3-D Holograms

A new storage technique that taps the technology behind the familiar hologram stickers on credit cards promises to put entire libraries and weeks worth of motion pictures on a couple CD-sized discs. But with an expected price tag of nearly $100,000, hologram storage remains little more than an apparition.

InPhase's prototype CD-sized hologram disc can hold up to 400 gigabytes of information and retrieve it at speeds of roughly 30 megabytes per second. At that speed, people could download a DVD movie in about 30 seconds. Meanwhile, IBM is working on a system that stores 250 gigabytes in a square inch of hologram space. And a prototype hologram storage machine exhibited last month at CeBIT, the world's largest computer and technology trade show, can hold 1 terabyte, or 1,000 gigabytes, of information in a hologram crystal chip the size of a watch face, according to German creators Optostor AG.

The secret is storing data in three dimensions throughout the entire thickness of the storage medium, be it a disc, a card or a wafer thin chip. Current magnetic and optical storage devices, such as computer hard drives or CD-ROMs, store data on their surfaces only. Hologram storage mediums also have lifetimes of up to 100 years, compared to the typical 4-year span of the typical hard drive, because they are more resistant to temperature swings, water, acid and electrical fields. The idea is for the lasers to hit the medium at thousands of different angles and depths, utilizing the entire thickness of the medium. By recalling data in packets of millions of bits, downloading from hologram storage is also envisioned as being at least 30 times faster than current storage methods, which read back data one bit at a time.

The storage material itself has long been a problem. It needs to be sensitive enough that a low power laser can write and read on it. But if it is too sensitive, the laser can actually wipe out stored data as it's being retrieved.

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