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Optical Drive

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  • Optical Drive





  • pengertian dari optical drive

    Optical Drive merupakan perangkat keras penyimpan data dengan menggunakan media

    penyimpanan berupa keping CD atau DVD yang terdiri dari jutaan benjolan kecil dan dips.

    Teknologi optik yang digunakan media ini adalah penggunaan laser untuk menulis dan mengambil data, laser ini membaca benjol dan dips sebagai

    satu dan nol, yang komputer dapat mengerti.

  • fungsi dari optical drive

    Optical Drive adalah alat pembaca untuk

    media penyimpan data berupa disk DVD / CD.

    DVD/ CD berupa kepingan cakram optik yang

    berisi data.

  • Jenis-jenis optical drive

    Optical drive terdapat

    beberapa jenis, contoh dan

    penjelasan secara garis

    besarnya sebagai berikut :

  • 1.CD-Rom (Compact Disc Read only


    1. adalah salahsatu bagian hardware computer yang

    berfungsi 'HANYA' untuk membaca file yang terdapat

    dalam CD saja.

    2. adalah sebuah piringan kompak dari jenis piringan optik

    (optical disc) yang dapat menyimpan data. Ukuran data

    yang dapat disimpan saat ini bisa mencapai 700MB atau

    700 juta bita.

    3. bersifat read only (hanya dapat dibaca, dan tidak dapat

    ditulisi). Untuk dapat membaca isi CD-ROM,

    4. CD-ROM terkini memungkinkan CD dapat ditulisi

    berulang kali (Re Write / RW) yang lebih dikenal dengan

    nama CD-RW.

    5. CD-ROM adalah hanya bisa ditulis saja tidak bisa


  • 2. CD-RW (Compact Disc Re Writer)

    1.adalah salahsatu bagian hardware computer yang

    berfungsi untuk membaca file yang terdapat dalam CD.

    2.Selain itu CD-RW juga dapat memasukan data/file

    kedalam CD, dengan menggunakan suatu software

    tambahan salahsatunya adalah Nero.

    3.Compact Disk Rewritable, yakni sebuah media

    penyimpanan cakram berbasis optik yang dapat ditulisi

    dan dihapus lagi untuk ditulisi lagi untuk menyimpan


    4.Compact Disk Read/Write, yakni sebuah alat komputer

    yang mampu menulisi sebuah compact disk recordable


    5.adalah media CD yang bisa di "rewrite". Artinya, CD itu

    bisa ditulis ulang atau berkali-kali (bisa di burning

    berkali2 dan juga bisa dihapus).

  • 3. DVD-Rom

    1.Adalah salahsatu bagian hardware


    2.Tapi hanya bisa membaca saja.

    3.hampir semua jenis cd dan dvd.

    4.kecuali dvd ram, yang biasanya

    membutuhkan drive dvd-rw.

    5.berfungsi 'HANYA' untuk membaca file

    yang terdapat dalam CD dan DVD saja.

  • 4. DVD-Combo

    1.adalah salahsatu bagian hardware

    computer yang Isinya gabungan dari CD-

    Rom, CD-RW, dan DVD-Rom.

    2.Kelebihannya DVD-Combo bisa

    memasukan data/file kedalam CD.

    3.drive ini mampu membaca kepingan cd dan

    dvd dan juga mampu menulis tapi hanya

    pada cd kosong.

    4.dapat membackup data ke kepingan CD.

    5.dan 'tidak dapat' membackup data ke

    kepingan DVD.

  • 5. DVD-RW

    1.adalah penggabungan fungsi dari CD-Rom, CD-

    RW, DVD Rom dan DVD-Combo. yaitu bisa

    membaca file dalam CD dan DVD, serta bisa

    memasukan data/file kedalam CD dan DVD.

    2.Dvd RW merupakan drive terlengkap yang ada

    dipasaran sekarang selain mampu membaca

    semua jenis cd dan dvd.

    3.DVD-RW merupakan perangkat tercanggih di

    kelas optical drive masa kini.

    4.mampu membaca dvd-ram dan juga mampu

    untuk menulis pada semua jenis kepingan, baik

    cd kosong, dvd kosong, dan juga dvd ram.

    5.Kecepatan penulisan DVD hingga kini masih 16X


  • How CD and DVD Players


  • www.themegallery.com

  • A Little History

    The history of the compact disk (CD) started in the 1970s with the

    videodisk in the form of Video Long Play (VLP) read-only systems. The

    videodisk did not become a commercial success, even after write-once

    optical disks of different formats and sizes were introduced. These

    were analog systems. In 1982 the CD-DA (compact disk-digital audio)

    was introduced to the market jointly by Phillips and Sony. It stored a

    high-quality stereo audio signal in a digital format. These systems

    became a huge success. In 1985, the technology was extended to

    computer storage, again in a collaboration between Phillips and Sony.

    This was called a CD-ROM (compact disk-read only memory). Early in

    1995, two major groups were competing to develop the next generation

    of high-density compact disks. Under the partnership of Philips and

    Sony, there began the development of one such format. Concurrently,

    a group led by Toshiba and Time Warner was working on another

    format. In September of 1995 the two camps agreed to develop a single

    standard for a high-density compact disk. The first DVD-video players

    were sold in Tokyo in November96, followed by their US introduction

    in August97.

  • CD Under a

    Microscope T





    Spiral track

    Low-magnification (32) image of a

    CD showing an edge of the data zone.

  • How Small are the Pits on a


    Cotton thread (150mm) Human hair (75mm) Dust (40mm)

    Fingerprint (15mm)

    CD pit (0.5 2mm)


  • Track Density and Data


    The CD is 12 cm in diameter, 1.2 mm thick, has a center

    hole 1.5 cm in diameter, and spins at a constant linear

    velocity (CLV) or constant angular velocity (CAV).

    There is only one track on the optical disk and all data are

    stored in a spiral of about 2 billion small pits on the

    surface. There are about 30,000 windings on a CD - all

    part of the same track. This translates into about 16,000

    tracks per inch and an areal density of 1 Mb/mm2.

    The total length of the track on a CD is almost 3 miles.

  • CD Versus


  • CD in Cross-


    A CD can store up to 74 minutes of music, so the total amount of

    digital data that must be stored on a CD is:

    2 channels 44,100 samples/channel/second 2

    bytes/sample 74 minutes 60 seconds/minute =

    783,216,000 bytes

    To fit more than 783 megabytes onto a disk only 12 cm in diameter

    requires that the individual bits be very small.

  • Different Types of DVD

  • Inside a CD Player

  • Optics of Readout

  • Intensity Distribution in the Focal Plane

    -2 x (mm) 2 -2 x (mm) 2 -2 x (mm)




    y (m


    Logarithmic plots of intensity distribution at the focal plane of a

    0.615NA objective at l = 633 nm. The incident uniform beam is

    linearly polarized along the X-axis. From left to right: X-, Y-, Z-

    components of polarization at best focus. The integrated

    intensities of these three components are in the ratio of

    1 : 0.002 : 0.113.

  • Focused Laser Beam Reading the Pits on a CD Surface

    The laser beam (wavelength ~ 780 nm) is focused onto

    the data side of the disk (focused spot diameter ~ 1mm).

    The laser moves in the radial direction over the fast

    spinning disk and scans the data track.

    Pits are 120 nm deep and 600 nm

    wide. Laser beam scatters when it

    scans a pit, which translates into a

    drop in reflected beam intensity.

  • Why Focus the Laser Light through the Substrate?

  • Substrate Tilt

  • Three-beam Tracking

    On the top and bottom frames, the central spot B has drifted to

    one side of the track and the modulation is greatest in one of the

    side beams A or C. In the center frame, the central spot B is

    correctly located over the track and the modulation from the

    central spot is a maximum.

  • Three-Beam Tracking

  • Three-beam Tracking

  • Effect of Defocus on Focal Plane Intensity


    Logarithmic plots of total intensity distribution at and near the

    focus of a 0.615NA objective at l = 633nm. From left to right:

    Dz = 0, 0.5mm, 1mm, 1.5mm, and 2mm. Because of symmetry

    between the two sides of focus the distributions for Dz are the

    same. At best focus the spots FWHM is 0.57mm along X and

    0.51mm along Y.

    -2 x ( mm)



    y (




    -2 x ( mm)


    Perfect focus Defocus: 0.5mm 1.0mm 1.5mm 2.0mm

  • Focus Actuator

    Inside the drive, the disk and the drive's optics are separated

    by a distance of about 1 mm, making mechanical interaction

    and crashes, even with wavy disks and imperfect clamping

    almost impossible.

  • Automatic Focusing

  • Automatic Focusing

  • Automatic Focusing

  • How Many 8-letter Words Are There?

























    28 =256

    268 =208,827,064,576

  • The ASCI

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