THe Optical memory is an electronic storage medium that uses a laser beam to store and retrieve digital (binary) data. In optical storage technology, a laser beam encodes digital data on an optical disc or laser disc in the form of tiny pits arranged in a spiral pattern on the surface of the disc. Digital Versatile Disk (DVD), Compact Disk (CD) and Blu-Ray Disk are the examples of optical storage device.
What is an Optical Storage System?
As compared to magnetic memory, optical memory is a relatively new secondary storage medium. It has provided to be a promising random medium for high-capacity secondary storage, as it can store large amounts of text of data in limited space. An optical-disk storage system consists of a rotating disk, which is coated. With a thin metal or any other material that is highly reflective. laser beam technology is used for recording/reading data on a disk. Due to this, optical disks are also known as laser disks or optical laser disks.
The optical memory can be classified into three categories:
- CD (Compact Disk)
- DVD (Digital Video Disk)
- Blu-Ray Disk
Properties of Optical Storage Systems
- Storage Capacity – It refers to the amount of data that can be stored in an optical storage system. It is directly proportional to the spot size and the geometrical dimensions of disk.
- Data Transfer Rate – It refers to the speed at which data can be read from the optical storage systems. It depends on the linear density and the rotational speed of the drive.
- Access Time – It refers to the time taken to access the desired data from the optical storage systems. It is directly proportional to the weight of head and rotation speed of the disk.
Example of Optical Storage Devices
The different optical media are CDs, DVDs, Blu-ray disks, etc.
Compact Disk
CD has a diameter of 12 cm. The track on the CD is spiral-shaped, with around 20,000 windings. We’ve already explored the notion of information storage within the substrate. It is affordable, portable, and has a storage capacity of approximately 700 Mb. A compact disk operates in such a way that when the disc is inserted in the disk tray of a CD player, the track of the disc is scanned by a low-intensity laser beam. By rotating the disc between 200 and 500 revolutions per minute, a consistent scanning pace is maintained.
It is classified into three ways.
- CD-ROM: Compact Disk Read Only Memory, on which the manufacturer has pre-stored data.
- CD-R: Compact Disk-R is recordable, the data within this is written only one time by the user but it is not rewritable.
- CD-RW: Compact Disk-RW is rewritable, the data can be modified multiple times i.e., this can be read, erased, and written again and again as well.
Digital Video Disk
DVD is also known as digital versatile disk. This is a different kind of optical disk that holds data and multimedia content. It is the second form of optical disc to be introduced, following the compact disk. Despite its appearance, it can hold 15 times the amount of data that a CD can. A DVD provides approximately 4.7 GB to 17 GB of storage space.
DVD is also classified into mainly three parts.
- DVD-ROM: DVD-Read Only Memory permits the manufacturer to store data/information within it at the time of disk manufacturing and does not allow the disk to be rewritten.
- DVD-R: DVD-Recordable data is available to the user in blank format, and the user can only store data in it once.
- DVD-RW: DVD-Rewritable provides users with the ability to read and write data many times.
Blu-ray Disk
It is regarded as the third generation of compact disk technology, following the launch of CDs and DVDs. It is the most recent optical storage medium for storing high-definition (HD) audio and video. It contains about 128 GB of storage space.
Unlike CDs and DVDs, which employ a red laser beam for read/write operations, blu-ray disks use a blue-violet laser with a wavelength of 405 nm. The tracks on the disk can be wounded more closely due to the shorter wavelength of the laser than the high wavelength beam utilized by CDs and DVDs. As a result, it has a large storage capacity and can hold more data than CDs and DVDs.
Applications of Optical Storage Systems
Optical storage devices are commonly employed in data storage media.
- In Computers: An optical disk can be used by a computer to store vast amounts of data. The use of optical discs has the advantage of being less expensive than magnetic disks. An optical disc can hold more data than a hard disk.
- In Audio Players: Every type of audio device, including CD players, MP3 players, and so on, stores data on an optical disc. This sort of storage is portable and has a huge storage capacity.
- In Digital Cameras: Digital cameras often save photos and films on optical discs. The benefit of employing this sort of storage is that it has a large storage capacity and fast data transport.
Advantages of Optical Storage Systems
- The cost-per-bit of storage for optical disks is very low.
- The use of a single spiral track optical disks an ideal storage medium for reading large blocks of sequential data such as music.
- Due to their compact size and light weight, optical disks are easy to handle, store, and port from one place to another.
Disadvantages of Optical Storage Systems
- It is read-only (permanent) storage medium. Data once recorded, cannot be erased and hence, the optical disks cannot be reused.
- The data access speed for optical disks is slower than magnetic disks.
- It requires a more complicated drive mechanism than magnetic disks.
FAQs On Optical Storage Systems
Q.1: What is storage capacity of optical storage device?
Answer:
A double-sided DVD can hold up to 700GB of data, whereas a CD-ROM has a maximum storage capacity of 650MB. For example, the smallest PMP format optical disc size is 2.5GB whereas double-sided and single layer.
Q.2: Can you retrieve data from an optical disc?
Answer:
If an optical disc is not too badly damaged, the data on it can typically be retrieved. Even when the data is being read from the disc, there are several circumstances where it might not be entirely recoverable or usable.
Q.3: Why laser beam is important to optical storage device?
Answer:
Without a laser beam, optical storage devices are nothing. Data is read from an optical disc using a laser. The laser beam is important for optical storage device to read and write the data. Laser beam produced by the laser source.