Abstract: The present invention provides a resin composition including a vinylidene fluoride-based resin (A), having a crystal melting enthalpy of 10 to 45 J/g as measured with a differential scanning calorimeter, and having (2) IHv of 60 or less as obtained by (1) a light scattering measurement.

Abstract: The present invention provides a resin composition including a vinylidene fluoride-based resin (A), having a crystal melting enthalpy of 10 to 45 J/g as measured with a differential scanning calorimeter, and having (2) IHv of 60 or less as obtained by (1) a light scattering measurement.

Abstract: The purpose of the present invention is to provide a rod lens array, which has a deep depth of focus and a small depth of focus spot. The present invention provides a rod lens array that is equipped with at least one line of rod lenses between two substrates, said line of rod lenses having a plurality of columnar rod lenses wherein the refractive index decreases toward the outer periphery from the center, said rod lenses being arranged in such a manner that the center axes of the rod lenses are substantially parallel to each other. The rod lens array is characterized in that the average value (DOFave) of the depth of focus (DOF) is at least 0.9 mm, and the depth of focus spot (DOFcv) in the scanning direction of the line of rod lenses is not more than 12%.

Abstract: The purpose of the present invention is to provide a rod lens array, which has a deep depth of focus and a small depth of focus spot. The present invention provides a rod lens array that is equipped with at least one line of rod lenses between two substrates, said line of rod lenses having a plurality of columnar rod lenses wherein the refractive index decreases toward the outer periphery from the center, said rod lenses being arranged in such a manner that the center axes of the rod lenses are substantially parallel to each other. The rod lens array is characterized in that the average value (DOFave) of the depth of focus (DOF) is at least 0.9 mm, and the depth of focus spot (DOFcv) in the scanning direction of the line of rod lenses is not more than 12%.

Abstract: A transparent plastic rod lens which has a cylindrical shape with a radius r in which a refractive index nD is reduced from a center thereof to an outer periphery thereof, the plastic rod lens includes a polymer mixture (I), in which the polymer mixture (I) includes, as constitutional units, an aromatic ring-containing monomer (a) unit and at least one monomer unit selected from a group consisting of a (meth)acrylate (b) unit which has a branched hydrocarbon group having 3 or more carbon atoms, a fluorine-containing monomer (c) unit, and an alicyclic ring-containing (meth)acrylate (d) unit, and a glass transition temperature is higher than or equal to 100° C.

Abstract: This invention relates to a copolymer prepared by polymerizing at least a vinyl compound (A) which gives a homopolymer with a refractive index of 1.50 or more, a fluoroalkyl (meth)acrylate (B) represented by the following formula (1) and methyl methacrylate (C), wherein a weight ratio of monomer (A) component/monomer (B) component ((A)/(B)) in the copolymer is within the range of 0.2 to 1; as well as a plastic optical fiber and a plastic optical fiber cable comprising a clad made of the copolymer. This invention can provide a plastic optical fiber and a plastic optical fiber cable exhibiting a reduced transmission loss, minimizing increase in a transmission loss even when being held as a bobbin-wound form, exhibiting a reduced bend loss and can transmit a wide-band data. (In the above formula, X represents H or CH3; and Rf represents fluoroalkyl having 7 to 14 carbon atoms both inclusive and 13 to 25 fluorine atoms both inclusive.).

Abstract: The present invention relates to a production method of a plastic optical fiber which comprises the steps of heat drawing an undrawn plastic optical fiber obtained by melt spinning and annealing the drawn fiber at a circumferential velocity ratio between the front and rear rollers (circumferential velocity of a rear roller/circumferential velocity of a front roller) of 0.5 to 1.2 under heating conditions which satisfy 4?y?1.5x+330 and (Tgc?5)° C.?x?(Tgc+110)° C. [Tgc: a glass transition temperature of a core, x: an annealing temperature (° C.), and y: an annealing time (seconds)]. According to the present invention, a plastic optical fiber having a small thermal shrinkage ratio and excellent heat resistance can be provided.

Abstract: The present invention relates to a production method of a plastic optical fiber which comprises the steps of heat drawing an undrawn plastic optical fiber obtained by melt spinning and annealing the drawn fiber at a circumferential velocity ratio between the front and rear rollers (circumferential velocity of a rear roller/circumferential velocity of a front roller) of 0.5 to 1.2 under heating conditions which satisfy 4?y??1.5x+330 and (Tgc?5)° C.?x?(Tgc+110)° C. [Tgc: a glass transition temperature of a core, x: an annealing temperature (° C.), and y: an annealing time (seconds)]. According to the present invention, a plastic optical fiber having a small thermal shrinkage ratio and excellent heat resistance can be provided.

Abstract: A plastic optical fiber includes having a first core, a second core having a different refractive index from the first core, disposed concentrically on the outside of the first core, and a clad disposed concentrically on the outside of the second core, wherein a ratio X (r1/r2) of a first core radius r1 to a second core radius r2 and a ratio Y (n2/n1) of a refractive index difference n2 between the second core and the clad to a refactive index difference n1 between the first core and the clad are in a range that satisfies the expressions Y≧−1.134X+1.0518 (1), and X≦−1.4842Y2+1.1097Y+0.7097 (2), and provided that Y<0.4 or X≧0.76 and that coordinate pairs X=0.8 and Y=0.35 as well as X=0.8 and Y=0.45 are excluded. The plastic optical fiber can have a high transmission power and a wide bandwidth. A cable and an optical transimission device can each include this plastic optical fiber.

Abstract: This invention relates to a copolymer prepared by polymerizing at least a vinyl compound (A) which gives a homopolymer with a refractive index of 1.50 or more, a fluoroalkyl (meth)acrylate (B) represented by the following formula (1) and methyl methacrylate (C), wherein a weight ratio of monomer (A) component/monomer (B) component ((A)/(B)) in the copolymer is within the range of 0.2 to 1; as well as a plastic optical fiber and a plastic optical fiber cable comprising a clad made of the copolymer. This invention can provide a plastic optical fiber and a plastic optical fiber cable exhibiting a reduced transmission loss, minimizing increase in a transmission loss even when being held as a bobbin-wound form, exhibiting a reduced bend loss and can transmit a wide-band data.

Abstract: The present invention relates to a plastic optical fiber having a first core, a second core with a different refractive index from the first core, disposed concentrically on the outside of the first core, and a clad disposed concentrically on the outside of the second core; wherein a ratio X (r1/r2) of a first core radius r1 to a second core radius r2 and a ratio Y (n2/n1) of a refractive index difference n2 between the second core and the clad to a refractive index difference n1, between the first core and the clad are in a range where the following Expressions

Abstract: This invention relates to a plastic optical fiber having a three-layer structure comprising a core, a cladding and a protective layer wherein the core material is polymethyl methacrylate and the cladding material is a copolymer composed of 20 to 45% by weight of long-chain fluoroalkyl methacrylate units represented by the following formula (1), 54 to 79% by weight of methyl methacrylate units, and 0.05 to 2% by weight of methacrylic acid units. This invention also relates to a plastic optical fiber cable having a four-layer structure wherein the optical fiber cable is produced by covering the aforesaid optical fiber with a jacket layer.CH.sub.2 .dbd.C(CH.sub.3)--COO--(CH.sub.2).sub.2 (CF.sub.2).sub.7 CF.sub.