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Holographic Data Storage

Stephen Rampur
Holographic data storage systems are believed to be the future of data storage technology. This story tells you, in short, about this advanced technology.
Nowadays, blue ray DVDs and hard drives are types of computer data storage devices which have the most capacity. The information in all these devices is stored in the form of bits. Data is recorded and read one bit at a time, which makes data processing slow.
Have you imagined a technology far more advanced than these mediums? One of such technologies that is considered to replace today's data storage systems is 'holographic data storage'.

What is Holographic Data Storage?

It is a new kind of technology that substantially helps in high-capacity data storage. This technology enables a device to record and read data at a million times faster rate than that in today's optical and magnetic drives.
Fundamentally, it works on the 3D data storage concept. The data processing in this holographic concept relates to accessing the whole of the storage medium rather than just its surface.
Data is stored on the disk using two rays intersecting each other. In this way, different data can be stored on the same photosensitive cells that hold data. So there can be data overlapping and hologram creation, wherein the data can be accessed using a beam equivalent to the hologram. At present, there are Holographic Versatile Discs (HVDs) and Holographic Versatile Cards (HVCs) developed, but are not yet commercially announced.

Invention and Development

In the early 1960s, a scientist named Pieter J. van Heerden brought forth the idea of creating a holographic system for fast and large data storage.
After some years, scientists working at RCA Laboratories, managed to record over 500 holograms in a lithium-niobate crystal and roughly another 500 images onto polymer material. Nevertheless, lack of cheap materials and the development of magnetic data storage components caused this idea to be put on hold.
InPhase Technologies, in the mid-2000s, publicly announced its holographic storage device. However, in February 2010, the company business was stopped, as Colorado government took over its assets for not paying taxes on time.
Recently, in April 2009, GE Global Research exhibited their holographic data storage device. It is believed that InPhase and Nintendo have entered a contract to come up with such storage systems for video games.

Storing and Reading Data

In order to record data on a holographic device, a blue-green argon laser is flashed on a beam splitter which divides it into two rays. The first beam that has data to be stored is referred to as a signal beam.
This light ray goes through a mirror then a Spatial Light Modulator (SLM) which is an LCD that is displaying binary data (i.e. '1' and '0') in the form of transparent and dark objects on its screen. This binary data is conveyed by the signal beam to a lithium-niobate crystal for storage as a hologram.
The second ray that beams out of the argon laser is known as the reference beam. Note that this beam does not hold any data for processing. It mirrors on the beam splitter and gets transmitted to the crystal using a different path.
The moment the signal beam and reference beam meet, the data on the signal beam is recorded on the recording medium in a holographic form.
Now, to access the stored data, the reference beam is flashed on the recording medium in the same angle that was used to record the holographic data before. The data is then transferred to a detector which has a reading capacity of a million bits in one go.
The data retrieval depends on the angle at which the reference light is beamed. So, using different rays at separate angles, you can read a number of pages from the same area of the storage medium. The main advantages of this piece of technology is faster data transfer and the ability to store a huge amount of information in a smaller area.