Optical advances to boost capacity, speed Startup promises 140GB; Maxoptix bets on OSD

Startup promises 140GB; Maxoptix bets on OSD

Zachary Shess

Growing mountains of data are forcing the storage industry to develop innovative approaches to keep up with demands. As a result, storage administrators should see significantly higher capacity optical drives and media by the end of the year.

For example, startup C3D Inc. recently demonstrated working prototypes of a technology that officials say will shatter capacity and data transfer characteristics of today's SmartCard and 120mm optical disk form factors, such as CD and DVD. Initial production of the credit-card-size FMC ClearCard-WORM (Write Once, Read Many) and FMC ClearCard-ROM media will hold 1GB and 10GB, respectively. First-generation FMD-ROM media is expected to hold 140GB, with data transfer speeds eventually approaching 1Gbps. First-generation FMC ClearCard-ROM or WORM versions could be used in PDAs and next-generation Internet-enabled mobile phones and devices. FMC-ROM disks could be appealing for applications demanding high capacity and lower cost per MB.

C3D's claims are based on the development of multi-layer fluorescent technology, which exponentially increases capacity by using several more recording layers than magnetic and other optical media.

In multilayer fluorescent technology, the light is filtered in the read-out system so that only the information- bearing fluorescent light is detected, thus reducing the effect of stray light and interference.
Click here to enlarge image

"The problem with the shiny reflective layers used in CD and DVD media is that signal integrity remains intact only to two layers," explains Patrick Maloney, C3D's business development manager. Current reflective technology is not conducive to adding more layers because excessive signal degradation would ensue, Maloney adds.

To combat that, C3D covers a translucent disc with fluorescent materials that emit fluorescent light when the laser beam reader hits a layer. Officials contend that the emitted light is not affected by data or other marks on the media and easily moves to adjacent layers. The light is filtered in the drive's read-out system, leaving only the information- containing fluorescent light, reducing stray light and crosstalk interference.

No significant modifications are required for existing drives to read clear, fluorescent media, but changes to the lenses and light detectors are necessary.

The capacity increases are derived from storing data over many layers. C3D demon-strated a 10-layer FMD-ROM disk and ClearCard WORM and a 20-layer ClearCard-ROM in late November to illustrate the capacity contrasts between CD and DVD media.

Being able to quickly move from 1- or 2-layer recording up to 10 or 20 layers will be an important selling point in securing joint manufacturing and licensing agreements, says Wolfgang Schlichting, an analyst with International Data Corp., in Framingham, MA.

Maxoptix developing OSD

Meanwhile, Maxoptix Corp. at Fall Comdex formally unveiled its Optical Super Density (OSD) technology. OSD promises a new class of removable, high-capacity optical disk drives and media for high-end backup/restore applications, potentially replacing MO devices and tape libraries in high-end backup/restore/archive applications such as Internet/email storage, data warehousing, and disaster recovery.

First-generation OSD drives, expected to begin shipping by year-end, will offer 40GB per disk with a transfer rate of 15MBps. Pricing will not be disclosed for at least six months, but Maxoptix officials say it will be less than current MO drives. "Typically, we've operated in high-end, specialized storage areas [with MO], but we consider OSD to be a mainstream storage technology," says Gary Potts, Maxoptix president and CEO.

Maxoptix officials say that while other next-generation optical technologies (such as TeraStor's Near-Field Recording and Seagate's Optically-Assisted Winchester technologies) have been delayed, OSD will succeed because it does not re-invent the wheel. For example, to achieve the smaller spot sizes necessary for higher areal densities, OSD engineers use standard far-field recording with a high-aperture lens. This technique provides smaller spot sizes and higher track and bit densities without the inherent dangers of flying heads too close to the disk surface.

Maxoptix is partnering with Mitsubishi Chemical Corp. on the media front (20GB-per-side disks with 30- to 50-year data integrity) and Lafe Group for magnetic recording heads. Pentax Technologies developed the Opto Mechanical Assembly (OMA) technology, which is designed to read and write greater capacities per disk through higher track and bit densities.

OSD cartridges are similar in size to MO cartridges and are compatible with the robotics in existing ISO-standard jukeboxes. Drives and media will be sold through OEMs, distributors, VARs, and system integrators.

OSD Technology Snapshot

Optical Super Density uses a number of new technologies, including:

  • High Numerical Aperture Lens. Developed by Pentax Technologies, a higher numerical aperture lens provides smaller diameter light spots on the disk, translating into higher capacities through higher track and bit densities.
  • Overcoat Incident Recording (OIR). OIR coating, a thick acrylic coating on the recording surface similar to that used on the back of CD and DVD media, is more than 500 times thicker than that of hard disk and tape products, but 1,000 times thinner than the substrate used on today's optical media. This thin coating allows the magnetic head to fly in close proximity to the recording surface, thus allowing magnetic field modulationx.
  • Magnetic Field Modulation (MFM). By using a small magnetic head in close proximity to the disk, MFM, which was developed by the Lafe Group, enables the polarity of the magnetic field to be switched at a very high frequency. The quick changes in polarity produce marks on the disk that are narrow and tall. These crescent-shaped marks provide a significant increase in bit density. Subsequently, the bit density is no longer limited by the laser wavelength. Because the polarity of the field can be switched rapidly, the disk can be written in a single pass, doubling the write performance.
  • Surface Array Recording. Provides simultaneous reads or writes to both sides of the media, enabling overall data rates nearly double those on a single side and similar to hard disk speeds. This also eliminates the need to flip media to read data stored on the opposite side of the disk.
  • Recessed Objective Lens. The objective lens, which is recessed above the magnetic head, is not subject to particulate contamination introduced into the drive during media insertion. By separating the objective lens from the magnetic head in the vertical direction, OSD drives are continuously focus by controlling the exact height of the objective lens over the media under servo control. This improves the reliability of the drive by allowing it to adapt to a wider range of environmental conditions.
  • Magnetic Super Resolution. A masking technology that enables read back of very high bit densities by isolating the individual bit to be read. During the read process, more energy is applied to the disk to pre-heat the "read-out layer" that lies on top of the recording layer. The read-out layer magnifies the bit area, providing higher resolution for progressively smaller marks.
Source: Maxoptix Corp.

This article was originally published on January 01, 2000