Abstract: A graded index type optical fiber having a multilayer structure comprising a plurality of concentrically arranged layers formed of (co)polymers selected from the group consisting of two or more homopolymers HP1, HP2, . . . , HPn derived from monomers M1, M2, . . . , Mn, respectively, and having refractive indices decreasing in that order, and one or more binary copolymers CP derived from these monomers, the multilayer structure being such that a mixed layer consisting of the (co)polymers constituting two adjacent layers is formed therebetween, and the refractive index is highest at the center and decreases gradually toward the outer periphery. This optical fiber can be continuously formed by feeding the (co)polymers to a multilayer concentric circular nozzle and thereby extruding them through the nozzle, and allowing the polymers to interdiffuse between adjacent layers of the fiber.

Abstract: A color image scanner is constructed by a three primary color LED array (4) for illuminating an original (2) to be read out, a monochromatic image sensor array (3) and a rod lens array (1) disposed between the original (1) and the image sensor array (3). The focusing parameters of the three kinds of refractive index distribution type rod lenses (11, 12, 13) constituting the rod lens array (1) are set so that each of the operating wavelength band and the predetermined wavelength is different among the kinds, the lens length Zo is equal among the kinds, and the conjugate length TC at each predetermined wavelength is substantially equal among all the kinds. Accordingly, when a color image reading operation is carried out by using the rod lens array which is effective in compactness and brightness, the chromatic aberration of the rod lens array can be sufficiently reduced and high-resolution can be implemented at low cost.

Abstract: A graded index type optical fiber having a multilayer structure comprising a plurality of concentrically arranged layers formed of (co)polymers selected from the group consisting of two or more homopolymers HP1, HP2, . . . , HPn derived from monomers M1, M2, . . . , Mn, respectively, and having refractive indices decreasing in that order, and one or more binary copolymers CP derived from these monomers, the multilayer structure being such that a mixed layer consisting of the (co)polymers constituting two adjacent layers is formed therebetween, and the refractive index is highest at the center and decreases gradually toward the outer periphery. This optical fiber can be continuously formed by feeding the (co)polymers to a multilayer concentric circular nozzle and thereby extruding them through the nozzle, and allowing the polymers to interdiffuse between adjacent layers of the fiber.

Abstract: A graded index type optical fiber having a multilayer structure comprising a plurality of concentrically arranged layers formed of (co)polymers selected from the group consisting of two or more homopolymers HP1, HP2, . . . , HPn derived from monomers M1, M2, . . . , Mn, respectively, and having refractive indices decreasing in that order, and one or more binary copolymers CP derived from these monomers, the multilayer structure being such that a mixed layer consisting of the (co)polymers constituting two adjacent layers is formed therebetween, and the refractive index is highest at the center and decreases gradually toward the outer periphery. This optical fiber can be continuously formed by feeding the (co)polymers to a multilayer concentric circular nozzle and thereby extruding them through the nozzle, and allowing the polymers to interdiffuse between adjacent layers of the fiber.

Abstract: A graded index type optical fiber having a multilayer structure comprising a plurality of concentrically arranged layers formed of (co)polymers selected from the group consisting of two or more homopolymers HP1, HP2, . . . , HPn derived from monomers M1, M2, . . . , Mn, respectively, and having refractive indices decreasing in that order, and one or more binary copolymers CP derived from these monomers, the multilayer structure being such that a mixed layer consisting of the (co)polymers constituting two adjacent layers is formed therebetween, and the refractive index is highest at the center and decreases gradually toward the outer periphery. This optical fiber can be continuously formed by feeding the (co)polymers to a multilayer concentric circular nozzle and thereby extruding them through the nozzle, and allowing the polymers to interdiffuse between adjacent layers of the fiber.

Abstract: A graded index type optical fiber having a multilayer structure comprising a plurality of concentrically arranged layers formed of (co)polymers selected from the group consisting of two or more homopolymers HP1, HP2, . . . , HPn derived from monomers M1, M2, . . . , Mn, respectively, and having refractive indices decreasing in that order, and one or more binary copolymers CP derived from these monomers, the multilayer structure being such that a mixed layer consisting of the (co)polymers constituting two adjacent layers is formed therebetween, and the refractive index is highest at the center and decreases gradually toward the outer periphery. This optical fiber can be continuously formed by feeding the (co)polymers to a multilayer concentric circular nozzle and thereby extruding them through the nozzle, and allowing the polymers to interdiffuse between adjacent layers of the fiber.

Abstract: A method and an apparatus for high-precision scattered light measurements characterized in that:in the optical path of a laser beam from the laser light source, the cross section of the laser beam is adjusted, and the laser beam is irradiated into a specimen fixed relatively to the laser beam to cause scattered lights to be scattered from the specimen;the angular distribution of the scattered lights is measured by adjusting the cross section for observing the scattered light in the optical path of the scattered light and scanning relatively with the specimen as its center; and by obtaining rapid and minute changes in the scattering intensities against minute changes in the scattering angles caused by the minute ununiformity in the structure of the specimen, the optical characteristics of transparent materials are evaluated.

Abstract: A plastic optical fiber which is superior in the light transmission characteristics, particularly in those within a visible light region and also superior in heat resistance, and a process for producing the same are provided, which plastic optical fiber comprises a polycarbonate as its core material and a polymer as its cladding material having a refractive index lower than that of the core material, wherein the relationship between the light transmission loss L.sub.500 (dB/km) of the fiber as measured at a wavelength of 500 nm and that as measured at 660 nm being expressed by the following inequality:L.sub.500 <L.sub.660 +4,000.

Abstract: There is provided a plastic optical fiber capable of exhibiting good light transmitting characteristics even at high temperatures, which comprises a core layer, a cladding layer, and a protective layer as basic consititutional units, wherein the protective layer has a heat distortion temperature [HDT] of at least 120.degree. C., a thickness of at least 10 .mu.m, and a cross-sectional area of at least 0.07 times the sum of cross-sectional areas of the core and cladding layers. There is also provided such a plastic optical fiber good in high-temperature light transmitting characteristics, which comprises a core layer, a cladding layer, and a protective layer as basic constitutional units and has a plastic coating layer having a silane-crosslinked structure provided as an outer layer thereof, wherein the protective layer has a heat distortion temperature [HDT] of at least 120.degree. C., a thickness of at least 10 .mu.m, and a cross-sectional area of at least 0.

Abstract: A process for the preparation of a multifilament optical fiber having 1,000 to 10,000 islands as optical filaments, which comprises using a composite spinning spinneret for the preparation of an islands-in-a-sea type multifilament fiber, which comprises at least three piled orifice plates including an orifice plate having many island-forming nozzle holes, an orifice plate having a sea-forming nozzle hole and an orifice plate having a filament-gathering nozzle hole, the nozzle hole of the orifice plate arranged just above the lowermost orifice plate having a trumpet-shaped opening extending toward the lower end face thereof and a sea component flow passage being formed between two orifice plates arranged just above the lowermost orifice plate, and supplying a thermoplastic polymer for forming cores of optical filaments from the island-forming nozzle holes and a sea-forming thermoplastic polymer from the sea-forming nozzle hole to effect composite spinning and gathering many filaments in the gathering nozzle ho

Abstract: An improved method and an equipment for detecting a pinhole in hollow filament, wherein the improvement comprises passing the hollow filament through a liquid maintained at a pressure higher than that of the gas in the interior of said hollow filament to allow the liquid to intrude through the pinhole into the interior of the hollow filament and detecting the intruded liquid.

Abstract: Provided is an apparatus for inspecting an optical fiber assembly through measuring irregularities in transmission loss of optical fibers which constitute said optical fiber assembly.

Abstract: An improved image-transmitting synthetic resin rod comprising a reaction product of an acrylic resin .circle.1 containing epoxy groups with a material .circle.2 having a refractive index 0.15-0.35 lower than that of said acrylic resin .circle.1 , and distributed in said rod so as to satisfy equation (1):n.sub.r.sup.2 =n.sub.a.sup.2 [1-(gr).sup.2 +h.sub.4 (gr).sup.4 +h.sub.6 (gr).sup.6 ] (1)0.03.ltoreq.gr.sub.0 .ltoreq.0.45.vertline.h.sub.4 -2/3.vertline..ltoreq.100.vertline.h.sub.6 +17/45.vertline..ltoreq.1,000wherein r is the radial distance from the center axis of the rod (0.ltoreq.r.ltoreq.r.sub.0),r.sub.0 is the radius of the rod,n.sub.r is the refractive index at point r,n.sub.a is the refractive index at the center of the rod,g is the distribution constant of the refractive index, andh.sub.4 and h.sub.6 are high order coefficients,and a process for producing the same.

Abstract: A method of and a system for detecting pinholes in hollow fibers by passing a liquid filled fiber into a zone of pressurized gas wherein the pressure of a gas is higher than that of a liquid inside the hollow fiber so that bubbles may be injected through pinholes contained in said hollow fiber and then passing the fiber through a bubble detector. The system can be operated continuously with the pinhole detector being between a device for continuously feeding the hollow fiber and a device for winding up said hollow fiber.

Abstract: A method of measuring light transmission losses of optical materials comprising projecting light beams at two separate points alternatively or a light beam through a part of an optical material to be measured, and detecting the intensities of light radiated at two separate points lying along the direction of propagation of said light beams in said part.