Researchers at the Tokyo University of Science Graduate School of Engineering Science have developed a technology that could lead to a holographic storage disc with a capacity equivalent to 2TB - about 400 DVDs. The "hologram memory" technology enables data to be written in three dimensions rather than simply etching data on the surface of discs.

The concept is not new, as many companies had created holographic storage prototype systems during the last 15 years, but they almost never reached the market.

A special material on the optical disc interacts with a laser beam light and hardens. That allows for the storage of data in a 3D column form deep under the surface of the disc. By slightly changing the angle at which the laser beam hits the surface, multiple copies of a collection of data can be stored in a single location in the disc.

Manabu Yamamoto, a professor at the university's applied electronics department who led the research team, says that the system uses a "3D cross-shift multiplexing method". A series of holograms are recorded with shift multiplexing and rotating recording material with the axis of rotation being perpendicular to the material's surface.

Expectations were originally high for hologram memory because it would allow the storage of huge volumes of data. However, the technology was affected by even the slightest vibrations when entering data. The problem was overcome by changing how the laser beam was projected onto the surface. That led to the possibility of storing about 2 terabytes of data on a disc the same size as a DVD.

The highly sensitive optical disc compatible with the system was developed by Mitsubishi Chemicals.

Yamamoto said the technology could be commercialized in about three years, although a company capable of developing the drive's mechanism should be found.

The hologram memory could be used for for facilities that store large volumes of data, such as videos, for long periods.