Abstract: A silica optical fiber is provided, which contains a pure-silica core and a cladding layer formed on the pure-silica core, wherein the pure-silica core contains a C element and has a content of elements belonging to the third period-the seventh period of the periodic table, except Si element that constitutes the quartz structure, of not more than 100 ppm. The present invention can provide a silica optical fiber superior in the resistance to high energy electromagnetic waves such as UV light and &ggr;-rays.

Abstract: A silica optical fiber is provided, which contains a pure-silica core and a cladding layer formed on the pure-silica core, wherein the pure-silica core contains a C element and has a content of elements belonging to the third period-the seventh period of the periodic table, except Si element that constitutes the quartz structure, of not more than 100 ppm. The present invention can provide a silica optical fiber superior in the resistance to high energy electromagnetic waves such as UV light and &ggr;-rays.

Abstract: A silica glass optical fiber superior in resistance to ultraviolet rays, which fiber comprises a doped silica glass cladding layer formed on a silica glass core, said silica glass core having an OH content of 10-1000 ppm, a fluorine content of 50-5000 ppm, and being substantially free of chlorine.

Abstract: A method for producing an optical multiple fiber unit wherein a multiplicity of optical fibers are fused together with each other and each optical fiber has a core made of pure silica glass and a cladding layer made of silica glass containing a dopant and disposed on the core, by bundling a multiplicity of preforms corresponding to the optical fibers and drawing the bundle at a high temperture using the optical fiber preforms, preforms having a three-layer construction wherein a support layer made of a silica glass having a drawable temperture of at least 1,800.degree. C. is further disposed on the cladding layer, and drawing the bundle of the preforms to give a multiple fiber wherein the support layer of each optical fiber has a thickness of 0.01 to 1 .mu.m, in order to produce a multiple fiber in which the cladding layer of each optical fiber has a sufficient thickness to fulfill the function as a cladding layer and which has an excellent image-transmitting capacity.

Abstract: It is disclosed a radiation resistant multiple fiber which is excellent in radiation resistance at the region of visible light, and therefore is suitable as an image transmitter of image scope, wherein a number of optical fiber elements each of which comprises a core composed of a pure silica glass and a cladding layer formed on the core and composed of a doped silica glass are mutually heat-fused, and said pure silica glass of the core having a chlorine content of lower than 1 ppm, and OH group content of lower than 1000 ppm, and also fluorine content of at least 100 ppm.

Abstract: A super-thin fiberscope having a main scope body which comprises a plurality of multi-component glass light guide fibers for transmitting light to illuminate a target to be viewed, a silica glass image guide for transmitting an image of the target, and a thin-walled main tube made of an imide resin and enclosing the image guide and the light guide fibers. The main tube has an outer diameter of 0.25 mm to 0.6 mm and a wall thickness of 10 .mu.m to 30 .mu.m.

Abstract: It is disclosed that an optical fiber conductor of glass type characterized in that the optical fiber conductor has a fiber-reinforcing layer which, at least in a desired region of the entire length thereof, is made of a charred material of an organic resin.

Abstract: An optical multiconductor of the silica glass type characterized in that the multiconductor comprises 10.sup.2 to 10.sup.7 optical fibers of the silica glass type fused to one another, each of the optical fibers comprising a core made of doped silica glass and occupying at least 20% of the fiber in cross sectional area, and a cladding layer made of a kind of silica glass and formed on the core, the core having a refractive index distribution satisfying the following expression:n2.gtoreq.n1+0.50(n0-n1)wherein n0 is the refractive index of the core at its center, n1 is the refractive index of the core at its outermost portion, and n2 is the refractive index of the core at a position centered about the axis of the core and having an average radius of 0.65r1, the r1 being an average radius of the core.The multiconductor is suited to use as the image transmitter of an image scope for industrial, medical or other uses.

Abstract: It is disclosed that a radiation-resistant optical conductor, such as an optical fiber for telecommunication, a multiple fiber for an image scope, and a light guide for illumination, which comprises a core composed of a pure silica glass which is prepared via an ultrahigh temperature of at least 3,000.degree. C. and has an OH group content of from 0.1 to 300 ppm, and a cladding layer formed on the core, and the cladding layer being composed of a silica glass which contains boron element and fluorine element as a dopant.

Abstract: An optical multiple fiber comprising a multiplicity of optical fibers which are fused together with each other, each optical fiber comprising a core made of pure silica glass and a cladding layer disposed on the core and made of a dopant-containing silica glass, characterized in that the thickness of the cladding layer satisfies the following equation (I):2 D.sub.1 .gtoreq.T.sub.1 .gtoreq.1.0 .mu.m. (I)wheren T.sub.1 is the thickness of the cladding layer in .mu.m. and D.sub.1 is the outer diameter of the core in .mu.m., in order to improve the image-transmitting capacity of the multiple fiber, including the sharpness and brightness of transmitted image.

Abstract: The invention relates to improvements in an image guide using optical silica glass fibers. The improved image guide has a light shielding and light absorbing thin layer formed on the periphery of an optical fiber bundle consisting of a multiplicity of optical fibers to prevent incidence of external light from the peripheral surface of the bundle and to absorb and remove any scattered light as it is transmitted to parts other than the core of each optical fiber, thereby providing improved picture quality.

Abstract: A method and an apparatus are disclosed for coating a metallic wire with a similar or dissimilar metallic plating layer having the desired uniform thickness and a compact metallic structure by passing the wire through electrolytic baths and through surface smoothing stations. The wire is passed through an electrolytic bath to coat the wire with a plating layer, then pressed against the peripheral surfaces of rotatable rollers to smooth the surface of the plating layer substantially over the entire periphery thereof. Subsequently the wire is coated with an electrolytic plating layer over the smoothed surface of the wire.