Abstract: In a holographic digital data storage system, a light source generates a reference beam, a holographic optical element saves a plurality of interference patterns between the reference beam and a plurality of beams of specific sizes and a beam splitter splits each reproduced beam into a holographic signal beam and a holographic reference beam. A medium records an interference pattern between the holographic reference beam and the holographic signal beam and reflecting the holographic reference beam to generate a reflective information beam and, if only the holographic reference beam is illuminated, a displaying means displays a holographic reproduced beam for the holographic signal beam and detecting the reflective information beam.

Abstract: A holographic digital data storage apparatus detects a wobbling in a disc shaped storage medium, wherein the apparatus includes a beam generator and finding means, the disc including therein one or more holographically generated patterns. The beam generator projects at least two wobble detection beams to the holographically generated patterns, the wobble detection beams having different diffraction efficiencies provided at respective characteristic angles, wherein the characteristic angle is an angle between an optical path of one wobble detection beam and that of its corresponding pattern forming beam used in forming one of the holographically generated patterns and a diffraction efficiency is given by a ratio of a power of a diffracted beam of one of the wobble detection beams to a power of said one of the wobble detection beams. The finding means finds at least a difference between the diffraction efficiencies to thereby determine the wobbling in the disc.

Abstract: A holographic digital data storage apparatus detects a wobbling in a disc shaped storage medium, wherein the apparatus includes a beam generator and finding means, the disc including therein one or more holographically generated patterns. The beam generator projects at least two wobble detection beams to the holographically generated patterns, the wobble detection beams having different diffraction efficiencies provided at respective characteristic angles, wherein the characteristic angle is an angle between an optical path of one wobble detection beam and that of its corresponding pattern forming beam used in forming one of the holographically generated patterns and a diffraction efficiency is given by a ratio of a power of a diffracted beam of one of the wobble detection beams to a power of said one of the wobble detection beams. The finding means finds at least a difference between the diffraction efficiencies to thereby determine the wobbling in the disc.

Abstract: A holographic digital data storage apparatus detects a wobbling in a disc shaped storage medium, wherein the apparatus includes a beam generator and finding means, the disc including therein one or more holographically generated patterns. The beam generator projects at least two wobble detection beams to the holographically generated patterns, the wobble detection beams having different diffraction efficiencies provided at respective characteristic angles, wherein the characteristic angle is an angle between an optical path of one wobble detection beam and that of its corresponding pattern forming beam used in forming one of the holographically generated patterns and a diffraction efficiency is given by a ratio of a power of a diffracted beam of one of the wobble detection beams to a power of said one of the wobble detection beams. The finding means finds at least a difference between the diffraction efficiencies to thereby determine the wobbling in the disc.

Abstract: A voice message service method for establishing voice message communication between transmission and reception client computers capable of storing/reproducing voice information, and a messenger for the same. A management server is connected between the transmission and reception client computers, and requests a call connection transaction from the reception client computer, such that it conducts voice communication only when the voice communication is requested by a user of the reception client computer desires. The voice data is divided into a plurality of packets, and the voice data packets are transmitted by a TCP connection. Therefore, the interruption of voice data is prevented, resulting in increased data transmission reliability.

Abstract: In a holographic digital data storage system, a light source generates a reference beam, a holographic optical element saves a plurality of interference patterns between the reference beam and a plurality of beams of specific sizes and a beam splitter splits each reproduced beam into a holographic signal beam and a holographic reference beam. A medium records an interference pattern between the holographic reference beam and the holographic signal beam and reflecting the holographic reference beam to generate a reflective information beam and, if only the holographic reference beam is illuminated, a displaying means displays a holographic reproduced beam for the holographic signal beam and detecting the reflective information beam.

Abstract: In a holographic digital data storage system, a light source generates a reference beam, a holographic optical element saves a plurality of interference patterns between the reference beam and a plurality of beams of specific sizes and a beam splitter splits each reproduced beam into a holographic signal beam and a holographic reference beam. A medium records an interference pattern between the holographic reference beam and the holographic signal beam and reflecting the holographic reference beam to generate a reflective information beam and, if only the holographic reference beam is illuminated, a displaying means displays a holographic reproduced beam for the holographic signal beam and detecting the reflective information beam.

Abstract: A holographic system for storing data on an interference pattern in a hologram storage medium includes a light source for emitting a laser beam, a beam splitter, modulating means and a refractive material. The beam splitter divides the laser beam into a reference beam and a signal beam and the modulating means modulates the signal beam to generate a modulated signal beam. The refractive material refracts the reference beam to generate a refracted reference beam, wherein the refracted reference beam interferes with the modulated signal beam in the hologram storage medium to generate the interference pattern.

Abstract: A holographic ROM system includes an alignment apparatus for aligning a holographic medium for storing data and a mask with patterns of the data. The alignment apparatus has a beam irradiating unit for irradiating a light beam to alignment marks of the holographic medium and the mask; an alignment mechanism for moving at least one of the holographic medium and the mask in response to a control signal; a photo detecting unit for detecting the beam passing through the alignment marks of the holographic medium and the mask while the holographic medium and/or the mask being moved; and a control unit for generating the control signal, the control unit controlling the alignment mechanism based on intensity of the beam detected by the photo detecting unit.

Abstract: A holographic ROM system includes an alignment apparatus for aligning a holographic medium for storing data and a mask with patterns of the data. The alignment apparatus has a beam irradiating unit for irradiating a light beam to alignment marks of the holographic medium and the mask; an alignment mechanism for moving at least one of the holographic medium and the mask in response to a control signal; a photo detecting unit for detecting the beam passing through the alignment marks of the holographic medium and the mask while the holographic medium and/or the mask being moved; and a control unit for generating the control signal, the control unit controlling the alignment mechanism based on intensity of the beam detected by the photo detecting unit.

Abstract: A holographic system for storing data on an interference pattern in a hologram storage medium includes a light source for emitting a laser beam, a beam splitter, modulating means and a refractive material. The beam splitter divides the laser beam into a reference beam and a signal beam and the modulating means modulates the signal beam to generate a modulated signal beam. The refractive material refracts the reference beam to generate a refracted reference beam, wherein the refracted reference beam interferes with the modulated signal beam in the hologram storage medium to generate the interference pattern.

Abstract: A holographic digital data storage apparatus detects a wobbling in a disc shaped storage medium, wherein the apparatus includes a beam generator and finding means, the disc including therein one or more holographically generated patterns. The beam generator projects at least two wobble detection beams to the holographically generated patterns, the wobble detection beams having different diffraction efficiencies provided at respective characteristic angles, wherein the characteristic angle is an angle between an optical path of one wobble detection beam and that of its corresponding pattern forming beam used in forming one of the holographically generated patterns and a diffraction efficiency is given by a ratio of a power of a diffracted beam of one of the wobble detection beams to a power of said one of the wobble detection beams. The finding means finds at least a difference between the diffraction efficiencies to thereby determine the wobbling in the disc.

Abstract: In a holographic digital data storage system, a light source generates a reference beam, a holographic optical element saves a plurality of interference patterns between the reference beam and a plurality of beams of specific sizes and a beam splitter splits each reproduced beam into a holographic signal beam and a holographic reference beam. A medium records an interference pattern between the holographic reference beam and the holographic signal beam and reflecting the holographic reference beam to generate a reflective information beam and, if only the holographic reference beam is illuminated, a displaying means displays a holographic reproduced beam for the holographic signal beam and detecting the reflective information beam.