摘要:
A holographic memory reproduction apparatus which makes a wavelength of a reproducing laser beam coincident with a wavelength of a laser beam used for holographic recording when information is reproduced from a holographic recording medium. In the holographic memory reproduction apparatus 10, a temperature adjustment device 26 is attached to a semiconductor laser 12. On the holographic recording medium 16, wavelength information of the laser beam used for recording is recorded as a wavelength address hologram 28. When the information is reproduced, the temperature adjustment device 26 is controlled by a wavelength control device 24 in accordance with a signal beam from the wavelength address hologram 28, thereby making an oscillation peak wavelength of the semiconductor laser 12 coincident with the wavelength of the laser beam used for recording.
摘要:
The present invention provides a hologram recording material which attains high refractive index change, high flexibility, high sensitivity, low scattering, environment resistance, durability, low dimensional change and high multiplicity, and is suitable for volume hologram recording. Also, the present invention provides a hologram recording medium. A hologram recording material comprising: an organometallic compound at least containing at least two kinds of metals, oxygen, and an aromatic group and having an organometallic unit wherein two aromatic groups are bonded directly to one metal; and a photopolymerizable compound. One of the at least two kinds of metals is Si, and the metal(s) other than Si is/are preferably selected from the group consisting of Ti, Zr, Ge, Sn, Al and Zn. The organometallic unit is preferably a unit wherein two aromatic groups are bonded directly to one Si atom. A hologram recording medium (11) has a hologram recording material layer (21).
摘要:
A holographic recording medium is superior in moisture resistance, thermal resistance, and rigidity and can certainly detect positional information to carry out a sophisticated recording and reproducing control and a recording and reproducing method thereof. The holographic recording medium 10 is configured to have substrates 12 made of a glass material and a hologram recording layer 14 provided on the substrate 12. Markers 16 are provided on the surface of the substrate 12 as positional information in the hologram recording layer 14.
摘要:
Provided is a hologram retrieval method and a holographic recording and reproducing apparatus for preventing an increase in SNR, a decrease in retrieval accuracy, or the retrieval itself from being made impossible, which would otherwise occur because of a small size of data used for retrieval. Digital information is recorded on a holographic recording medium as data pages DP formed of a two-dimensional bit map image with each page being multiplexed. The data page DP is divided into a plurality of equal data blocks DB11 to 13, DB21 to DB23, and DB31 to DB33, and each data block DB is provided with a data image that is encoded by an encoding method for providing a certain number of ON pixels within each data block DB. A spatial light modulator allows the to-be-retrieved data image to be encoded by the encoding method and displayed as block information on a retrieval data block associated with the data block, and a signal beam to be thereby modulated. Of resulting diffracted beams, the diffracted beam of the maximum intensity is used to detect the target data image and the address of the reference beam.
摘要:
A holographic recording and reproduction apparatus has a spatial light modulator for converting digital information to a two-dimensional image and for intensity modulating an object beam based on the two-dimensional image. The spatial light modulator is configured to employ four or more pixels on the two-dimensional image as a unit pixel block, and allow at least two types of encoded patterns having a different number of ON pixels in the unit pixel block to be present at the same time for display of the two-dimensional image. During a reproduction operation, a two-dimensional photo detector detects the amount of light on per unit pixel block basis to determine the number of its ON pixels and then set a threshold, and thereafter an image pickup device detects the image.
摘要:
A method and apparatus for performing reproduction position servo-control without reducing the recording capacity of a holographic recording medium is provided. Upon the reproduction of a holographic recording medium 18, part of a reproduction beam serving as a servo beam is projected onto a recording layer 18A of the holographic recording medium 18 from the side opposite to the side of the reproduction beam (a reference beam) along the same optical axis as that of the reproduction beam,-and the diffraction beam thereof is detected by a photodetector 26C through a polarizing beam splitter 26B.
摘要:
A holographic record erasing method and a holographic recording and reproducing apparatus in which data reproduction can be disabled without irradiating a holographic recording medium with a high energy erasing beam or physically destroying the medium. A holographic recording medium 16 in a holographic recording and reproducing apparatus 10 has a recording layer 17 formed of two split recording layers 17A and 17B, and a crosstalk layer 17C is provided therebetween. The crosstalk 17C layer still has photosensitivity after completion of multiplex recording of data holograms 24 in the recording layer 17. An object beam IOb for erasing and a reference beam IRe for erasing each having a large beam diameter are projected onto the layer to form a crosstalk hologram 26 having low selectivity. Hence, when a reproduction beam is projected onto the data holograms 24, a diffraction beam is always generated also from the crosstalk hologram 26.
摘要:
When an optical material layer such as an organic-inorganic hybrid material is employed as an optical component or an optical recording medium, the effect of thickness unevenness caused by drying is eliminated. An optical recording medium 20 is configured by providing on a substrate 10 an organic-inorganic hybrid material layer 12 applied thereto and dried thereon, covering this layer with an organosilicon resin 16, and stacking a translucent substrate 18 on the organosilicon resin 16. The effect of the thickness unevenness of the hybrid material layer 12 is eliminated by reducing the refractive index difference between the hybrid material layer 12 and the organosilicon resin 16 to thereby make them optically continuous and integrated.
摘要:
When recording on a holographic recording medium by using a recording beam, the time required for an asking servo control to recover is reduced to increase the data transfer rate. In the holographic recording apparatus 10, a laser beam from a laser light source 16 is formed into a collimated beam having an expanded beam diameter and then is divided into an object beam and a reference beam. The divided object beam is modulated according to information to be recorded, and these object and reference beams are made incident on the reflective surface of a rotating polygon mirror 18, while maintaining collimated beam shapes and being adjacent to each other, through a condenser lens 24 having a focal point behind the reflective surface of the polygon mirror 18. The object and reference beams are made incident on the holographic recording medium 12 moving in the same direction as their scanning direction with angles different from each other so as to interfere with each other within the holographic recording medium 12.
摘要:
An information recording method enables the precise formation of a recording mark on a recording layer having a high light transmittance such as an L1 layer of a double-layered optical recording medium. The information recording method uses the following recording strategy. A laser beam is pulse-modulated so as to create a pulse series including a write pulse of a recording power and a cooling pulse of a base power. Data to be recorded is modulated to have a length of a recording mark along a track of the recording layer. At the same time, the length of the recording mark is made to correspond to an integral multiple nT of T where T is one clock cycle. An nT recording mark corresponding to nT is recorded by using the same number of write pulses and cooling pulses when n is 4 or larger. Moreover, an average width AveTc for a single cooling pulse width Tc is set to satisfy: 1.0