FR2643741A1 - OPTICAL MEMORY METHOD AND DEVICE - Google Patents

Abstract

Optical memory 12 and associated manufacturing method using electron trapping materials. Data can be written, in an optical memory 12 made of an electron-trapping material 16, by applying a visible light source 20 to the material 16. The visible light source 20 causes the electrons to be trapped in the electron. material 16, electrons can be released and emit visible light upon application of an infrared source 22 to the material. One embodiment performs logic functions through parallel memories 212A, 212B each having strips of storage material 216A, 216B placed on a plastic substrate.

Description

This invention relates to optical memory methods and systems.

  More specifically, this invention relates to the use of electron trapping materials in such

processes and systems.

  Optical techniques for storing information allow hardened removable media to carry ten to twenty times more data than the best available fixed magnetic induction media and one hundred times more than the best removable media. After years of research and development, optical reading memories and their media have recently been marketed. These optical memories were generally based on a technology of video discs with

  laser, a special type of read-only memory.

  As defined here, an "optical memory" is a memory in which the value of the data is read from the memory

  according to an optical energy (defined here as infrared visible light

red or ultraviolet radiation).

  Although read-only analog video disc systems have been mostly useful, such systems are subject to many disadvantages. Specifically, these systems are based on a burned disc configuration

  laser and are generally not susceptible to reprogramming.

  Initial programming of a laser disc requires a source to

  generally high power laser to register the configuration

  ration in the disc, although additional copies may

be made by photolithography.

  Various developments relating to optical memories are described in the article entitled "SPECIAL REPORT: THE OPTIONS MULTIPLY IN MASS STORAGE" starting on page 28 of the review

  "Electronics" dated May 19, 1986 (publ. Mc Gram-Hill).

  Among current optical memory projects and non-optical memory designs, a large number of drawbacks are common. Examples include high access time,

  expensive building materials, low storage density,

  tion, low programming and / or access speed, high error rates, inability to erase or even high power requirements. In addition, certain known storage systems require a "refresh" step when accessing the memory or as often as possible, in order to avoid loss of data in memory. That is, the data is lost S05 in the memory during access or whenever "refresh" methods and similar techniques have to be performed.

  used. An additional disadvantage of memory systems

  sation is that they are volatile in the sense that they

  lose their data at each power failure.

  A main object of the invention is to provide a system

  teme and a method of manufacturing optical memory which avoids or

  Reduces the above drawbacks.

  Another object of the present invention is to provide a manufacturing method and a new optical memory system and

  improved, based on the use of an electric trapping material

  are sensitive enough to be marked at high levels of imprint-

  low power sources and usable for main-

  keep data practically error-free and erasable.

  Another object of the present invention is to provide a

  optical memory manufacturing system and method which

  cause the data to be stored at a very high density.

  Another object of the present application is to provide a storage system which is easily accessible in parallel

  and which provides great freedom in its architecture of con-

ception.

  The above objects and others will be

  more obvious on reading the description which follows. They

  are carried out using a method comprising the steps of: writing in an area of a first optical write-read memory with electron trapping by addressing the area, and applying an optical writing energy to the area in order to enter data therein by electron trapping; and read the area by addressing the area; apply optical reading energy to the area to create

  an emission of photons from the release of piezoelectrons

  aged; and capture the optical emission energy corresponding to the emission

  photon sion. The data being erased from the area by applying an erasing optical energy to said area. Optical writing energy has a wavelength different from

  the optical energy of Reading. The optical erasure energy pos-

  sedes a higher power and the same wavelength as the optical reading energy. The optical writing energy is part of the visible light domain, the optical reading energy is in the infrared domain and the emitted optical energy is part of the visible light domain. Optical energy

  writing is applied by a laser and Lec's optical energy

  ture is also applied by a laser. The optical energy of Reading is applied by a laser from a first face of a first memory, and the optical energy emitted is captured from a second face of the first memory, opposite to the first face. A plurality of data bits can be written simultaneously to said first memory. The memories have a storage medium which contains: a basic material chosen from the group consisting of sulfides and selenides of alkaline earth metals; and from 50 to 300 parts per million of samarium. The storage medium also contains a europium compound selected from the group consisting of europium oxide, europium fluoride, europium chloride and europium sulfide, in an amount of 300 to 800 parts per million of the europium compound. Alternatively, the storage medium further comprises: from 300 to 1,500 parts per million of cerium oxide, and in that there are from 50 to 200 parts per million of samarium in said storage medium. The storage medium also contains from 1% to 5% by weight of barium sulfate. Alternatively, the invention can be formulated as comprising: a first optical read-write memory

  electron trapping; an addressing device for selecting

  operating memory areas in the first memory; a first source of optical energy intended to apply an optical writing energy to a storage area determined by the addressing device; and a sensor intended to capture the optical energy emitted relating to the release of the trapped electrons from the first memory. An address register is connected so as to provide the addressing device with a chosen address. The first source of optical energy is fixed on a head movable relative

  at the first memory. Alternatively, the device for addressing

  sage is a deflector usable to direct a beam of energy

  optical gie from the first optical energy source to different storage areas of the first memory. A second optical energy source is used to apply read and erase optical energy to the first memory. The first source is a visible light laser and the second source is an infrared laser. The first source and the

  sensor are located on opposite sides of the memory.

  The invention further comprises a second reading memory.

  electron trapping writing arranged for simultaneous application of optical energy to said first and second memory, such that a sensor depends only on a logical data function contained in the first and second

  memory. The storage medium contains the same materials

mentioned above.

  Alternatively, the invention can be defined by electron trapping storage materials as described above when they are mounted on an aluminum oxide substrate to form a disc, or a strip, of addressable optical memory, or other suitable devices for

memorization.

  The characteristics set forth above and others of the present invention will become evident on reading the following reading made with reference to the accompanying drawings in which identical references represent identical parts throughout the various figures, and according to which: Figure 1 shows the operating principle of the

  memory according to the present invention.

  FIG. 2 shows a frequency spectrum of the output signal from a particular storage medium according to the present

invention.

  Figure 3 shows a frequency spectrum of the signal

  output of a storage material according to the present invention.

  Figure 4 is a diagram of a first arrangement of

  memory according to the present invention.

  Figure 5 shows a simplified view of a second arrangement.

  storage device according to the invention.

  Figure 6 shows a third embodiment

  of a memory according to the present invention.

  Figure 7 is an arrangement of a fourth memory

according to the present invention.

  The storage system and the method according to the pre-

  sente invention are based on the use of materials pié-

  electron geage. Such materials produce free electrons upon the use of electron trapping materials. Of

  such materials produce free electrons when applied

  tion of light or other energy agents. (As used above

  before, the term "light" should include infrared light,

  visible light and ultraviolet light.) When removing

  ion of the energy-carrying agent, such as optical energy,

  free electrons can be trapped at a higher energy level

  laughter than that of their fundamental state. If the thickness of the trap (i.e. the amount of energy required to release the electron from the trap) is large and the temperature is low, the electron will remain trapped for a long time. In fact if

  the thickness of the material on which the electron is trapped is sufficient

  large enough, the electron will remain trapped almost indefinitely if there is no application of external energy such as thermal energy

and / or other optical energy.

  As shown in Figure 1, the left electron

  is originally in a valence band G and it is pro-

  pulsed to a communication strip E by application of a (visible) loading light. When removing the charging light, the electron will fall to a trapping level T. The electron will remain trapped in the trapping level until sufficient additional energy is supplied to the electron to to bring it back to the communication band E. As it is visible on the right part of Figure 1, the electron can be stimulated by infrared optical energy in order to move again to the communication band E for a recombination from which it can be brought down to the valence band G by visible light in the process. The present invention is based on the principle illustrated in FIG. 1 in the sense that light can be "memorized" by the phenomenon of electron trapping and light can be released by application of infrared radiation intended to push the electron up above the trapping level and at it

  allow to return to the valence strip.

  Before considering the specific memory systems and methods according to the present invention, it will be useful to discuss several preferred embodiments of the materials which produce the optical sensitivity necessary to achieve the

  storage systems and methods according to the present invention

  tion. The materials which can be used in the present invention will be discussed in more detail in the following examples.

EXAMPLE 1

  A storage support material is produced from the mixture having the following composition: Strontium sulphide 100 parts Barium sulphate 5.5 parts Lithium fluoride 5.5 parts Samarium 150 parts per million

  Europium oxide 550 parts per million.

  As used above and throughout this request, the words "parts" and "parts per million" will refer

  parts by weight unless otherwise noted.

  The mixture is placed in a graphite crucible inside.

  inside an oven filled with a dry nitrogen atmosphere (or a

  other dry inert gas) and heated between 1150 and 1300 degrees centi

  grades (preferably 1150 degrees) for 45 min to 1 h, such

  so that a molten mass is formed.

  After cooling, the molten mass is ground until a fine powder is obtained, the particle size of which

is from I to 10 microns.

  After grinding, the powdered material is heated to

  about 300 to 700 degrees centigrade (preferably 600

  degrees) in the graphite crucible inside the atmosphere furnace

  nitrogen sphere. This second heating is located below the melting temperature of the material and is maintained for 10 to min (preferably 30 min). This second heating results in a

  repair of the crystalline surfaces of the resulting powder material

so many of the previous steps.

  After the second heating, the material is cooled and the powdered material is then mixed with a binder or a suitable agent. After the powdered material has been mixed with a transparent binder, it is applied as a thin coating to a clear plastic substrate in order to make a memory device according to the present invention. The coating of memory material on the clear plastic substrate will preferably be between

1 micron and 20 mils.

  In the above-mentioned mixture, strontium sulfide is used as the base material, while lithium fluoride is used to provide the fusibility characteristic useful for the preferred specific embodiment. In a way

  alternative, other alkali metal sulfides and selenides

  earth can be used as basic materials.

  Barium sulfate (optional) from the previous mixture is used to improve the reflectivity of the output light from the storage material. Preferably, as indicated above, 5.5 parts are used, but between 2 and 10 parts can be used for barium sulphate, as well as between 2 and 10 parts of lithium fluoride relative to the 100 parts

strontium sulfide.

  Samarium and europium oxide from the previous mixture

  are used to establish electronic trapping. Preferably

  rence, 150 parts per million samarium are used, but the samarium could alternatively be between 50 parts per

  million and 300 parts per million. Europium oxide will be pre-

  ference between 300 and 800 parts per million, but between 400 and 600 parts per million is better with an optimal value of 550 parts per million. Europium fluoride, europium chloride or europium sulfide can also be used

  instead of europium oxide. -

  The mixture resulting from the process which has just been described provides a thickness for the electron trapping layer of 1.2 electron volts and has an output spectrum as shown in FIG. 2 which shows the frequency center of the exit at

approximately 620 nanometers.

  The memorizing material of the above composition will give an orange output light and will be valid for memorizing visible light in the sense that visible light can be used to trap electrons inside the material. During the lecture". of material, by applying infrared light

  to the material, the trapped electrons will be released, so that there-

  will release visible light. Thus, the material can serve as an optical memory, because one can memorize information by applying visible light and one can read the information by

application of infrared light.

  More details on the processes, areas of use

  reading and proportions for each of the examples cited here are

  explained in the incorporated reference requests.

EXAMPLE 2

  A second preferred mixture intended for use with the present invention has the following composition: Strontium sulphide 1CO parts Barium sulphate 5 parts Lithium fluoride 10 parts Samarium 100 parts per million

  Cerium oxide 1,200 parts per millior.

  The above mixture is treated in the same way as in Example 1 by heating it first until melting, by grinding

  the resulting molten mass and then reheating to a temperature

  ture below the melting temperature, but high enough to allow the repair of damage to the crystalline parts. The same process steps in terms of temperature and time intervals can be used when processing this second material. The resulting powder can be used with

  particles combined with a transparent binder or agent, and applied

  to a plastic substrate in order to make a memo material

  rization which produces an electron trapping at a level of

trapping 1.2 electron volts.

  In the above mixture, barium sulphate can vary between 2 and 10 parts, the samarium can vary between 50 and ZOO parts per million, lithium fluoride can vary between 2 and 10 parts, and cerium oxide can vary between 300 and 1,500 parts per million. However, the specific values of

  proportionality, which are given above, give characteristics

optimal statistics.

  The above materials will provide electronic trapping characteristics required for storage methods and systems, as defined in the present invention. The first material can be loaded very quickly with visible light having a loading wavelength of 600 nanometers or less. This material maintains the charge for very long times, years. In order to trigger the reemission of visible light, an infrared source, of the order of 8001,200 nanometers is necessary. Visible exit light will be centered around

  620 nanometers (orange) with the spectrum of Figure 2.

  The second material can be charged very quickly with visible light and will maintain the charge for periods

  very extended times, similar to the first material. We declare

  will seek a re-emission of visible light by application of an infrared source. The emission is centered around 500 nanometers, a visible blue-green light. The material can maintain the charge for extended periods of time similar to that of the first material and will re-trigger the re-emission of visible light

  approximately 500 nanometers per application of an infrared source.

  The emission spectrum under IR stimulation is illustrated on the

figure 4.

EXAMPLE 3

  A photoluminescent material is produced according to the

  ments and the method of Example 2 above, except that the mixture is heated for 2 h during the melting step. The

  output spectrum of this photoluminescent material will be essential-

  the same as in figure 4, but this material is different from

  Example 2 in that the melting step extends the infrared sensitivity

  red at higher wavelengths.

EXAMPLE 4

  A photoluminescent material is produced having the following composition: Strontium sulphide 100 parts Barium sulphate 5.5 parts Samarium 150 parts per million

  Europium oxide 550 parts per million.

  The materials listed (in the value ranges

  as specified in Example 1) are deposited on a subs-

  aluminum oxide trat by any known technique including chemical vapor deposition or physical vapor deposition (evaporation, spraying, etc.), gas diffusion, ion beam deposition, molecular beam deposition, and electron beam deposition . The materials and substrates are placed in a furnace for melting under the conditions of Example 1. The material melts without the use of the lithium fluoride of Example 1. The photoluminescent material binds so well to the oxide substrate d aluminum, the use of separate agents or binders is not necessary. The structure resulting from the melting step can optionally be encapsulated in a clear plastic in order to produce the device of FIG. 3. No grinding or reheating is necessary. The method of Example 4 can be applied to an aluminum oxide disc in order to produce an optical memory

  which can, in an identical way, be coated with a clear plastic.

  The method of Example 4 can be used with the base materials of Examples 2 and 3 with the exception of lithium fluoride which is not used. The melting step can be carried out under the conditions of Example 2 or of Example 3. As in Examples 1, 2 and 3, the use of barium sulfate is not

  not absolutely necessary, but greatly improves the characteristics

optical ticks of the material.

  The substrate for Example 4 can be an aluminum oxide.

  minimum in the form of sapphire or ruby, in which case the layer of optical material can be as thin as 0.5 microns in order to

  form a memory of very good quality.

  The optical materials of the present invention can be used for memories and / or IR sensors by their characteristics of electron trapping in a crystalline form (for example, the form of examples 1, 2, 3 before grinding), the pulverized form (examples 1, 2 and 3), and an amorphous form

(example 4).

  Returning now to FIG. 4, a memory system

  sation 10 according to the present invention will be described in detail.

  The storage system 10 uses an optical memory

  12 having a plastic substrate 14 and one of the memo materials

  described above in detail. The optical memory material 16 adheres to the substrate 14 using a binder and the method

described above.

  A read-write head 18 is used to write data to the electron trapping material 16, and to

  reading data from the electron trapping material 16.

  More specifically, the read-write head 18 comprises a source of writing optical energy, such as a visible light laser 20, a source of reading electromagnetic energy such as an infrared laser 22, a modulator of amplitude 24 for varying the intensity of the laser output 22, and a sensor 26. A beam decomposition mirror 28 and a dichroic mirror 30 are used to ensure correct orientation of the light beams used in the optical system. In place

  of the sensor 26 placed inside the read head 18

  write, a sensor 26A can be placed on a face of the memory 12 opposite to the face on which the read-write head 18

is willing.

  The read-write head 18 can be mounted mobile in order to access different storage areas inside the optical memory 12. More specifically, the head 18 can be mobile under the control of a motor and a reader 32 which are used as an addressing device in that they control

  the address to which the beams coming from the laser are directed.

  The motor and reader 32 used to move the housing in which the read-write head 18 is placed and is controlled by the address register 34. The memory 12 can be a rotating disc and the head 18 can be radially movable and usable to initiate read-write operations when the disc is in a specific part of its rotation corresponding to the desired memory area aligned with the read laser beam or

  writing. The head 18 can be connected and mounted for movement.

  ment with respect to the optical memory 12 in a similar manner to mounting a head for a compact disk drive, also known as a laser disk drive. This type of connection being well known, it is not necessary to describe specific details here. The operation of the embodiment of Figure 4 will now be described. Data can be written to the storage medium material 16 of the optical memory 12 by triggering the visible light source, such as (although

  the sources are all designated as laser, the present invention

  advantageously does not require lasers and leds for

  should be used instead) the laser 20. In particular, the laser 20 produces a light beam 36 which passes through the beam splitter 28 and the dichroic filter 30 and will excite a particular storage area in the memory

  optics 12 with visible light. Thus, the laser 20 pro-

  evoke an electron trapping in the storage area on which the beam 36 is directed, this storage area being determined by the output of the address register 34. The output of the address register 34 controls the motor and reader 32 so to move the head 18 to an area corresponding to the address to

inside register 34.

  When it is desired to read a particular address inside the optical memory 12, the address is loaded into the address register 34 and the motor and reader 32 moves the head 18 to an appropriate position so that that the exit of

  laser 22 infrared reading is aimed at the appropriate area

  prayed. The output of the laser 22 is a beam 38 which is modulated by the amplitude modulation 24 for reasons discussed in detail below. After the modulation, the beam 38 hits the dichroic filter 30 and is reflected by the dichroic filter also called "" hot mirror ". The filter 30 reflects the infrared, but allows visible light to pass through. Once the infrared beam from the laser 22 has struck the storage area at

  inside the optical memory 12, the optical material 16 pro-

  produces visible light corresponding to the release or release of a few trapped electrons provided that the zone has previously been activated by the writing beam 20. The visible light output corresponding to the reading beam passes

  easily through the filter 30 and it is directed by the frac-

  beam cutter 28 to the sensor 26 which can thus read the data contained in the particular storage area. If no visible light is captured, the address to which we had access will be read as zero. On the other hand, if the writing laser

  has already written in the storage area which is addressed

  The sensor 26 will indicate the presence of a visible light beam corresponding to 1 in this storage area. The sensor 26 can be a photomultiplier, a phototransistor, or

  one of the many possible optical sensor devices.

  In the embodiment in which the sensor 26A is used in place of the sensor 26, visible light from the optical memory 12 passes through the substrate 14 and reaches the

  sensor 26A where it can be processed.

  The sensors 26 or 26A can be connected to a computer

  in any case known, as is the address register 34

  can be connected in any way known per se to a computer.

  Thus, it is not necessary to describe in detail the connections between these components and the computer. Of course, one or more buffer registers or other elements can be connected between

  sensor 26 or sensor 26A and the computer.

  The head 18 can be connected and mounted for its movement

  ment to the optical memory 12 in a manner similar to mounting a head in a compact disc drive also known as a laser disc drive. This type of connection being well known, it is not necessary to describe it here in more detail.

detail.

  When reading the optical memory 12, the infrared beam from the laser 22 will be sufficiently attenuated by the

  amplitude modulator 24 so that only some of the electro

  trapped sections from the particular storage area are not released. The optical material 16 being sufficiently dense in

  trapped electrons, the beam will not release all the electrons.

  Thus, a particular storage area, which has been established or written by the laser beam 20, will retain its data for numerous readings thus minimizing the need for refresh circuits. When it is desired to erase the data within a particular storage area or write a zero in the memory, the infrared reading laser can be fully applied to the storage area, so that virtually every electrons trapped in it will be released, thereby zeroing the storage area again. (Thus, laser 22 can be used as a writing source when writing zero and as a reading source when applied at low power.) In order to apply Laser 22 at full power

  to the optical memory 12, the amplitude modulator will be posi-

  operated in minimum position or in position without modulation or in

attenuation position.

  The preceding discussion assumes that the optical memory is in a charged state (ie having trapped electrons) which corresponds to a logical level "one". However, the optical memory 12 can also be arranged so that the presence of trapped electrons indicates a zero logic level being

  given that the particular logic (positive or negative) is arbitrary

to milk.

  Turning now to Figure 5, a memory system

  additional sation is shown. The 110 storage system

  comprising several identical or practically identical components

  ticks to the components of system 10 of figure 4, the components of figure 5 have been numbered with the same two last

  hundred figures as the corresponding components.

  The system 110 comprises a write source 120, an acousto-optical deflector serving as an addressing device 132, a reading source 122, a separate acousto-optical deflector serving as an addressing device 140, a reader 142, a digital converter. analog 144, and an address register 134. An optical memory 112A is constructed identically to the optical memory 12 of FIG. 4. The memory of FIG. 5 includes an optical coating of the electron trapping material

  116A and a corresponding substrate 114A.

  A sensor 126 is arranged on a face of the memory opposite to the face on which the reading source and the source

writing are arranged.

  16- In order to write in the storage system shown in FIG. 5, the visible light laser 120 produces a beam 136 which is loaded into the acousto-optical deflector 132 from which it can

  be deviated by a variable angle corresponding to the appropriate address

  prayed. The address can be determined by an address register loading a digital-analog converter and a reader such

  than the arrangement shown immediately above for the deflec-

  acousto-optic sensor 140. The arrangement in FIG. 5 shows the visible light laser 120 as being capable of writing on the

* first memory 112A.

  When you want to access data contained in

  inside the memory 112A, the infrared laser 120 is com-

  ordered by the acousto-optical deflector 140 in order to have access to a storage zone corresponding to a trigger in the address register 134. The output of the address register 134 is converted into an analog signal controlling a reader 142. The reader 142 is preferably a voltage-frequency converter or

  a voltage controlled oscillator and its output will be a

  quence which depends on the desired address. The output of the reader 142 will control the deflection angle of the deflector 140 so that it has access to the address for which data reading is desired. A galvanometer deflector can be

  used in place of the acousto-optic deflector 140.

  The output of the infrared reading laser 122

  can, optionally, be modulated by a modulator

  lation of similar amplitude to that referenced 24 in FIG. 4, so as to provide the erasure of the data and to program the

storage areas at zero.

  If the beam 138 is directed to the appropriate address by the acousto-optical deflector 140, it causes the emission of light from the optical memory 112A provided that the storage area has previously been set to 1. The light output from memory 112A, if it exists, will then be passed to

  through the plastic substrate as light 150.

  FIG. 6 shows another optical storage system 210 in which the components are marked with the same last two digits and belong to the series 200 as the corresponding components of the embodiment of FIG. 4. The arrangement of FIG. 6 shows a plurality of read-write heads 218A and 218B which can be used for parallel access in combination with sensors 226A and 226B. An address register and a reader will be used for each of heads 218A and 218B, but they have no not been represented for a purpose

of simplification.

  FIG. 6 also schematically illustrates a provision

  sition for a logical or Boolean "OR" function. Specifically

  two memories 212A and 212B are arranged in parallel,

  each memory having alternate strips of memo material

  216A and 216B. Alternative bands 216A and 216B allow

  provide access to two memory areas, one memory area on

  212A and the other on memory 212B, with a single beam of reads

  ture 238. For the purpose of explanation, the beam 238 is shown as consisting of two beams in the upper part of FIG. 6. However, in reality, this can be a single beam of sufficient width for it to strike a memory area on the strip of storage material 216A and that part of the beam strikes a part of the memory 212A not covered with a storage material. This last part simply passes through the transparent plastic and strikes part of one (216B) of the storage strips. Thus, the beam 238 and the read-write head 218A can be used to read two (2) memory areas simultaneously, with the output to the sensor 226A as a logic "OR" function. If one of the two (2) memory areas has been set to logic state 1, the sensor 226A will detect the light and provide a positive signal for use by the other computer. A simplified version could perform an "OR" function by accessing two (2) storage cells on a single memory, so that the sensor can capture visible light if one of the storage areas stores a "one". Another version of the memory arrangement illustrated in FIG. 6 could use a sensor having three output levels: a "zero" corresponding to a low level of the two cells, a level one for the case where only one of the cells is a high level, and a "two" level when the two cells are at a high level. A logical "AND" operation can be performed

by detection of level "two".

  FIG. 7 shows a read / write memory paraL-

  the light in which the writing light is delivered to

  360 optical fibers if desired. Memory 312 is cons-

  with memory material (one of those in the examples

  mentioned above) directly connected or covered with a 362 inter-

  face with the optical fibers corresponding to the connection of the fibers 360, so that a parallel writing (and, optionally, a reading and / or erasing) can be made through the optical fibers 360. The output of the memory 312 is a light 350 so that all the areas of the memory 312 can be read in parallel by the sensor 326 when a stimulation light 364 is applied by the reading source 322 through the diverging lens 366 and reflected by the filter dichroic 330. One or more lenses can be used between the memory 312 and the sensor 328 in order to focus the output light 350. The areas (one or more memory cells) of the memory 312 could be addressed by delivering optical radiation ( writing, reading, and / or erasing) through fibers 360 and / or by delivering optical radiation (for writing, reading, and / or

  erasure) through lens 366.

  Although the present invention has been illustrated by

  various specific materials, through constructions and arrangements

  specific regulations, it should be understood that these only illustrate the aforementioned remarks. Many modifications and

  adaptations can be made by those skilled in the art.

Claims (31)

  1. Data storage and extraction process,   characterized in that it includes the steps -   at. writing data in an area of a first optical memory made up of a fluorescent electron trapping substance consisting in: i) - addressing said area; and ii) - applying to said memory an optical energy (36) intended for writing having a first wavelength in said zone in order to enter the data therein, so that the electrons are trapped in the substance at a level high energy; and B. of reading data from said zone consisting in: i) - addressing said zone; ii) - applying a reading optical energy of a second wavelength greater than the first to said zone in order to release a part of the electrons trapped in said zone and in order to cause an emission of photons from the released electrons; and iii) - capture the optical energy emitted, corresponding to an emission of photons, so that the stored data   can be read in an essentially non-destructive way   and that the fluorescent electron trapping substance is formed as a thin film vapor deposited on a substrate to   obtain a fine storage resolution.   2. Seton method Claim 1, characterized in that it comprises the step of erasing data in said zone by: a. addressing of said area; and B. applying erasing optical energy to said area to essentially release all of the electrons trapped in said area zoned.   3. Method according to claim 2, characterized in that the optical erasing energy is of a higher power and has substantially the same wavelength as said optical reading energy.   4. Method according to claim 1, characterized in that said optical writing energy belongs to the visible light domain, in that the optical reading energy is in the infrared domain and in that the optical energy issued   belongs to the field of visible light.   5. Method according to claim 1, characterized in that the optical writing energy and the optical reading energy   are each applied by a laser (20, 22).   6. Method according to claim 1, characterized in that the optical writing energy is applied by a laser (22) from a first face of said storage (16) and in that said emitted optical energy is captured from a second side   of said storage medium, opposite to said first face.   7. Method according to claim 1, characterized in that a plurality of data bits are simultaneously written in said first memory.   8. Method according to claim 1, characterized in that said fluorescent electron trapping substance contains a mixture of a base material chosen from the group consisting of sulfides and seLenides of alkaline earth metals, intended to form a crystal- host; and 50 to 300 parts per million by weight of samarium as the first dopant, so that the substance   fluorescent acquires its electron trapping characteristics.   9. Method according to claim 8, characterized in that the fluorescent electron trapping substance also contains a europium compound chosen from the group consisting of: europium oxide, europium fluoride, chloride of europium and europium sulfide, in an amount of 300 to 800 parts per   million by weight of the europium compound as a second dopant.   10. The method of claim 8, characterized in that the fluorescent electron trapping substance also contains 300 to 1500 parts per million by weight of cerium oxide as a second dopant, and in that it there are 50 to 200 games   per million by weight of samarium in the said fluo- substance resent of electron trapping.   11. Method according to claim 8, characterized in that the fluorescent electron trapping substance contains in   addition from 1% to 5% by weight of barium sulfate.   12. Data storage device, characterized in that it comprises: a - a first optical memory (12) constituted   of a fluorescent substance trapping elect   sections with several storage areas; b - addressing means (32) for selecting storage areas in said first memory (12);   c - a first source (20) of optical energy for   determined to apply optical writing energy to a storage area determined by   said addressing means, so that the electors   trons are trapped in said zone at a high energy level and the data is memorized;   d - a second source (22) of optical energy for   keen to apply a controlled amount   of reading optical energy to a memo area   rization determined by said addressing means (32), so that a portion of the electrons trapped in said area is released, resulting in a fluorescent emission from the released electrons; and e - a sensor (26; 26A) intended to capture the energy   optics emitted, relating to the relaxation of the elect   trapped areas of said area, so that a data   memorized born is read in an essential way non-destructive.   13. Device according to claim 12, characterized in that it further comprises an address register (34) connected to   so as to provide said addressing means (32) with a chosen address.   14. Device according to claim 12, characterized in that said first and second optical energy sources are fixed on a head (18) movable relative to said first memory (12).   15. Device according to claim 12, characterized in that the addressing means comprises a first and a second deflector usable for directing an optical energy beam from said first and second sources (20, 22) towards   different storage areas of said first memory (12).   16. Device according to claim 12, characterized in that said second source (22) can also be used to apply an erasing optical energy to an addressing zone in order to release almost all of the electrons trapped in said area.   17. Device according to claim 12, characterized in that said first source (20) is a visible light laser   and in that the second source (22) is an infrared laser.   18. Device according to claim 12, characterized in that said first and second sources (20, 22) and said sensor (26A) are located on opposite faces of said first memory (12).   19. Device according to claim 12, characterized in   which it further comprises a second optical memory (212B) cons-   containing a fluorescent electron trapping substance possessed   dant several storage areas and arranged for a simultaneous application of optical energy to said first (212A) and said second memory (212B), - in that said sensor captures the optical energy from said first and second memories, and in that that the output of the sensor depends on a logical function of data belonging to said first and second memories. 20. Device according to claim 12, characterized in that said fluorescent electron trapping substance contains a mixture of a basic material chosen from the group consisting of sulphides and seLenides of alkaline earth metals intended to form a host crystal ; and from 50 to 300 parts per million by weight of samarium as the first dopant, so that the fluorescent substance acquires its characteristics electron trapping.   21. Device according to claim 20, characterized in that the fluorescent electron trapping substance also contains a europium compound chosen from the group consisting   by: europium oxide, europium fluoride, eu chloride   ropium and Europium sulfide, in an amount of 300 to 800 per-   parts per million by weight of the europium compound as a second doping.   22. Device according to claim 20, characterized in that the fluorescent electron trapping substance (216A) contains from 300 to 1500 parts per million by weight of oxide of cerium as a second dopant.   23. Device according to claim 20, characterized in that the fluorescent electron trapping substance (216A)   additionally contains from 1% to 5% by weight of barium sulfate.   24. Data storage device (12; 112A; 212A, 212B; 312) containing an optical storage medium (16;   116A; 216A, 216B), characterized in that said storage medium   rization consists of a base material selected from the group consisting of sulfides and selenides of alkaline earth metals which forms a host crystal; from 50 to 300 parts per million by weight of samarium as the first dopant; and of an aluminum oxide substrate supporting said storage means, and in that the fluorescent electron trapping substance is a thin film obtained by vapor deposition on said aluminum oxide substrate   to obtain a fine storage resolution.   25. Device according to claim 24, characterized in that it further contains a - addressing means (32) intended to select storage areas in said storage medium (12);   b - a first source (20) of optical energy for   determined to apply optical writing energy to a storage area determined by   said addressing means, so that the elect   sections in the substance are trapped at a high energy level in said zone and the data is memorized;   c - a second source (22) of optical energy intended   born to apply an optical energy of reading towards a storage area chosen by the addressing means (32), so that a part of the electrons trapped in said area is released, from where an emission of photons from the released electrons ; and d - a sensor (26; 26A) intended to capture the energy   optics emitted, relating to the relaxation of the elect   trapped sections of said area, so that a   stored data is Read in an essential way non-destructive.   26. Method according to claim 1, characterized in that the first data item is written in a first area, while   that the second datum is read simultaneously in another zone.   27. The method of claim 1, characterized in that it further comprises the step of reading and simultaneously writing additional data in other areas of said first optical memory.   28. Method according to claim 1, characterized in that   that a second optical memory (212B) is furthermore provided.   killed with a fluorescent electron trapping substance and in that   that it includes an additional step consisting in reading simultaneously-   a datum in an area of the first memory (212A) and a datum in an area of the second memory (212B) by simultaneously applying optical reading energy to the two areas in order to release a part of the electrons from said areas and cause a emission of photons from released electrons and then capturing the combined optical energy emitted, so that "OR" functions and "AND" can be set.   29. Method according to claim 1, characterized in that the optical energies of reading and writing are applied   as directed beams of optical energy.   30. Device according to one of claims 12 or 24,   characterized in that it further comprises means (24) for   modulate the optical reading energy, so that a memory area   rization can be subjected to a higher optical reading energy, causing the Release of almost all electrons   trapped in said area, thereby erasing all stored data located in said area.   31. Device according to claim 12, characterized in that said first (20) and second (22) sources of energy   optics provide directed beams of optical energy.