LS-R, or the Layer-Selection-Type Recordable Optical Disk, is the term coined by

Hitachi () is a Japanese multinational conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Nissan ''zaibatsu'' and later DKB Group and Fuyo G ...

in 2003 for a next-generation

optical disc In computing and optical disc recording technologies, an optical disc (OD) is a flat, usually circular disc that encodes binary data ( bits) in the form of pits and lands on a special material, often aluminum, on one of its flat surface ...

technology which allows much larger data storage densities than DVD,

HD DVD HD DVD (short for High Definition Digital Versatile Disc) is an obsolete high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the ...

Blu-ray Disc The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and capable of sto ...

, by allowing the use of many data layers in a single disc. In previous optical disc technologies, relatively few data layers can be incorporated in a single disc, since the reflections from the different layers interfere with each other. However, in LS-R, only the layer of interest generates a reflection, meaning that very many layers can theoretically be stacked in the same disc. This feat is accomplished by an electronic "selection" mechanism, whereby each data layer is coated with electrodes and only the electrodes associated with the layer of interest are activated. This activation changes the "selected" data layer from being transparent to being reflective or opaque, thus it can be addressed.

Technology

In the Hitachi implementation, LS-R technology utilizes an electrochromic film, for example of tungsten oxide or an organic material to accomplish the optical change. A two-layer feasibility prototype has been demonstrated, and it was estimated that a 20-layer CD-sized disc could provide 1

terabyte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable uni ...

of data capacity. Electrical activation of layers has been achieved with transparent ITO electrodes, and a contactless

power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As ...

has been developed in order to allow long-term operation (given that the disc is spinning at several thousand

revolutions per minute Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensio ...

Commercial product

No plans or timeline for the development of a commercial product have been released. It is possible that this technology, while interesting, will remain in the realms of research, either because it is superseded by an alternative technology (such as

holographic storage Holographic data storage is a potential technology in the area of high-capacity data storage. While magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recor ...

or another

3D optical data storage 3D optical data storage is any form of optical data storage in which information can be recorded or read with three-dimensional resolution (as opposed to the two-dimensional resolution afforded, for example, by CD). This innovation has the pot ...

variant), or because it can not be made to be economically viable. The need for the disc to be meticulously constructed from many layers of different materials, and the need for the drive to be able to electrically address each layer specifically, may make this solution too expensive for commercialization. In the next generation LS-R may compete with other next-generation optical disc format such as the

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, but it never arrived ...

and Protein-coated disc formats.

References

{{Hitachi Audiovisual introductions in 2003 Rotating disc computer storage media Video storage Upcoming products