Abstract: This invention relates to an optical information recording medium, characterized in that on a substrate there is applied a coloring matter film chemically inert to said substrate, said coloring matter film having an extinction coefficient of at least 1.

Abstract: This invention relates to an optical information recording medium having an organic thin film recording layer, and optionally having an underlayer and/or protective layer, characterized in that at least one of said recording layer, underlayer and protective layer contains a compound expressed by the general formula (1), ##STR1## wherein R represents hydrogen or a lower alkyl group; X represents acid anion; m represents 0, 1 or 2; and A represents ##STR2## (n being 1 or 2) or ##STR3## (when m is 2); all the aromatic rings optionally having a substituent selected from the group of a lower alkyl group, lower alkoxy group, halogen and hydroxyl group.

Abstract: An optical information recording medium which comprises the provision of a thin film (recording layer) formed of a cyanine coloring matter and a transition metal complex being superior in long wavelength range light absorbability to said coloring matter on a transparent or opaque substrate and which permits writing and reading by using laser beam.

Abstract: An optical information recording medium being capable of writing and reading with laser beam which comprises forming, on a transparent or opaque substrate, a thin film (recording layer) containing a cyanine coloring matter represented by the general formula: ##STR1## (wherein, R.sup.1, R.sup.2 and R.sup.3 may be the same or different, and each stands for C.sub.1 -C.sub.6 alkyl; X stands for halogen, perhalogenate, boron tetrafluoride, toluenesulfonic acid or alkylsulfonic acid; A stands for a benzene ring or a naphthyl ring and a substituent such as alkyl, alkoxy, hydroxy, carboxyl, halogen, allyl or alkylcarboxyl may be or may be not present on each ring; and n is an integer of 1-3.).

Abstract: Disclosed in this specification is a focussing control method for a laser retrieval apparatus. An astigmatic light flux of a laser beam is produced by a diffraction grating or hologram. It is received by a light sensitive device which is divided into four equal areas. The output signals from two pairs of oppositely facing areas are compared with each other, and the optical distance between the converging lens and the reflection surface is compensated, whereby the focus of the apparatus is controlled.

Abstract: An optical information recording medium comprising a substrate and a recording layer superimposed on said substrate, said recording layer comprising a reflective layer in which metal particles with a particle diameter of 1500.ANG. or less have been distributed closely and a light absorptive layer in which metal compounds and a very small amount of metal particles with a particle diameter of 200-2000.ANG. have been dispersed unformly or substantially uniformly in the volume ratio of 1-30% in a resin.

Abstract: An optical information recording medium comprises a transparent or opaque substrate and a cyanine coloring matter-containing thin coloring matter layer formed on said substrate. This recording material is adapted for laser beam reading and writing.

Abstract: A coating material such as a solution of polyvinyl butyral resin in benzene is applied to a transparent base in such a manner that the thickness thereof varies in a continuous and random manner so that concentration of light in the central area of a hologram produced using the plate is below a predetermined tolerable value.

Abstract: A large number of closely spaced holograms are formed on a sheet, each hologram comprising an information portion and an identification portion. First scan means movably position the sheet relative to a reconstruction beam and a sensor means for reading a selected hologram. The sensor means reads the identification portion of the reconstructed hologram to determine whether said hologram is the selected hologram. If said hologram is the selected hologram, a second scan means is actuated to read the information area. If said hologram is not the selected hologram, the first scan means is actuated to move to the next hologram. The process is continued until the selected hologram is located. The identification area further comprises a density reference section which is read to produce a bias reference signal for combination with the information signals. In digital applications the bias reference signal establishes the quantization threshold.

Abstract: Thermoplastic recording member in which a thermoplastic film recording layer is formed on a conductive support with the optional provision of an intermediate photoconductive layer, the resin film containing from 0.1 to 10% by weight of a silicone, fluorocarbon or chlorofluorocarbon oil, based on the weight of the film.

Abstract: In a system especially suited to holography a transparent photoconductive material comprises a glass substrate, an electroconductive heating layer formed on the substrate, a photoconductive layer formed on the electroconductive layer and a thermoplastic layer formed on the photoconductive layer. The photoconductive material is electrostatically charged and radiated with a coherent light image to produce an electrostatic image across the thermoplastic layer. An electric voltage is applied to the electroconductive heating layer to produce heat which softens the thermoplastic layer. The electrostatic force of the electrostatic image across the thermoplastic layer causes the same to deform and produce a diffraction pattern which constitutes a holographic representation of the light image. A photosensor is disposed in a position to sense the intensity of light which is diffracted by the diffraction pattern which is in the process of being formed.

Abstract: A holographic recording process uses a thermoplastic photosensitive member in which charging on the member and exposing the same to light having holographic information are carried out simultaneously, and an unevenness image corresponding to the information is ultimately formed on the member through a heating and a cooling step. The charging rate, charging-exposing time interval, light intensity and other factors are chosen to assure a high quality recording and hence a favorable image reproduction. In particular, the charging rate is chosen from those which lie in a region of characteristic curves above the line corresponding to 7 dB S/N ratio, the characteristic curves representing the relationship between the S/N ratio of the reproduced holographic image and the charging rate with parameters of the light intensity and the charging-exposing time interval. Further, if 15 dB S/N ratio is used as the limiting line, more than 30 times repeated use of the thermoplastic member is possible.

Abstract: A phase mask for use in a holographic apparatus comprising a combination of phase mask and data mask and being so devised that an illuminant beam transmitting these masks is irradiated on a Fourier transform plane together with a reference beam coherent with said illuminant bean, said phase mask being composed of a transparent plate and random undulations formed on the surface of said transparent plate by coating a solution of high molecular weight compound by means of a spin coater.