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: Disclosed is a graded index type optical fiber having a multilayer structure comprising a plurality of concentrically arranged non-blended layers LNB1 to LNBm formed of (co)polymers P1 to Pm selected from the group consisting of two or more homopolymers HP1, HP2, . . . and HPn composed of units of vinyl monomers M1, M2, . . . and Mn, respectively (provided that the refractive indices of the homopolymers decrease in that order), and one or more binary copolymers CPs composed of units of vinyl monomers M1, M2, . . . and Mn, each of (co)polymers P1 to Pm having a glass transition temperature (Tg) of 80° C. or above, wherein the refractive index is highest at the center of the multilayer structure and decreases gradually toward the outer periphery thereof. This optical fiber has a small transmission loss, a large numerical aperture, and excellent resistance to moist heat.

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.