Optical Disc

Optical disk is a storage device. Read & Write operations are done using optical (light) signals. Optical disks  came to use after 'Floppies' which was used as storage device. Optical disks contains many advantages over floppies. Some of the advantages are:

• Portable (easy to transport)
• More storage space
• Reusable

Types
      Optical discs are differentiated based on size and some other factors. Some of the types are:

• CD (Compact Disc)

            It was developed by Sony in the year 1976. The maximum size a CD is 700 MB. This uses Compact Disk File Format (CDFS) filesystem. The various types of CD are: CD-R (CD Recordable), CD-ROM (CD Read Only Memory), CD-RW (CD Rewritable).

          

• DVD (Digital Versatile Disc)

                  It was developed by Philips, Sony, Toshiba and Panasonic in 1995. DVD's have more storage capacity compared to CD's. The storage capacity is from 4.7 GB to 9.4 GB. This uses Universal Digital Format (UDF) format filesystem. The various types of DVD are: DVD-ROM (Read Only Memory), DVD-R (DVD Recordable), DVD-RW (DVD Rewritable).

• Blu-ray

                It was developed in the year 2000 by Sony and Philips. Blu-ray discs has more storage capacity compared to DVD's. This uses Universal Disk Format (UDF) filesystem. The storage capacity is 25 and 50 GB for single and dual layers respectively. 

           Blu-ray can be used upto 200 GB by using multiple dual layers.

• LaserDisc

             It is the grandfather of the optical storage medium. It was developed in the year 1958 by Philips, MCA and Pioneer. This uses analog signals to record the videos. Its diameter is 30cm, which looks like a huge sized DVD. It can be recorded only once. It can be used for playback only.

• Magneto Optical Disc

                  Magneto optical discs looks like floppy discs. But both are different. Floppies use magnetic signals to read and write. But the magneto optical disk uses optical signals to read and write the data. The size of magneto optical disc exists from 650MB to 9.2GB. These disks are available in SCSI (Small Computer System Interface), IDE (Integrated Drive Electronics), USB (Universal Serial BUS).

• FMD (Fluorescent Multilayer Disc)

                 FMD is different from CD and DVD. CD and DVD uses reflective light to store data's, but FMD uses fluorescent light for storing data. CD's and DVD's have the limitations (upto 2 layers) for storing data's. FMD uses 3D optical data storage principle in which the data's can be stored even in 100 layers. The size of FMD's is from 50GB to TB's(terabytes). The FMD will be a transparent disc.

• DMD (Digital Multilayer Disc)

                  DMD's are based on FMD principles. It is developed by D Data Inc. It can store 22 to 32GB binary data. The storage capacity can potentially support upto 100GB. DMD is also a transparent disc.

• UDO (Ultra Density Optical)

                    UDO's are designed to store the data's (videos) in high definition. The size of UDO's are 30 and 60GB. The types of UDO are: WORM (Write Once Read Many), R/W (Rewritable), Compliant WORM.

• PFD (Professional Disc)

                      PFD was introduced in 2003 by Sony. It is a digital recording optical disc for XDCAM and tapeless camcorder. 23GB data can be stored in a single layer PFD and 50GB data can be stored in a dual-layer PFD. PFD supports both standard definition and high definition. Professional Disc for Data (PDD) is a type of PFD, which is used to store data's. It is mostly used by the enterprises for taking backup's.

• VMD (Versatile Multilayer Disc)

                       VMD is a high capacity red laser optical disc. It was developed to compete with Blue-ray. VMD was developed by New Medium Enterprises. The capacity of each layer in VMD is 5GB. The standard size of VMD is 20GB and the maximum size is 30GB. This disc can be used for storing high definition videos.

• HVD (Holographic Versatile Disc)

                     It was developed between 2004 and 2008. HVD was designed to store data's in terabytes (TB). The principle used here is holography, in which red and green rays are combined as a single ray and used for reading and writing. The reading and writing of different type of information are done by using different rays. 100 and 200GB HVD's were introduced in the year 2007.The maximum size of an HVD is 6TB.

• Tapestry Media

                  Tapestry media is similar to holographic versatile disc (HVD). It was developed by InPhase Technologies. Tapestry holographic media is designed to store upto 300GB data. This is used for storing high definition videos and high-end enterprise applications.