DVD CDs (0.74 µm for DVD versus 1.6 µm for CD), accounting in part for DVD's increased storage capacity. In comparison, Blu-ray Disc, the successor to the DVD format, uses a wavelength of 405 nm (violet), and one dual-layer disc has a 50 GB storage capacity. Read and write speeds for the first DVD drives and players were 1,385 kB/s (1,353 KiB/s); this speed is usually called "1×". More recent models, at 18× or 20×, have 18 or 20 times that speed. Note that for CD drives, 1× means 153.6 kB/s (150 KiB/s), about one-ninth as swift. DVD-Video is a standard
Optical disc to be used in the Library of Congress archiving efforts. The STC disks utilized a sealed cartridge with an optical window for protection . The CD-ROM format was developed by Sony and Denon, introduced in 1984, as an extension of Compact Disc Digital Audio and adapted to hold any form of digital data. The same year, Sony demonstrated a LaserDisc data storage format, with a larger data capacity of 3.28 GB. In the late 1980s and early 1990s, Optex, Inc. of Rockville, MD, built an erasable optical digital video disc system using Electron Trapping Optical Media (ETOM). Although this technology