Computer Science
Optical Storage
Optical storage refers to the storage of data on optical discs, such as CDs, DVDs, and Blu-ray discs. These discs use laser technology to read and write data, making them non-volatile and capable of storing large amounts of information. Optical storage is commonly used for archiving and distributing software, music, movies, and other digital content.
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eBook - PDFDigital Storage in Consumer Electronics
The Essential Guide
- Thomas M. Coughlin(Author)
- 2011(Publication Date)
- Newnes(Publisher)
www.newnespress.com CHAPTER 3 Fundamentals of Optical Storage 3.1 Optical Disc Technologies Optical discs serve a variety of uses in consumer and computer applications. They are the most widespread medium for physical content distribution (CDs for music and DVDs for video). They are used in computers for backup and archiving of content as well as file sharing. Optical discs are used to record television programs that a user Objectives in This Chapter • Go through the Optical Storage products now available on the market. • Understand the basic operation of optical drives and discs. • Teach the differences between CD, DVD, and blue laser Optical Storage systems and why the blue laser products can store more digital content. • Provide the quick overview of how data is organized on an optical disc. • Review the history of optical disc form factors. • Guide the user through the issues and expectations of optical disc reliability and longevity. • Learn about holographic recording technology and other advanced optical disc technologies. • Gain insight on what could drive the use of very large capacity optical disc technology. 54 Chapter 3 www.newnespress.com wants to see later. They also allow users to burn discs containing personal videos to share with friends and family. Optical Storage over the past 35 years has provided a multiplicity of storage solutions. The range spans the first analog video disc and 12-inch Write Once (WO) systems in the 1970s to today’s blue laser DVD drives and media. Optical Storage is designed for specific consumer applications (primarily, digital audio and video for Read Only (RO) and rewritable CD and DVD media). Strict media standards (specifications) permit specific applications to be implemented by means of signal processing, logical and applications level software, and packaging. For example, DVD-Video is a consumer electronics application of DVD-ROM (a computer storage technology), not a separate format.
- Suresh, Jange(Authors)
- 2021(Publication Date)
- Regency Publications(Publisher)
Chapter 6 CD-ROM Databases and Online Catalogues 6.1Information Storage Media Due to the enormous growth of information as a result of research and development, more and more data is needed to be stored and retrieved. This has resulted in development of various technologies to meet the information storage and retrieval. These storage technologies can be divided into Magnetic storage and Optical Storage. 6.1.1Magnetic Storage With magnetic storage, the computer stores data on disks and tapes by magnetizing selected particles of an oxide-based surface coating. The particles retain their magnetic orientation until that orientation is changed, thereby making disks and tape fairly permanent but modifiable storage media. Users can intentionally change or erase files stored on magnetic media. Data stored on magnetic media can also be unintentionally altered. Magnetic media can be disrupted by magnetic fields and gradually lose their magnetic charge and lose data. The reliable life span of data stored on magnetic media is about three years and recommend that users refresh data every two years by recopying it. It is important to realize that data stored on magnetic media is subject to device and media failures, which make the data unusable. Magnetic storage and retrieval systems include: flexible disk, hard disk, and tape. This ebook is exclusively for this university only. Cannot be resold/distributed. 6.1.2Optical Storage Optical media is the most preferred storing device in the flourishing information era for storing large amount of data which makes use of beams of laser light. Therefore, most common Optical Storage is read only memory (ROM) but some types of Optical Storage media allow user to read, write, erase, and modify files. Magneto optical drives merge magnetic and optical technologies. So users can read, write, erase, and modify files, as on a hard disk drive, but they offer very large storage capacity and reliable long-term storage.
eBook - ePubLaser Beam Scanning
Opto-Mechanical Devices, Systems, and Data Storage Optics
- Gerald F. Marshall(Author)
- 2017(Publication Date)
- Routledge(Publisher)
7 Optics for Data Storage Optical Disk Technology Paul KuttnerOptische Werke G. Rodenstock, Munich, Federal Republic of Germany1. PRINCIPLE OF OPTICAL DATA STORAGEDigital storage and retrieval of information on optical disks offer widespread applications in several versions, such as laser vision, compact disk, and data storage. The advantages of this technique are its high storage capacity, rapid access, and favorable manufacturing costs. The technique generally consists of burning small holes called pits in a thin film deposited on a rotating optical disk. Tellurium deposited on a carrier is an especially suitable material. Holes less than 1 μm in diameter can be burned into a layer 0.06 μm thick. This results in a storage density of about 108 bits/cm2 . Storage capacities of 5 x 1010 bits or even more are quite feasible.A laser is controlled by a light modulator and focused onto the film by a high-numerical-aperture objective lens. The holes are formed in the film with an illuminance of over 106 W/cm2 , which heats up the material, partly melts the metal, and opens the hole. The required illuminance is attained with lasers of 10-mW output. The irradiation time used for burning holes is typically 0.5 μsec. Thus the information is stored as a progressing sequence of pits arranged along a spiral in the optical disk.To read the stored information, the disk is rotated and an individual pit is illuminated by a laser beam focused onto the disk by a high-numerical-aperture objective lens. Means are provided for automatically focusing the objective lens relative to the disk and for radial tracking of the spiral-shaped information trace. The light source may be either a gas laser or a semiconductor laser, and therefore they have to be either expanded or collimated, respectively. Using semiconductor lasers, anamorphic imaging components are added to compensate for the elliptical cross section of the beam and cylindrical lenses to compensate, and thereby eliminate, the astigmatism.
eBook - ePubThe New Communications Technologies
Applications, Policy, and Impact
- Michael Mirabito, Barbara Morgenstern(Authors)
- 2004(Publication Date)
- Routledge(Publisher)
III
INFORMATION STORAGE
Passage contains an image
9 Information Storage: The Optical Disk and Holography
The optical disk emerged as an important information storage tool in the 1980s. A popular application is the compact disk (CD), a small, round disk that stores digital audio information in the form of microscopic pits. To retrieve this information, you place a CD in a player.1 A laser subsequently reads back or recovers the information.A laser’s light scans the CD, and its beam is reflected to different degrees, in terms of its strength, when it passes over the pits and unpitted areas called lands. A light-sensitive detector picks up the reflected light, an optical representation of the stored information. After processing, the final output for a CD is an analog signal.The CD and other optical disks are also constructed like sandwiches: These include the information layer with the code of pits and a reflective metallic layer. The latter enables the read or playback operation.OPTICAL DISK OVERVIEW
For our discussion, the growing optical disk family falls into two categories: nonrecordable and recordable media. CDs, conventional Compact Disk-Read Only Memory (CD-ROM) and Digital Versatile or Video disks (DVDs) are nonrecordable. Write Once, Read Many (WORM) and erasable systems, including members of the CDROM and DVD families, are recordable.Both categories of disks share some characteristics: 1. Information can be stored in the form of pits, or in erasable systems, through other techniques. This information is also digital, with the major exception of the videodisk.2. Optical disks are fairly rugged since the stored information is physically protected from fingerprints and scratches. The laser is also focused beneath a disk’s surface at the information layer, so dust and other minor surface obstructions may not adversely affect a playback.3. A disk is not subject to wear because the playback is conducted by a beam of light. The same disk can be played multiple times with no discernible loss of quality.
eBook - PDFMagnetic Information Storage Technology
A Volume in the ELECTROMAGNETISM Series
- Shan X. Wang, Alex M. Taratorin(Authors)
- 1999(Publication Date)
- Academic Press(Publisher)
For example, compact-disk-read only memory (CD-ROM) using light to read information is regarded as an optical recording device. Most optical recording systems employ disks 495 496 CHAPTER 17 Alternative Information Storage Technologies or tapes as storage media. Holographic recording belongs to optical re- cording, but the storage media are very different from optical disk re- cording in nature, so it will be treated separately in Section 17.2. Optical tape recording is very similar to optical disk recording except that the latter employs flexible tape media, so we will focus on optical disk recording hereafter. The principle of optical disk recording can be generally illustrated in Fig. 17.1. The light is focused by an objective lens to form the optical stylus, i.e., a tightly focused spot of light. Diffraction effects related to the wave- like nature of light limit the minimum size of the focused spot. The tightest possible focus is achieved using a coherent light source such as a laser. The smallest possible diameter is D -= 0.56~ (17.1) NA' where NA is the numerical aperture of the objective lens, and ,~ is the wave length of the laser. 17.1.1 CD-ROM The read-only optical disks, including audio compact disk (CD) and CD- ROM, were first introduced by Philips and Sony in 1980 and 1985, respec- tively. Digital information is replicated into these disks in factories and cannot be altered by users. CD-ROM is a direct extension of audio CD. The main difference between audio CD and CD-ROM is the formatting of their digital data: the former is formatted for audio applications while the latter is for computer applications. CD-ROM must have superior data reliability than audio CD. Nowadays a CD-ROM drive can play audio CDs with appropriate software, but not vice versa. FIGURE 17.1. Schematic of typical optical disk recording device.
eBook - PDF- Mool C. Gupta, John Ballato, Mool C. Gupta, John Ballato(Authors)
- 2018(Publication Date)
- CRC Press(Publisher)
15 Optical Data Storage Charles F. Brucker Terry W. McDaniel Mool C. Gupta 15.1 Introduction ...................................................................... 15 -1 15.2 Design and Modeling ........................................................ 15 -4 Optical Thin-Film Design † Thermal Design and Modeling † Optical Design and Modeling 15.3 Optical Storage Media .................................................... 15 -15 Compact Disk † Write-Once Ablative Media † Phase-Change Media † Magneto-Optical Media † Substrates † Optical Tape 15.4 Optical Storage Systems .................................................. 15 -27 Optical Heads † Data Encoding and Decoding † ISO Standards 15.5 Future Optical Storage .................................................... 15 -34 Heads and Systems † Media † Holographic Storage References ....................................................................................... 15 -43 15.1 Introduction Optical disk storage technology for data storage typically finds application as a computer, video, or audio peripheral device that competes with other storage devices over a full spectrum of attributes including entry cost, media cost, media removability, form factor, power consumption, data rate, data accessing, reliability, ruggedness, interface support, and standardization. Optical tape drives and optical card readers would have a similar list of attributes. Different subsets of these attributes claim priority for different applications.
eBook - PDFHandbook of Magneto-Optical Data Recording
Materials, Subsystems, Techniques
- Terry W. McDaniel, Randall Victora(Authors)
- 1995(Publication Date)
- William Andrew(Publisher)
Photo CD’s and CD- Recordable disks are WORM (write once, read many) disks, they allow a user to write the data once, then read it as many times as desired. Magneto- optical disks allow a customer to read, write, erase, and rewrite the same disk a nearly infinite number of times. They provide the same functionality as other forms of magnetic storage such as magnetic tape and magnetic hard disks. 1.3 Rotating Mass Memories Optical Readout of Information. Optical data storage in the context of this handbook will mean the storage of data on a rotating medium where the readout is done by optical means. The information may be written optically or by optically assisted techniques. In general, this means a beam of light is focused to a spot of radiant energy which interacts with a storage medium in the form of a rotating The data on the disk is generally organized into tracks. The information is stored serially along the track in a binary fashion and might represent video, audio, or computer data. It may be e n d e d via a variety of recording techniques. The interaction between the light and the medium can occur in a number of ways but must m d @ some detectable property of the light, that is, it’s amplitude, phase, or polarization. In almost all cases, the light is reflected from the media, reenters the focusing lens where it is directed to a set of photodetectors which convert the optical signals into electrical signals. These electronic signals are decoded to produce the information of interest. Readout from magneto-optical disks” 51 follows the above descrip- tion. For a magneto-optical disk, the storage medium is a thin magnetic film (or films) deposited onto a transparent substrate. Data is recorded in a binary form as submicron-sized magnetic domains arranged serially in tracks on the disk.
eBook - ePub- Jerry C. Whitaker(Author)
- 2018(Publication Date)
- CRC Press(Publisher)
25 Optical Storage Systems Praveen Asthana 25.1 Introduction 25.2 The Optical HeadThe Servosystem • Optical Recording and Read Channel • Phase-Change Recording25.3 Worm Technology 25.4 Magneto-Optic Technology 25.5 Compact Disk-Recordable (CD-R) Recording Modes of CD-R 25.6 Optical Disk SystemsDisks • Automated Optical Storage Systems • Applications of Optical Library Systems • Future Technology and Improvements in Optical Storage25.1 IntroductionRecordable optical disk drive technology provides a well-matched solution to the increasing demands for removable storage. An optical disk drive provides, in a sense, infinite storage capabilities: Extra storage space is easily acquired by using additional media cartridges (which are relatively inexpensive). Such cost effective storage capabilities are welcome in storage-intensive modern computer applications such as desktop publishing, computer aided design/computer aided manufacturing (CAD/CAM), or multimedia authoring.25.2 The Optical HeadThe purposes of the optical head are to transmit the laser beam to the optical disk, focus the laser beam to a diffraction limited spot, and to transmit readout signal information from the optical disk to the data and servo-detectors.The laser diode is a key component in Optical Storage, whether the recording technology is magneto-optic, ablative WORM, or phase change. Early generations of optical drives used infrared lasers emitting in the 780 nm or 830 nm wavelengths. Later generation of drives use red laser wavelengths emitting at around 690 nm. The lasers are typically rated to have a maximum continuous output power in the 40-mW range and are index guided to ensure good wavefront quality.In a laser diode, light is emitted from the facets
eBook - PDFHigh Density Data Storage: Principle, Technology, And Materials
Principle, Technology, and Materials
- Yanlin Song, Daoben Zhu(Authors)
- 2009(Publication Date)
- World Scientific(Publisher)
CHAPTER 2 OPTICAL DATA STORAGE FOR THE FUTURE Wenfang Yuan and Yanlin Song* Beijing National Laboratory for Molecular Sciences Key Laboratory of Organic Solids, Institute of Chemistry , Chinese Academy of Sciences, Beijing 100190, China *E-mail: [email protected] In past decades, optical data storage has undergone great developments, both technically and commercially. However, pushed by the urgent demands for a much higher storage density and a faster data process rate, we still need to put a great deal of effort into exploring new storage media and data process methods so as to overcome the current physical limits on optical data storage devices. So far, among various materials, photochromic compounds are regarded as the promising one, which can be manipulated in all photon modes and processed at the molecular scale with response times ultimately within nano- or pico-second levels. In the technical aspects, the main goals are to overcome the diffraction limit on 2D storage by near-field recording and to take advantage of volumetric storage by adding the third dimension. 1. Introduction Optical data storage, which appeared after magnetic information storage, is now blossoming. The advantages it provides, such as high storage capacity, removability, compatibility of the formats developed later with the drives already installed, as well as the low costs per Mbyte, have made optical data storage a dominator in multimedia content and software dis-tribution, and even a prime candidate for massive data warehouses. Eversince it was introduced into the market by Philips and Sony, the Optical Storage medium has undergone great developments in both the storage capacity and the recording method of the content. On one hand, the storage capacity has increased from the CD with 0.65 GB to the DVD 69
eBook - PDF- Guenther, Arthur H.(Authors)
- 2002(Publication Date)
Optical Storage, however, is dominated by interchangeable media and backward compatibility. This compatibility facilitates the introduction of each new generation of technology in the market, but forces a time-consuming standards process for each higher-density generation. Still, Optical Storage has substantial potential as a storage technology. While the limits of magnetic recording are still being debated, 8 the limits of conventional op-tical recording are well understood. 5 Current Optical Storage technology is already working close to the optical diffraction limit. However, significan future increases in density are possible by taking advantage of the wavelength and/or numerical aperture dependence of the diffraction limit, or by going beyond it with near fie d techniques. In addition, if the signal-to-noise ratio (SNR) is suff cient, then gray-scale techniques allow the storage of more than one bit per location. 9 The diameter of the diffraction-limited spot is directly proportional to the laser wavelength λ and inversely proportional to the numerical aperture (NA) of the imaging lens (Fig. 26.1). The area of the spot is then proportional to the square of these parameters 10 A ∼ λ NA 2 , (26.1) and the resulting maximum areal density is simply the inverse of this area times the number of bits per spot b , D ∼ b NA λ 2 . (26.2) As described in Table 26.1, the differences in capacity and data rate between the CD and DVD formats is a clear consequence of reducing the diffraction-limited spot size of the focus at the medium. Other factors were also involved in the density improvement found in DVDs—such as stronger modulation coding, signal process-ing, error correction, and more aggressive tolerancing—but it is unclear how much more improvement could be extracted from these areas in future optical disk stan-dards. Optical Data Storage 613 Figure 26.1 Conventional Optical Storage uses a tightly focused laser beam to access indi-vidual bits in a single layer.
eBook - ePubMoving Media Storage Technologies
Applications & Workflows for Video and Media Server Platforms
- Karl Paulsen(Author)
- 2012(Publication Date)
- Routledge(Publisher)
Today there are many more reliable, durable, and higherdensity formats in use for the storage of computer data. We find those form factors to be in the shape of solid state memory, transportable spinning hard disk drives, data tape, videotape, holographic devices, and optical mediums. This chapter focuses primarily on the evolution of Optical Storage, which includes familiar recent developments such as Blu-ray Disc and less familiar forms, such as the early laser disc and holographic recording.KEY CHAPTER POINTS• Defining removable optical media along with the development of the compact disc (CD), DVD, laser disc, and Blu-ray Disc followed by the death of HD DVD • Holographic media for data storage, its development and history, and how holograms are made for moving images and other data using various innovative technologies • Guidelines for the care, storage, and handling of optical mediaDefining Removable Media
Removable media that contains data may be divided into two broad categories: (1) those which are essentially self-contained storage systems (e.g., a USB stick, SSD memory card, a transportable hard disk, or a solid state drive) and (2) those which depend upon a secondary mechanical device that performs the read and/ or write functions to and from physical media (e.g., a CD-ROM, DVD, or laser disc). These kinds of media are intended to be easily interchanged and can be stored in an off-line environment usually for indefinite periods of time.Removable Hard Drives
Although it is certainly possible to remove the spinning hard drive from your personal computer by opening the chassis and disconnecting it from the rest of the computer, this is not a practical approach for most of the common applications for the physical exchange of media. Drive products that can be removed from a chassis and plugged into another chassis, which are actually hard drives and which differ in physical architecture from transportable drives, are still available and employed when highvolume data sets are needed. Such drives usually have no power supplies and cannot be directly connected with USB or eSATA connections. These drives are set into a transportable “sled” configuration and are often found in video or film-transfer production facilities that are not equipped with high-speed data links or in those that require the security of a lockable device that can be removed and then stored off-line in a vault or other secure location.
eBook - PDF- Francis T.S. Yu, Suganda Jutamulia, Shizuhuo Yin(Authors)
- 2001(Publication Date)
- Academic Press(Publisher)
Information Storage with Optics metal coating [65]. The small-apertured laser diode directly delivers optical power to the near field substrate with unity efficiency. Light not passing through the aperture will be recycled in the laser diode and no energy is wasted. 8.7. CONCLUDING REMARKS This chapter gave a brief overview of the basic mechanisms of materials that have been employed to store optical information or light patterns. The fundamental architectures for 3-D Optical Storage were discussed in detail. The architecture for 2-D bit pattern Optical Storage and the 2-D holographic storage were described. Novel near field Optical Storage that can store a bit in an area smaller that the wavelength of light was also presented. The aim of this chapter has been to present a broad survey of information storage with optics. The main objective of the research in Optical Storage is to realize an ideal device that can store a bit in an area of or smaller, or a volume of or smaller. REFERENCES 8.1 F. T. S. Yu, Optics and Information T heory , R. E. Krieger, Malabar, Florida, 1984. 8.2 F. T. S. Yu and S. Jutamulia, Optical Signal Processing , Computing , and Neural Networks , Wiley-Interscience, New York, 1992. 8.3 E. Hecht and A. Zajac, Optics , Addison-Wesley, Reading, Mass., 1974. 8.4 J. W. Goodman, Introduction to Fourier Optics , McGraw-Hill, New York, 1968. 8.5 P. J. van Heerden, 1963, ‘‘A New Optical Method of Storing and Retrieving Information,’’ Appl. Opt. 2, 387 — 392. 8.6 P. J. van Heerden, 1963, ‘‘Theory of Optical Information Storage in Solids,’’ Appl. Opt. 2, 393 — 400. 8.7 L. Solymar and D. J. Cooke, Volume Holography and Volume Gratings , Academic Press, London, 1981. 8.8 G. Saxby, Practical Display Holography , Prentice Hall, New York, 1988, pp. 273 — 280. 8.9 J. R. Magarin os and D. J. Coleman, 1985, ‘‘Holographic Mirrors,’’ Opt. Eng. 24, 769 — 780. 8.10 S. V. Pappu, 1990, ‘‘Holographic Memories: A Critical Review,’’ Int.
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