Computers and holographic memory
A new evolution renewed from the past
A report by:
FComm. D.L.Wey
DCOSR: SFS-SFC
The first attempts made at storing data holographically were made during the seventh decade of the 20th century. The crystals were constructed of iron-doped lithium niobate. But it wasn’t until the ninth decade of the 20th century that holographic memory really began to show promise.
With the advances in the manufacture of new polymers [such as photopolymer] permanent storage of information has advanced. Because photopolymer is chemically altered once written to, it cannot be erased. But it does have a diffractive efficiency 2,500 times greater than a lithium niobate crystal of the same thickness.
Computers have used a variety of storage mediums, from punch cards, magnetic tape, and now…technology has advanced to the point an old idea becomes new again.
The concept of holographic memory is one where two laser beams interfere with one another through a material that is sensitive to light in a way that alters their optical properties in the process.
By use of what is referred to as a ‘reference beam’, information can be stored and retrieved simply. By using the refractive properties of a crystal, information can be stored and read as whole ‘chunks’ of data.
The amount of information capable of being stored on a data crystal is determined by various factors: The size of the crystal, and the numbers of refractive points within. Thus, the capacity for storage is equal to the inverse defractive efficiency times the number of holograms stored.
In other words, the more information stored on a crystal, the less reliable their reconstruction.
Although the science of holography has come a long way, it has yet to provide a reliable and cost effective alternative to conventional means of data storage. But the jury is still out, and we may yet see a system comprised of holographic drives.
Further updates will be provided, as they become available.