Holographic storage is one of those snake-oil technologies that’s almost as vaporous as Duke Nukem Forever or Half-Life 2: Episode 3. It has been been something of a digital philosopher’s stone since the ’60s, promising infinite storage and massive data rates. When a holographic storage prototype was finally demonstrated at NAB 2005 by InPhase Technologies, many of us couldn’t believe that we might actually be standing on the cusp of a storage renaissance.

In 2010, though, with no further public demonstrations, $100 million spent, 10 years of R&D, and commercial viability remaining elusive, InPhase ran out of money and shut up shop. For many of us storage nerds, it was the end of a dream. Well, good news: InPhase’s assets have been bought up by a company called HVault, and it’s currently demonstrating its holographic storage tech at NAB 2012 in Las Vegas. Better yet, HVault’s tech will apparently launch in “spring 2012” — i.e. soon.

Holographic storage, if you haven’t heard of it before, is (generally) a write-once-read-many (WORM) archival storage technique. Where tape and hard drives are magnetic, and optical discs bounce lasers off little pits, holographic storage actually uses a photosensitive medium — like photographic film — to store 3D images that represent data.

To store data, two lasers are used: a reference beam and a signal beam. The signal beam is modulated by the data being written, while the reference beam illuminates the target region and effectively keeps track of where the data is being recorded. To read data, the reference beam is pointed at exactly the same location, creating a hologram of the data stored by the signal beam. This hologram is immediately “read” by a sensor, much like the CMOS sensor found in a digital camera. Unlike conventional, linear storage mediums (HDD, DVD, tape) every “bit” of the holographic image is read in parallel, potentially resulting in huge data rates.

Holographic storage can also (in theory) store a vast amount of data — about four gigabits per cubic millimeter. Basically, depending on the thickness and quality of the storage medium, and the laser, thousands of individual holograms can be stored, stacked on top of each other. Depending on the angle and wavelength of the reference beam, and the position of the media, different holograms can be projected. HVault advertises that its system could replace petabyte storage clusters, but it doesn’t directly say how much data it can store on each holographic storage disc. Four gigabits per cubic millimeter equates to around 2.5 terabits per square inch — more than two times denser than Seagate’s recently-announced HAMR hard drive tech.

Finally, holographic media is meant to be blessed with a lifespan of over 50 years, compared to 2-5 years for magnetic storage. Of course, whether holographic readers will still exist in 50 years is another question entirely.

Now we just have to wait and see if HVault actually launches this spring, or whether it’s still just vaporware. For a technology that promises to revolutionize storage, its website does not instill me with hope. The fact that I don’t have a pretty photo of some holographic storage to share with you probably isn’t a good sign either. Still, you never know!

Read more about holographic storage on Wikipedia