An active medium, typically a photochromic material and more typically spirbenzopyran, maintained in a three-dimensional matrix, typically of polymer, is illuminated in selected regions by two UV laser light beams, typically of 532 nm. and 1064 nm. wavelength, to change from a first, spiropyran, to a second, merocyanine, stable molecular isomeric form by process of two-photon absorption. Regions not temporally and spatially coincidently illuminated are unchanged. Later illumination of the selected regions by two green-red laser light beams, typically of 1064 nm wavelength each, causes only the second, merocyanine, isomeric form to fluoresce. This fluorescence is detectable by photodetectors as stored binary data. The three-dimensional memory may be erased by heat, or by infrared radiation, typically 2.12 microns wavelength. Use of other medium permit the three-dimensional patterning of three-dimensional forms, such as polystyrene polymer solids patterned from liquid styrene monomer. Three-dimensional displays, or other inhomogeneity patterns, can also be created.
There is provided an optical detection method comprising the steps of preparing a solid body having an energy level structure constituted by at least three energy levels, and irradiating first and second coherent light on the solid body to optically detect the physical structure of the solid body, wherein the detection step satisfies the following conditions: min(.epsilon..sub.i31)<h.omega..sub.p /2.pi.<max(.epsilon..sub.i31), min(.epsilon..sub.i32)<h.omega..sub.c /2.pi.<max(.epsilon..sub.i32), and h.OMEGA..sub.c /2.pi.<max(.epsilon..sub.i31)-min(.epsilon..sub.i31) where the number of physical structures included in the solid body is N, the predetermined three levels of ith physical structure are called first, second, and third levels, and energies of the first, second, and third levels are .epsilon..sub.i1, .epsilon..sub.i2, and .epsilon..sub.i3, respectively, of the N physical structures, the maximum value of .vertline..epsilon..sub.i3 -.epsilon..sub.i1 .vertline. is max(.epsilon..sub.i31), and the minimum value is min(.epsilon..sub.i31), of the N physical structures, the maximum value of .vertline..epsilon..sub.i3 -.epsilon..sub.i2 .vertline. is max(.epsilon..sub.i32), and the minimum value is min(.epsilon..sub.i32), the angular frequency of the first coherent light is .omega..sub.p, and a Rabi frequency is .OMEGA..sub.p, and the angular frequency of the second coherent light is .omega..sub.c, and a Rabi frequency is .OMEGA..sub.c, and includes the step of measuring at least one of absorption of the first coherent light in the solid body and photoluminescence of the solid body generated through the absorption of the first coherent light with respect to a plurality of pairs (.omega..sub.p, .omega..sub.c).
A master hologram is generated in a first optical medium by use of a plurality m of different reference beams, each beam bearing information suitably recorded in one or more of a plurality n layers of the second optical medium that are distinct from layers in which information in all other beams is suitably recorded. The generated master hologram is then used to optically holographically stamp, or record, multi-layer bit-oriented optical media by writing all n layers of the volume of the blank optical medium with m recording beams produced by simultaneously illuminating the master hologram with all m different reference beams, each illuminating reference beam being at a different reference angle and from a coherent light source which is incoherent with respect to every other illuminating reference beam. By this generating and this using a high degree of incoherency is obtained, making that during subsequent readout of a selected, focused, layer of the recorded optical medium signals from all other layers will become as background noise having nearly uniform intensity. The method requires a highly non-linear optical medium: a new dye-doped photopolymer is preferred.
The optical storage device and method includes a fluorescent layer arranged on a substrate and having a surface. The fluorescent layer is composed of fluorescent dye molecules embedded in a transparent polymeric base material. A group of data-carrying structures are arranged in the fluorescent layer. Each of the data-carrying structures has more than two optical states represented by a specific degree of quenching of fluorescence emitted from the data-carrying structure when irradiated with a fluorescence exciting radiation.
This invention relates to a three-dimensional optical memory made from a fluorescent photosensitive material, and a method and device for the storage and retrieval of information on the three-dimensional optical memory. The fluorescent photosensitive material can be glass and vitroceramic, both of which exhibit both fluorescent and photosensitive properties. Both one-photon and two-photon processes can be used for writing and reading the digital information on to the three-dimensional optical memory, in conjunction with a confocal microscope. A high reading sensitivity is obtained by using fluorescence during the reading cycle.
A method and apparatus for reading in a three-dimensional information carrier are presented. The three-dimensional information carrier is formed with a plurality of spaced-apart data regions, each surrounded by surrounding-regions. The data regions are made of a material capable of generating an output excited radiation, when interacting with a predetermined incident exciting radiation, while the surrounding regions are substantially optically transparent. The apparatus comprises an illumination unit, a light directing unit and a detector unit. The illumination unit produces a scanning beam of the incident radiation. The light directing unit projects the incident radiation onto a scan region located in an addressed plane inside the carrier and collects the output radiation. The light directing unit is capable of picking up a predetermined portion of the collected output radiation, so as to provide spatial separation of the output radiation components produced by the data regions located in the addressed plane and the output radiation components produced by the data regions located at any other location inside the carrier.
