Sony Uses Blue Lasers to Boost Storage

Sony will launch a new optical disc format in November that allows for storage of up to 23.3GB per disc, the company said Tuesday.

The format, called Professional Disc for Data, is being positioned by the Tokyo company as a replacement for the 5.25-inch MO (Magneto-Optical) disc format that it currently sells in the professional data storage sector. MO has been on the market for around 15 years, and the highest-capacity version sold by Sony can store 9.1GB per disc.

The key to the higher capacity of Professional Disc is in the type of laser used to read and write information from and to the disc.

Unlike MO, CD, and DVD formats, which all use red lasers, the new format uses a blue laser. Because the wavelength of blue light is shorter than that of a red laser, the beam from a blue laser, with suitable optics, makes a much smaller spot on the recording layer of the disc. A smaller spot means less space is needed to record one bit of data, and so more data can be stored on a 4.7-inch disc.

The discs are enclosed in cartridges to help keep dirt and dust off the disc surface.

Coming Soon

Sony will put on sale an internal drive, BW-F101, and write-once (recordable) and rewritable versions of Professional Disc media, PDDWO23 and PDDRW23 respectively, in major world markets beginning in November, says Aki Shimazu, a spokesperson for Sony in Tokyo.

The first-generation drive will cost around $3300, and blank media will cost between $45 and $50 per disc for both types, according to Shimazu, as well as Sony's marketing center for the format. That's roughly the price Sony promised when it first unveiled the format in prototype form earlier this year.

As MO technology continues to improve, Sony has plans to increase the capacity and sustained write transfer rate of Professional Disc, beyond the 23.3GB and 9 megabytes per second that are features of the first products to be launched in November.

Sony's roadmap has two steps, the first in 2005 when transfer rate will be increased to 18 MBps and capacity increased to 50GB through the addition of a second recording layer in the discs. The second step is scheduled for 2007, when transfer rate and capacity will be doubled again to 36 MBps and 100GB, respectively--the latter through the use of double-sided discs, says Sony.

The new format is related to the Blu-ray Disc video disc format that Sony launched earlier this year. Both formats store the same amount of data on cartridges that look almost identical (with Blu-ray having additional 25GB and 27GB versions), though the data transfer rates to the discs are different. Blu-ray, which is designed to record high-definition television, records at a rate of 4.5 MBps, or half the rate of Professional Disc.

Irreconcilable Differences

These differences mean the two formats, although similar, are incompatible.

While that incompatibility may sound like a disadvantage for consumers, Sony says the two are targeted at different markets, so it shouldn't cause a problem. It also means Sony has full control over the Professional Disc format, which it developed alone, unlike Blu-ray, which is controlled by a consortium of nine companies, of which Sony is one.

"There are certain differences, but it's pretty much the same format," says Shimazu. "There is no compatibility at this point. If you make it a Blu-ray [Disc], you have to ask the eight other companies involved in the project. [Professional Disc] is a Sony exclusive."

A version of the Professional Disc format has already been launched by Sony as part of its professional broadcasting product line under the name XDCAM. That variant uses similar discs but a different data transfer rate, and is aimed at video acquisition, editing, and post-production applications. Despite its similarities with the Professional Disc for Data, the two formats are also incompatible, says Sony.

Sony is not the only company looking at utilizing blue-laser technology for data storage.

Plasmon, a Cambridge, UK-based data storage systems company, has developed its own format, called UDO (Ultra Density Optical), which it is also targeting as a replacement for MO. UDO can accommodate 30GB of data on an optical disc that is enclosed in a cartridge made to the same dimensions as current MO cartridges. Its future roadmap includes 60GB and 120GB versions of UDO.

Toshiba and NEC are also developing a blue-laser based format called Advanced Optical Disc. The format can store 20GB on a single-layer, single-sided disc or 36GB on a dual-layer, single-sided disc. It has been proposed by the two companies to the DVD Forum as a next-generation replacement for the existing DVD format.