Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/64—Fluorescence; Phosphorescence
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B21/00—Microscopes
  • G02B21/0004—Microscopes specially adapted for specific applications
  • G02B21/002—Scanning microscopes
  • G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
  • G02B21/0052—Optical details of the image generation
  • G02B21/0076—Optical details of the image generation arrangements using fluorescence or luminescence
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B21/00—Microscopes
  • G02B21/0004—Microscopes specially adapted for specific applications
  • G02B21/002—Scanning microscopes
  • G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
  • G02B21/008—Details of detection or image processing, including general computer control
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B21/00—Microscopes
  • G02B21/34—Microscope slides, e.g. mounting specimens on microscope slides
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
  • G11B7/0045—Recording
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
  • G11B7/005—Reproducing
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
  • G11B7/0065—Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
  • G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
  • G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
  • G11B7/1267—Power calibration
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
  • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
  • G11B7/1381—Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/2407—Tracks or pits; Shape, structure or physical properties thereof
  • G11B7/24085—Pits
  • G11B7/24088—Pits for storing more than two values, i.e. multi-valued recording for data or prepits
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
  • G11B2007/0009—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage
  • G11B2007/0013—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage for carriers having multiple discrete layers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
  • G11B7/244—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only
  • G11B7/246—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only containing dyes
  • G11B2007/24624—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only containing dyes fluorescent dyes

Definitions

• the present invention relates to methods for recording and reading data on photosensitive media for storing high capacity data.
• the invention also relates to devices for recording and reading data on such media.
• the invention also relates to such supports.
• the field of the invention relates to the field of writing processes by pulsed laser emission at high speed to sufficiently irradiate a dopant of a glass-type support.
• the field of the invention also relates to methods for forming metal aggregates in such media and the reading methods implemented by means of a suitable lighting of said aggregates. Aggregates with a signature specific to their radiation.
• Presently, widely used data storage methods are especially suitable for media such as CDs, DVDs or Blu-ray discs.
• the method of writing data on such media can be realized on some superimposed layers of the disk in 2D.
• Blu-ray support provides the largest amount of 2D data storage, usually close to or slightly larger than 50 Gbits. This capacity is in theory limited in theory to 100 Gbits.
• the generally accepted lifetime of such a medium is about ten years.
• a limitation is in particular due to the short life of the polymer layer.
• New 3D data recording techniques have been developed in particular by multi-photon absorption of a material subjected to the high intensity of a laser beam.
• the recording by photochromism induces in particular a reversible transformation of the dopant incorporated in a transparent support.
• the dopant comprises two states according to the irradiation undergone, each state corresponding to a modification of the absorption coefficient and the refractive index of the support. These two states make it possible to multiplex the light differently according to the characteristics of polarization, wavelength and phase. These characteristics can be chosen to use the absorption and refraction properties modifying the reflected waves during illumination for reading data and can thus be used to decode the information read.
• a problem of the recording by photochromism is that the reading of the information for example by using the polarization is very difficult to control. Indeed, the illumination light of the support is modified or not according to the refractive index of the illuminated area of the support, but it is very difficult to control the polarization of light on consumer optics, which leads to implement error correctors. In addition, this technique requires the use of a laser tunable write. As a result, it is difficult to implement and is expensive. Finally, the gain with regard to the storage of data is not sufficiently significant in view of the implementation of such a solution. Fluorescence recording has never been implemented because the stabilization of fluorescent species in a transparent support has never been achieved. This limitation is due to the modification of the fluorescence intensity in time, in particular resulting from the readings on the support which consist of successive lighting. Fluorescence recording could not then allow stability and durability of the coded information.
• this type of technology has not hitherto made it possible to irradiate an area of a transparent support in order to encode information at the level of the fluorescence of photoinduced species.
• the irradiation generally induces a modification of the refractive index which does not allow the reading of the data in 3D because of the scattering of the light of the irradiated zones.
• the invention overcomes the aforementioned drawbacks.
• the three-dimensional data recording method of the invention makes it possible to record information on a support formed of a transparent photosensitive material comprising at least one photosensitive dopant.
• the recording method of the invention comprises in particular:
• ⁇ a first step of calibration and control of a pulsed light source comprising a calibration of the number of pulses of fluence level of each transmitted pulse and the pulse rate;
• the method of the invention makes it possible to define the fluence of each transmitted pulse, the number of pulses and the rate of the pulses so that the irradiation makes it possible to form fluorescent aggregates stabilized from the dopant while minimizing the modification. of the refractive index and the coefficient absorption of the carrier in a wavelength range from visible to near infrared.
• the invention comprises a method of reading on a medium the information recorded with the recording method of the invention.
• the reading method of the invention allows the reading of a modified transparent support locally comprising a set of aggregates of stabilized metal ions arranged in 3D, each of the aggregates emitting fluorescence during a light excitation.
• the reading method comprises:
• the method of three-dimensional recording of data on a support formed of a transparent photosensitive material comprising at least one dopant comprises:
• a first calibration and control step of a first pulsed light source comprising a calibration of the number of pulses, the level of fluence of each transmitted pulse and the rate of the pulses; ⁇ a step of writing an area of the material.
• the fluence of each transmitted pulse, the number of pulses and the rate of the pulses are adapted to irradiate the material in said zone so as to form stabilized fluorescent aggregates from the dopant while minimizing the modification of the refraction and the absorption coefficient of the support in a wavelength range from visible to near infrared.
• the first light source is calibrated so that:
• the pulse rate is greater than a second predetermined threshold to create a temperature higher than a third predetermined temperature threshold in the irradiated area
• the duration of each emitted light pulse being shorter than the characteristic thermalization time of the material so as to achieve excitation of the support area by multi-photon ionization.
• each aggregate forms a fluorescent emitter whose spectrum and fluorescence intensity correspond to a signature for coding a data word, said aggregates stabilized.
• ⁇ the rate of each pulse of the first light source is greater than 1 kHz; and more particularly greater than 10 kHz where the thermal effects in the materials are better notably because the material no longer has time to cool;
• the wavelength of the laser is at least twice the cutoff wavelength of the transparent support.
• the first light source comprises at least one of the following two light sources: an infrared femtosecond laser, an infrared picosecond laser.
• the support formed of a vitreous material and the dopant comprises at least one type of metal ion of the following set of ions: the silver ion, denoted Ag, the gold ion, denoted Au, the Copper ion, noted Cu.
• the irradiation step comprises a set of pulses on the same zone of the support of in order to form stable irradiated aggregates, the formed aggregates defining a fluorescent emitter whose spectrum and fluorescence intensity, corresponding to a given calibration of the first light source, defines a signature.
• the pulse rate of the first light source is substantially equal to 10 MHz.
• the steps of the recording method are repeated on a set of zones situated at the same depth of the support, the set of zones situated at the same depth being called a layer, each calibration of the first source being adapted to a given inscription. on each of the zones, the process being reiterated on superimposed layers of the support.
• the invention relates to a device for recording data of a transparent data storage medium formed of a material comprising a dopant.
• the recording device comprises a femtosecond laser emitting a pulsed beam intended to irradiate an area of the support, the rate and the number of the pulses being controlled by means of a light modulation device, the irradiation being carried out at by means of an objective for focusing the laser light locally in an area of the support, the impulse transmitting energy to the support ionizing the material at the focal point of the microscope, the recording device comprising motor means to move the support by relative to the light source so as to successively reiterate the steps of the method of the invention on a set of three-dimensional zones.
• the invention relates to a transparent data storage medium formed of a material comprising at least one dopant.
• the material comprises stable irradiated aggregates, said aggregates forming a fluorescent emitter whose spectrum and fluorescence intensity correspond to a signature for coding a data word.
• the transparent support can be:
• the invention relates to a method of reading a transparent support formed of a modified material locally comprising a set of stabilized aggregates inscribed in 3D in the material, each of the aggregates emitting fluorescence during a light excitation.
• the reading method comprises:
• a second step of capturing the light intensity re-emitted by the transmitter and
• the method for reading a modified transparent support comprises a third step of filtering the excitatory light of the re-emitted light making it possible to capture only the visible fluorescent light.
• the support comprises a plurality of superposed layers formed in the material, a layer comprising a set of zones of the same depth in the material, the first step being performed by means of a confocal filtering device for discriminating the fluorescence light emitted by an emitter of an area of a given layer from that emitted by an area of another layer.
• the invention further relates to a device for reading data from a transparent data storage medium comprising at least one dopant.
• the reading device comprises an illuminating laser diode in the range [330 nm; A region of the support comprising a set of fluorescent aggregates, the set of aggregates of a zone being called a transmitter, the reading device comprising means for collecting different levels of fluorescent light intensity of the illuminated emitters and means for converting the luminescence into a digital signal so as to form a data word corresponding to the spectrum and the fluorescence intensity, the reading device further comprising driving means for moving the support relative to the light source so as to successively reiterate the steps of the reading method of the invention on a set of zones of at least one layer of the support.
• the three-dimensional calibration plate for an optical system comprises at least one stable fluorescent aggregate whose intensity and spectrum makes it possible to define the characteristics of a calibration pattern making it possible to control at least one of the following characteristics of an optical measuring system corresponding to the response functions of an optical system:
• the optical system is one of the following: microscope, detectors, light sources.
• the test pattern allows a calibration of the positioning system of the optics, the optical system.
• test pattern allows a calibration of the optical resolution of the optical system.
• the invention comprises a recording device, a reading device and a support for implementing the recording and reading methods of the invention.
• FIG. 1 a data recording device of the invention
• FIG. 3 the absorption and emission spectra of an irradiated zone of a support of the invention
• FIG. 5 a zoom of a pattern forming linear portions
• FIG. 6 a back of a fluorescent aggregate formed by the process of the invention.
• the methods of the invention which are described successively include:
• a transparent support having data storage stable photo-induced aggregates, said aggregates of a predetermined area forming a fluorescent transmitter whose spectrum and intensity correspond to a signature.
• the data recording method of the invention makes it possible to record data on a support formed of a transparent photosensitive material comprising at least one dopant.
• the recording method comprises a first calibration step:
• the recording method of the invention comprises a step of irradiating an area of the support.
• the fluence of each pulse, the number of pulses and the pulse rate are adapted to irradiate in said zone a portion of the material so as to form stabilized aggregates from the dopant while minimizing the modification of the refractive index of the support.
• the rate of pulses emitted is a laser configuration datum also called laser repetition rate.
• the recording method of the invention may further include a step of reiterating the first two steps on a set of areas of the support.
• FIG. 1 represents means making it possible to implement the data recording method of the invention, in particular:
• a laser 12, denoted L for generating a laser beam onto an area of interaction of a transparent substrate 13 doped with metal ions;
• the function of the microscope objective can be achieved by any means of a focusing element such as a microscope objective or a lens.
• the transparent support is a photosensitive glass doped with silver ions
• the laser is a femtosecond laser emitting in the infrared at an energy such that at the focal point a fluence close to 1 J.cm -2 per pulse is generated.
• the laser is a picosecond laser. The invention can be implemented when the duration of the pulse is less than or equal to one picosecond.
• the wavelength of the laser and the cutoff wavelength of the glass, the wavelength from which the glass absorbs light, are chosen so that the wavelength of the laser is much larger. than the cutoff wavelength of the glass, that is to say at least twice as large.
• the wavelength of the laser may be chosen to be close to 1030 nm for a cutoff wavelength of the glass substantially close to 270 nm.
• the data recording method includes a configuration such that the laser repetition rate is greater than 1 kHz and more preferably greater than 10 kHz. Indeed, beyond this frequency, the material no longer has the time to cool between two pulses and the thermal effects are more favorable to the formation of aggregates.
• This configuration can be obtained from a light modulation device such as an acousto-optic modulator 11.
• a preferred mode makes it possible to adjust the value of the repetition rate to a value substantially close to 10 MHz. This configuration makes it possible, when the data recording method of the invention is executed, to stabilize the irradiated particles of the support material.
• Photo-sensitization of the glass is a nonlinear phenomenon caused by the multi-photonic absorption of the material which makes it possible to form aggregates of irradiated particles, called species.
• the fluence is sufficient to create an image, called "latent image”.
• the laser energy is deposited in the material faster. that the characteristic time of thermalization of the irradiated particles.
• FIG. 2 shows a microscope optics 10 which makes it possible to focus the laser in an interaction zone 25 of the support 13.
• the aggregates 21 which form in the neck 22 of the beam at a depth data of the carrier material particles 20 are irradiated Silver Ag + x m. The irradiated particles that form are stabilized in the material.
• the aggregates formed in an irradiated zone define a fluorescent emitter whose spectrum and fluorescence intensity make it possible to define a signature.
• the recording method of the invention makes it possible, starting from the calibration step, to define the irradiation parameters such as in particular the fluence, the number of pulses and the repetition rate of the laser. From the irradiation parameters, the recording method of the invention makes it possible, from a number of laser pulses, to create a fluorescent emitter in an interaction zone.
• the emitter is defined by a spectrum and a fluorescence intensity specific to the irradiated zone thus defining a signature of the irradiated zone.
• the irradiation step comprises a set of pulses on the same zone of the support of in order to form stable irradiated aggregates in said zone.
• the aggregates When the aggregates are lit, they in turn emit a fluorescent light.
• the fluorescent light intensity emitted by the aggregates corresponds to a signature which can notably be read by the interpretation of the spectrum retransmitted from a data reading method of the invention described hereinafter.
• the configuration of the irradiation whose fluence, the number of pulses and the rate of the pulses, of a given zone of the support defines a level of gray corresponding to a level of fluorescence of the aggregates formed in said zone when they emit in turn a luminescence.
• One embodiment of the data recording device of the invention comprises a pulsed beam emitting femtosecond laser for irradiating an area of the medium, the pulse rate, also referred to as the repetition rate, being realized by means of a modulator. acousto-optic.
• the irradiation is preferably carried out by means of a microscope objective making it possible to focus the laser light locally on an area of the support.
• the laser pulse transmits energy to the ionizing support for the dopant in an area near the focal point of the microscope.
• the recording device further comprises motor means for moving the support relative to the light source so as to successively reiterate the irradiation step of the recording method of the invention on a set of zones of the support. adapting the fluence, the number of pulses and the rate of pulses to each irradiated zone.
• the zones may for example be layered in the material when they are located at a same depth.
• the support may comprise a plurality of superposed layers.
• FIG. 2 represents a sample 26 of the support in which several layers 27 can be superimposed so as to organize the recording of data by stratum in the support.
• the method of reading the information of the invention is then implemented by a succession of operations for reading an area in the same layer and a layer for another layer.
• the acousto-optical modulator also makes it possible to vary the laser repetition rate or the number of pulses per interaction zone.
• the microscope objective focuses the laser beam with a numerical aperture of 0.52, which corresponds to a focal spot of 2 ⁇ m in diameter.
• the 3 - axis motorized stage allows positioning the neck of the beam in an irradiation zone, forming a sample of material defined in volume, the irradiation being done with an accuracy of 50 nm on the irradiated volume.
• the glass After irradiation according to the recording method, the glass is modified and comprises a so-called latent image because it is visible only by fluorescence microscopy, without apparent index modification.
• the fluorescence intensity of the aggregates depends in particular on the one hand on the intensity of the incident laser beam and on the other hand on the number of pulses.
• FIG. 3 represents a first graph representing the absorption spectrum ⁇ ( ⁇ ) of the irradiated zone, where A represents the absorption and ⁇ the wavelength.
• FIG. 3 represents a second graph representing the emission spectrum I ( ⁇ ) of an area irradiated glass, where I represents the intensity emitted by the illuminated aggregates.
• the method of the invention provides a support in which the material is modified, the pulsed laser irradiation having created small stabilized aggregates forming a latent image.
• the aggregates are aggregates of Ag m x + type silver with m ⁇ 8 and x ⁇ 2.
• the metal clusters are gold or copper clusters.
• the material comprises ions of different natures such as gold, copper or silver in different or equal quantities.
• the absorption spectrum of the first graph notably has a first absorption zone centered between 320 nm and 400 nm.
• the emission spectrum of the second graph has a band centered at 500 nm.
• the fluorescence of the irradiated species makes it possible to define a signature. These species have absorptions between 300 and 400 nm and broadband emission in the visible white emission type. The lifetime of the fluorescence is of the order of 3 nanoseconds. The white fluorescence is intense and perhaps in some cases observed with the naked eye.
• Impulse laser irradiation like other types of irradiation, is used to create small metal aggregates in the photosensitive glass.
• the temperature rise in the glass is greater than 300 ° C. This temperature is sufficient for the cash flow process to start.
• An elevated temperature near 350 ° C in the irradiation zone contributes to good species stabilization conditions.
• the aggregates that form as a result of the irradiation make it possible to stabilize the silver Ag ° neutral atoms outside their thermodynamic equilibrium.
• the method of the invention makes it possible to generate an intensity of the femtosecond laser such that in the center of the neck of the beam, the aggregates can not last because they are photo-dissociated by multi-photon effect.
• the method of the invention therefore makes it possible to force the diffusion of the photosensitive agent from the center of the laser beam towards the periphery where the intensity is not sufficient to dissociate the aggregates.
• the recording method of the invention makes it possible to stop the diffusion on the periphery of the irradiated zone because the silver Ag m x + silver species created stabilize said zone. These aggregates hardly diffuse because of their size.
• a latent image at the focus of the beam is created. This image is erased in the center at the same time as it is created. Only an image on the periphery of the zone continues and intensifies with the exposure time by diffusion.
• a preferred embodiment of the invention makes it possible to record information on the support by irradiating zones located at the same depth of the material. The latter then form a layer in the material.
• the method of the invention then makes it possible to record in the material information at different depths so that different layers comprising data can be superimposed, the irradiation of a zone of a layer not having of influence on the zones of superimposed layers when they are separated by a few micrometers.
• An exemplary embodiment is obtained by repetition of the method in different areas, for example chosen adjacent and consecutive in the material at the same depth.
• the intensity of the emitted laser beam is taken constant at 20> ⁇ 10 12 W. cm "2 and a number of pulses is emitted from a first zone to a last zone from 10 2 to 10 7 pulses per irradiated zone.
• the method of the invention makes it possible to create zones each having a gray level among 256 gray levels, the gray level being measured after illumination of the zones, during a re-emission of a fluorescent intensity. aggregates contained in each zone.
• An advantage of the recording method of the invention is that the emission spectra as well as the fluorescence intensity of the aggregates do not vary after exposure under violet laser beam with a luminous power of 150 mW and a wavelength of 405 nm for millions of read cycles.
• the invention also relates to a transparent medium for storing data and a method for reading data from said medium.
• the transparent support of the invention is formed of a modified material.
• the support comprises at least one latent image formed by a set of aggregates distributed locally in the volume of the support and stabilized with metal ions. Each of the aggregates behaves as a fluorescent emitting source, all the aggregates of the same zone being called emitter, when the zone is excited by a suitable light source.
• the method of reading the data of the invention comprises:
• the second duration t2 may be in an embodiment substantially of the same order of magnitude as the lifetime of the fluorescence of the transmitter.
• the method optionally comprises a third step of filtering the violet excitation light of the fluorescent light re-emitted by the emitters.
• the filtering of the violet light makes it possible to capture only the fluorescent light visible by the reading device according to the invention detailed hereinafter.
• the first step can be performed by means of a confocal filtering for focusing the light emitted by the second source to the depth of one of the layers.
• An advantage of the reading method of the invention is that it does not require a radical change of technology compared to currently used methods.
• the current Blu-ray technology can be adapted especially with regard to the emission wavelength of the second light source.
• An emission wavelength of the second source close to 405 nm is compatible with the excitation band of the photoinduced species in the reading method of the invention.
• the numerical aperture of the lens for example with an aperture of 0.85, is sufficient to discriminate layers separated by a few micrometers.
• the high intensity of the signal does not require a sensor change.
• the method of reading the data of the invention advantageously comprises a fourth analog / digital conversion step making it possible to discriminate a level of fluorescence luminous intensity so as to form a corresponding data word.
• An advantage of discrimination of a gray level of digitization is to be able to code the information on several levels thus multiplying the amount of information contained in the medium.
• the invention relates to a device for reading data.
• the data reading device comprises an illuminating laser diode in the range [330 nm; 450nm] an area comprising fluorescent aggregates stabilized in a support. All of the aggregates of the same area defines a fluorescent emitter.
• the reading device comprises means for capturing the luminous intensity emitted by fluorescence by an emitter and means for converting the luminescence or the fluorescence into a digital signal so as to form a data word corresponding to the spectrum and the frequency. intensity of the transmitter.
• the reading device comprises motor means for moving the support relative to the light source so as to successively reiterate the steps of the reading method on a set of zones of at least one layer of the support and advantageously on different layers. of the support.
• laser diodes having a wavelength shorter than 405 nm and lenses allowing significant numerical aperture so as to improve the performance of reading data on the medium.
• An advantage of the device and the method of reading the data is that the reading speed is limited by the lifetime of the fluorescence, ie 500 Mbits. s "1 .
• vitreous support makes it possible to obtain perennial supports for periods of several decades.
• the use of a glass is much more effective in stability than a polymer in particular doped with an organic dye which has low stability properties related to photo-bleaching. This disadvantage limits the good preservation of the recorded data.
• the glass is unsuitable for use with an organic dye, especially since it can not be used as a dopant with glass.
• a variant of the invention is the use of a polymer-type support with, for example, silver ions. According to the recording method of the invention, silver aggregates are formed, but these will be less stable in time than with the use of a glass-type support. Data storage is less durable.
• the glass-type support has real advantages as to the stability and durability of the support, since the stability of the emitters is ensured by the vitreous matrix, which can not be the case in polymers.
• An application of the invention in particular a support of the invention, is to make it possible to manufacture a calibration slide for fluorescence microscopy.
• the different optical microscopy platforms need to calibrate and deconvolve their images taken by confocal laser scanning microscopy calibration patterns to perfectly determine the response function of their optical system in 3D. Platforms also need stable reference fluorescent objects over time. Indeed, the response of photo-detectors, the misalignment of the instruments, the photo-whitening of fluorescent species create difficulties in comparing images taken at different places and times.
• the invention can be adapted to measure an electric current.
• the stability of fluorescent centers at high temperature makes it possible to envisage applications for fluorescent patch electrodes.
• fluorescent patch electrodes For example, in neurobiology when an electric current flows between two electrodes composed of silver aggregates implanted on a biological system, they emit light fluorescent whose intensity depends on the electric current. It is therefore possible to measure very low electric currents (or potential differences) thanks to this type of electrodes.
• the support is for example an electrode.
• Another application of the invention makes it possible to apply the recording method of the invention to the etching of a signature of a glass-type support.
• the method can be applied to the fight against counterfeiting.
• the laser inscription in the glass is not visible to the eye, but only when it is excited with a blue laser diode in the form of fluorescence.
• the method of the invention makes it possible to record on a medium of the inscriptions in the form of "datamatrix", a generic Anglo-Saxon name with barcode type codes.
• datamatrix a generic Anglo-Saxon name with barcode type codes.
• the "datamatrix” code is a high-density two-dimensional symbology for representing a large amount of information on a small area, up to 2,335 alphanumeric characters or 3,116 numeric characters, on about 1 cm 2 .
• Another advantage of the "datamatrix” code is that it is in the public domain and is free of rights. In addition, it meets the IEC16022 standard. Typically, this signature in glasses incorporated in objects makes it possible to identify them simply while maintaining a visible external appearance without any trace of data registration. The method can therefore be applied to any type of object comprising a glass part. In particular, it is advantageous to make such an engraving on luxury items such as a watch, a bottle or a pair of glasses.
• the reader for identifying the code "datamatrix” is a reading device as defined in the invention. It can be embedded and miniaturized so that it can be transported simply.
• the reading method of the invention makes it possible to decode the inscription on the support of the invention.
• Another application of the invention is the manufacture of a support of the invention of optical analog disk type.
• the latter can advantageously be similar to vinyl records.
• the reading device of the invention can advantageously replace the diamond tip usually used when playing a vinyl record with a UV laser, on fluorescent tracks, and whose fluorescence intensity corresponds to an analog level.
• an application of the invention makes it possible to produce fluorescent lighting.
• the medium is a fluorescent emitter. By exciting the emitters composed of silver aggregates with an electric current, the latter emit fluorescence, in the same way as electroluminescent diodes.
• a percentage of dopant in the glass is greater than 4%. This proportion allows an optimal configuration, in particular so as to increase the stability of the aggregates in the glass.
• the stability of the aggregates is also improved when the laser pulses have a luminous intensity configured between 1 and 5 J / cm 2 .
• the number ofroues is also advantageously adapted to obtain a local temperature during the writing process, the temperature being around 300 ° C., typically> 100 ° C.
• fluorescent aggregates can be created and arranged in a calibration plate so as to form patterns having particular properties.
• the test patterns make it possible to calibrate the homogeneity of the field, the lateral resolution, the response of the detectors, the lifetime of the fluorescence, the repositioning of the plates, the depth of field or the longitudinal and axial resolution, the laser stability.
• FIG. 4 represents a calibration blade comprising different aggregation arrangements for calibrating the microscope.
• a given arrangement of aggregates is called a "pattern".
• the latter forms a 2D or 3D pattern engraved at a given depth or at different depths of the blade.
• the registration is performed using the method of the invention so that the aggregates form a data word.
• a data word may correspond to a given fluorescence intensity.
• a data word is coded according to the level of luminescence re-emitted after illumination of the aggregate.
• the advantage of the formation of fluorescent aggregates is that they remain stable over time.
• a data word formed by a fluorescent aggregate is not modified by photo whitening or any other phenomenon that may alter the properties of an aggregate.
• the method of the invention allows non-alteration of the aggregates which are directly formed and trapped in the support.
• the Aggregate stability allows reliable calibration microscopes for fluorescence microscopy and provides a high level of accuracy of calibrations.
• Figure 4 shows a first uniform pattern 40.
• the data recording method of the invention makes it possible to uniformly etch all over the field aggregates having the same properties and being equidistributed over a given surface and at a given depth of the blade.
• This pattern makes it possible to calibrate the homogenization of a field during the calibration of a microscope.
• a second example of a pattern 41 is shown in FIG. 4.
• the patterns 41 make it possible to calibrate the optical resolution of the objectives of the microscopes.
• the target 41 comprises a series of horizontal linear sections 45 engraved in 3D in a glass-type support according to the method of the invention.
• Each apparent linear section 45 of the test pattern 41 comprises four lines whose spacing is very small and is of the order of magnitude of the width of the lines.
• FIG. 5 is a zoom of part of the test pattern 41.
• An aggregate etched according to the method of the invention forms a kind of ring 62 shown in Figure 6 having a diameter of the order of 1.6 .mu.m. In 3D, it is a tubular structure.
• the analysis of the dispersion and the recording read noise makes it possible to display an intensity level curve making it possible to code different values.
• it is possible to code the aggregates so as to obtain 16 value levels corresponding to 16 given fluorescent intensities. These levels can be obtained by increasing the number of pulses of a laser whose intensity is of the order of 5J / cm 2 during the data recording method according to the invention. So a image can also be encoded in this way where each pixel is recorded in the volume as a fluorescent tube.
• the area near the ring comprises a central portion 63 and an outer portion 61 slightly less irradiated than the portion forming the ring.
• FIG. 5 represents a first linear section 45 comprising two linear traces each forming two lines. There are four straight lines represented. Each of the traces is spaced apart by a first spacing 51.
• the second linear section shown below the first section, comprises two linear traces each forming two lines, each of the traces being spaced apart by a second spacing 52.
• the third linear section shown below the second section comprises two linear traces each forming two lines, each of the traces being spaced apart by a fifth spacing 53.
• the fourth linear section shown below the third section comprises two linear traces each forming two lines, each of the traces being spaced apart by a fourth spacing 54.
• the linear sections arranged one below the other comprise a spacing between the two linear traces increasing from one section to another.
• a first section comprises a spacing substantially close to 100 nm to a last section whose spacing is of the order of 2 ⁇ m.
• a third example makes it possible to consider a pattern 42 forming a grid of 9 squares or rectangles comprising a plurality of uniformly distributed aggregates.
• the target is preferably engraved at a depth close to 170 ⁇ m. This last depth is optimally adapted to fluorescence microscopes and thus allows an adjustment closer to the usual observation conditions in microscopy.
• each square of the pattern 42 comprises a given fluorescence intensity, that is to say that the illumination of a square by an external light source causes a light emission of the fluorescent aggregates well determined at a certain brightness .
• the aggregates of the same square have the same characteristics. That is, the irradiation of the slide to form the aggregates was made with the same number of pulses and an intensity selected so as to obtain a given fluorescence intensity per unit area.
• Each of the squares in the example of Figure 4 comprises 16 fluorescent aggregates whose irradiation in the same square allowed to homogenize the properties for each of the squares. Consequently, each square is capable of emitting a given fluorescent intensity after suitable lighting. Different configurations are possible and can be realized as to the number of squares, their arrangement and the number of aggregates per square.
• An advantage of this pattern is to be an invariable reference in fluorescence allowing the calibration and comparison of fluorescence microscopes with each other. stability of the aggregates formed in the calibration plate but also by the invariability of the fluorescence level emitted by each of the squares which make it possible to calibrate different values.
• the fluorescent light source being included in the blade, this pattern overcomes all the disadvantages of calibration methods by lighting and reflection of a light beam on the blade.
• each square has an increasing intensity of fluorescence making it possible to create a scale of reference values.
• a fourth example of a pattern 43 is shown in FIG. 4.
• the pattern 43 represents vertical lines engraved in the strip at different depths along the lines.
• This pattern 43 allows a 3D calibration precisely giving the depth of field of a microscope objective.
• the accuracy on the calibration of the measurement of an optical depth of field is of the order of a few hundred nanometers.
• a fifth test 44 makes it possible to calibrate the temporal response of the detectors by measuring the lifetime of the fluorescence after excitation of the aggregates and observation of the arrival time on the detector of the photons emitted by these same aggregates.
• This test pattern calibrates the fluorescence lifetime measurement system.
• the life of the aggregates is stable and is not degraded by photo bleaching thanks to the recording method of the invention which makes it possible to form stable aggregates in a glass-type support.

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