Three-dimensional optical memory

A radiation volume memory comprising:

• a three-dimensional volume of active medium responsive in each of a multiplicity of three-dimensionally arrayed regions thereof to a first set of two or more temporally and spatially coincident radiation beams which are jointly possessed of a first energy in order to change from a first form to a second form by process of plural photon absorption, and also responsive in each of the multiplicity of three-dimensionally arrayed regions to a second set of two or more temporally and spatially coincident beams of directed radiation which are jointly possessed of a second energy, different than the first energy, to fluoresce in each such region as is within its second form by process of plural photon absorption;
• means for impressing at a first, write, time a single temporal wavefront of a first beam of a first set of two beams of directed radiation with a plurality of binary bits of information, this first-set first beam thus carrying a plurality of binary bits of information at the same time and in parallel;
• means for focusing at the first, write, time the information-impressed first-set first beam of directed radiation so that the single wavefront bearing in parallel the plurality of binary bits of information is focused upon a like plurality of regions in a single plane of the three-dimensional volume of active media, the beam being substantially unfocused in other planes of the three-dimensional volume of active media;
• and
• means for illuminating at the first, write, time with a second beam of the first set of two beams of directed radiation the single plane, in all regions thereof, selectively and to the substantially exclusion of any illuminating of other planes parallel to the single plane;
• wherein coincidence at the first, write, time of the information impressed focused first beam and the second beam of the first set of two beams of radiation in the single plane is sufficient to change the form of such ones of the plurality of regions in the single plane as are in their first form to their second form in accordance with the plurality of binary bits, the binary information thus being written in parallel to the volume of active medium by radiation;
• means for impressing at a second, read, time a single temporal wavefront of a first beam of a second set of two beams of directed radiation with a pattern of binary bits corresponding to the locations of regions upon the single plane that are to be read, this second-set first beam thus carrying at the same time and in parallel a mask of the locations upon the single plane that are to be read;
• means for focusing at the second, read, time the mask-impressed second-set first beam of directed radiation so that the single wavefront bearing in parallel the pattern of binary bits is focused upon a like plurality of regions in the single plane of the three-dimensional volume of active media, the beam being substantially unfocused in other planes of the three-dimensional volume of active media;
• and
• means for illuminating at the second, read, time with a second beam of the second set of two beams of directed radiation the single plane, in all regions thereof, selectively and to the substantial exclusion of any illuminating of other planes parallel to the single plane;
• wherein coincidence at the second, read, time of the information impressed focused first beam and the second beam of the second set of two beams of radiation in selected regions of the single plane is sufficient to cause those of such selected regions as are in their second form to fluoresce, the binary information that is within these selected regions thus being optically read in parallel from the volume of active medium by radiation.

A system responsive to a plurality of bits of binary information for producing at one time a corresponding plurality of inhomogeneous regions within a three-dimensional volume of active medium having a multiplicity of regions by use of directed radiation, the system comprising:

• a three-dimensional volume of active medium having a multiplicity of regions
• that are individually responsive to radiation of a first energy level to change from a first form to a second form, and that are substantially transparent and substantially non-responsive to the radiation of the first energy level if within their second form, and
• that are individually responsive to radiation of a second energy level to fluoresce if within their second form, and that are substantially transparent and substantially non-responsive to the radiation of the second energy to do anything appreciable, including fluorescing, if within their first form;
• radiation source means for producing beams of radiation on a first, and upon a second, path which first-path and second-path beams are each individually less than either the first or the second energy but which first-path and second-path beams, at times, jointly sum to the first energy level and, at other separate times, jointly sum to the second energy level;
• first directing means for directing the first-path beam to simultaneously first-radiate at least a plurality of regions within the three-dimensional volume of active medium, the first-radiation alone being individually insufficient to either change the form of any of the multiplicity of regions within the three-dimensional volume of active medium or to cause any of the multiplicity of active regions to fluoresce;
• beam spatial gating means responsive to the plurality of bits of binary data for selectively gating the second-path beam in a corresponding plurality of the locations thereof that are simultaneously upon a single wavefront, the selective gating serving to encode the second-path beam's wavefront with the information;
• selective second-beam directing means for directing the second-path beam's wavefront into the three-dimensional volume of active medium selectively so that the plurality of encoded locations of the second-path beam's wavefront are radiatively directed onto the plurality of regions of the three-dimensional volume of active medium, second-radiating these regions temporally and spatially simultaneously that they are first-radiated by the first directing means
• so that, upon such times as the first-path and the second-path beams jointly sum to the first energy (i) regions of the volume of active medium corresponding to the binary information receive from both the first-path radiation and the second-path radiation jointly the first energy and, when within their first form, change from their first form to their second form responsively thereto, (ii) meanwhile that these regions corresponding to the binary information that are within their second form are unchanged, and (iii) meanwhile that remaining regions not corresponding to the binary information fail to receive from both the first-path radiation and the second-path radiation the first energy, and are thus unchanged in form whether within the first or within the second form;
• so that, upon such times as the first-path and the second-path beams jointly sum to the second energy, (i) regions of the volume of active medium corresponding to the binary information receive from both the first-path radiation and the second-path radiation jointly the second energy and, when within their second form, fluoresce responsively thereto, (ii) meanwhile that these regions corresponding to the binary information that are within their first form neither fluoresce nor change, and (iii) meanwhile that remaining regions not corresponding to the binary information fail to receive from both the first-path radiation and the second-path radiation the second energy, and thus neither fluoresce nor change in form.

A system for radiatively reading and writing a volume of active medium, the system comprising:

• a three-dimensional volume of active medium that is possessed of, and at least momentarily persists in, each of two, a first and a second, forms
• wherein the first form is sensitive to radiation of a first energy to undergo a first photoconversion so as to change to the second form, but which first form exhibits substantial insensitivity to radiation of a different, second, energy, and
• wherein the second form is sensitive to radiation of the second energy to undergo a second photoconversion;
• a first radiation source for producing at a writing time a first and a second beam of radiation, which beams jointly are of a combined energy equal to the first energy, but which beams individually are each of an energy that is both less than the first energy and unequal to the second energy;
• first beam-directing means for directing at the writing time the first beam of radiation to illuminate a writing-time first portion, less than the entirety, of the three-dimensional volume of active medium so as to cause this writing-time first portion to assume a virtual state;
• second beam-directing means for directing at the writing time the second beam of radiation to illuminate the three-dimensional volume of active medium in order to intersect therein the first beam of radiation within a writing-time intersection volume that includes at least a second portion of the first portion;
• wherein parts of the writing-time intersection volume that existed in the first form, and that have assumed a virtual state responsive to the first beam of radiation, are photoconverted, by temporal and spatial coincidence of the second beam of radiation, to the second form by a process of two-photon absorption;
• wherein parts of the writing-time intersection volume that existed in the second form are substantially unchanged;
• wherein all portions of the three-dimensional volume of active medium that are not within the writing-time intersection volume are substantially unchanged;
• a source of third and a fourth beam of radiation, which beams are, at the reading time separate from the writing time, jointly of a combined energy equal to the second energy, but which beams individually are each of an energy less than the second energy;
• a second radiation source for producing, at a reading time separate from the writing time, radiation having an energy equal to the second energy, the second radiation source including
• a source of third and a fourth beam of radiation, which beams are, at the reading time separate from the writing time, jointly of a combined energy equal to the second energy, but which beams individually are each of an energy less than the second energy;
• directing means for directing the radiation having an energy equal to the second energy onto the three-dimensional volume of active medium in order to illuminate reading-time intersection volume, less than the entirety of the volume, therein causing within this reading-time intersection volume a second photoconversion by such of the medium of the second form as is present therein, the directing means including
• third beam-directing means for directing at the reading time the third beam of radiation to illuminate a reading-time first portion, less than the entirety, of the three-dimensional volume of active medium so as to cause this reading-time first portion to assume a virtual state;
• and
• fourth beam-directing means for directing at the reading time the fourth beam of radiation to illuminate the three-dimensional volume of active medium in order to intersect therein the directed third beam of radiation within a reading-time intersection volume that includes at least a second portion of the reading-time first portion;
• wherein parts of the reading-time intersection volume that are in the second form undergo photoconversion by process of two-photon absorption in response to joint illumination by the third and the fourth beam of the detector;
• wherein the parts of the reading-time intersection volume that undergo photoconversion are detected by the detection;
• wherein parts of the reading-time intersection volume that exists in the first form are substantially unchanged;
• wherein all portions of the three-dimensional volume of active medium that are not within the reading-time intersection volume are substantially unchanged;
• and
• a detector of the second photoconversion occurring within the reading-time intersection volume of active medium;
• wherein the memory system is stimulated for detection, in and by the detector, of information that is contained within the volume of active medium by radiation.

A system for radiatively reading and writing a volume of active medium, the system comprising:

• a three-dimensional volume of active medium that is possessed of, and at least momentarily persists in, each of two, a first and a second, forms
• wherein the first form is sensitive to radiation of a first energy to undergo a first photoconversion so as to change to the second form, but which first form exhibits substantial insensitivity to radiation of a different, second, energy, and
• wherein the second form of the three-dimensional volume of active medium is sensitive to radiation of a second energy so as to undergo a second photoconversion where fluorescent light is emitted;
• a first radiation source for producing at a writing time a first and a second beam of radiation, which beams jointly are of a combined energy equal to the first energy, but which beams individually are each of an energy that is both less than the first energy and unequal to the second energy;
• first beam-directing means for directing at the writing time the first beam of radiation to illuminate a writing-time first portion, less than the entirety, of the three-dimensional volume of active medium so as to cause this writing-time first portion to assume a virtual state;
• second beam-directing means for directing at the writing time the second beam of radiation to illuminate the three-dimensional volume of active medium in order to intersect therein the first beam of radiation within a writing-time intersection volume that includes at least a second portion of the first portion;
• wherein parts of the writing-time intersection volume that existed in the first form, and that have assumed a virtual state responsive to the first beam of radiation, are photoconverted, by temporal and spatial coincidence of the second beam of radiation, to the second form by a process of two-photon absorption;
• wherein parts of the writing-time intersection volume that existed in the second form are substantially unchanged;
• wherein all portions of the three-dimensional volume of active medium that are not within the writing-time intersection volume are substantially unchanged.
• a source of third and a fourth beam of radiation, which beams are, at the reading time separate from the writing time, jointly of a combined energy equal to the second energy, but which beams individually are each of an energy less than the second energy;
• a second radiation source for producing, at a reading time separate from the writing time, radiation having an energy equal to the second energy;
• directing means for directing the radiation having an energy equal to the second energy onto the three-dimensional volume of active medium in order to illuminate reading-time intersection volume, less than the entirety of the volume, therein causing within this reading-time intersection volume a second photoconversion by such of the medium of the second form as is present therein;
• and
• a detector of the second photoconversion occurring within the reading-time intersection volume of active medium, the detector including
• a detector of fluorescent light;
• wherein the memory system is not only stimulated by radiation for a detection, in and by the detector, of information that is contained within the volume of active medium, but this detection, in and by the detector, is itself of radiation, namely fluorescent light;
• wherein the memory system is read as well as written by radiation.

A system for radiatively writing a volume of active medium, the system comprising:

• a three-dimensional volume of active medium that is possessed of, and at least momentarily persists in, each of two, a first and a second, forms
• wherein the first form is sensitive to radiation of a first energy to undergo a first photoconversion so as to change to the second form, but which first form exhibits substantial insensitivity to radiation of a different, second, energy;
• wherein the second form is sensitive to radiation of the second energy to undergo a second photoconversion;
• wherein the second form of the three-dimensional volume of active medium is substantially insensitive to radiation of the first energy;
• a first radiation source for producing at a writing time a first and a second beam of radiation, which beams jointly are of a combined energy equal to the first energy, but which beams individually are each of an energy that is both less than the first energy and unequal to the second energy;
• first beam-directing means for directing at the writing time the first beam of radiation to illuminate a writing-time first portion, less than the entirety, of the three-dimensional volume of active medium so as to cause this writing-time first portion to assume a virtual state;
• second beam-directing means for directing at the writing time the second beam of radiation to illuminate the three-dimensional volume of active medium in order to intersect therein the first beam of radiation within a writing-time intersection volume that includes at least a second portion of the first portion;
• wherein parts of the writing-time intersection volume that existed in the first form, and that have assumed a virtual state responsive to the first beam of radiation, are photoconverted, by temporal and spatial coincidence of the second beam of radiation, to the second form by a process of two-photon absorption;
• wherein parts of the writing-time intersection volume that existed in the second form are substantially unchanged;
• wherein all portions of the three-dimensional volume of active medium that are not within the writing-time intersection volume are substantially unchanged.

A volume memory stimulated for a reading of the information contents thereof by radiation, the memory comprising:

• a three-dimensional volume of active medium that is possessed of, and at least momentarily persists in, each of two, a first and a second, forms
• wherein the first form is sensitive to radiation of a first energy to undergo a first photoconversion so as to change to the second form, but which first form exhibits substantial insensitivity to radiation of a different, second, energy, and
• wherein the second form of the three-dimensional volume of active medium is sensitive to radiation of the second energy to undergo a second photoconversion causing the emission of fluorescent light;
• a radiation source of a first and a second beam of radiation, which beams are, at a reading time, jointly of a combined energy equal to the second energy, but which beams are individually each of an energy less than the second energy;
• first beam-directing means for directing at the reading time the first beam of radiation to illuminate a reading-time first portion, less than the entirety, of the three-dimensional volume of active medium so as to cause this reading-time first portion to assume a virtual state;
• second beam-directing means for directing at the reading time the second beam of radiation to illuminate the three-dimensional volume of active medium in order to intersect therein the first beam of radiation within a reading-time intersection volume that includes at least a second portion of the first portion;
• and
• a detector of the second photoconversion occurring anywhere within the three-dimensional volume of active medium including the reading-time intersection volume of active medium, the detector including
• a detector of fluorescent light;
• wherein parts of the reading-time intersection volume that exist in the second form undergo photoconversions by process of two-photon absorption in response to joint illumination by the first and the second beam of radiation;
• wherein those parts of the reading-time intersection volume that undergo photoconversions are detected by the detector;
• wherein those parts of the reading-time intersection volume undergoing photoconversions that are detected by the detector serve to convey information that was stored within the volume of active medium;
• wherein parts of the reading-time intersection volume that exist in the first form are substantially unchanged;
• wherein all portions of the three-dimensional volume of active medium that are not within the reading-time intersection volume are substantially unchanged;
• wherein the memory system is not only stimulated by radiation for detection, in and by the detector, of information that is contained within the volume of active medium, but this detection, in and by the detector, is itself by radiation;
• and
• wherein the memory system is read as well as written by radiation.