Holographic Versatile Disc

The Holographic Versatile Disc (HVD) is an optical disc technology that was expected to store up to several terabytes of data on an optical disc 10 cm or 12 cm in diameter. Its development commenced in April 2004. The technology was abandoned due to funding issues. One of the responsible companies went bankrupt in 2010.
The reduced radius was meant to reduce costs and materials used. It employs a technique known as Collinear <a href="/facts/Holography/4J1gW0M6">Holography</a>, whereby a blue-green and red <a href="/facts/Laser/jk6PTvvT">laser</a> beam are <a href="/facts/Collimated_light/lhd2hhPt">collimated</a> in a single beam. The <a href="/facts/Blue-green/y1t6W9RY">blue-green</a> laser reads data encoded as laser interference fringes from a <a href="/facts/Holographic/4J1gW0M6">holographic</a> layer near the top of the disc. A <a href="/facts/Red/gLnFAVx4">red</a> laser is used as the reference beam to read <a href="/facts/Servomechanism/lS3l6sY2">servoinformation</a> from a regular CD-style <a href="/facts/Aluminium/7wmR8jYE">aluminium</a> layer near the bottom. Servoinformation is used to monitor the position of the read head over the disc, similar to the head, track, and sector information on a conventional <a href="/facts/Hard_disk/kekLSGSE">hard disk drive</a>. On a CD or DVD this servoinformation is interspersed among the data. A <a href="/facts/Dichroic_mirror/frH5wglM">dichroic mirror</a> layer between the holographic data and the servo data reflects the blue-green laser while letting the <a href="/facts/Red/gLnFAVx4">red</a> laser pass through. This prevents interference from refraction of the blue-green laser off the servo data pits and is an advance over past holographic storage media, which either experienced too much interference, or lacked the servo data entirely, making them incompatible with current CD and DVD drive technology.
Standards for 100 GB read-only holographic discs and 200 GB recordable cartridges were published by <a href="/facts/Ecma_International/HCbnIU6n">ECMA</a> in 2007, but no further holographic disc product has ever appeared in the market. A number of release dates were announced, all since passed, likely due to actual high costs of the drives and discs itself, lack of compatibility with existing or new standards, and competition from more established optical disc <a href="/facts/Blu-ray/zyPalhfG">Blu-ray</a> and <a href="/facts/Video_streaming/4rPhSq0Y">video streaming</a>.

Holographic Versatile Disc open-in-new

Holographic Versatile Disc