Abstract: The present disclosure relates to an optical member in which an antireflection concave-convex structure for suppressing reflection of light is provided on its surface, and an optical system, an optical unit and an optical device each including the optical member. The present disclosure provides an optical member in which the generation of reflection light and diffraction light is sufficiently suppressed and which can be fabricated in a simple manner. A antireflection concave-convex structure (15) for suppressing reflection of light, formed of filiform convex portions (16) regularly arranged, is provided on an interior surface (1a) of a lens tube (1). The antireflection concave-convex structure (15) is configured so that an angle between a normal vector of an incident plane of the light whose reflection is to be suppressed and a vector connecting respective apexes of adjacent two of the structure units at the incident surface is 60 degrees or less.

Abstract: A method for manufacturing an optical element comprises a step of press molding an optical element material 6 disposed between an upper press head (7) and its paired lower press head (8), wherein in the upper press head (7) and/or the lower press head (8) is formed a groove-like component that forms a non-cylindrical face or a cylindrical face as an optically effective component in the optical element material (6). This makes it possible to obtain an optical element with stable face shape precision, boosts productivity, and is also advantageous in terms of cost.

Abstract: When a molded lens is taken out from a molding die, it may be broken or damaged. The present invention provides a molding die comprising an upper die for lens molding, a lower die for lens molding, a support die, and a mold. At least either the upper die or lower die has no flange. The support die is provided below the die having no flanges. One or more through-holes are formed in the support die so that lifting pins can be inserted through the respective through holes. The upper and lower dies and can be slid relative to the mold.

Abstract: A theophylline sustained release tablet obtained by coating core granules composed mainly of theophylline with a layer of a coating film composed of a hydrophobic material and a plastic excipient and optionally containing an enteric polymer material to form coated granules and then by compressing the coated granules together with a disintegrating excipient.

Abstract: A method for manufacturing preforms used in molding optical elements includes: (1) forming an array made from a material for optical elements, in which a plurality of preform portions used in molding optical elements are connected; (2) applying vibration to the outer peripheral part of the preform portion in the thickness direction of the array by a pair of punches; and then (3) punching the preform portions.

Abstract: A method for making optical preforms of optical elements without residual stress or distortion is provided. In this method, an optical material is supplied between upper and lower molds. The upper mold has a plurality of recesses arranged in a predetermined pitch, and each recess corresponds to a first surface shape of the optical element. The lower mold has a plurality of recesses facing the recesses of the upper mold and each recess of the lower mold corresponds to a second surface shape of the optical element. The supplied optical material is pressed between the upper and lower molds to be a set of optical preforms. The set of optical preforms is processed by die punching or tool cutting to separate each optical preform from the set of optical preforms. Each optical preform is used for producing an optical element by further pressing. Alternatively, optical element can be formed directly by the press molding process.

Abstract: Optical material, which was already roughly molded, is deposited into a space defined by a top mold, a bottom mold and a drum mold, and is then heated, pressed and molded, thus providing an optical element. By controlling the rate of plastic deformation of the optical material so as to prevent the material from entering clearance sections between the outside diameter of the top mold or of the bottom mold and the inside diameter of the drum mold, an optical element of high precision with no burr nor strain is provided at low cost.

Abstract: A method of producing a glass blank, comprising the steps of: supplying a desired weight of molten glass material to a bearer heated to a temperature of not more than a softening point of the glass material; performing and cancelling, at a temperature of not less than the softening point, pressing of the glass material supplied to the bearer so as to adjust a thickness of the glass material; and cooling the glass material to a temperature of not more than the softening point.

Abstract: A machine is provided for molding an optical element by using a molding block having upper and lower molding dies, a sleeve die and a glass blank combined integrally with each other. The machine includes a chamber which accommodates a heating zone having a plurality of sections for heating the molding block from above and below, a deformation zone for pressing the molding dies and a cooling zone having a plurality of sections for cooling the molding block. The chamber is formed with an inlet and an outlet for the molding block. The sections of the heating zone, the deformation zone and the sections of the cooling zone are provided independently of one another. A transport member is provided for sequentially transporting the molding block through the heating zone, the deformation zone and the cooling zone, and first and second shutters are provided for opening gas supply member is provided for introducing nonoxidizing gas into the chamber.

Abstract: A machine is provided for molding an optical element by using a molding block having upper and lower molding dies, a sleeve die and a glass blank combined integrally with each other. The machine includes a chamber which accommodates a heating zone having a plurality of sections for heating the molding block from above and below, a deformation zone for pressing the molding dies and a cooling zone having a plurality of sections for cooling the molding block. The chamber is formed with an inlet and an outlet for the molding block. The sections of the heating zone, the deformation zone and the sections of the cooling zone are provided independently of one another. A transport member is provided for sequentially transporting the molding block through the heating zone, the deformation zone and the cooling zone, and first and second shutters are provided for opening gas supply member is provided for introducing nonoxidizing gas into the chamber.

Abstract: A die for press-molding an optical element with high precision comprises a base material made of a material excellent in heat resistance, heat shock resistance and mechanical strength at high temperature, an intermediate layer formed on the base material and made of a thin film excellent in grinding machinability and cutting machinability, and a surface protective layer formed on the intermediate layer and made of a metal thin film excellent in heat resistance and mechanical strength at high temperature and less reactive to a material of the optical element. Additional thin film may be inserted between the base material and the intermediate layer so as to enhance the adhesion strength between the base material and the intermediate layer. In place of the additional thin film to be inserted, a peripheral flange part of the intermediate layer is removed and thus on the removed peripheral part, the surface protective layer is directly adhered to the base material.

Abstract: A method of manufacturing optical elements which is capable of obtaining optical elements at high accuracy by molding through employment of an optical element molding glass material preliminarily processed to prevent such defects as crack formation or chipping at the corner portions of the molding material which contact dies when the material is charged into the mold. An optical element molding glass material to be employed for the above method is formed with curvatures at boundary portions i.e. corner portions where its cylindrical portion contacts at right angles with its end flat portions by applying chemical etching, heat of a carbon dioxide gas laser or radiation heat to such corner portions.

Abstract: An apparatus of producing an optical glass element of the present invention comprises the steps of displacing a gob of optical glass on a first heat working jig to a second heat working jig by making the gob of optical glass to adhere to the second heat working jig on the basis of the difference in wettability with high temperature glass between the first heat working jig and the second heat working jig, thermally deforming the gob of optical glass on the second heat working jig to form an optical glass preform, and forming the optical glass preform under heating and pressure by using pressing moulds to form an optical glass element.

Abstract: A method and apparatus are provided for producing an optical glass element, including displacing a gob of optical glass on a first heat working jig to a second heat working jig by making the gob of optical glass adhere to the second heat working jig due to a difference in wettability with high temperature glass between the first heat working jig and the second heat working jig. The gob of optical glass on the second heat working jig is thermally deformed to form an optical glass preform. The optical glass preform is formed under heat and pressure by using pressure molds to form an optical glass element.

Abstract: A lens molding method where a lens material is set between an upper mold and a lower mold, and the molding pressure is reduced or made zero at least once during a heating & pressing step without the mold surfaces breaking contact with the lens materials, and during a cooling & pressing step.

Abstract: A mold arranged between a pair of heater blocks for molding an optical element comprises a pair of first and second elements each having a molding surface for defining a cavity and an outer surface opposite to the molding surface and in contact with a corresponding heater block, and a ring member for guiding the first and second elements. The rear surface of at least one of the first and second elements has a part which is not in contact with the corresponding heater block. Also, another mold comprises a pair of first and second elements each having a molding surface for defining a cavity and an outer surface opposite to the molding surface, a first ring member for guiding the first and second elements, and a second outer ring member made of a material with a lower thermal conductivity than that of the first ring member. A molding method for optical elements is such that a glass with a viscosity of 10.sup.

Abstract: A lens controls the chromatic aberration of an objective lens for practical use in an optical disk system. The lens has first and second aspherical surfaces each providing a positive refractive power for focusing a light through a transparent plate and satisfies a condition: ##EQU1## where f.sub.L =focal length of the lens, d.sub.c =thickness of the transparent plate, n.sub.c =refractive index of the transparent plate, .lambda.=center wavelength of the light, NA=numerical apperture of the lens, .nu..sub.L =local dispersion of the lens, and .nu..sub.c =local dispersion of the transparent plate. The local dispersion of each element is expressed by: ##EQU2## where n.sub.80 is refractive index at a center wavelength .lambda. nm, n.sub..lambda. +5 a refractive index at .lambda.+5 nm, and n.sub..lambda. -5 a refractive index at .lambda.-5 nm.

Abstract: A method of molding a plastic is initiated by injecting molten resin into a mold at a high pressure. The energy of the high pressure is partially stored in the form of elongation of tie bars of a molding machine. After the gate seals completely, the restoring force of the tie bars due to elastic deformation acts on the molded article as the mold article cools down. Each tie bar comprises a first member having a small modulus of elasticity and a second member. When the elongation of each tie bar is small, only the first member of small modulus of elasticity works. After the elongation reaches a certain amount of .DELTA.l.sub.1, the two members are connected parallel. As a result, the apparent modulus of elasticity of each tie bar increases rapidly. This makes it possible to mold a plastic with high dimensional accuracy.

Abstract: There is provided an optical disc of high reliability, with the recording film protected from deterioration. The optical disc of this invention is produced by forming a tellurium suboxide film or optomagnetic recording film on a substrate made by injection molding from a polycarbonate resin. The substrate is made from a polycarbonate resin containing a phosphite ester-based antioxidant in a specific low amount.

Abstract: An optical disc comprises a resin disc substrate, a recording medium layer formed on the disc substrate, a high purity of transparent layer, and a transparent protective resin layer. The transparency of the transparent layer is larger than that of the transparent protective resin layer. A laser beam is focused on the recording medium layer through the transparent protective layer and the transparent layer. The transparent layer is a transparent adhesive layer or an air layer. The focused laser beam is not affected by foreign matter in the vicinity of the recording medium layer due to the high transparency of the transparent layer on the recording medium layer.