Top Tech Site

Join Top Tech Site and post your articles.

Holographic Versatile Disc (HVD) is an optical disc technology based on collinear holography, still in the stages of research would soon supersede existing optical technologies like the blue-ray and optical disc systems & probably Solid State Discs (SSDs) considering its storage capacity. HVD is expected to enable storage capacities of more than terabytes of data on a single disc.

Holography breaks through the density limits of conventional storage by going beyond recording only on the surface, to recording through the full depth of the medium. Unlike other technologies that record one data bit at a time, holography allows a million bits of data to be written and read in parallel with a single flash of light. This enables transfer rates significantly higher than current optical storage devices.

The technology behind these disks is called collinear holography wherein two lasers, one red and the other blue or green, are used. The red laser reads servo information from normal or regular CDs. The servo information is used to monitor the position of the read head over the disk. The blue or green laser reads data encoded as laser interference fringes from the holographic layer. A Dichroic Mirror layer between holographic data and servo data reflects the blue or green laser while allowing the red laser to pass through.

How is data recorded?
Light from a single laser beam is split into two beams, the signal beam (which carries the data) and the reference beam. The hologram is formed where these two beams intersect in the recording medium.

The process for encoding data onto the signal beam is accomplished by a device called a spatial light modulator (SLM). The SLM translates the electronic data of 0s and 1s into an optical "checkerboard" pattern of light and dark pixels. The data is arranged in an array or page of around a million bits. The exact number of bits is determined by the pixel count of the SLM.

At the point of intersection of the reference beam and the data carrying signal beam, the hologram is recorded in the light sensitive storage medium. A chemical reaction occurs in the medium when the bright elements of the signal beam intersect the reference beam, causing the hologram stored. By varying the reference beam angle, wavelength, or media position many different holograms can be recorded in the same volume of material.

While HVD is attempting to revolutionize data storage,So how does HVD stack up? Because HVD is still in the late stages of development, nothing concrete can be predicted. But we do
hope some outcome of the ongoing developments in the optical data storage technologies.

Keep visiting Top Tech Site for more updates on the latest technology.