Plasmon Data Ltd has announced the PD2000e, a multifunctional drive that combines optical storage with CD-ROM capabilities. The drive uses phase-change rewritable technology and Melbourn, Hertfordshire-based Plasmon Data is the first non-Japanese company to get a licence from Matsushita Electrical Industrial Co for this technology. The company has also extended its range of optical disk jukeboxes. Plasmon Data says it has licensed the Japanese technology on the grounds that although phase-change technology is still relatively new, Matsushita has established the de facto standard and users will eventually move to phase-change because it is faster and cheaper than magneto-optical disks. So far, Plasmon has invested ú1.3m into the coating system for the disks: the quality of the protective layer determines the laser power required by the system. It is also in the process of opening a clean room for making the disks at its Cambridge fab. Magneto-optical technology requires that the spots be erased before writing, but with phase-change technology this step is eliminated, making the procedure faster. With a magneto-optical disk, the spots that represent the bits are heated with a high-power laser to their melting point in a magnetic field; the polarity is set while the spot is molten, and remains fixed when the spot cools. Switching the polarity of the spot changes the phase of the reflected light, so spots of alternate polarities can be read as zeros and ones with a low-power laser.
Amorphous state
With all-optical phase-change technology, the phase of the reflected light is again used, but the medium comes in an amorphous state. Heating the surface with a medium-power laser to the glass transition temperature causes the spot to crystallise, heating it with a high-power laser melts it to the point where it returns to the amorphous state – revitrification. This direct overwrite capability means the head assemblies are less complicated than those used in magneto-optical systems, making the products cheaper. In its PD2000e the micro-optical head assembly consists of a laser module and a movable unit made up of an object lens, a polarised hologram designed by Matsushita and a wavelength plate. The PD2000e us a tray-loading multifunction CD drive that can take a phase-change erasable disk cartridge, a CD-ROM or an audio CD. The 4.7 single-sided phase-change PD650 disks store up to 650Mb of data: one costs ú45. Plasmon believes that to begin with the PD2000e will be seen as an add-on product, particularly useful to small workgroups, but it says that it is likely to appeal to network users looking for back-up and data access in one product. It will be available in February and will cost ú750. The Micro Multi is a optical disk juke box that comes either as one to hold magneto-optical disks or one for phase-change media disks. The Micro Multi is aimed at small networks, workgroups or organisations implementing hierarchical storage management; it can store up to 450Gb. Both types can be configured for one or two multifunction drives and Plasmon says that there is full compatibility and data interchange between these systems and earler generations of magneto optical and phase change technology. Both types cost ú5,000 with one drive and are available now. The RF20J-690 comes with 20 of Plasmon’s 1.3Gb half height magneto-optical drives with an average seek time of 39mS. The RF22J-703 uses 22 of Plasmon’s 1.5Gb phase-change optical drives that have an average seek time of 45mS. Plasmon reckons it has brought the cost of storage down to ú150 per Gigabyte with these drives. Other optical disk jukeboxes Plasmon has launched extend its Multi III line with models storing 343Gb and 450Gb. The RF264-690 has 264 magneto-optical platters to provide 343Gb of storage. The RF300J-703 has 300 platters, offers 450Gb of storage and uses phase-change technology. Both can have include to six drives and cost a minimum of ú53,280. These boxes have what Plasmon describes as intelligent clean air systems that maintain positive air pressur
e and display messages indicating when they should be cleaned.
