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Although CD, DVD, and Blu-Ray disks differ from each other, they are commonly referred to as compact disks because of the technology used to produce them. They differ from each other the way they store information.

The first two letters of the word compact disk are commonly known as CDs. Similarly, DVD is a digital video disk with the first three letters of the three words. Also known as VCD, video compact disk.

What are the raw materials used to make the CD/DVD?

DVD or VCD are all made of two layers of plastic with a very thin aluminum plate. This thin plate is made of gold to hold the information for a long time. The top of the plate is a thin acrylic plastic plate. On the bottom is a polycarbonate plastic plate.


How information is stored on CD/DVD? 

Information is stored by creating a pit hole on the aluminum plate. The hole is at least 100 nanometers (nm – manometer is one-millionth of a millimeter). Five hundred manometers are wide. But these values ​​vary according to the information included. The distance between two holes in the adjacent ring hole is 1.6 micrometers (ie, one-thousandth of a millimeter). The distance between two holes is called lands.


The distance between two sheets on a CD, DVD, and BLU-Ray disk is less than the distance between two sheets on a CD (1.6 µm) and the distance (0.74 µm) on a DVD. Also, the distance between two blobs on a BLU-RAY disk is much shorter. That is, most of the information is stored on BLU-RAY disks.

How information is read stored on CD/DVD?

The information stored on a CD is read by an infrared current of 780nm wavelength piercing the polycarbonate plate beneath it. When it hits the disk, it is reflected in the patterns of holes and holes in the disk. The CD Drive has sensors that can reflect those rays. This information is read from a computerized circuit and uses a 650nm wavelength red light to read the information on a DVD. BLU-RAY disks use a blue wavelength of 450nm wavelength.


It is a typical CD / DVD. They are permanently compiled, or ROM (ie CD ROM and DVD ROM). But once in an R (eg:- CD R and DVD R) and rewrite, RW (CD RW and DVD RW) type disks are used to write information, not an aluminum plate, but a dye layer of color. The dye layer, which is heated in the presence of a beam of light from a CD or DVD writer, stores the information in the individual cells, using cyanine as discs. (
Pthalo-cyanide) applied disc yellow/gold color. The blue dye disk is a metal-azo type

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