Physics trivia

CDs and DVDs burned

DVDs and CDs are recorded from grooves, grooves made along the disc that allow the reflection of the laser focused by an optical reader.

Slot distances and sizes make the difference between CDs and DVDs
The CD, an acronym for compact disc , was invented in 1960 by the American James Russell. It is a disc made of plastic material on which information can be recorded and read from the incidence of a specific type of laser .

CDs arrived on the market in 1982, but they only gained space among the existing media and became the main form of dissemination of musical artistic works from the 1990s onwards.

How does recording occur?

CDs and DVDs are burned in the same way, and the difference between them is in the space available for storage. The discs have throughout their length, and in a spiral shape, grooves, which are small depressions or grooves. When the laser of the readers focuses on the slots, there will be a difference in reflection between the smooth parts of the disc and the grooves, so the reader can differentiate the bits and decode the data.

Device that reads CDs and DVDs


Blu-ray technology has even more advantages over DVDs in terms of storage capacity. DVD and CD players use red lasers , with a wavelength ranging from 500 mm to 650 mm . Blu-ray players use blue laser , which has a wavelength on the order of 405 mm, so the grooves that make up a disc of this technology are smaller and closer to each other, so the data storage capacity is higher than that of DVDs and can reach up to 50 GB .

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