Compact discs were a revolutionary product at its time and influenced many spheres of

human activity. People started recording music of high quality which didn't get worse with
the time as it happens to be on tape or vinyl. As soon as CDs appeared in computer industry
they immediately became an undoubted helper both for users and for programmers. The
latter were able to increase volume of their program products by adding video and audio
elements etc. Later discs were used for digital video (VideoCD).
But technologies are progressing. Data are growing faster and faster. A usual CD is far not
enough (640 MBytes). So, there appeared DVD technology. Of course we are happy with
those 17 GBytes that can be kept on one DVD disc, but this is a limiting point.
So we need a completely new method of storing information on portable data medium. And
at last, the company Constellation 3D demonstrates a new format: FMD (Fluorescent
Multilayer Disk) which can soon become a leader.

Constellation 3D Inc.(C3D)

The President and Executive Director of the company C3D is a physicist EvgenyLevich.
The company C3D was founded in 1995. The company is aimed at developing progressive
technologies in the field of data storage and in production in the sphere of consumption and
education. Constellation 3D provides revolutionary solutions in the sphere of data storage
and it positions itself that all their announced products must set the pitching high-efficiency
technologies of data keeping. The company has opened their offices in New-York, Florida
and California, and some laboratories in Israel and Russia. The company possesses over 60
patents.
The first generation of disc productions from Constellation 3D will be a family of 120 mm
multi-layer FM-discs with capacity up to 140 GBytes and with read speed up to 1 GBytes/s.
It's interesting to compare them with DVD that keep up to 17.4 GBytes. New discs will be
capable for example to keep up to 20 hours of compressed movies in HDTV format.

FMD-ROM: operating principle

On the picture you can see how a FMD-ROM looks like.

You can see that a disc is transparent. But where is a reflective layer like on CD and DVD
discs? The matter is that this technology doesn't need it. Let's consider FM disc in detail.
In optical discs such as CD, DVD and MÎ the process of reading is implemented the following
way. A beam of a semi-conducting laser gets on the surface of an informational layer and
then reflects from aluminum (or any other metallic) layer and fixed with a detector-receiver.
In FMD there is no reflected laser beam: when a laser beam reaches an informational layer
the latter starts radiating.
The principle of operation of FM-discs is based on a phenomenon of photochromism. Some
years ago russian chemists discovered a stable organic material a "stable photochrome"
which when acted upon by a laser beam obtains fluorescent properties.
The matter is that an informational element of FM-disc (photochrome) can change its
physical properties (such as color and presence of fluorescence) under influence of a laser of
a definite power and wavelength. Initially photochrome doesn't possess fluorescent
properties. When switching on a laser a photochemical reaction starts what causes
fluorescent properties to appear. When reading, this matter becomes excited again but with
a laser of lower power. The fluorescence is caught up by a photo-receiver and is fixed as a
value "1".
Besides, according to the company there will be no worsening of the photochrome state
with the time.

Excited photochrome radiates shifting the spectrum of falling light to the red color side
within 30-50 nm what allows to differ laser signal from the light from the disc.
Note that this technology allows preventing a problem of multiple inference between layers
since the reflected light is not coherent; it passes through layers without any difficulties and
is easily defined by a receiver. Let's talk about it a bit in depth.
In usual optical discs (CD/DVD) with increasing number of informational layers a signal gets
worse. It's explained by the fact that these technologies use a reflected signal, it means that
there is necessity in mirror surfaces. That's why in DVD technology an external layer is
made to be semitransparent in order to allow a laser to reach an internal one.

And a signal while passing an external layer leaves a part of its energy because of
reflecting. Signals reflected from both layers interfere because of their coherence, it results
in losses of useful signal. Increasing number of layers aggravates an effect of multiple
interference between the layers what makes reading more complicated. The problem can be
solved by improving detector-receivers, but it is possible only in laboratory. In case of
fluorescent discs the quality of the signal gets worse much slower with increasing number of
layers. Look at the graph below:
According to FMD-ROM developers, even with a hundred layers a useful signal will be
acceptable.

FM-disc
As you can see in the picture a disc consists of several plastic (polycarbone) layers
connected to each other. A layer contains surface structures (pits) which are filled with
fluorescent material. When reading a laser focuses on a certain layer and excites its
fluorescent elements, and then this radiation is caught by a photodetector.

The developers state that with a blue laser (480 nm) it's possible to increase record density
up to tensTbyte on one FM disc.
Another interesting feature is parallel reading. If we record a sequence of bits not along a
track but deep into layers we can increase speed of data access. That's why such disc is
called "3-dimensional".
Here is a list of advantages of FMD/C:
1. Multilayer disc is transparent and homogeneous
2. Small loss of useful signal while passing through several layers
3. Fluorescence of a separate element easily passes through disc layers
4. Less sensitivity (than of CD/DVD) to different imperfections of reading devices.
Fluorescent technology doesn't require special manufacturing conditions
5. Reflective fluorescent light from any layer is not coherent, it prevents a problem of
multiple interferences
6. FMD-technology is compatible with CD and DVD formats supporting the same data
distribution system on each layer.
Here is a table demonstrating one of the future projects of C3D: 50 GBytes disc (12-layer):
Parameter CD DVD FMD
Disc diameter, mm 120 120 130
Capacity, GBytes 0,64 17,4 50,8
2 (on each
Number of layers 1 12
side)
Distance between layers , micron - 40 25±5
Total width of informational layers, micron 0,11 2 275
Format CD DVD Modified DVD
Distance between tracks, micron 1,6 0,74 0,8
Optical system:
780 635-650 532
Wavelength, nm

FM disc production
Many stages of their production are put on the basis of CD and DVD manufacture. However,
some alterations are to be made here. In particular, they concern form of surface structures
and methods of filling with fluorescent material. Besides, there is no technology of
sputtering of aluminum layer what reduces the number of steps.
Mastering process is very similar to that of CD/DVD. A few words on a process of
manufacturing CD discs.
As a storage device they use a glass plate covered with a thin photoresistive layer. A laser
beam, intensity of which is modulated with digital information, gets into photoresist causing
markings that correspond to bits of digital code. After that the photoresist is developed and
covered with a metallic layer. This Master-copy after recording contains digital information
in the form of pits. Then they make an exact negative copy by a galvanic way which later
serves as a press-matrix. This negative can already be used for CD manufacture. But in
order to save this single matrix they produce several intermediate copies (negative), and
then several press-matrix (the same way) which serve for stamping CDs. After recording of
data on an informational surface in vacuum a thin layer of aluminum is sputtered. Outside,
the metallic layer is lacquered in order to prevent mechanical damage.
In FMD technology an exact copy of pit is of vital importance since later it's filled with
fluorescent material. That's why these two technologies differ. Here, a master-copy is a
nickel matrix (a stamp). It is a negative copy, like in CD-technology. A FM disc consists of
several layers that's why the process contains several steps: informational layers are
produced separately and then they are combined together.
Technological process of FM discs is divided into two types.
In the first one there used a method of hot stamping. Each layer is reached by pressing of
polycorbone layer with two stamps (Master-copies) at high temperature. So we receive one
layer with two informational sides. Then, pits starts being filled with fluorescent material.
And when it becomes hard the informational layers are pressed.
In the picture you can see a structure of a 7-layer disc produced according to the described
method.

The second method uses a process of photopolymerization when a multiple disc is reached
by stacking of discs one after another which are made from thin informational layers.
Manufacture of one informational layer lies in manufacture of plastic film with definite
optical characteristics. The film is 25 to 30 micron in width. The film which will get
information soon is either stamped or cut out with a laser. After that the film is installed on
an external surface of a nickel matrix that carries a negative copy of produced informational
layer. While rotating, photopolymer matter is evenly brought in in the space between stamp
surface and plastic film. Later, when the photopolymer matter becomes hard the film get
detached from the stamp surface. The base plate now contains pits of definite geometry. A
pit's geometry is better in terms of quality than that received when manufacturing matrices
for CD or DVD since those technologies use a process of stamping of pits. When a layer with
the required position of pits is ready, they are filled with fluorescent material (it covers
evenly the whole informational side). After that the surface is processed chemically in order
to reach necessary contrast of pits and flats. Then, in order to check the copy for different
defects, photoelements get excited and the whole picture is analyzed with the help of CCD
cameras. After that the layers are "stuck" to the base plate 0.6 mm in width. And all this is
covered with a protective layer which can be used for graphics decoration. In order to
prevent a physical contact with informational layers on the edge of the disc this area is filled
as well with polymeric material, like in CD or DVD technologies.

FM read devices
On the photo you can see a prototype of such device. The developers say that the drives
intended for FM discs will easily understand CD and DVD formats. In structure the drives are
similar to CD/DVD ones for example in such parameters as laser, optics, servodrive,
tracking and focusing system, different controllers. There appear only systems that can
catch and discern fluorescence, and a service in choosing an informational layer.

Recording on FMD-ROM
We still haven't seen a prototype of record device but the company says that it is under
developing now. There used a technology WORM (Write Once Read Many). A series of
rewritable discs will be called FMD WORM. A technology of manufacturing these discs will be
the same as for FMD ROM except the fact that they will use another fluorescent material
which will be able to change the state under the influence of a laser. And when recording
you should follow two rules:
• sufficient power of a laser in order to provide an element with fluorescent properties
• threshold power of laser should be used for recording (in order to change fluorescent
properties of the material) and for reading must be used less power.
Besides, it's very important to choose a recording method. The FMD developers offer two
record principles.
The first principle (thermal) implies usage of material which possesses fluorescent
properties from the beginning (logical one). And when recording those segments which are
thermally acted upon with a laser lose these properties (logical zero).
The second principle (chemical) means usage of a material that doesn't possess fluorescent
properties form the beginning. When acting upon with a laser a photochemical reaction
starts, and the material gets fluorescent properties. There, a low-power laser is enough, or
even a usual LED. With the latter (LED matrix) there is possible a simultaneous record of
the whole array of information.
Record devices don't differ much from read ones. The only difference lies in a bit different
laser form allowing both reading and writing. Besides, we should note that it's possible to
combine WORM and ROM on one storage device! For example, imagine a 20-layer disc with
10 layers already recorded and 10 left for a user.
The company C-3d also plans to release rewritable FM discs (in the end of 2001). The
record principle is practically the same as in CD-RW technology except for the fact that
there it isn't necessary to control reflective ability of a layer - there is enough to convert
fluorescent material from one state (absence of fluorescence) into the other (presence of
fluorescence). For example, the whole layer of a FM disc will be covered with a fluorescent
material which initially doesn't possess fluorescent properties (logical zero) and when
recording a logical one a low-power laser excites a photochemical reaction in the required
place. Erasure will be done with the help of a more powerful laser.
An advantage of this technology is that the fluorescent material is much more resistant to
phase transformations than that used in CD-RW discs that's why you can rewrite it much
more times.

Parallel reading
As we have already mentioned this technology allows parallel reading; it means that a
sequence of bits is recorded not along a track but deep into layers. That's why we receive
three types of data reading: successive, successive-parallel and parallel.
A little about what in fact parallel reading is.
Reading process is carried out with the help of a solar cell (an array of CDD cameras). This
device can read low-power fluorescence of several tens MHz. And the reading speed reaches
1 Gbit/s. We should notice that mechanical speed of the drive is 450 times lower than that
of DVD.
Below you can see pictures from the site of the company C3D which clearly demonstrates
the principle of operation of parallel reading.

FMD fragment
12x enlargement of FMD segment received with CDD cameras

Signals received from each element of CDD array

Some words on other products of C3D company

Beside FM discs the company has another product called FMC ClearCard ROM. This is a
device for data storage sized a credit card. Inside there is a FM disc 50 mm in diameter. The
first models of this device will keep up to 10 GBytes in 20 layers with 400 MBytes/cm2
record density. Prime cost of this product will be less than $10. It's considered to be a good
substitute for current flash-cards in many spheres. The FMC read devices are not big and
requires little power.
Besides, the company states that in their laboratory they ha received a disc with 50 layers,
capacity of 1 Tbyte and up to 1 GBytes/s data rate.

Conclusion
Well, the only I can say here is that these products will be the roughest competitors to CD
and DVD.
The company C3D plans to release its first products already in the end of 2000. We don't
know anything about prices, and today it's difficult to say when it will enter in mass sales
market.

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FLUORESCENT MULTILAYER DISC

Fluorescent Multilayer Disc
Submitted by: Jagan.R.V.
M.Tech Computer Science [1st year]
Anna University Tirunelveli
jaganrv1992@gmail.com

Abstract— “Fluorescent Multilayer Disc (FMD) was an optical disc format

developed by Constellation 3D that uses fluorescent, rather than reflective
materials to store data. However, the use of fluorescence allowed FMDs to
operate according to the principles of 3D optical data storage and have up
to 100 data layers. These extra layers potentially allowed FMDs to have
capacities of up to a terabyte, while maintaining the same physical size of
traditional optical discs.

I.INTRODUCTION
Today the need for digital storage capacity is on increase, with a rate
growth of 60% per annum. There is strong requirement for more storage
facility for the amenities like the storage area networks, data warehouses,
supercomputers and e-commerce related data mining as the volume of
data to be processed is ever rising.
The arrival of high bandwidth Internet and data-intensive applications such
as high definition TV (HDTV) and video & music on-demand, even smaller
devices such as personal VCRs, PDAs, mobile phones etc will require
 multi-gigabyte and terabyte capacity in the next couple of years.This
increase is best achieved with optical memory technologies.
Fluorescent multiplayer disc (FMD) is a three dimensional storage that
can store a large volume of data and is also capable of increasing the
capacity of a given volume with an aim to achieve a cubic storage
element having the dimensions of writing or reading laser wavelength.
II.WHY FMD?
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 - 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 aime and multiple tracks at a time nearly
impossible using the reflective technology of a CD/DVD - is easily achieved
in FMD. This will allow for retrieval speeds of up to 1 gigabyte per second.
MEDIA TOLERANCES:
By using incoherent light to read data the FMD/FMC media will have far
fewer restrictions intemperature range, vibration and air- cleanness during
manufacturing. And will provide a considerably more robust data carrier
than existing CD and DVDs.

III.FLUORESCENT MULTILAYER
Multilayer, fluorescent discs address the problem of signal degradation by
offering a unique solution. Specifically, each data layer is coated with a
proprietary fluorescent material (dye). When the layer is struck by the laser
beam fluorescent light is emitted. This light is different in wave-length than
the incident laser light, being slightly red-shifted and incoherent in nature.
The emitted light is not affected by data or other marks and moves through
adjacent layers without being distorted. In the read system of the FMD
drive, the light is filtered; this allows only data-carrying fluorescent light to
be received, lessening the effect of interference and stray light. Unlike
reflection-based systems (DVD), the signal-to-noise ratio (SNR) degrades
much more slowly with each additional layer. This remarkable ability will
permit a single disc with as many as 100 layers.
IV.MEDIA DEVELOPMENT
The FMD media is composed of several bonded polycarbonate substrates.
Each substrate contains surface structures (pits) that are filled with a
proprietary fluorescent compound (Fig. 3). According to Ingolf Sandler of
C3D, 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 allows the use of existing facilities, with only minor
changes (i.e., addition of fluorescent compound). Compared to DVD, there
are fewer process steps per layer since a reflective, metallic layer is not
needed. For the mastering process, each layer of an FMD requires a data-
containing metal stamper, similar to CD/DVD. Unique to FMD, two
replication processes have been developed:

Hot-Embossing: Using hot metal stampers, thin polycarbonate sheets are

embossed on both sides. After the sheets cool, the embossed pits are filled
with fluorescent dye. After the dye is cured, the individual sheets are
stacked and bonded together under pressure. The result is a storage
mediahaving multiple layers: a Fluorescent Multilayer Disc .

Photo-Polymerization(2P)process:
This method, in which layers are sequentially replicated by creating
ìthinreplicasî, will eventually allow FMD to incorporate up to 100 layers
(Sandler, 1999).

V.Fluorescent Material
The fluorescent material - arguably, the main ingredient of FMD
technology- converts incident (incoherent) laser light into incoherent
fluorescent light. C3D has several material formulations. The most-
developed material is used in read-only discs. Writable (recordable) and re-
writable formulations (and their corresponding drives) have also been
demonstrated using proprietary photochromic compounds.

VI.FMD ROM (Read-Only) Technology

The fluorescent material, used in FMD ROM media, must adhere to the
following
requirements :

• Compatibility with substrate material .

• Absorption wavelength must be the same wavelength found in
commercially available, low-cost semiconductor lasers used in CD/DVD
player.
• Emitted fluorescent light must be wavelength-shifted by 50 nm (minimum)
to allow easy separation of incident and signal light .
• High conversion efficiency .
• Refraction index close to that of the polycarbonate .
• Stability over an extended period of time .
• Response time ≤ 1 nsec.
VII.FMS TECHNOLOGY
The FMS recording media consists of layers of substrate, which contain
'pits' of fluorescent material, each about 0.5um across. These substrate
layers are bound together in 10-50 layers, and held on a support platter,
which could be like a CD-ROM or like a credit card.
The read heads are very similar to a DVD drive, except they have the
ability to read more layers. This means that a FMS drive could read a DVD
disk, which could help the product the gain acceptance.

WORM (write once read many) heads use heat to destroy the fluorescent
material in selected 'pits', to create a digital pattern. Once the pattern is
burnt in, it is permanent..

VIII.Light-sensitive material
The photo-polymer composition (PPC) consists of monomers and
oligomers. With the addition of a photo-initiator, operating under a specific-
range radiation, the polymerization process is initialized. PPC functions as
the substrate for the data carrier, oxazine-1, methylene blue, methylene
violet while other red dyes function as the photo-initiator.
IX.Pit-filling process
The working surface of a polycarbonate disc is a plane with billions of pits
(0.5 µm in diameter), positioned with a specific order. These pits can be
filled with liquid monomeric or oligomeric materials that convert to hard
polymer substances when placed under UV light. The substances fill the
pits and overflow to form a thicker layer on the media surface. The greater
the difference between the layer thickness in the pit to that on the surface,
the better the contrast .
X.FMD WORM (Write Once, Read Many) Technology

In addition to the requirements for ROM media, writable (recordable) media

require the following:

• A write process in which the write laser is able to turn the fluorescence on
or off
• A standardized level above which the fluorescent material is changed by
the power level of the write laser, and below which the material is
unchanged during read-only operation .
To meet these requirements, two procedures have been developed:
Thermal Bleaching :
In this procedure, the material is initially fluorescent. The incident write
laser heats the material, destroying the fluorescence. The write parameters
are similar to CD-R; thus, a standard 15mW optical-writing laser works just
fine in an FMD-R drive. Also developed are materials that can be used with
red, green and blue lasers .

Photochemical Reaction:
Materials used in this class are not initially fluorescent. When the material
is struck by the write laser, a photochemical reaction occurs creating
fluorescence. Since no heat is required in this process, the write-power
needs are low. This allows the possibility of using inexpensive light-emitting
diodes (LEDs). Using LED arrays, huge quantities of data can be written in
parallel, allowing smaller FM technologies (cards) to become viable. C3D
has successfully demonstrated materials sensitive to green and violet
wavelengths.

XI.SECURITY

FMD will offer an extraordinary amount of security. In addition to complying

with the newest and most sophisticated encryption technologies, FMDís
unique dye chemistry will offer much greater control over access to
intellectual property. In the digital cinema realm, for example, FMDís
capacity allows for digital watermarking of each frame (there are 24 frames
per second). Dyes can even be customized to work exclusively with FMD
players used in cinemas, rendering stolen copies inaccessible to those
using consumer drives. As for protection from mass-duplicating pirates,
dyes can be designed to last only for a specific number of plays or limited
amount of time . One can easily see that FMDs security options will be
useful beyond cinema. Governments, businesses large and small, and
consumers will all benefit from them.

XII.PREVENTION OF DATA CORRUPTION:

When researchers at IBM tried increasing the number of layers, however,
their multiple laser beams encountered so much interference that the
company decided to forego further explorations in this field. Thelaser
beams required to read each layer were corrupted upon passing through
other layers. It might have been a dead end for multilayer systems, had
fluorescent coatings not stepped in to save the day.
When multiple layers of storage material are coated with fluorescent
material, they turn intervening laser beams into fluorescent light. This
fluorescent light is immune to corruption from intervening layers and other
lasers. More specifically, each base layer is marked with a pattern of "pits."
When this layer is coated with fluorescent material, the pits gather a greater
thickness of fluorescent stuff. The contrast between pit-thickness and layer-
thickness of fluorescent material results in a unique reading of stored data.
This fluorescent material is currently made of polymers that are owned by
Constellation 3D. The company intends to market these polymers to other
firms, as well as produce the 3D data-storage systems themselves. It looks
to be a huge score for the firm. In a field where increasing storage
capacities mean greater danger of data corruption

Constellation 3D has found a back door to long-term, high-capacity

memory. Research has shown that systems using fluorescent material
resist corruption much longer than naked systems. And researchers have
recently posited devices containing as many as 100 layers separated by
fluorescent coatings -- shattering earlier forecasts of feasible storage
capacities.

XIII.EASY TO UPGRADE
Ease of upgrading is another strategic advantage to multilayer fluorescent
technology. Existing CD and DVD manufacturing lines can be modified to
FMD standards without altering their essential structure. Most systems
would only require a few extra steps to deposit coatings with fluorescent
materials.

XIV.FMD HARDWARE
FMD drives have components similar to those of CD/DVD drives: laser,
beam- Generating optics,spindle, tracking/focusing actuators, servo, control
processors, data channel and data interface . The only additional
components are filters to separate the fluorescent light from the laser light
and a spherical aberration unit to correct for optical path length, depending
on selected
layer. Electronic differences include a high-sensitivity detector circuit and
additional servo electronics to address different layers within the multi-layer
disc.

XVI.FUTURE FM HARDWARE
For consumers and businesses, FMD hardware will be similar to todayís
CD/DVD hardware in both form and function. There will be internal and
external drives and burners for computer applications. In addition, there will
stand-alone FMD video players and recorders, similar to current DVD
players and VCRs. Portable units such as FMD disc men and boom boxes
are also possible.

XVII.CONCLUSION
Hence due to high data storage ,the FMD’s could be used in various field
which needs lots of space for storage.
Since the chance for data corruption is very less when compared to DVD’s
they could be used for security purposes.
First generation FMDs were to use 650 nm red lasers, yielding roughly 140
GB per disc. Second and third generation FMDs were to use 405 nm blue
lasers, giving capacities of up to a terabyte.