C3D or constellation 3Dâ„¢s innovative technology enables the recording,reading and storing of information on many layers within a storage media.Flourescent materials are embedded in the pits and grooves of each layer of the media and information is then stored and retrieved using the principles of fluorescence ,instead of optical reflection as currently used with CDs and DVDs .The media can be produced in card or disk format of any size. This technology holds the promise of exciting new applications and vast commercial potential. The ability to store data on multiple layers within the media allows the creation of compact removable storage devices with amazing capacity.
Constellation 3Dâ„¢s planned first generation disk, in standard (120mm diameter and 1.2mm thick)DVD format, will store up to 140 gigabytes in 10 layers .As production techniques using this technology evolve ,the number of layers and the distance between them will shrink ,eventually allowing terabytes of data to be stored on a single disk. Factors such as the ability to read simultaneously from multiple data layers allow exponential increase in data access and retrieval speeds, eventually resulting in retrieval speeds of 1 gigabyte per second.
Other new technologies, such as the simultaneous reading of multiple sectors within a single layer, can bring yet further increase in speed and provides true 3-dimensional data access/retrieval time. The implications of all of this for the data storage industry are enormous, as the technology offers quantum improvements in storage capacity, access/retrieval speeds and cost per gigabyte â€œin a compact, rugged and portable media format. A whole new range of applications and devices will be spawned, which take advantage of these superior capabilities.
Requirements for removable media storage devices (RMSDs) used with personal computers have changed significantly since the introduction of the floppy disk in 1971. At one time, desktop computers depended on floppy disks for all of their storage requirements. Even with the advent of multigigabyte hard drives, floppy disks and other RMSDs are still an integral part of most computer systems, providing.
Transport between computers for data files and software
Backup to preserve data from the hard dive
A way to load the operating system software in the event of a hard failure.
Data storage devices currently come in a variety of different capacities, access time, data transfer rate and cost per Gigabyte. The best overall performance figures are currently achieved using hard disk drives (HDD), which can be integrated into RAID systems (reliable arrays of inexpensive drives) at costs of $10 per GByte (1999). Optical disc drives (ODD) and tapes can be configured in the form of jukeboxes and tape libraries, with cost of a few dollars per GByte for the removable media. However, the complex mechanical library mechanism serves to limit data access time to several seconds and affects the reliability adversely.
Most information is still stored in non-electronic form, with very slow access and excessive costs (e.g., text on paper, at a cost of $10 000 per GByte).
Some RMSD options available today are approaching the performance, capacity, and cost of hard-disk drives. Considerations for selecting an RMSD include capacity, speed, convenience, durability, data availability, and backward-compatibility. Technology options used to read and write data include.
Magnetic formats that use magnetic particles and magnetic fields.
Optical formats that use laser light and optical sensors.
Magneto-optical and magneto-optical hybrids that use a combination of magnetic and optical properties to increase storage capacity.
The introduction of the Fluorescent Multi-layer Disc (FMD) smashes the barriers of existing data storage formats. Depending on the application and the market requirements, the first generation of 120mm (CD Sized) FMD ROM discs will hold 20 - 100 GigaBytes of pre -recorded data on 12 â€ 30 data layers with a total thickness of under 2mm.In comparison, a standard DVD disc holds just 4.7 gigabytes. With C3Dâ„¢s (Constellation 3D) proprietary parallel reading and writing technology, data transfer speeds can exceed 1 gigabit per second, again depending on the application and market need.
Increased Disc Capacity
DVD data density (4.7 GB) on each layer of data carriers up to 100 layers. Initially, the FMD disc will hold anywhere from 25 â€ 140 GB of data depending on market need. Eventually a terabyte of data on a single disc will be achievable.
Quick Parallel Access and Retrieval of Information
Reading from several layers at a ime and multiple tracks at a time nearly impossible using the reflective technology of a CD/DVD â€ is easily achieved in FMD. This will allow for retrieval speeds of up to 1 gigabyte per second.
By using incoherent light to read data the FMD/FMC media will have far fewer restrictions in temperature range, vibration and air- cleanness during manufacturing. And will provide a considerably more robust data carrier than existing CD and DVDs.
FMD/FMC presents a wide variety of potential media sizes and types (read only, write-able and re-writeable) for a broad range of applications.
Potential for Further Growth
The technology is young and will grow and evolve, providing a clear road map for the future of data storage.
FMD ROM Disc and Drive
The introduction of the Fluorescent Multi-layer Disc (FMD) smashes the barriers of existing data storage formats. Depending on the application and the market requirements, the first generation of 120mm (CD Sized) FMD ROM discs will hold 20 - 100 Gigabytes of pre recorded data on 12 - 30 data layers with a total thickness of under 2mm. In comparison, a standard DVD disc holds just 4.7 gigabytes. With C3Dâ„¢s proprietary parallel reading and writing technology, data transfer speeds could exceed 1 gigabyte per second, again depending on the application and market need. Constellation 3D has signed several key strategic partnerships to assist in the development of Fluorescent Multilayer technology.
FMD drives will be similar in size, design and price to CD and DVD drives and players currently on the market. Lasers and laser focusing technology will be the same and only minor modifications are required in the signal processing unit to allow for the reading of the incoherent light emitted by an FMD disc rather than the coherent light of a CD or DVD.
Early applications for this exciting new product include digital cinema and HDTV players, internet content streaming and data warehousing. As consumer storage needs grow, so too will the market for FMD discs and drives. The technologyâ„¢s robust nature and low manufacturing cost make it ideally suited for broad market acceptance.
FMD ROM Disk
FMD WORM Disc and Drive
Just as previous optical disc products have evolved from pre-recorded to recordable technologies, the next generation of fluorescent multi- layer technologies will give users the ability to write and record their own content for future playback. FMD WORM media will be based on the same simple technologies as ROM but will use fluorescent dyes capable of the phase change need for recording. One advantage of the media will be its ability to have both WORM and ROM on the same carrier.
Concept FMD Peripheral Drive
WORM drives will have the same cost structure as ROM drives but incorporate a slightly different laser configuration to allow for writing and reading.
ClearCard Disc and Drive
To meet the capacity needs of the growing mobile computing marketplace, including everything from E books to MP3 players to PDAâ„¢s and (IPS units, Constellation 3D has announced a miniaturized version of its Fluorescent Multi-layer technology.
ClearCard is a credit card sized media. As with the FMD disc technology, the first product release will be a ROM version with future releases to be WORM versions or combined WORM and ROM versions.
First generation WORM and ROM products will likely hold up to 10 gigabytes. This gives ClearCard hundreds of times the potential storage flash memory now used in many mobile applications, at a fraction of the manufacturing cost.
The ClearCard drive will be a miniaturized version of the FMD drive with the low power requirements and small size required by the mobile market.
Concept FMC Peripheral Drive
Future Disks & Cards
By adding layers and taking advantage of blue laser technology, second and third generation cards and discs will have capacities up to and exceeding 1 Terabyte (1,000 Gigabytes). In addition Read/Write versions of disc and card are planned.
DIGITAL DATA STORAGE
Mass Storage Products
Data storage devices currently come in a variety of difterent capacities, access time, data transfer rate and cost per Gigabyte. The best overall performance figures are currently achieved using hard disk drives (HDD), which can be integrated into RAID systems (reliable arrays of inexpensive drives) at costs of $10 per GByte. Optical disc drives (ODD) and tapes can be configured in the form of jukeboxes and tape libraries, with cost of a few dollars per GByte for the removable media. However, the complex mechanical library mechanism serves to limit data access time to several seconds and affects the reliability adversely. Most information is still stored in non-electronic form, with very slow access and excessive costs (e.g., text on paper, at a cost of $10 000 per GByte).
Figure shows the basic components of different recording technologies. Magnetic disk heads fly on a slider at a distance of approximately 0.1 micrometer above the surface of the storage medium.
During the writing process small magnetic domains are written, the magnetic fields of these domains are detected during the read process. The information can be overwritten indefinitely. The areal density of magnetic recording has grown by approximately 60% per year during the last decade. Devices with 10 Gbit/sqi are currently in production, 3OGbit/sqi have been demonstrated. However, there appears to be a limit - the super paramagnetic limit where the magnetic domains become unstable, thus limiting further growth in the areal density achievable. In optical disc drives (ODD) such as CD, DVD and MO, light from a semiconductor laser is focused onto the storage layer to perform writing/reading. The storage layer is protected through the disc substrate or a thick overcoat, making this technology well suited for removable media. The achievable storage density is determined by the size of the recording spot, which in turn is determined by the wavelength of the laser light, resulting (with current 650 nm red lasers) in a maximum a real density of 5 bits/micrometer 2. Advances in laser technology leading to utilization of 480 nm blue lasers will increase this density four-fold. Advanced optical techniques using magneto-optic MSR,MAMMOS, HYBRID, near-field and super-RENS technologies are expected to achieve areal densities of approximately 50 bit/ sqi over the next ten years, making capacities of up to 100 GByte per disk possible on CD/DVD sized 120-mm diameter, 1.2-mm thick disks.These systems will need to use blue lasers, complex-structured media and extremely sophisticated optics and mechanics. Areal densities of various techniques are shown in Figure 2.
As can be seen from the above, the storage density of media using current HDD and ODD technologies is limited due to the need to store data within a thin layer near the surface of the media.
With the advent of lasers in the 1960s, storage in 3D has been proposed by using holographic techniques. However, attempts at commercialisation have so far failed, primarily due to lack of suitable storage materials for media manufacturing.
In a multi-layer card or disc, several layers are integrated into the media, separated from each other by distances as small as 15 micrometers. A recording laser beam is focused onto one layer at a time writing and reading the layers separately.
The concept of multilayer optical discs has been proposed by Philips and IBM, and has been demonstrated up to several layers. The DVD is an implementation of this concept with two layers. However, for many layers the coherent nature of the probing laser beam causes interference scatter and intra-layer cross talkâ€the combination of which results in a signal that is degraded to unacceptable levels. Following its research into the feasibility of producing a 6-layer optical disc, IBM announced that it would not proceed to production of such devices due to the many difficulties involved in its implementation and thus commercialisation.
The concept of multi-layer, fluorescent cards/discs (FMD/C) is a unique breakthrough; solving the problems of signal degradation. Here the storage layer is coated with a fluorescent material. When the laser beam hits the layer, fluorescent light is emitted. This emitted light has a different wavelength from the incident laser lightâ€slightly shifted towards the red end of the light spectrumâ€and is incoherent in nature, in contrast to the reflected light in current optical devices. The emitted light is not affected by data or other marks, and transverses adjacent layers undisturbed. In the read-out system of the drive the light is filtered, so that only the information-bearing fluorescent light is detected, thus reducing the effect of stray light and interference.
Theoretical studies, confirmed by experimental results, have shown that in conventional reflection systems the signal quality degrades rapidly with the number of layers .In fluorescent read out system, on the other hand the signal quality degrades much more slowly with each additional layer (see below). Research has shown that media containing up to a hundred layers are currently feasible, there by increasing the potential capacity of a single card or disk to hundreds of Gigabytes. Use of blue lasers would increase the capacities to over 1 Terabyte.
The main advantages of multilayer fluorescent read out are:
1. The multi-layer system is optically transparent and homogeneous.
2. Low absorption in each layer.
3. No absorption for the emitted signal fluorescent light.
4. Lower than CD/DVD sensitivity to imperfections in media and drives. The fluorescent technique does not depend on interference effects and requires less stringent manufacturing tolerances for media and drives.
5. The emitted fluorescent light from any given layer is non coherent, eliminating the problem of parasite inter-ference.
6. The limited lateral spatial resolution for this system is twice that for coherent-light-based systems (e.g. current CD/DVD reflective systems). In the case of FMD/C, this two-fold improvement over three (3) dimensions, results in an eight-fold improvement in achievable data density.
7. FMD technology is compatible with current CD and DVD formats having the capacity to handle the same data rates over each of its layers
The above qualities make FMC unique in its techno-logical capability to facilitate production of a multilayer optical card, ClearCard, in any form factor including postage-stamp-sized SmartMedia, credit card sized ClearCard, or otherwise. The capacity and speed of reading from these cards can be enormous. For instance, with the level of existing technology ClearCard of 16 cm 2 of area with 50 layers can furnish consumers with 1 terabyte capacity and, through parallel access to all its layers, allow over 1 gigabyte/s speed of reading. Another major advantage for both cards and discs using the technology is the ability to read data on every layer of the media in parallel, thereby allowing the potential of much greater data transfer rates compared with single layer media. This can be combined with parallel reading from multiple sectors of the same layer to increase data speeds still further, producing 3-dimensional data transfer.
STATUS OF DEVELOPMENT
A principal obstacle to the development of small portable appliances with large data storage capacity is the lack of inexpensive small size memory carriers that can store Gigabytes of information in a media allowing fast data transfer rates. Constellation 3Dâ„¢s fluorescent multi-layer technology enables the production, in a wide variety of form factors, of storage media satisfying these criteria.
The FMD/C media consist of several plastic (polycar-bonate) substrates bonded together.The substrates contain surface structures (pits) that a re filled with a proprietary fluorescent storage material.
A major design goal in the development of CD/DVD replacements using this technology was to allow a simple and cost-effective upgrade for existing manufacturers of optical devices. FMD technology enables the use, with only relatively minor changes (such as impregnation with flourescent materials), of existing components and processes from high volume products such as CDs/DV D s, and avoids the need for new infrastructure for media and drive production. The number of process steps per layer is actually reduced, because a reflective metallic layer is not required. For the individual layer of a multilayer disc, metal stampers containing the digital content are produced in a mastering process that is similar to CD or DVD processes. For FMD/C, two replication processes have been developed:
1. Hot-embossing: In this process, thin sheets of polycarbonate are embossed on both sides with the metal stampers at elevated temperatures. The embossed pits are then filled with the fluorescent dye. After the dye is cured, the individual sheets are bonded together under pressure, resulting in a storage media having multiple layers. Figure 4 shows a 7-layer media.
2. Photo-polymerisation (2P) process: In this method, layers are replicated one after the other the formation of thin replicas. This technology has been demonstrated for up to ten layers.
Perhaps the most critical component of the storage media is the fluorescent material that converts the incident (incoherent) laser light into incoherent fluorescent light. The materials and associated drives for read-only cards and discs (ROM) are currently the most mature FM technology. Recordable materials and associated drives have also been developed and demonstrated, and improvement of this FM technology continues. FMD/C write/read technology based on proprietary photochromic substances has been demonstrated in Constellation 3Dâ„¢s laboratories during write! read / erase / re-write experiments.
FMD/C ROM (read only) Devices
There are several requirements for the fluorescent materials:
1. The fluorescent ROM material has to be compatible with the substrate material
2. The absorption wavelength should be the same wavelength as commercially available, low-cost semiconductor lasers used in CD players
3. The emitted fluorescent light should be wavelength-shifted by at least 35 nm, to allow easy separation of the incident and signal light
4. The material should have a high conversion efficiency
5. The material should have a refractive index close to that of the polycarbonate
6. The material should remain stable over a reasonable time
7. Fast response â€ 1 ns
Light-sensitive material: The photo-polymer composition (PPC) is a mixture of monomers and oligomers with photo-initiator, which initiates the polymerisation process under radiation in a certain spectral range. PPC serves as the substrate for the data carrier, oxazine- 1, methylene blue, methylene violet and other red dyes serve as the photo-initiator.
Pit-filling process: The working surface of a polycar-bonate disc is a plane with pits: cavities 0.5 micrometer in size, located in a certain order. Such micro relief can be filled with liquid monomeric or oligomeric substances that turn into hard polymer substances when subjected to UV light. The substances fill the pits and overflow to form a thicker layer on the media surface. The ratio of layer thickness in the pit to its thickness on the surface makes the contrast. One of the main tasks confronting the scientists in developing the process of filling the pits, creating the overflow and choosing the material, was to find the combination of these that provided the largest such contrast.
FMD/C Recordable (write once read many) Devices
In additiqn requirements for ROM media, RECORDABLE media require the following:
A writing proess where the writing light is able to turn on or off the fluorescence
A threshold level above which the fluorescent material is changed by the power level of the write, and below which the material is unchanged during any subsequent read-out
Currently 2 techniques have been developed:
Thermal bleaching: In this technique the material is initially fluorescent. The incident write light heats the material, destroying the fluorescence. The write parameters are similar to CD/R recording and the standard optical-writing 15-mW laser is well suited for providing CD-R equivalent data-writing rates. Materials suitable for applying this technique for use with red, green and blue laser wavelengths have been developed.
Photochemical reaction: Materials of this class are initially not fluorescent, and the write light initiates photo-chemical reactions, thereby creating fluorescence. The highly non-linear process associated with this reaction causes an effective threshold. Because no heating is involved, the required write power is low, allowing even light emitting diodes (LED arrays) to be used. With LED arrays, pages of information can be written simultaneously, thereby additionally enabling card applications. Current materials are sensitive to green and violet wavelengths. Constellation 3D is currently applying for further patents in respect of its FMD/C RECORD-ABLE devices, and further details on this technology will be published thereafter.
10-layer discs with CD type density have been demon-strated (650 Mbyte per layer).
The above mentioned requirements have been fulfilled:
1. 650-nm laser, 680-nm peak of the fluorescent light
2. Stable media, no degradation during read-out
3. The conversion efficiency is more than 90%
4. The time response is approximately one nanosecond The saturation level is with 1 MW/cm2, above the read power intensity
Note: In a disc player device demonstrated in Israel , digital audio was played using different content from each of the layers. 10-layer and 20- layer ClearCard was demonstrated as well.
FMC Clearcard Reader
Figure shows the device for retrieving data from a fluorescent multilayer card (FMC)-ClearCard.
A semiconductor laser produces a beam, which is then focused on a selected layer of the card. A cylindrical lens forms a 500â„¢2 mm line, which by means of a scanning mirror, scans across a page area of the card The induced fluorescent light is imaged to a CCD array.
A frame grabber receives data from the CCD. In the subsequent image processing step the image is aligned, distortions are corrected, the image is thresholded and digital data is generated. Figure 6 shows a magnified fragment of a page during the decoding process.
FMD Disc Drive
A schematic diagram of a FMD drive is shown in Figure. The drives have most componens common with CD/DvD
Systems: Laser, beam-forming optics, spindle, tracking/ focusing actuators control electronics, data channel, data interface. The only additional components are filters to separate the fluorescent light from the laser light, and an optical element to correct for different optical path lengths in the storage medium, depending on the selected layer. Modifications in the electronics include detector circuit with higher sensitivity and the addition of servo electronics to address different layers within the multi-layer disc.
50-GB Disc Project
Principle Scheme of Disc and Reading System
The principle scheme of a 50-GB disc is shown in Figure.
Â¢ Disk diameter â€ 130 Ã‚Â±0.3 mm
Â¢ Substrate width from objective side â€ 0.6 m
Â¢ Number of layers â€ 12
Â¢ Distance between layers â€ 25 Ã‚Â±5 m
Â¢ Total width. of information area - 275 m
Â¢ Format - modified DVD
Â¢ Distance between tracks â€ 0.8 m
Â¢ Channel bit length - 5/4 of that of DVD
Â¢ Pitwidthâ€0.5 Elm
Â¢ Pitdepthâ€O.5 m
Â¢ Information capacity - 50.8 GB
Â¢ Laser â€ single-mode diode pumped CW with stabilisation
Â¢ Laser power â€ 10 mW
Â¢ Wavelength - 532 nm
Â¢ Aspheric objective with NA = 0.5
Â¢ Objective lens is designed for 8 10-m thickness of substrate
Â¢ Lens and compensator have wideband antireflection coatings for 500-700 nm
Principle diagram of reading head
The principle diagram of the head is shown in figure.
Â¢ Single lens objective with NA=0.5
Â¢ Parallel beam
Â¢ Spatial filtration by means of matching of pit image and photo detector size
Inter-track cross talk
The role of the information layer image on the detector surface is
Â¢ Spatial filtration is provided by matching of pits image and photo detector sizes
Â¢ Magnification of the system â€ 20
Â¢ Detector surface area serves as aperture
Â¢ Photo detector size is 20 -20 mm
Â¢ Detector collection coefficient is 90% for useful fluorescent signal
Â¢ Signal-to-noise (from neighbor tracks) ratio is 190
The HF component of interlayer cross-talk is negligibly small Even integral photo-detector illumination by all neighbour layers is small Spatial filtration system described above with distance between layers equal to 25 [ leads to integral background illumination less than 40 dB.
Parallel read out
Using a CCD array as a photosensitive element opens up new opportunities for parallel reading with high data rate. Mega-pixel CCD arrays with frame rate of several kHz provide data rates up to Gbit/s. The CCD-array-based on time delay integration (TDI) technology is capable of reading a low-intensity signal with data rates of about several tens of MHz. For average data density the corresponding data rate is 10 Mb/s.. Note that the mechanical velocity is 450 times less than in a DVD player. Standard demand for reading in DVD format SNR > 20 dB is satisfied even for velocity of 100 mm/s with corresponding data rate of 0.1 Gbit/s. The imaging of fluorescent marks provides the spatial resolution twice that for the reflected signal because of the non-coherent nature of fluorescence.
INDUSTRIAL PRODUCTION PROTOTYPES
Constellation 3D, Inc. has developed and proven the basic technology and will continue to develop fully functional prototypes of end-user products. With respect to each of the following products, the company will seek and establish joint ventures with strategic partners having an established market share and manufacturing capability in the relevant product market.
The planned initial production model is a credit card â€ sized ClearCard ROM with up to 20 layers, 400 MB/cm 2 data density and up to 10 GB capacity, twice the current single-sided DVD disc, but at a fraction of the cost and size. The design of the reader will be simple, with virtually no moving parts, making them resilient to all kinds of shocks. The potential number of applications for which these cards could be used is almost limitlessâ€from e-books and home entertainment systems to e- books and archival and navigational systems. The ClearCard could also be used in many applications where CD/DVD discs are currently used. The cost of production of these cards is less than $10.
Note: Constellation 3D has recently confirmed in its labs the feasibility of production of a 50-layer ClearCard ROM with a storage capacity of 1 Terabyte and data transfer speeds of up to 1 Gigabyte/s. The card would be intended for use in HDTV, video and music-on- demand and other multimedia applications.
FMC Clearcard Recordable
The card is a compact version of the FMC ClearCard that enables the user to record the initial information to be stored. The planned initial production model is a credit card sized 10-layer disk with a 1 Gigabyte capacity. It is designed to fit into devices such as laptop and hand-held computers, digital cameras, cellular phones and video recorders and players, for which it will offer light weight, high capacity storage and quick access to data. The next generations of recordable cards will have nearly as much capacity read-only cards. For cameras and video players, the ClearCard Recordable will not only offer the same gains as for laptop and hand-held computers but also offer higher quality video. This technology will be ideal for downloading information from the Internet.
This disc takes the CD-ROM and DV D-ROM concept to the next level. The planned initial production model is a 120-mm 10-layer disk with 140 Gigabyte capacity, compared to less than 18 Gigabytes for a maximum capacity DVD, giving it the capacity to store up to 20 h of compressed HDTV film viewing. As mentioned above, existing CD and DVD 120-mm disc and drive manufac-turing equipment will be adaptable with minimal re tooling to accommodate the new technology. The new FMD drives will also be backward compatible with (i.e. capable of reading) existing CD and DVD media. However, it is anticipated that the majority of users will, at an early stage, decide to take advantage of the much larger capacities and superior performance characteristics of the new FMD discs and make it their media of choice for future data storage applications.
FMD/ C Reâ€Writable
Re-writable optical memory carriers have recently been gaining attention within the optical memory community and provide the maximum amount of flexibility in the determination of data stored at any given time it is a fundamental requirement of hard disk drives in PCs. In between the two extreme approaches to storing memory, ROM and re-writable, are data storage applications where the user requires the flexibility of deciding the initial data to be stored on the media and then the certainty that the data will not later be erased or amended. The initial solution to the most effective data management is FMD/C RECORDABLE storage carriers of very significant capacity. In particular Constellation 3D intends to produce a credit card sized ClearCard TM - RECORDABLE with 4.7 GBytes capacity and costing under $1O,thereby providing users of handheld devices with a cost- effective solution to their Internet downloading and other data write- once needs. The next generation products will include genuinely rewritable layers based on the most recent development carried out by Constellation 3D.
Media Manufacturing Technology
The fluorescent media manufacturing process described here utilises many processes that are typical for CD and/or DVD manufacturing However, fluorescent media requires many proprietary polymers and compositions that were exclusively developed by Constellation 3D Inc the Company intends to make these materials available to media manufacturers through its selected industry affiliated partners. The media manufacturing process described in this article relies on well known optical disc replication process. Further developments related to increase of data storage capacity to the level of multihundreds of gigabytes per disc, will require adoption of other disc manufacturing technologies currently under internal development:
Pre-mastering and mastering process
Pre-mastering and mastering processes are very similar to those utilised by CD/DVD industry. However, certain modifications of the mastering process will be required (namely glass master and stamper preparation).
These modifications are mainly related to pit geometries that are designed to facilitate reliable pit replication and pit filling.
Replica manufacturing involves preparation of circular substrates made of low birefringence plastic film (polycar-bonate, PMMA or other films with appropriate optical characteristics). Film thickness is between 25 to 30 res. prior to usage substrates are die or laser-cut to appropriate diameter (media dependent, see above). The prepared substrate is placed over radial bead of photo-polymer deposited onto a nickel matrix top surface (stamper). During the spinning process photopolymer evenly spreads between the stamper surface and the plastic substrate. Subsequently, UV curing hardens the photo-polymer and now the substrate can be separated from the top surface of the stamper. The substrate contains the precise pit geometry. The precision of pit replication exceeds quality of injection-moulded substrates (such as CDs or DVDs).
During pit filling, the fluorescent dye-polymer evenly s p reads over the entire replicaâ„¢s informational side by utilizing the spin-coating process (similarly to CD-R dye application) .After the dye-polymer is UV cured; a certain chemical bleaching process is applied to achieve the desired signal contrast ratio of pits and lands.
Each replica is optically inspected to verify proper dye-polymer filling. Such inspection is achieved by observing the emitted light from the entire area of data pits by utilizing a CCD camera. At this stage each replica is optically inspected for various physical defects such scratches, inclusions, etc.
Layers or replicas are centrally bonded onto an optical spacer (0.6-mm thick polycarbonate or PMMA substrate), by utilizing a capillary bonding method well known to the DVD industry. Since replicas are thin and thus more pliable, formation of air bubbles in the bonding layer is minimized. The requirements on centricity of informational layers are similar to DVD discs (or Ã‚Â±25 micrometer).
After multiple replicas are bonded on the top of optical spacer (see above) an additional support/protection substrate is bonded on the stack top. These decorated elsewhere substrates are made of solid color inexpensive plastic materials.
In order to prevent layer separation by physical contact, the disc outer edge is sealed with UV curable photo-polymers typically used for protection of CDs and DVDs.
SCOPE OF FMD
Dell monitoring advancements in optical technology, and expects the cost and performance of CD-RW drives to become more competitive with the magnetic formats. Dell plans to offer CD-RW/DVD-ROM Combo drives when reasonably priced, reliable devices become available. These devices should eventually replace current CD-RW drive and offer convenience, large storage capacities that are backward- compatible with previous CD formats, and DVD-ROM readability. Dell expects DVD-RAM systems to be adopted by highend users, initially. RAMbo systems, when available, are expected to provide another step in the evolution to a universal RMSD providing a large-capacity drive capable of reading and writing to the most popular CD/DVD formats.
Dell is also monitoring the development of blue laser and FMD/FMC technologies for their potential applications with existing optical formats. The smaller wavelength of the blue laser may allow data density increases from three to four times the storage capacity of current optical discs. FMD technology could provide an eight-fold increase incurrent optical disc storage capacity, and a new, smaller card format could provide an attractive, high-capacity alternative to disc storage.
Most PC applications today require more removable storage capacity than a standard floppy disk provides. At best, floppy drives offer inconvenient and time-consuming data transport for large files and applications, and require numerous disks to accomplish the task. There are a number of other magnetic storage options available today, but none of them are an ideal successor to the floppy drive. Zip drives provide adequate storage for most data transactions, but the drives are limited by their lack of compatibility with floppy disks. Imation Super Disk drives provide acceptable storage space per disk, floppy disk compatibility, and system bootabiity, but have not become a universal standard.
Optical systems are becoming the PC storage devices most likely to replace the floppy drive standard. CDROMs already are the media of choice for software applications. Zip and Super Disk drives provide a good interim RMSD solution for recording requirements, and CD-RW drives will offer a more universal standard as their costs decrease. DVD-RAM and combination systems should provide high-end RMSD solutions using large-capacity DVD discs, and providing speed, durability, data availability, bootability, and backward compatibility to CDs. Current CD-ROM/DVD-ROM disc production processes will need relatively minor changes to incorporate fluorescent multilayer technology. An FMD requires slightly deeper grooves and data pits, filled with a proprietary fluorescent storage material, for each data layer of a multilayer disc. Initial claims for the ROM version describe a multilayer disc with a 140-GB storage capacity, equivalent to approximately 20 hours of compressed HDTV data. FMD drives could be made to read existing CD-ROM/DVD-ROM discs.
Future enhancements of multilayer fluorescent storage technologies, may contribute to this longevity with the potential to provide even greater increases in data densities and transfer rates.
Â¢ computer PC magazines
Â¢ INTRODUCTION 01
Â¢ WHY FMD? 03
Â¢ FMD ROM DISC AND DRIVE 04
Â¢ DIGITAL DATA STORAGE DEVELOPMENT 08
Â¢ STATUS OF DEVELOPMENT 13
Â¢ INDUSTRIAL PRODUCTION PROTOTYPE 23
Â¢ SCOPE OF FMD 28
Â¢ CONCLUSION 29
Â¢ REFERENCES 30
I express my sincere gratitude to Dr. Agnisarman Namboodiri, Head of Department of Information Technology and Computer Science , for his guidance and support to shape this paper in a systematic way.
I am also greatly indebted to Mr. Saheer H.B. and Ms. S.S. Deepa, Department of IT for their valuable suggestions in the preparation of the paper.
In addition I would like to thank all staff members of IT department and all my friends of S7 IT for their suggestions and constrictive criticism.