IE85162B1 - System and method for multi-laser optical medium - Google Patents
System and method for multi-laser optical mediumInfo
- Publication number
- IE85162B1 IE85162B1 IE2008/0133A IE20080133A IE85162B1 IE 85162 B1 IE85162 B1 IE 85162B1 IE 2008/0133 A IE2008/0133 A IE 2008/0133A IE 20080133 A IE20080133 A IE 20080133A IE 85162 B1 IE85162 B1 IE 85162B1
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- IE
- Ireland
- Prior art keywords
- optical medium
- laser
- information
- enabling
- read
- Prior art date
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- 230000003287 optical Effects 0.000 title claims abstract description 87
- 238000002310 reflectometry Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 4
- 230000002708 enhancing Effects 0.000 claims 1
- 238000003860 storage Methods 0.000 abstract description 7
- 238000005286 illumination Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Abstract
ABSTRACT The present invention relates in general to the field of information handling system optical storage media, and more particularly to a system and method for multi- laser optical medium.
Description
System and Method for Multi—Laser Optical Medium
Dell Products LP
E85162
SYSTEM AND METHOD FOR MULTI-LASER OPTICAL MEDIUM
B GROUND INVENT ON
Field of the Invention
The present invention relates in general to the field of information handling
system optical storage media, and more particularly to a system and method for multi-
laser optical medium.
Descr_-lg‘ tion of g_l_I_e fielated Ag
As the value and use of information continues to increase, individuals and
businesses seek additional ways to process and store information. One option
available to users is information handling systems. An information handling system
generally processes, compiles, stores. and/or communicates information or data for
business. personal, or other purposes thereby allowing users to take advantage of the
value of the information. Because technology and information handling needs and
requirements vary between different users or applications, information handling
systems may also vary regarding what information is handled, how the information is
handled. how much information is processed, stored. or communicated, and how
quickly and efficiently the information may be processed, stored. or communicated
The variations in information handling systems allow for information handling
systems to be general or configured for a specific user or specific use such as financial
transaction processing; airline reservations, enterprise data storage, or global
communications. in addition. information handling systems may include a variety of
hardware and sofiware components that may be configured to process, store. and
communicate information and may include one or more computer systems. data
storage systems, and networking systems.
As information handling systems have grown more powerful over time,
demand has increased for media to store greater quantities of information. Optical
media have proven to be an effective portable storage media that is cost effective.
Initially, inflated lasers were used to read and write Compact Disc (CD) optical
media Eventually, in an efi‘ort to store more information in a medium of a given size
red lasers were developed to read and write Digital Versatile Discs (DVD) media.
Red lasers have a shorter wavelength than infrared lasers and thus interface with
smaller-sized marks on a medium, allowing greaternumbers of marks in a given area.
Currently, in an effort to store even greater amounts of information in a given-sized
medium, industry is developing blue laser based media. The ‘shorter wavelength of
the blue laser allows smaller-sized marks and more dense storage of information.
In order for a laser to read from an optical medium, the light from the laser is
focused to illuminate the area in the medium where information is stored as marks
having varying reflectivity. For CD media, the laser focuses through the thickness of
the disc of approximately 1.2mm to reach marks at the rear of the disc while DVD
media have the marks halfway through the thickness of the disc at approximately .6
mm. One proposal for blue laser media, known as the Blu-ray standard, places the
marks near the front surface of the disc so that the laser focuses at approximately .1
mm into the disc. For each type of laser, adjustments are made to account for the
cfiects of disc material on the focus point of the laser. Overall, the placement of the
blue laser marks near the front surface of the disc allows a greater density of marks
compared with placement of the marks as greater depths by having a smaller laser
focus point.
The Bluvray standard may include red laser readable discs (BD9 discs) as well
as blue laser readable discs (BDZS and BDSO discs). DVD density BD9 media may
have lower manufacturing costs by extending DVD technology to read discs with a
red laser. However, potential confusion may arise with users if optical drives are
labeled as Blu-ray compliant but include only a red laser for reading BD9 discs. Such
Blu-ray’ compliant drives would not be capable of interacting with blue laser media.
The Blu-ray standards body may have considerable difficulty enforcing a requirement
to include both blue and red lasers in optical drives.
SUMMARY OF THE ON
Therefore a need has arisen for a system and method which requires the use of
a first laser type on an optical medium having information stored for access by a
second laser type.
In accordance with the present invention, a system and method are provided
which substantially reduce the disadvantages and problems associated with previous
methods and systems for reading information from an optical medium. Content is
stored on first portion of an optical medium readable by a first laser. Enabling
information stored in a second portion of the optical medium is read by a second laser
and applied to read content information stored in the first portion of the optical
medium with the first laser. Enabling information readable by the second laser but
indistinguishable by the first laser ensures the inclusion of boar lasers in an optical
drive for the optical drive to be compatible with the optical medium.
More specifically, -upon insertion of an optical medium in an information
handling system optical drive, a read engine illuminates an enabling information
portion of the optical medium with a blue laser to read enabling information, such as
content protection information, optical disc type information or a key to access the
content information. The read engine applies the enabling information to enable the
reading of content information from a content portion of the optical medium with a
red laser. For instance, the blue laser reads information containing a required “key"
which unlocks or enables reading the content portion of the optical medium with the
red laser. Alternative! y, the blue laser reads content protection information needed to
decode content and applies the content protection information to decode information
read from the content portion of the optical medium with the red laser. The enabling
information is stored in a format readable by the blue laser but not distinguishable by
the red laser. For instance. the enabling information is stored at the front surface of
the optical medium or slightly into the depth of the optical medium. such as
approximately at the focus point of the blue laser, around 0.! mm into the thickness of
the medium. The red laser focus at the front surface is insufficiently precise to read
the enabling information. The content information is stored midway through the
thickness of the optical medium, around 0.6 mm into the thickness of the medium,
substantially at the focus point of the red laser, and thus is readable by the red laser.
The present invention provides a number of important technical advantages.
One example of an important technical advantage is that optical drives that support
blue laser standard operations using a red laser will include both the blue and red
lasers. Users are thus less likely to face confusion by the availability of blue laser
format optical drives that lack blue laser capability. Further, by storing enabling
information readable by a blue laser to establish red laser read parameters, the optical
disc is able to more quickly identify an optical disc type and set up to read content
from the optical disc. For instance, the blue laser initiates the read of enabling
information for both blue and red laser types of optical media rather than having to
step from blue to red laser reads of enabling information.
BRIEE QESQBIK [1913 OF THE DEAEILIGS
The present invention may be better understood, and its numerous objects,
features and advantages made apparent to those skilled in the art by referencing the
accompanying drawings. The use of the same reference number throughout the
several figures designates a like or similar element
Figure I depicts a block diagram of an information handling system having a
rnulti-laser optical medium; and
Figure 2 depicts a side cutaway view of a multi-laser optical medium.
DE [LED D ON
Support for both blue and red laser operations in an information handling
system optical drive is enforced by disposing enabling information readable only by a
blue laser on an optical medium having content readable only by a red laser. For
purposes of this disclosure. an information handling system may include any
instmmentality or aggregate of instmmentalities operable to compute, classify.
process. uansmit. receive, retrieve. originate. switch, store, display, manifest, detect.
record, reproduce. handle. or utilize any form of information. intelligence, or data for
business, scientific, control. or other purposes. For example, an information handling
system may be a personal computer, a network storage device, or any other suitable
device and may vary in size, shape, performance, functionality, and price. The
information handling system may include random access memory (RAM), one or
more processing resources such as a central processing unit (CPU). or hardware or
software control logic, ROM, and/or other types of nonvolatile memory. Additional
components of the information handling system may include one or more disk drives,
one or more network ports for communicating with external devices as well as various
input and output (I/0) devices, such as a keyboard, a ‘mouse, and a video display. The
information handling system may also include one or more buses operable to transmit
communications between the various hardware components. V
Referring now to Figure l, a block diagram depicts an information handling
system 10 having a multi-laser optical medium. Information handling system 10 has
processing components that process information, such as a CPU 12, RAM 14 and
hard disk drive 16. The processing components interface with an optical drive 18 to
communicate information for writing to an optical medium 20 and/or to receive
information read from optical medium 20. Optical drive 18 has a red laser 22 and a
blue laser 24. each operable to illuminate optical medium 20 to write information or
to read information by changes in the reflectivity of optical medium 20 as it moves
relative to the laser. A read engine 26 coordinates settings for lasers 22 and 24 to
illuminate and read information from optical medium disc 20, such as by reading disc
type information for optical medium 20 and selecting read parameters associated with
the disc type. An optional write engine 28 coordinates settings for lasers 22 and 24 to
illuminate optical medium 20 so as to alter the reflective qualities to record
information.
Upon initial insertion of optical medium 20 into optical drive 18 the optical
medium is spun about spindle 30 and blue laser 24 is positioned at the inner
circumference to read enabling information from an enabling information area. Read
engine,26 applies the enabling information to enable red laser 22 to read content from
a content area 34 of optical medium 20. For example. the enabling information is
content protection information needed to decode the content stored in content area 34.
such as is used to protect commercially sold DVD movies. Alternatively. the
enabling information is a “key” which unlocks or enables reading of the content
portion. As another example, the enabling information is optical medium type
identification information tint enables read engine 26 to configure laser 22 or 24 to
illuminate optical medium 20 and read the content. Identifying both red and blue
laser parameters readable by a blue laser reduces the time needed for read engine 26
to identify the optical medium type since both types of optical media are identified by
illumination of one type of laser. Enabling information is stored in enabling
information area 32 so as to be indistinguishable by red laser 20. Thus, a blue laser is
required to enable reading of content stored with a red laser fonnat.
Referring now to Figure 2, a side cutaway view of a multi-laser optical
medium depicts information stored to be readable by a red laser or a blue laser. One
technique to make enabling information readable by a blue laser but indistinguishable
to a red laser is to adjust the depth and size of enabling information marks 36 at the
media surface relative to focused blue laser illumination 38 and red laser illumination
40. Blue laser illumination 38 using Blu-ray Disc type optics focused at the surface of
optical medium 20 produces a spot less than 2 micrometers wide while red laser
illumination 40 using DVD-type optics focused at the surface of optical medium 20
will produce a spot approximately 5 micrometers wide. By placing enabling
information marks 36 at the surface of optical medium 20 and sizing marks 36 to
approximately the size used for CD marks (about 2 micrometers), blue laser
illumination 38 is able to distinguish individual marks on the surface of optical
medium 20 while red laser illumination cannot since it is unable to resolve the
individual marks. Content marks 42 formed in content information area 34 are
located at the focus point of red laser illumination 40, approximately 0.6 m depth in
the thickness of optical medium 20, and have standardized dimensions to allow
«reading of content by red laser 22. Since the enabling information is needed to read
the content, both a blue and red laser are needed to read the content.
Three different techniques may be used separately or in combination so that
enabling information is readable by a blue laser but indistinguishable by a red laser:
manipulation of the size and dimensions of the marks; the use of marks having
selected reflectivity; and the use of pits having a specific depth. The size. depth and
dimensions of enabling infonnation malts 36 are adjustable to make the enabling
information indistinguishable by the red laser using DVD optics but distinguishable
by the blue laser using Blu-ray optics at the surface of optical medium 20. For
instance, the spot size focused at a disc front surface of a red laser optimized for use at
a depth of 0.6 mm is approximately 5 micrometers so that marks sized under 2.5
micrometers are indistinguishable. For the blue laser, marks as small as 1.6
micrometers are distinguishable at a disc front surface. Thus, enabling information
mark dimensions of less than 2.5 micrometers but greater than 1.6 micrometers will
make the marks indistinguishable to a red laser but distinguishable by a blue laser. In
alternative embodiments, the enabling information marks may reside at varying
depths with the size varied accordingly to allow reading of the marks by a blue laser
but not by a red laser. Reflectivity is managed by manipulating the material that
makes the marks to reflect blue light but not red light. For instance, the marks are
inked on the surface of optical medium 20 with a color that reflects blue light but
absorbs red light Phase extinction can minimize the reflection of red light fiom the
enabling information marks 36. The marks arefonned as pits 44 having a depth
where red light reflects from the base of the pit 180 degrees out of phase with light
reflected from the top, causing extinction. This depth equal to one-quarter of the red
wavelength will not cause extinction for blue light. In fact, reflection will be close to
maximum for blue. Phase extinction generally occurs at a depth that is a factor of
one-half of the wavelength of the light. Enabling information marks 36 may have an
increased width to ensure their readability by the blue laser in the absence of tracking
information to align the blue laser.
Although the present invention has been described in detail, it should be
understood that various changes. substitutions and alterations can be made hereto
without departing from the scope of the invention as defined by the appended claims.
Claims (15)
1. An optical medium comprising: content information stored in a first portion of the optical medium, wherein the content is readable by a first laser; and enabling information stored in a second portion of the optical medium. wherein the enabling information is readable by a second laser and is applied to read the content information stored in the first portion of the optical medium. .
2. An optical medium of Claim 1, wherein the enabling information is not distinguishable by the first laser.
3. The optical medium of Claim 2. wherein the enabling information comprises one or more of content protection information associated with protection of the content information, identification of the optical medium type for setting laser read parameters, identification of the optical medium type for setting write parameters. and a key to read content stored in the data layer.
4. The optical medium of Claim 1. Clalrn 2 or Claim 3. wherein the first laser comprises a red laser and the second laser comprises a blue laser.
5. The optical medium of any one of the preceding claims. wherein the enabling information is stored using marks that have a width sufficient for reading by the second laser without tracking.
6. The optical medium of any of the preceding claims, wherein the enabling infonnation comprises marks inked on the outer surface of the optical medium. the ink having inhibited reflectivity of red light.
7. The optical medium of Claim 2, wherein the content information and the enabling information is stored by marks in the material of the optical 20 medium, the marks comprise pits having a depth. the enabling information pits having a depth of approximately one-half the wavelength of the first laser to enhance phase extinction of light reflected by the first laser from the enabling information pits.
8. The optical medium of Claim 7, wherein the enabling infomiation marks are at the surface of the optical medium.
9. The optical medium of any of the preceding claims. wherein the enabfing information is marked with a material having reduced reflectivity of tight from the first laser.
10. A read engine associated with an optical drive. the read engine comprising: means for illuminating a first portion of an optical medium with a blue laser to read enabling information; and means for applying the enabling infonnation to illuminate a second portion of the optical medium with a red laser to read content information.
11. The read engine of Claim 10. wherein the content information is inaccessible without the enabling information.
12. The read engine of Claim 10, wherein the enabling information comprises at least one of content protection infonnation need to decode the content information, optical medium disc type identification and, a key to access content information.
13. The read engine of Claim 12. arranged to select reading parameters associated with an identified disk type.
14. The read engine of any of Claims 10 to 13, arranged to focus the blue laser at a predetennined depth to read the enabling information, the enabling infonnation indistinguishable to the red laser at the predetermined depth.
15. The read engine of any of Claims 10 to 14, arranged so that the blue laser reads the enabling information without tracking infonnation.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
USUNITEDSTATESOFAMERICA09/05/20051 | |||
US11/124,747 US20060250912A1 (en) | 2005-05-09 | 2005-05-09 | System and method for multi-laser optical medium |
Publications (2)
Publication Number | Publication Date |
---|---|
IE20080133A1 IE20080133A1 (en) | 2008-04-02 |
IE85162B1 true IE85162B1 (en) | 2009-03-18 |
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