摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
An upright injection-compression pressing machine for the manufacture of information carrier discs, such as photograph records and video discs, has a mold clamper assembly including a pair of stamper bearing molds movable relative to each other in a vertical direction towards and away from each other, and an injector assembly mounted on the clamper assembly in alignment with the direction of the relative movement of the molds.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.