CA2310059A1

CA2310059A1 - Apparatus, holographic process for duplicating optical and holographic memories, and memory copy obtained thereof

Info

Publication number: CA2310059A1
Application number: CA002310059A
Authority: CA
Inventors: Eugen Pavel
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-09-10
Filing date: 1999-09-09
Publication date: 2000-03-23
Also published as: AU6375099A; WO2000016169A1; IL136091A0; EP1046083A1

Abstract

This invention relates to a holographic process for duplicating optical media. The duplication process according to the present invention uses fluorescence holography and holographic materials such as fluorescent photosensitive vitroceramics. During the duplication, a memory template (12) is first created containing an interference pattern representing an original memory (9) to be duplicated. Second, the memory template is used to recreate a hologram (13) representing a copy of the original memory. The invention provides a procedure for the large scale reproduction of optical media.

Description

APPARATUS, HOLOGRAPHIC PROCESS FOR
DUPLICATING OPTICAL AND HOLOGRAPHIC MEMORIES, AND MEMORY COPY OBTAINED THEREOF
BACKGROUND OF THE INVENTION
This invention relates to a holographic process for duplicating optical data storage media. More specifically, this invention relates to the use of fluorescence holography for duplicating optical data storage media.
Optical data storage is a known form of data storage. Known optical data storage media, such as compact discs, CD-Roms and DVDs are two dimensional media storing separate bits of information in separate small areas on one or more surfaces. Although these optical data storage media have the capacity to store large amounts of information, there is an ever - increasing need to increase capacity and improve access time. These storage media are reaching the linut of improvement in storage capacity because of physical limitations on the ability to I S reduce the size of the area needed to store a single bit. In addition, access time is deteriorating as storage capacity increases.
The use of the third dimension in optical data storage media provides a solution to the desire for increased storage capacity, fast data transfer rates, and improved access time. Known three- dimensional optical media have data storage densities that exceed the storage capacity of any present conventional two -dimensional optical storage media by more than three to four orders of magnitude.
A disadvantage of obtaining an increase in storage capacities using these three-dimensional optical storage~media is an increase in the duplication time for making additional copies of these pre-recorded media.
Currently, three-dimensional optical storage media are duplicated on a bit - by - bit basis. Each bit of information stored in an optical storage medium is stored in an individual volume, and each volume is written to individually.
Known duplication techniques for such storage media simply write each copy on a bit - by - basis. As storage capacities increase, the duplication time increases because of the greater number of individual bits to process.
Accordingly, it would be desirable to provide a duplication process for duplicating three-dimensional optical storage media within a commercially reasonable amount of time to allow for the large scale reproduction of these 3 5 storage media.
it would also be desirable to provide a duplication process for duplicating three-dimensional optical storage media that does not write copies on a bit -by -bit basis.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a duplication process for duplicating three-dimensional optical storage media within a commercially amount of time to allow for the large scale reproduction of these storage media.
It is another object of this invention to provide a duplication process for duplicating three-dimensional optical storage media that does not write copies on a bit -by -bit basis.
In accordance with the present invention, there is provided a fluorescence holographic duplicating process for duplicating optical storage media of the type where data is stored in fluorescent photosensitive materials. More particularly, an original memory is illuminated with a first coherent beam at a first wavelength.
This creates a fluorescent radiation emission at a second wavelength.
The fluorescent radiation emission is directed to a second medium, while the second medium is also being illuminated with a reference beam at the second wavelength to create a holographic record of the original memory within the second medium.
More specifically, an original storage m~ium to be duplicated is illuminated by a coherent light source at a first predetermined excitation wavelength to create a fluorescent radiation emission having a second wavelength.
The fluorescent radiation emission is directed to a second medium, which may by considered a holographic memory template blank. The fluorescent radiation emission contains all of the data to be duplicated from the original storage medium. Simultaneously, a reference beam at the second wavelength (fluorescent radiation emission .wavelength) is used to illuminate the second medium (holographic memory template blank). The fluorescent radiation emission and the reference beam create an interference pattern within the second medium.
This second medium is not a recognizable copy of the original memory, because the interference patterns cannot be read directly to extract the original data. Instead, this second medium becomes a holographic memory template that can be used to create a copy of the original memory. To make a copy, a second excitation beam at the first predetermined excitation wavelength is applied to the second medium. The resulting fluorescent radiation emission is diffracted by the interference pattern created within the second medium and reconstructs an image of the original memory, which can then be recorded on another recording medium.
In the fluorescence holography process of this invention, fluorescent photosensitive vitroceramic substrates are preferably used for the holographic template and the recording medium. This fluorescent photosensitive WO 00/16169 PG"f/R099/00013 vitroceramics combine the characteristics of two known vitroceramic types:
fluorescent vitroceramic and photosensitive vitroceramic. These vitroceramics, described in more detail in copending U.S. Patent Application No. 09/123,133 filed on July 27, 1998, which is hereby incorporated by reference in its entirety, exhibit both fluorescent and photosensitive properties.
Alternatively, in the fluorescence holography process of this invention, fluorescent photosensitive glass substrates may be used for the holographic template and the recording medium. These fluorescent photosensitive glass substrates combine the characteristics of fluorescent glasses and photosensitive glasses. These glasses, described in more detail in copending U.S. Patent Application No. 09/123, 131 filed July 27, 1998, which is hereby incorporated by reference in its entirety, exhibit both fluorescent and photosensitive properties.
The fluorescent holographic duplication process of this invention allows for large scale reproduction of optical media at reasonable duplication speeds.

The above and other objects and advantages of the invention wilt be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:
FIG. 1 is a diagram showing the optical layout used for holographic recording of an object image;
FIG.2 is a diagram showing the optical layout used for reconstruction of a holographic image;
FIG. 3 is a block diagram of the holographic duplication process used to record an interference pattern on a memory template; and FIG. 4 is a block diagram of the holographic duplication process used to recreate a copy of the original memory based on the interference pattern recorded on the memory template.

In accordance with the present invention, fluorescence holography is used for duplicating three-dimensianal optical media, to provide a practical and commercially viable duplication process. For example, duplicating an optical memory having a capacity of ten terabytes, such as that disclosed in copending, concurrently filed on September 10, I 998 as U. S. Patent Application No.
09/151,141 entitled "Three Dimensional Optical Memory With Fluorescent Photosensitive Material" which is incorporated herein by reference in its entirety, can take approximately three months to accomplish if each bit of information must be written individually. Such a process would not be practical or commercially viable. The present invention uses fluorescence holography to reduce that duplication time to about 30 minutes.
Fluorescence holography uses the hologram phenomenon to duplicate optical media. Generally, holograms store images on a holographic recording medium. The process for storing an image involves splitting a coherent light beam into an object beam and a reference beam. The reference beam is directed to the holographic recording medium. The object beam passes through or reflects offthe object being recorded, and is directed to the holographic recording medium. An interference pattern results from the combined and simultaneous application of the reference beam and the object beam onto the holographic recording medium. This resulting interference pattern is recorded on the holographic medium. After recording, the image can be holographically reconstructed by again illuminating the holographic medium with a reference beam. The reference beam is diffracted by the interference pattern to recreate the original image with all of the information contained therein.
Fluorescence holography refers to the excitation of fluorescent photosensitive materials, such as fluorescent photosensitive vitroceramics;
described in above - incorporated U.S. Patent Application No. 09/123,133, and fluorescent photosensitive glasses, described in above-incorporated U.S.
Patent Application No. 09/123,131, to generate holographic images and recordings at the fluorescence frequencies of the materials.
In accordance with the present invention, holographic duplication of three-dimensional optical media occurs in two stages. First, a memory template is created holographically and stores a representation of an original memory to be duplicated. Second, the memory template is excited by a light source to recreate a copy of the original memory.
More specifically, in a holographic duplication process according to the invention, an original storage medium (e.g. , a three - dimensional optical storage medium) is created and information (data) is recorded on the medium, preferably using a storage and retrieval system and method such as that described in above-incorporated U.S. Patent Application No. 09/151,141, and using a one-photon or two-photon absorption process. Two-photon absorption is preferred because it allows storage of information in individually selected volume locations throughout an entire optical storage media without affecting neighboring bit locations. A two-photon absorption process refers to the excitation of a molecule to an electronic state of higher energy by the absorption of two photons.
The first photon emitted by a laser at a first predetermined wavelength excites the molecule to a virtual state, while the second photon emitted by a laser at a second predetermined wavelength further excites the molecule to a real excited state.
The wavelength of the two excitation beams are such that although neither beam is absorbed individually, the combination of the two wavelengths is in resonance with a molecular transition. Therefore, both beams must temporally and spatially overlap for two-photon absorption to result. see S. Hunter, F. Kiamilev, S.
Esener, D.A. Parthenopoulos, P.M. Rentzepis, Applied Optics 29 (14) (1990), 2058 ). After undergoing this recording process, the original memory preferably is then subjected to a heat treatment to develop and fix the data recording.
The recording of information preferably is accomplished by irradiating a selected volume of the optical storage medium with a light beam which operates at a predetermined wavelength ~ - preferably the fluorescence excitation wavelength of the storage medium. Volume selection is preferably accomplished using a confocal microscope in conjunction with vertical and radial scanning systems to allow the user to focus on a specific volume anywhere in the three-dimensional material.
Upon being irradiated, the selected volume of fluorescence material that has been irradiated suffers a transition (at a structural level for the fluorescent photosensitive vitroceramic described above and at the electronic level for fluorescent photosensitive glass described above) which produces a fluorescence enhancement in the case of the vitroceramic described above, and a fluorescence extinction in the case of the glass described above.As a result, individually selected volumes of the fluorescent photosensitive vitroceramic will fluoresce more than the remainder of the vitroceramic upon being irradiated by a light beam at a predetermined excitation wavelength. In the case of fluorescent photosensitive glass, the specific volume that has been irradiated will fluoresce less than the remainder of the glass. Preferably, the light beam should be coherent and have a frequency tuned to the excitation frequency of the fluorescent holographic material. This enhancement or extinction of fluorescence allows information to be written and read by identifying the difference in fluorescence intensities between a recorded volume of the medium and a non-recorded volume in the medium. These differences in fluorescence intensities can represent a sequence of code characters (e.g. , 0's and 1's). For example, in the case of vitroceramic, enhanced fluorescence can be considered a "1" while normal fluorescence can be considered a "0" , or vice versa. In the case.of glass, extinction of fluorescence can be considered a "1" while normal fluorescence can be considered a "0" , or vice versa. Of course, whatever convention is selected should be used consistently.
The fluorescent photosensitive materials used for the three - dimensional optical storage media and used in the holographic duplication process of the present invention are preferably fluorescent photosensitive vitroceramics.
More specif cally, the materials can be fluorosilicate vitroceramics which also include one or more rare earths and one or more photosensitizing materials. These fluorescent photosensitive vitroceramics exhibit both fluorescent and photosensitive properties.
As described in more detail in above-incorporated U.S. Patent Application No. 09/123,133, a vitroceramic is a glass matrix having fme crystals precipitated therein. Vitroceramic material is obtained by first melting a glass, such as a fluorosilicate glass, in any conventional manner. The resultant glass is then subjected to a heat treatment at a temperature above the glass transition temperature, thereby preferably precipitating small crystals. Cfice the crystals are precipitated, the material has been transformed from glass to a vitroceramic.
A vitroceramic exhibits different physical and chenucal properties than the S glass material from which it originates. Vitroceramic also are isotropic, flexible as to shape in which they can be formed, and their production cost is relatively low.
Some vitroceramics are fluorescent. Fluorescent materials convert incident light having a wavelength in one portion of the spectrum into light having a wavelength in a different portion of the spectrum. For example, when exposed to ultraviolet light, some fluorescent materials can convert that ultraviolet light into visible light. Some fluorescent materials can convert infrared light into visible light in a phenomenon known as up-conversion. In 1975, F. Auzel doped vitroceramics with rare earth metals. These vitroceramics converted infrared 1 S radiation into visible light (see F. Azuel, et al. , Journal of Electrochemical Socie 122 ( 1 ) ( 197S), 101 ).
Some vitroceramics are photosensitive. When photosensitive vitroceramics are irradiated with short wavelength radiation such as ultraviolet radiation or X-rays, the optical properties of the material in the irradiated areas are modified. Photosensitive vitroceramics generally contain photosensitive metals such as copper (Cu), silver (Ag) and gold (Au). The photosensitive metals, upon exposure to the incident radiation, absorb that radiation. Upon heat treatment, the photosensitive metal particles are precipitated in the irradiated areas and serve as nucleation seeds for subsequent crystal formation. The resultant crystals change 2S the color of the vitroceramic in those irradiated areas.
Photosensitive vitroceramics have been obtained as described in U.S.
Patent No. 2, 6S 1, 14S. This process for producing a photosensitive vitroceramic requires that a sodium-silica base glass containing silver as a photosensitive element be exposed to ultraviolet light. The silver absorbs the incident radiation.
Next, a heating process is employed to generate a photographic image by precipitating silver particles in the irradiated areas. These silver particles, in turn, provide nucleation sites for the growth of NaF crystals. The NaF crystals are large enough to scatter visible light, resulting in a white opaque image, which is opal-like in appearance.
3S In order to make a vitroceramic which is both fluorescent and photosensitive for use in the duplication process according to the present invention, it is first necessary to formulate a base glass, preferably a fluorosilicate glass, which also includes one or more photosensitizing metals and one or more rare earths.
Suitable fluorosilicate base glass composition comprise about l0 mole percent to about 60 mole percent Si02, about S mole percent to about 60 mole percent PbF2, about O.OS mole percent to about 0.3 male percent Sb20s, up to about O.OS mole percent Ce02, up to about 60 mole percent CdF2, up to about _7_ 30 mole percent Ge02, up to about 10 mole percent Ti02, up to about 10 mole percent Zr02, up to about 40 mole percent A12O3, up to about 40 mole percent Ga243 and about 10 mole percent to about 30 mole percent Ln 1 F3 where Ln 1 is yttrium (Y) or ytterbium (Yb).
The fluorescent photosensitive vitroceramic is made by including in the fluorosilicate base glass one or more photosensitive metals such as silver (Ag), gold (Au) and copper (Cu) and one or more rare earths such as terbium (Tb), praseodymium (Pr), dysprosium (Dy), erbium (Er), holmium (Ho), europium (Eu) and thulium (Tm). These rare earths may be incorporated into the glass in the form of Ln2F3 (where Ln2 is the rare earth) in amounts from about 0.1 mole percent to about 5 mole percent. The photosensitive metal is incorporated in amounts of about 0.01 mole percent to about 0.5 mole percent. Preferably, the vitroceramics can contain up to about 5 weight percent of these rare earth elements.
If after the fluorosilicate base glass containing one or more rare earths and one or more photosensitizing metals is prepared, the resulting glass is then exposed to ultraviolet light in specific areas, the photosensitizing metals in those areas absorb the radiation. If glass is then subjected to heat treatment at a temperature higher than the glass transition temperature thereby causing the photosensitizing metals in the irradiated areas to precipitate and become available to serve as nucleation seeds for crystallization of fine fluoride crystals.
The resulting fine fluoride crystals contain a large amount of rare earth ions.
If the entire resulting vitroceramic is then exposed to an excitation radiation in order to cause the rare earths ions to fluoresce (the requisite excitation radiation is dependent on the particular rare earth ions present in the material composition), the presence of fluoride crystals containing rare earth ions can increase the fluorescence intensity of the areas subject to the first irradiation step to levels at least 100 times the fluorescence intensity of the areas that were not subject to the first irradiation step.
In another embodiment, the fluorescent photosensitive material used for the three-dimensional optical media and used in holographic duplication process of this invention is preferably fluorescent photosensitive glass as described in more detail in above-incorporated U. S. Patent Application No. 09/123,131 .
Some glasses are fluorescent. Fluorescent glasses, when exposed to ultraviolet light, convert that ultraviolet light inta visible light. The fluorescence of rare earth metal ions in glass was first observed in the 1880s (~ W.A. Weyl, "The Fluorescence of Glasses", in "Coloured Glasses", Society of Glass Technology, Sheffield, England, 1951 ). Fluorescent glasses are used in lasers, and the discovery of the lasing phenomenon gave a strong impetus to the development of rare-earth activated fluorescent glasses. Various fluorescent glasses and their industrial applications are disclosed in U.S. Patents Nos.
3, 549, 554, 3, 846, 142, 4, 075, 120, and 4, 076, 541.

_g_ Some glasses are photosensitive. When photosensitive glasses are irradiated with short wave radiation such as ultraviolet radiation or X-rays, the optical properties of the glass in the irradiated areas are modified.
Photosensitive glasses generally contain photosensitive elements such as: copper (Cu), silver (Ag) and gold (Au). The photosensitive elements in the glass, upon exposure to the incident radiation, absorb the radiation. Upon heat treatment of the glass (typically above the annealing point of the glass), metal particles are precipitated thus changing the color of the glass in the irradiated areas. Upon cooling of the glass, the colored areas remain colored unless subseduently reheated to a high temperature.
Photosensitivity was initially observed by Dalton and described in U. S.
Patents nos. 2, 326, 012 and 2, 422, 472. Development of photosensitive glasses is described in U. S. Patent No. 2, 515, 937.
Suitable base silicate glass compositions for use in this invention are both fluorescent and photosensitive, and comprise about 10 mole percent to about 80 mole percent SiOz, up to about 54 mole percent K20; up to about 58 mole percent NazO, up to about 35 mole percent Li20, up to about 40 mole percent BaO, up to about 40 mole percent SrO, up to about 56 mole percent CaO, up to about 42 mole percent Mg0 and up to about 48 mole percent ZnO.
Suitable base phosphate glass compositions for use in this invention are both fluorescent and photosensitive, and comprise about 20 mole percent to about 80 mole percent Pz05, up to about 47 mole percent K20, up to about 60 mole percent Na20, up to about 60 mole percent LizO, up to about 58 mote percent BaO, up to about 56 mole percent SrO, up to about 56 mole percent CaO, up to about 60 mole percent Mg0 and up to about 64 mole percent ZnO. Additionally, yttrium (Y) may be included in amounts up to about 5 mole percent.
When the fluorescent holographic process of the present invention is used with fluorescent photosensitive glass, that glass preferably is made by including two types of rare earths in a silicate or phosphate base glass. This two types of rare earths are ( 1 ) fluorescence - imparting rare earths {e.g. , ytterbium (Yb), samarium (Sm), europium (Eu) ) and (2) rare earths photosensitive agents (e.g., erbium (Er), thulium (Tm), praseodymium (Pr), ytterbium (Yb), holmium (Ho), samarium (Sm), cerium (Ce), dysprosium {Dy), terbium (Tb), neodymium (Nd) ).
These rare earths may be incorporated in oxide form into the glass in amounts up to about 5 mole percent of the rare earth oxide.
If a specific area of such a glass is irradiated of a wavelength sufficient to photoionize the photosensitive rare earth in the glass, fluorescence in that specific area diminishes. Areas which have not been so irradiated continue to exhibit a strong fluorescence. Without being bound by theory, it is believed that fluorescence is diminished in the fluorescent photosensitive glasses in areas exposed to the photoionizing radiation because the resulting photoionized photosensitive rare earths inhibit the fluorescence in that area.
Three-dimensional optical made from these fluorescent photosensitive materials (e.g. , vitroceramic or glass) provide the ability to store vast amounts of information. The holographic duplication process according to the invention provides a way to duplicate such storage media at a commercially acceptable speed.
In the holographic duplication process of the invention, an original three-dimensional optical storage medium containing fluorescent photosensitive materials (e.g. , fluorescent photosensitive vitroceramic) is recorded with information and preferably subjected to a heat treatment to develop and fix the memory. Heat treatment preferably results in the precipitation of fine crystals which enhance the fluorescence emission of the vitroceramic. The original medium to be duplicated is then illuminated with a preferably coherent excitation beam (e.g. , from a coherent beam generator such as a laser) at a first wavelength which preferably is the fluorescence excitation frequency of the rare earth ions present in the fluorescent photosensitive vitroceramic to create a fluorescent radiation at a second wavelength. Preferably, the laser beam is emitted from any type of laser (e.g. , a gas, liquid, semiconductor or solid laser) having a frequency tunable to the fluorescence excitation wavelength of the optical memory material (e.g. , the fluorescent photosensitive vitroceramic).
The fluorescent radiation emission is directed to a holographic memory template blank, which is also illuminated by a reference beam of the same wavelength as the fluorescence radiation emission. The reference beam is in a predetermined phase relationship with the fluorescence emission. This is preferably accomplished by using a portion of the first laser beam as a precursor reference beam to excite a fluorescent material which then emits the reference beam. The splitting of the precursor reference beam from the laser beam can be accomplished, e.g. , by using a beam sputter.
As a result, an interference pattern is created within the holographic memory template blank when the fluorescence emission radiation interferes with the reference beam inside the holographic memory template blank, resulting in the formation of a latent holographic image and transforming the holographic memory template blank into a holographic memory template. The memory template containing the interference pattern and latent holographic image is then treated - - e.g. , by heat treatment - - to develop and fix the image. The holographic image recorded in the holographic memory template does not itself represent a recognizable copy of the original memory, but can be made into a recognizable copy, as follows.
The memory template preferably is illuminated with another excitation beam, which is phase-conjugate of excitation beam used to produce the recording reference beam at the first wavelength to reconstruct a copy of the original memory. This excitation beam results in a fluorescent emission in the template which is diffracted by the interference pattern created in the memory template to reconstruct an image of the original memory. If another fluorescent photosensitive substrate is placed where the image appears, a latent copy of the original memory is formed on that substrate. The substrate is then treated, e.g. , by heat treatment, to develop and fix the image. After this, the substrate will represent an exact replica of the original memory and contain all of the information stored in the original memory.
The holographic materials are preferably block-shaped having planar surfaces. This permits the application of the laser beams substantially perpendicular to these planar surfaces.
The invention will now be described with reference to FIGS. 1 - 4.
FIG. 1 illustrates the general process for recording an image of an object on a holographic medium. A laser 1 emits a coherent laser beam towards a beam splitter 2. The beam splitter 2 splits the laser beam into a reference beam 3 which is directed toward the holographic recording material and an object beam 5 which is directed to mirror 14 and reflected towards object 6 where the object beam 5 passes through or reflects off the object 6 being recorded.
Because reference beam 3 and object beam 5 originate within the same beam 1, they are in a known predetermined phase relationship.
The object beam 5, obtained by the scattering of a part of the incident beam through or off the object 6 , will interfere with the reference beam 3, creating an interference pattern inside the holographic material 4 as a result of their phase relationship. The interference pattern creates a latent holographic image of the original object memory 6.
The angle between the object beam 5 and the reference beam 3, as the two beams converge on the holographic material 4, is preferably about 90°.
Both beams converge on the holographic recording material preferably perpendicular to the preferably planar surface of the material.
After stabilization of the interference pattern (developing in the case of a photographic plate) the reconstructed holographic image 8 depicted in FIG. 2 can be obtained by illumination of the holographic material 4 with an excitation beam 7, such as a laser beam. In FIG. 2, an excitation beam 7, having the same wavelength as object beam 5, is used to illuminate holographic recording medium 4. The excitation beam 7 is scattered due to the interference pattern recorded in the holographic recording medium 4. The scattering results is a reconstruction image 8 of original object 6.
A real image is obtained if the excitation beam 7 is phase-conjugate of the reference beam 3. Otherwise a virtual image is produced. A phase-conjugate reference beam used for the reconstruction eliminate the need for imaging optics..
The phase-conjugate reference beam can be obtained by a phase-conjugated mirror, or it can consist of a counterpropagating beam in the situation of plane waves.
FIGS. 3 and 4 describe procedure that are utilized to create duplicate copies of the three-dimensional optical data storage media.

-Il-FIG. 3 illustrates the recording of an interference pattern and latent holographic image within a memory template blank 12 based on the information contained in original memory 9. Original memory 9 and memory template 12 preferably are cut from the same plate, preferably have planar surfaces, and preferably are placed in contact with each other along a preferably flat planar face (FIG. 3). Original memory 9 and memory template blank 12 are preferably secured in position during the duplication process by any suitable type of holders 3 5.
Original memory 9 contains information that can have been recorded in a number of ways. Recording of information on the original memory 9 is preferably accomplished by a storage and retrieval system as described in above-incorporated U.S. Patent Application No. 09/L51,141. The duplication process according to the invention includes creating a holographic copy of the original memory 9 by creating an interference pattern and latent holographic image in memory template 1 S blank 12, and transforming it into a memory template. This is accomplished by illuminating the original memory 9 with excitation beam 10 which operates at wavelength ~,~ - - the fluorescence excitation wavelength of original memory 9.
Fluorescence radiation (having a fluorescence wavelength ~,2) is emitted as a result of excitation beam 10 illuminating original memory 9 at its fluorescence excitation wavelength. The fluorescence radiation emission is directed to a second medium 12, which may be considered a holographic memory template blank 12.
The fluorescent radiation emission contains all of the data contained in original memory 9 which is to be duplicated. A reference beam 11' - - which is tunable to the fluorescence radiation having wavelength ~,2 - - is used to ZS illuminate the s~ond medium 12. The reference beam is in a predetermined phase relationship with the fluorescent radiation emission. This is preferably accomplished by originating the first excitation beam 10 and reference beam 11' from the same laser 30 at the fluorescence excitation wavelength ~,, as follows.
Preferably a beam splitter 31 splits a precursor reference beam 11 from the first excitation beam 10 so that two beams continue to have the proper phase relationship. After being directed by a mirror 32 toward memory template blank 12, precursor reference beam 11 preferably passes through a fluorescent material 33 to create a reference beam 11' at the fluorescent wavelength ~,2.
Fluorescence wavelength matching between the reference beam and fluorescent radiation wavelength, and maintenance of the predetermined phase relationship, may also be accomplished by other methods known in the art.
The preferably planar surfaces of the original memory 9 and the memory template blank 12 allow the beams to converge on the original memory 9 and the memory template blank 12 substantially perpendicular to the preferably planar surfaces.
The reference beam 1 I' and the fluorescence radiation emission 34 from the original memory 9 create an interference pattern within memory template blank 1 Z, which is preferably a fluorescent photosensitive vitroceramic, resulting in the formation of a latent holographic image, and transforming the memory template blank 12 into a memory template. Memory template 12 is also preferably treated, e.g. , by heat treatment, to develop and fix the image.
FIG. 4 illustrates the process for recreating a copy 13 of the original memory 9 by using the holographic image created in memory template 12.
Memory template 12 and copy substrate 13 preferably have planar surfaces and are preferably placed in contact with each other preferably along a flat planar face.
The preferably planar surfaces of the memory template 12 permits the reference beam to illuminate the memory template 12 substantially perpendicular to the preferably planar surface. Memory template 12 and copy substrate 13 are preferably secured in position during the duplication process by any suitable type of holders 35. Memory 12 is illuminated by excitation beam 10, phase- conjugate of excitation beam 11 , having wavelength ~,I to reconstruct an image of the original memory 9. The excitation beam 10 results in a fluorescence emission 40 which is diffracted by the interference pattern created in memory template 12 to reconstruct an image of the original memory 9. That image forms a latent copy of the original memory inside copy substrate 13. Copy substrate 13 is then preferably treated, e.g. , by heat treatment, to fix or develop the image, and will represent an exact replica of all the information originally stored in original memory 9. The entire copying process preferably has a duration of about thirty minutes.
In the preferred embodiment, all of the holographic materials (original memory 9, memory template 12 and copy 13) preferably are of the same fluorescent photosensitive vitroceramic material so that the refractive index is the same throughout each media and the optical paths will also be the same throughout each memory for accurate duplication.
In another embodiment, all of the holographic materials (original memory 9, memory template 12 and copy 13) are fluorescent photosensitive glass.
In another embodiment, memories 9 and 13 are of the same material (e.g. , glass) and the memory template 12 is a different material (e.g. , vitroceramic).
Although in this embodiment the optical path lengths are preserved, and the process will duplicate the original memory, the duplication time may be greater than the duplication time when all three media are the same.
The present invention is illustrated in greater detail by the following examples. The invention and the merits are not intended to be limited by the materials, compositions and production procedures described in these examples.

Exams la a 1 A fluorescent photosensitive vitroceramic based on an opal fluorosilicate glass doped with terbium was used as the holographic material. The composition of the holographic material was (in weight percent) : about b9% SiOz , about 15.3% Na20 , about 5% Zn0 , about 7% AlzO3 , about 2.3% F' , about 0.01% Ag , about 0.2% Sbz03 , about 0.5% Tb40~ . After recording, the original memory 9, was subsequently subjected to a heat treatment at 550° C for 30 minutes. This resulted in the precipitation of fine crystals of NaF doped with Tb3+~ The fluorescence emission of Tb3+ ions observed in NaF crystals is at least 100 times more intense than the fluorescence emission of Tb3+ ions contained in glass matrix.
After excitation with a nitrogen laser, ~,~ = 337 nm, a strong fluorescence emission at ~,z = 351 nm was observed in the irradiated areas.
The recording of the memory template 12 as described in FIG. 3, occurred as follows. The entire original memory 9 was illuminated by laser beam 10 at ~,~ = 337 nm which excited the Tb3+ ions. The fluorescence emission radiation ( ~,z = 351 nm) interfered with reference beam 11' (~,z = 351 nm) inside memory template 12. A latent holographic image was formed. Subsequently, during the developing process, the memory template was subjected to a heat treatment at 24 550° C for 30 minutes to develop or fix the image.
The copy 13 of the original memory 9 was obtained by the procedure illustrated in FIG. 4. The memory template 12 is illuminated by excitation beam 10 (h~ = 337 nm) and a lateen image of the original memory 9 was recorded by fluorescence radiation inside the copy 13 of original memory 9. After developing with a heat treatment, the copy l 3 of original memory represented an accurate replica of the original memory 9.
Example 2 A fluorescent photosensitive vitroceramic doped with Terbium and Cerium was used as the holographic material. The base glass had the composition (in weight percent) : about 69% Si~z, about 15.31% Na24, about 5% ZnO, about 7% AIzO3, about 2.3% F' , about 0.01% Ag , about 0.02% Sbz03 , about 0.25% Tb40~ , about 0.25% CeOz .
An XeCI laser with ~,z = 308 nm supplied the excitation radiation. A
similar procedure as described in Example 1 was carried out in order to obtain an accurate replica of the original memory.
Exam I
A fluorescent photosensitive vitroceramic doped with Thulium was used as the holographic material. The composition of the holographic material was (in weight percent) : about 69% SiOz , about 15.3% NazO , about 5%

Zn0 , about 7% A1203 , about 2.3% F' , about 0.01% Ag , about 0.2%
Sb203 , about 0.5% Tm203 .
A tunable laser with ~,2 = 288 nm supplied the excitation radiation.
A similar procedure as described in Example 1 was carried out in order to obtain an accurate replica of the original memory.
Example 4 This example is a version of example l.There is changed only the copy substrate with a fluorescent photosensitive polymer as spirobenzopyran embedded in a transparent polymethylmethacrylate matrix.
The copy 13 was obtained by the procedure illustrated in FIG. 4. The memory template 12 is illuminated by excitation beam 10 (~, ~ = 337 nm) and an image of the original memory 9 was recorded by fluorescence radiation inside the copy 13 of original memory 9. The copy 13 of original memory represented an accurate replica of the original memory 9.
Thus it is seen that a duplication process has been provided for duplicating three-dimensional optical storage media within a commercially reasonable amount of time to allow for the large scale reproduction of these storage media. (3ne skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which are presented for purposes of illustration and not of limitation, and the present invention is limited only by the claims which follow.

Claims

WHAT IS CLAIMED IS:

1. A fluorescent holographic duplicating apparatus for duplicating optical memories comprising fluorescent photosensitive materials, said apparatus comprising:
(a) an original memory holder for positioning an original memory;
(b) a memory template blank holder for positioning a memory template blank; and (c) a coherent beam generator for illuminating said original memory with a coherent beam at a first wavelength to create a fluorescent radiation emission at a second wavelength and for illuminating said memory template blank with a reference beam at said second wavelength to create a holographic record of said original memory within said memory template blank;
wherein said memory template holder further positions said memory template blank for irradiation by said fluorescence radiation emission, said fluorescence radiation emission interacting with said first reference beam to transform said memory template blank into a memory template.

2. The duplicating apparatus of claim 1 further comprising a copy substrate holder for positioning a copy substrate onto which to transfer a copy of said holographic recording from said memory template.

3. The duplicating apparatus of claim 2 wherein said coherent beam generator illuminates said memory template with an excitation beam at said first wavelength to reconstruct said copy of said original memory on copy substrate.

4. The duplicating apparatus of claim 1 wherein said original memory and said memory template have planar surfaces.

5. The duplicating apparatus of claim 4 wherein said coherent beam and said reference beam are applied substantially perpendicular to said planar surfaces.

6. The duplicating apparatus of claim 1 wherein said reference beam is in a predetermined phase relation with said cohered beam.

7. The duplicating apparatus of claim 1 further comprising a beam sputter, wherein (a) said coherent beam generator directs a beam through said beam sputter to form said coherent beam and a reference precursor beam; and (b) said beam sputter directs said reference precursor beam to a fluorescent material, said reference precursor beam exciting said fluorescent material to create said reference beam.

8. The duplicating apparatus of claim 3 wherein said coherent beam generator is tuned to a fluorescence excitation frequency of said memory template.

9. The duplicating apparatus of claim 1 further comprising means for treating said memory template to develop and fix said holographic recording.

10. The duplicating apparatus of claim 9 wherein said treating means comprises a heater.

11. The duplicating apparatus of claim 3 further comprising means for treating said copy substrate to develop and fix said copy.

12. The duplicating apparatus of claim 11 wherein said treating means comprises a heater.

13. The duplicating apparatus of claim 2, wherein at least one of (a) said original memory, (b) said memory template blank, and (c) said copy substrate, comprises fluorescent photosensitive vitroceramic.

14. The duplicating apparatus of claim 13, wherein said fluorescent photosensitive vitroceramic comprises one or more photosensitizing metals and one or more rare earths, said one or more photosensitizing metals impart photosensitive properties to said vitroceramic and said one or more rare earths impart fluorescent properties to said vitroceramic.

15. The duplicating apparatus of claim 14, wherein said one or more photosensitizing metals are selected from the group consisting of silver (Ag), gold (Au), copper (Cu) and combinations thereof; and said one or more rare earths are selected from the group consisting of terbium (Tb), praseodymium (Pr), dysprosium (Dy), erbium (Er), holmium (Ho), europium (Eu), thulium (Tm) and combinations thereof.

16. The duplicating apparatus of claim 15, wherein said vitroceramic further comprises a fluorosilicate vitroceramic.

17. The duplicating apparatus of claim 16, wherein said vitroceramic further comprises, in mole percent, about 10% to about 60% SiO2, about 5%
to about 60% PbF2 , about 0.05% to about 0.3% Sb2O3, up to about 0.5%CeO2, up to about 60% CdF2, up to about 30 % GeO2, up to about 10% TiO2, up to about 10% ZiO2, up to about 40% Al2O3, up to about 40%
Ga2O3, and about 10% to about 30% Ln1Fa where Ln1 is selected from the group consisting of yttrium (Y) and ytterbium (Yb).

18. The duplicating apparatus of claim 17, wherein said vitroceramic further comprises about 0.01 mole percent to about 0.5 mole percent of said photosensitizing metal and about 0.1 mole percent to about 5 mole percent of said rare earth in the form of Ln2F3 where Ln2 is said rare earth.

19. The duplicating apparatus of claim 18, wherein said Ln1 comprises ytterbium (Yb) and said Ln2 is selected from the group consisting of Er, Ho, Tm and combinations thereof; whereby said vitroceramic is capable of converting incident infrared radiation into visible light.

20. The duplicating apparatus of claim 18, wherein said Ln1 comprises yttrium (Y) and said Ln2 is selected from the group consisting of Tb, Pr, Dy, Ho, Er, Eu, Tm, and combination thereof; whereby said vitroceramic is capable of converting incident ultraviolet light into visible light.

21. The duplicating apparatus of claim 2, wherein at least one of (a) said original memory, (b) said memory template blank, and (c) said copy substrate, comprises fluorescent photosensitive glass.

22. The duplicating apparatus according to claim 21, wherein said glass comprises two or more rare earths at least one of said two or more rare earths impart fluorescent properties to said glass and at least one of said two or more earths impart photosensitive properties to said glass.

23. The duplicating apparatus of claim 22, wherein said at least one of said two or more rare earths is selected from the group consisting of ytterbium (Yb), samarium (Sm), europium (Eu) and combinations thereof; and at least one of said two or more rare earths is selected from a group consisting of erbium (Er), thulium (Tm), praseodymium (Pr), ytterbium (Yb), holmium (Ho), samarium (Sm), cerium (Ce), dysprosium (Dy), terbium (Tb), neodymium (Nd) and combinations thereof.

24. The duplicating apparatus of claim 23 wherein said glass is silicate glass.

25. The duplicating apparatus of claim 24, wherein said glass further comprises about 10 mole percent to about 80 mole percent SiO2, up to about 54 mole percent K2O, up to about 58 mole percent Na2O, up to about 35 mole percent Li2O, up to about 40 mole percent BaO, up to about 40 mole percent SrO, up to about 56 mole percent GaO, up to about 42 mole percent MgO, up to about 48 mole percent ZnO and up to about 5 mole percent of said two or more rare earths in oxide form.

26. The duplicating apparatus of claim 23 wherein said glass is a phosphate glass.

27. The duplicating apparatus of claim 26, wherein said glass further comprises about 20 mole percent to about 80 mole percent P2O5, up to about 47 mole percent K2O, up to about 60 mole percent Na2O, up to about 60 mole percent Li2O, up to about 58 mole percent BaO, up to about 56 mole percent SrO, up to about 56 mole percent CaO, up to about 60 percent MgO, up to about 64 mole percent ZnO, up to about 5 mole percent yttrium (Y), and up to about 5 mole percent of said two or more rare earths in oxide form.

28. A fluorescence holographic process for duplicating optical memories comprising fluorescent photosensitive material, said process comprising:
(a) illuminating an original memory with a coherent beam at a first wavelength to create a fluorescent radiation emission at a second wavelength;
(b) directing said fluorescent radiation emission to a memory template blank; and illuminating said memory template blank with a reference beam at said second wavelength to create a holographic record of said original memory within said memory template blank, thereby transforming said memory template blank into a memory template.

29. The fluorescence holographic process according to claim 28 further comprising treating said memory template to develop and fix said holographic recording.

30. The fluorescence holographic process according to claim 29 wherein said treating comprises heat treating.

31. The fluorescence holographic process according to claim 28 further comprising providing said original memory and said memory template with planar surfaces.

32. The fluorescence holographic process according to claim 31 further comprising applying said cohered beam and said reference beam perpendicularly to said planar surfaces.

33. The fluorescence holographic process according to claim 28 further comprising providing a copy substrate onto which to transfer a copy of said holographic recording from said memory template.

34. The fluorescence holographic process according to claim 33 further comprising illuminating said memory template with an excitation beam at said first wavelength to construct said copy of said original memory on said copy substrate.

35. The fluorescence holographic duplicating process according to claim 34, wherein said excitation beam is phase-conjugate of the reference beam used for recording.

36. The fluorescence holographic duplicating process according to claim 35, wherein said phase-conjugate reference beam is counterpropagating reference beam when reference beam is a plane wave.

37. The fluorescence holographic process according to claim 34 further comprising applying said excitation beam perpendicularly to said memory template.

38. The fluorescent holographic process according to claim 34 further comprising treating said copy substrate to develop and fix said copy.

39 The fluorescence holographic process according to claim 38 wherein said treating of said copy substrate comprises heat treating.

40. The fluorescence holographic process of claim 34, wherein said excitation beam is emitted from a laser, further comprising tuning said excitation beam to a fluorescence excitation frequency of said memory template.

41. The fluorescent holographic process according to claim 28, wherein said reference beam is in a predetermined phase relation with said coherent beam.

42. The fluorescent holographic process according to claim 41, further comprising:
(a) directing a beam through a beam splitter to form said coherent beam and reference precursor beam; and (b) directing said reference precursor beam to a fluorescent material, said reference precursor beam exciting said fluorescent material to create said reference beam.

43. The fluorescence holographic process according to claim 28, further comprising tuning said coherent beam frequency to a fluorescence excitation frequency of said original memory.

44. The fluorescence holographic process according to claim 33, further comprising providing at least one of (a) said original memory, (b) said memory template blank, and (c) said copy substrate, as a fluorescent photosensitive vitroceramic.

45. The fluorescence holographic process of claim 44, comprising using fluorescent photosensitive vitroceramic comprising one or more photosensitizing metals and one or more rare earths, said one or more photosensitizing metals imparting photosensitive properties to said vitroceramic and said one or more rare earths imparting fluorescent properties to said vitroceramic.

46. The fluorescence holographic process of claim 45, further comprising selecting said one or more photosensitizing metals from the group consisting of silver (Ag), gold (Au), copper (Cu) and combinations thereof;
and selecting said one or more rare earths from the group consisting of terbium (Tb), praseodymium (Pr), dysprosium (Dy), erbium (Er), holmium (Ho), europium (Eu), thulium (Tm) and combinations thereof.

47. The fluorescence holographic process of claim 46, further comprising using a fluorosilicate vitroceramic.

48. The fluorescence holographic process of claim 47, comprising using said vitroceramic further comprising, in mole percent, about 10% to about 60% SiO2, about 5% to about 60% PbF2, about 0.05% to about 0.3%
Sb2O3, up to about 0.5% CeO2, up to about 60% CdF2, up to about 30 %
GeO2, up to about 10% TiO2, up to about 10% ZrO2, up to about 40%
Al2O3, up to about 40% Ga2O3, and about 10% to about 30% Ln1F3 where Ln1 is selected from the group consisting of yttrium (Y) and ytterbium (Yb).

49. The fluorescence holographic process of claim 48, comprising using said vitroceramic further comprising about 0.01 mole percent to about 0.5 mole percent of said photosensitizing metal and about 0.1 mole percent to about 5 mole percent of said rare earth in the form of Ln2F3 where Ln2 is said rare earth.

50. The fluorescence holographic process of claim 49 comprising using said vitroceramic wherein said Ln1 comprises ytterbium (Yb) and said Ln2 is selected from the group consisting of Er, Ho, Tm and combinations thereof; whereby said vitroceramic is capable of converting incident infrared radiation into visible light.

51. The fluorescence holographic process of claim 49 comprising using said vitroceramic wherein said Ln1 comprises yttrium (Y) and said Ln2 is selected from the group consisting of Tb, Pr, Dy, Ho, Er, Eu, Tm, and combination thereof; whereby said vitroceramic is capable of converting incident ultraviolet light into visible light.

52. The fluorescence holographic process of claim 45 comprising using said vitroceramic wherein said vitroceramic comprises up to 5 weight percent of rare earths selected from the group consisting of erbium (Er), thulium (Tm), praseodymium (Pr), holmium (Ho), dysprosium (Dy), terbium (Tb), neodymium (Nd), cerium (Ce), europium (Eu) and combinations thereof.

53. The fluorescence holographic process according to claim 33, further comprising providing at least one of (a) said original memory, (b) said memory template blank, and (c) said copy substrate as a fluorescent photosensitive glass.

54. The fluorescence holographic process of claim 53 comprising using fluorescent photosensitive glass comprising two or more rare earths at least one of said two or more rare earths imparting fluorescent properties to said glass and at least one of said two or more earths imparting photosensitive properties to said glass.

55. The fluorescence holographic process of claim 54, further comprising selecting at least one of said two or more rare earths from the group consisting of ytterbium (Yb), samarium (Sm), europium (Eu) and combinations thereof; and selecting at least one of said two or more rare earths from a group consisting of erbium (Er), thulium (Tm), praseodymium (Pr), ytterbium (Yb), holmium (Ho), samarium (Sm), cerium (Ce), dysprosium (Dy), terbium (Tb), neodymium (Nd) and combinations thereof.

56. The fluorescence holographic process of claim 55, further composing using a silicate glass.

57. The fluorescence holographic process of claim 56, comprising using said glass further comprising about 10 mole percent to about 80 mole percent SiO2, up to about 54 mole percent K2O, up to about 58 mole percent Na2O, up to about 35 mole percent Li2O, up to about 40 mole percent BaO, up to about 40 mole percent SrO, up to about 56 mole percent CaO, up to about 42 mole percent MgO, up to about 48 mole percent ZnO and up to about 5 mole percent of said two or more rare earths in oxide form.

58. The fluorescence holographic process of claim 55, further comprising using a phosphate glass.

59. The fluorescence holographic process of claim 58, comprising using said glass further comprising about 20 mole percent to about 80 mole percent P2O5, up to about 47 mole percent K2O, up to about 60 mole percent Na2O, up to about 60 mole percent Li2O, up to about 58 mole percent BaO, up to about 56 mole percent SrO, up to about 56 mole percent CaO, up to about 60 percent MgO, up to about 64 mole percent ZnO, up to about mole percent yttrium (Y0), and up to about 5 mole percent of said two or more rare earths in oxide form.

60. A fluorescence holographic duplicating process using fluorescent photosensitive materials.

61. The fluorescence holographic duplicating process according to claim 60 wherein said fluorescent photosensitive material comprises vitroceramic.

62. The fluorescence holographic duplicating process according to claim 60 wherein said fluorescent photosensitive material comprises glass.

63. The fluorescence holographic duplicating process according to claim 33, further comprising said copy substrate as an organic material.

64. The fluorescence holographic duplicating process according to claim 63, wherein said organic material comprises polymer.

65. An optical memory copy created by duplicating an original optical memory, said memory copy and said original optical memory comprising fluorescent photosensitive materials, said memory copy recorded by a recording process comprising:
(a) illuminating an original memory with a coherent beam at a first wavelength to create a fluorescent radiation emission at a second wavelength;
(b) directing said fluorescent radiation emission to a memory template blank; and (c) illuminating said memory template blank with a reference beam at said second wavelength to create a holographic record of said original memory within said memory template blank, thereby transforming said memory template blank into a memory template.

66. The optical memory copy created in accordance with claim 65 wherein said recording process further comprises providing said original memory and said memory template with planar surfaces.

67. The optical memory copy created in accordance with claim 66 wherein said recording process further comprises applying said coherent beam and said reference beam perpendicularly to said planar surfaces.

68. The optical memory copy created in accordance with claim 65 wherein said recording process further comprises providing a copy substrate onto which to transfer a copy of said holographic recording from said memory template.

69. The optical memory copy created in accordance with claim 68 wherein said recording process further comprises illuminating said memory template with an excitation beam at said first wavelength to reconstruct said copy of said original memory on said copy substrate.

70. The fluorescence holographic duplicating process according to claim 69, wherein said excitation beam is phase-conjugate of the reference beam used for recording.

71. The fluorescence holographic duplicating process according to claim 70, wherein said phase-conjugate reference beam is counterpropagating reference beam when reference beam is a plane wave.

72. The optical memory copy created in accordance with claim 69 wherein said recording process further comprises applying said excitation beam perpendicular to said memory template.

73. The optical memory copy created in accordance with claim 65 wherein said reference beam is in a predetermined phase relation with said coherent beam.

74. The optical memory copy created in accordance with claim 65, wherein said recording process further comprises:
(a) directing a beam through a beam splitter to form said coherent beam and a reference precursor beam; and (b) directing said reference precursor beam to a fluorescent material, said reference precursor beam exciting said fluorescent material to create said reference beam.

75. The optical memory copy created in accordance with claim 69, wherein said excitation beam is emitted from a laser, said recording process further comprising tuning said excitation beam to a fluorescence excitation frequency of said memory template.

76. The optical memory copy created in accordance with claim 65, wherein said recording process further comprises tuning said coherent beam frequency to a fluorescence excitation frequency of said original memory.

77. The optical memory copy created in accordance with claim 65 wherein said recording process further comprises treating said memory template to develop and fix said holographic recording.

78. The optical memory copy created in accordance with claim 77 wherein said treating comprises heat treating.

79. The optical memory copy created in accordance with claim 69 wherein said recording process further comprises treating said copy substrate to develop and fix said copy.

80. The optical memory copy created in accordance with claim 79 wherein said treating comprises heat treating.

81. The optical memory copy created in accordance with claim 68, wherein said recording process further comprises providing at least one of (a) said original memory, (b) said memory template blank, and (c) said copy substrate, as a fluorescent photosensitive vitroceramic.

82. The optical memory copy of claim 81, wherein said recording method comprises using fluorescent photosensitive vitroceramic comprising one or more photosensitizing metals and one or more rare earths, said one or more photosensitizing metals imparting photosensitive properties to said vitroceramic and said one or more rare earths imparting fluorescent properties to said vitroceramic.

83. The optical memory copy of claim 82, wherein said recording method further comprises selecting said one or more photosensitizing metals from the group consisting of silver (Ag), gold (Au), copper (Cu) and combinations thereof; and selecting said one or more rare earths from the group consisting of terbium (Tb), praseodymium (Pr), dysprosium (Dy), erbium (Er), holmium (Ho), europium (Eu), thulium (Tm) and combinations thereof.

84. The optical memory copy of claim 83, wherein said recording process further comprises using a fluorosilicate vitroceramic.

85. The optical memory copy of claim 84 , wherein said recording method comprises using said vitroceramic further comprising, in mole percent, about 10% to about 60% SiO2, about 5% to about 60% PbF2, about 0.05% to about 0.3% Sb2O3, up to about 0.5% CeO2, up to about 60% CdF2, up to about 30 % GeO2, up to about 10% TiO2, up to about 10% ZrO2, up to about 40% Al2O3, up to about 40% Ga2O3, and about 10% to about 30%
LnlF3 where Ln1 is selected from the group consisting of yttrium (Y) and ytterbium (Yb).

86. The optical memory copy of claim 85, wherein said recording method comprises using said vitroceramic further comprising about 0.01 mole percent to about 0.5 mole percent of said photosensitizing metal and about 0.1 mole percent to about 5 mole percent of said rare earth in the form of Ln2F3 where Ln2 is said rare earth.

87. The optical memory copy of claim 86, wherein said recording method comprises using said vitroceramic wherein said Ln1 comprises ytterbium (Yb) and said Ln2 is selected from the group consisting of Er, Ho, Tm and combinations thereof; whereby said vitroceramic is capable of converting incident infrared radiation into visible light.

88. The optical memory copy of claim 86, wherein said recording method comprises using said vitroceramic wherein said Ln1 comprises yttrium (Y) and said Ln2 is selected from the group consisting of Tb, Pr, Dy, Ho, Er, Eu, Tm, and combination thereof; whereby said vitroceramic is capable of converting incident ultraviolet light into visible light.

89. The optical memory copy of claim 82, wherein said recording method comprises using said vitroceramic wherein said vitroceramic comprises up to 5 weight percent of rare earths selected from the group consisting of erbium (Er), thulium (Tm), praseodymium (Pr), holmium (Ho), dysprosium (Dy), terbium (Tb), neodymium (Nd), cerium (Ce), europium (Eu) and combinations thereof.

90. The optical memory copy characterized in that the copy substrate is a fluorescent photosensitive vitroceramic, wherein said memory copy contains zones with difference in fluorescence intensities, enhancement with more than 5%, between recorded volume of the medium and a non-recorded volume in the medium.

91. The optical memory copy according to claim 68, wherein said recording process further comprises providing at least one of (a) said original memory, (b) said memory template blank, and (c) said copy substrate, as a fluorescent photosensitive glass.

92. The optical memory copy of claim 91, wherein said recording process comprises using fluorescent photosensitive glass comprising two or more rare earths at least one of said two or more rare earths imparting fluorescent properties to said glass and at least one of said two or more earths imparting photosensitive properties to said glass.

93. The optical memory copy of claim 92, wherein said recording process further comprises selecting at least one of said two or more rare earths from the group consisting of ytterbium (Yb), samarium (Sm), europium (Eu) and combinations thereof; and selecting at least one of said two or more rare earths from a group consisting of erbium (Er), thulium (Tm), praseodymium (Pr), ytterbium (Yb), holmium (Ho), samarium (Sm), cerium (Ce), dysprosium (Dy), terbium (Tb), neodymium (Nd) and combinations thereof.

94. The optical memory copy of claim 93, wherein said process further comprises using a silicate glass.

95. The optical memory copy of claim 94, wherein said recording process comprises using said glass further comprising about 10 mole percent to about 80 mole percent SiO2, up to about 54 mole percent K2O, up to about 58 mole percent Na2O, up to about 35 mole percent Li2O, up to about 40 mole percent BaO, up to about 40 mole percent SrO, up to about 56 mole percent CaO, up to about 42 mole percent MgO, up to about 48 mole percent ZnO
and up to about 5 mole percent of said two or more rare earths in oxide form.

96. The optical memory copy of claim 93, wherein said recording process further comprises using a phosphate glass.

97. The optical memory copy of claim 96, wherein said recording process comprises using said glass further comprising about 20 mole percent to about 80 mole percent P2O5, up to about 47 mole percent K2O, up to about 60 mole percent Na2O, up to about 60 mole percent Li2O, up to about 58 mole percent BaO, up to about 56 mole percent SrO, up to about 56 mole percent CaO, up to about 60 percent MgO, up to about 64 mole percent ZnO, up to about 5 mole percent yttrium (Y), and up to about 5 mole percent of said two or more rare earths in oxide form.

98. The optical memory copy characterized in that the copy substrate is a fluorescent photosensitive glass, wherein said memory copy contains zones with difference in fluorescence intensities, extinction with more than 5%, between recorded volume of the medium and a non-recorded volume in the medium.

99. The optical memory copy of claim 68, further comprising said copy substrate as an organic material

100. The optical memory copy of claim 99, wherein said organic material comprises a fluorescent photosensitive polymer.

101. The optical memory copy characterized in that the copy substrate is a fluorescent photosensitive polymer , wherein said memory copy contains zones with difference in fluorescence intensities, enhancement with more than 5%, between recorded volume of the medium and a non-recorded volume in the medium.