Blu-ray

Blu-ray is an optical disc format that stores high-density digital data using a blue-violet laser, whose short wavelength allows smaller recording marks than DVD.

Blue laser: A laser that emits blue or violet light, with a shorter wavelength than red light. Blu-ray’s blue-violet beam focuses on smaller recording marks than the red laser used for DVD.
DVD: An optical disc format that uses a red laser to store digital data. DVD provides the direct capacity and laser-wavelength comparison that motivated Blu-ray’s denser design.
BD-R: A recordable Blu-ray format that can be written once and read repeatedly. BD-R adapts Blu-ray capacity to archival and personal recording.
HD DVD: A high-definition optical disc format that competed with Blu-ray in the 2000s. HD DVD was Blu-ray’s principal rival in the high-definition disc format war.
Numerical aperture: A measure of how strongly an optical system gathers or focuses light. Blu-ray’s high-aperture objective lens produces a smaller focused spot on the disc.
Compact disc: An optical disc format introduced for digital audio and later used for computer data. The CD-to-DVD-to-Blu-ray lineage shows successive increases in optical storage density.
BD-RE: A rewritable Blu-ray format that supports repeated erasure and recording. BD-RE makes the format usable as reusable removable storage.
Video streaming: The delivery of audiovisual content over a network for playback as data arrives. Streaming later challenged Blu-ray’s role as a convenient way to watch films.
Optical disc: A flat storage medium whose data is read or written using light. Blu-ray is one format within the broader optical-disc family.
Optical storage: Data storage that uses light to read or write information on a medium. Blu-ray is a specific implementation of optical storage.

Linked from 11 pages