How is a Blu-Ray player able to read more information that a CD player?

CDs (Compact Discs) typically have a storage capacity of 700 MB (megabytes) whereas Blu-Ray discs have a much larger capacity, ranging from 25 GB (gigabytes) for a single-layer disc to 50 GB for a dual-layer disc. This increased capacity allows Blu-Ray discs to hold more information, such as high-definition movies and high-resolution audio.

The laser technology used in CD and Blu-Ray players is one of the main factors behind the increased data storage capacity of Blu-Ray discs. CD players use an infrared laser with a wavelength of 780 nm (nanometers) to read the information on the disc, while Blu-Ray players use a blue-violet laser with a shorter wavelength of 405 nm. The shorter wavelength of the blue-violet laser allows for a more focused and narrow beam, which enables the Blu-Ray player to read smaller data pits on the disc than the CD player.

The data on both CDs and Blu-Ray discs is stored in the form of small pits and lands in the disc's reflective layer. The density and size of these pits and lands determine the amount of information that can be stored on the disc. Blu-Ray discs have more densely packed and smaller pits (as little as 0.15 μm in width) compared to CDs (0.5 μm in width). This contributes to the higher storage capacity of Blu-Ray discs. Additionally, the track pitch (distance between tracks) is smaller for Blu-Ray discs (0.32 μm) than for CDs (1.6 μm).

Another factor influencing the amount of information that can be read by a Blu-Ray player compared to a CD player is the data encoding method. Blu-Ray players use an advanced modulation scheme called Eight-to-Fourteen Modulation Plus (EFMPlus) for encoding data, which reduces the number of errors and allows for more efficient storage. In contrast, CD players use the simpler Eight-to-Fourteen Modulation (EFM) method. In conclusion, a Blu-Ray player is able to read more information than a CD player due to the combination of increased disc capacity, advanced laser technology, smaller pits and lands on the disc, and an improved data encoding method. This enables Blu-Ray discs to hold more data, allowing for higher quality media such as high-definition movies and high-resolution audio.