BACKGROUND: Scientists have developed a holographic data storage system that promises to revolutionize the way we store data. Movie and broadcast companies will be among the first users because the technology is well suited for broadcasting and video editing: data is read and stored in parallel at a million bits at a time, and prototypes of holographic disk arrays have data transfer rates of 27 megabytes per second. Eventually consumers will be able to purchase high-definition videos, and have greater storage capacity in their cell phones and digital cameras.
HOW IT WORKS: While CDs and DVDs store information in single bits over the surface of the disk, holographic storage can store much more information faster (one million bits at a time) throughout the entire thickness of the disk. Holographic data storage would offer better copyright protection. DVDs and CDs can easily be copied by making an imprint of the "bumps" on the surface of the disk, but it's harder to this with holographic data storage because information is stored throughout the disks.
The key technology that makes this possible is the development of a material to make the disk that can support the way holograms are made. Earlier materials ý most notably lithium niobate -- could be both recorded and read back, but in the process of reading back the data, the holograms were erased. Companies have been searching for the perfect recording material for 50 years. They haven't found it yet, but the emphasis has switched to polymeric materials onto which data can be recorded once, instead of being erasable.
ABOUT HOLOGRAMS: A hologram records the interference pattern made by two beams of light that interact with each other. One beam comes directly from the laser, while the other comes from the same laser but bounces off the object being imaged. Light waves behave just like water waves when they meet. Wherever a crest of one coincides with a crest of the other, an extra high crest will form, and where two troughs coincide, they will form an extra low trough. If a crest meets a trough, the two will cancel each other out. With light, the waves will form light (crests) and dark (troughs) fringes -- the telltale wave pattern that can be recorded on photographic film. After it is developed, the hologram is lit by a beam of light to recreate the 3D object in space.