drives now can transfer data at speeds
- f up to 7800 KBps. Data transfer speeds are
getting faster.
- CD-ROM is typically used to store software
- programs. CDs can store audio and video data,
as well as text and program instructions.
SLIDE 25
25
Optical Storage Devices
- A CD-Recordable (CD-R) drive lets you
record your own CDs, but data cannot be
- verwritten once it is recorded to the disk.
- A CD-Rewritable (CD-RW) drive lets you
record a CD, then write new data over the already recorded data.
- PhotoCD technology is used to store digital
photographs.
SLIDE 26
26
Digital Video Disk (DVD)
Storage capacity ranges from 4.7 GB
to 9.4 GB
SLIDE 27
27
Optical Storage Devices - DVD-ROM
- A variation of CD-ROM is called Digital Video
Disk Read-Only Memory (DVD-ROM), and is being used in place of CD-ROM in many newer PCs.
- Standard DVD disks store up to 4.7 GB of
data—enough to store an entire movie. Dual- layer DVD disks can store up to 9.4 GB.
- DVD disks can store so much data because both
sides of the disk are used, along with sophisticated data compression technologies.
SLIDE 28
28
Write Once – DVD-R
- Preformed polycarbonate substrate
– “wobbled groove” to guide and
clock laser
- Photo/heat sensitive dye layer
– cyanine
- Reflection layer
– gold
- Laser spot heats dye, changes its
structure which in turn deforms the substrate
- Read-out laser is absorbed/scattered
by the deformation
recording laser deformation
protective layer reflective layer cyanine dye substrate
SLIDE 29
29
DVD-R
laser system: – λ
= 640 nm; numerical aperture = 0.6; refractive index = 0.8
– spot diameter = 0.4 μ capacity of side : 4.7GB 1.3 MB/sec record & read speed
SLIDE 30
30
Erasable DVD-RAM
- phase change recording
layer - TeGeSb
- heated by laser spot
– high power write
fast melt-cool cycle leaves amorphous spot with low reflectivity
– lower power erase
slower melt-cool cycle leaves crystalline spot with high reflectivity
- read-out - low power laser
- land & groove recording
graphic - Balzers Process System s
phase change phase change recording layer recording layer
SLIDE 31
31
Blu-ray Disk (BD)
Storage capacity ranges from 20 GB
to 25 GB
SLIDE 32
32
λ = 650 nm NA = 0.6 4.7 GBytes λ = 405 nm NA = 0.85 22.5 GBytes 1.2 mm substrate 0.6 mm substrate 0.1 mm substrate
CD DVD BD
0.65 GByte 4.7 GByte 25 GByte
Generations of Optical Recording
SLIDE 33
33
SLIDE 34
34
SLIDE 35
35
SLIDE 36
36
SLIDE 37
37
holographic storage
SLIDE 38
38
holographic storage
graphic: Byte Magazine
SLIDE 39
39
Writing holographically
SLIDE 40
40
Reading holographically
SLIDE 41
SLIDE 42
SLIDE 43
SLIDE 44
SLIDE 45
45