Continuous production of light-conducting glass filaments with refractive index gradient

Claim 1

A method of continuous production of a light-conducting glass filament having a distribution of refractive index wherein said index decreases continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the axis, which comprises: a. providing a bath of molten glass containing high refractive index cations; b. drawing molten glass continuously out of a first area of a surface of the bath of molten glass to form a glass filament which is gradually cooled; c. positioning an annular first electrode means in contact with an annular second area of said surface surrounding said first area of said surface of the bath of molten glass out of which the filament is drawn, said second area being a continuation of said first area and closely surrounding the glass filament being drawn whereby the glass of said second area flows into said first area and is drawn into said filament so as to produce the outer surface of the glass filament, said first electrode means containing low refractive index cations that are exchangeable with said high refractive index cations within the molten glass to cause the refractive index of the glass to decrease through the exchange; d. positioning a second electrode means in contact with the bath of molten glass spaced from said surface and located centrally of the first electrode means, said second electrode means being so arranged that molten glass nearer the second electrode means is drawn into said filament so as to produce the central portion of the glass filament, said second electrode means having thE capacity of receiving said high refractive index cations from the molten glass; e. applying a unidirectional electric voltage across the first and the second electrode means so that the polarity of the first electrode means is positive with respect to the second electrode means to cause an electric current to flow through a portion of the molten glass from the first electrode means to the second electrode means thereby to promote transfer and diffusion toward said second electrode means of said low refractive index cations into the molten glass in contact with the first electrode means and thereby promote diffusion toward and transfer to said second electrode means of said high refractive index cations in the body of molten glass; whereby said high refractive index cations originally contained within the part of the molten glass nearer the first electrode means are exchanged to a greater extent by said low refractive index cations thereby to reduce to a greater extent the refractive index of the part of the molten glass nearer the first electrode means so that concentration distributions are produced within the molten glass such that the concentration of said low refractive index cations continuously decreases and the concentration of said high refractive index cations continuously increases, respectively, from said first electrode means toward said second electrode means whereby concentrations within the glass filament of said low refractive index cations continuously increases and said high refractive index cations continuously decreases from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the center axis thereof, the progressive variation in concentrations of said high refractive index cations and said low refractive index cations within the glass filament producing said distribution of refractive index as said filament is being formed.

Claim 2

A method of continuous production of a light-conducting glass filament having a distribution of refractive index wherein said index decreases continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the axis, which comprises: a. providing a bath of molten glass containing high refractive index cations; b. drawing molten glass continuously out of a first area of a surface of the bath of molten glass to form a glass filament which is gradually cooled; c. positioning an annular first electrode means in contact with an annular second area of said surface surrounding said first area of said surface of the bath of molten glass out of which the filament is drawn, said second area being a continuation of said first area and closely surrounding the glass filament being drawn whereby the glass of said second area flows into said first area and is drawn into said filament so as to produce the outer surface of the glass filament, said first electrode means containing low refractive index cations that are exchangeable with said high refractive index cations within the molten glass to cause the refractive index of the glass to decrease through the exchange; d. positioning a second electrode means in contact with the bath of molten glass spaced from said surface and located centrally of the first electrode means, said second electrode means being so arranged that molten glass nearer the second electrode means is drawn into said filament so as to produce the central portion of the glass filament, said second electrode means having thE capacity of receiving said high refractive index cations from the molten glass; e. applying a unidirectional electric voltage across the first and the second electrode means so that the polarity of the first electrode means is positive with respect to the second electrode means to cause an electric current to flow through a portion of the molten glass from the first electrode means to the second electrode means thereby to promote transfer and diffusion toward said second electrode means of said low refractive index cations into the molten glass in contact with the first electrode means and thereby promote diffusion toward and transfer to said second electrode means of said high refractive index cations in the body of molten glass; whereby said high refractive index cations originally contained within the part of the molten glass nearer the first electrode means are exchanged to a greater extent by said low refractive index cations thereby to reduce to a greater extent the refractive index of the part of the molten glass nearer the first electrode means so that concentration distributions are produced within the molten glass such that the concentration of said low refractive index cations continuously decreases and the concentration of said high refractive index cations continuously increases, respectively, from said first electrode means toward said second electrode means whereby concentrations within the glass filament of said low refractive index cations continuously increases and said high refractive index cations continuously decreases from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the center axis thereof, the progressive variation in concentrations of said high refractive index cations and said low refractive index cations within the glass filament producing said distribution of refractive index as said filament is being formed.

Claim 5

A method of continuous production of a light-conducting glass filament having a distribution of refractive index wherein said index decreases continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the axis, which comprises: a. providing a bath of molten glass containing low refractive cations; b. drawing molten glass continuously out of a surface of the bath of molten glass to form a glass filament which is gradually cooled; c. positioning an annular electrode means in contact with and surrounding an area of the surface of the bath of molten glass out of which the filament is drawn, the area being a continuation of and near the surface of the glass filament, the glass of the area being to produce the outer surface of the glass filament being drawn after having moved by the drawing, said annular first electrode means being such that it can have low refractive index cations within the molten glass dissolve into said annular electrode means; d. positioning a second electrode means in contact with the bath of molten glass spaced from said surface and opposite to the first electrode means, said second electrode means being so arranged that a part of the molten glass nearer the second electrode means will produce glass nearer the center of the glass filament after having moved by the drawing of said filament, said second electrode means containing high refractive index cations that can exchange with Exchangeable low refractive index cations within the molten glass and thereby cause the refractive index of the glass to increase through the exchange; e. applying a unidirectional electric voltage across the first and the second electrode means, the application of said electric voltage being effected so that the polarity of the second electrode means is positive with respect to the first electrode means to cause an electric current to flow through a body of molten glass from the second electrode means to the first electrode means thereby to promote transfer and diffusion toward said first electrode means of said high refractive index cations into the body of molten glass in contact with the second electrode means and thereby to promote transfer and diffusion toward said first electrode means of said low refractive index cations into the body of molten glass; f. whereby said low refractive index cations originally contained within the part of the molten glass nearer the second electrode means are exchanged to a greater extent by the high refractive index cations thereby to increase to a greater extent the refractive index of the part of the molten glass nearer the second electrode means so that concentration distributions are produced within the molten glass such that the concentration of said high refractive index cations continuously increases from said first electrode means toward said second electrode means, and the concentration of said low refractive index cations decreases from said first electrode means toward said second electrode means and whereby the concentration within the glass filament of said high refractive index cations decreases and the concentration of said low refractive index cations increases continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the center axis thereof, the variations in concentrations of said high refractive index cations and said low refractive index cations within the glass filament producing said distribution of refractive index.

Claim 6

A method of continuous production of a light-conducting glass filament having a distribution of refractive index wherein said index decreases continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the axis, which comprises: a. providing a bath of molten glass containing low refractive cations; b. drawing molten glass continuously out of a surface of the bath of molten glass to form a glass filament which is gradually cooled; c. positioning an annular electrode means in contact with and surrounding an area of the surface of the bath of molten glass out of which the filament is drawn, the area being a continuation of and near the surface of the glass filament, the glass of the area being to produce the outer surface of the glass filament being drawn after having moved by the drawing, said annular first electrode means being such that it can have low refractive index cations within the molten glass dissolve into said annular electrode means; d. positioning a second electrode means in contact with the bath of molten glass spaced from said surface and opposite to the first electrode means, said second electrode means being so arranged that a part of the molten glass nearer the second electrode means will produce glass nearer the center of the glass filament after having moved by the drawing of said filament, said second electrode means containing high refractive index cations that can exchange with Exchangeable low refractive index cations within the molten glass and thereby cause the refractive index of the glass to increase through the exchange; e. applying a unidirectional electric voltage across the first and the second electrode means, the application of said electric voltage being effected so that the polarity of the second electrode means is positive with respect to the first electrode means to cause an electric current to flow through a body of molten glass from the second electrode means to the first electrode means thereby to promote transfer and diffusion toward said first electrode means of said high refractive index cations into the body of molten glass in contact with the second electrode means and thereby to promote transfer and diffusion toward said first electrode means of said low refractive index cations into the body of molten glass; f. whereby said low refractive index cations originally contained within the part of the molten glass nearer the second electrode means are exchanged to a greater extent by the high refractive index cations thereby to increase to a greater extent the refractive index of the part of the molten glass nearer the second electrode means so that concentration distributions are produced within the molten glass such that the concentration of said high refractive index cations continuously increases from said first electrode means toward said second electrode means, and the concentration of said low refractive index cations decreases from said first electrode means toward said second electrode means and whereby the concentration within the glass filament of said high refractive index cations decreases and the concentration of said low refractive index cations increases continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the center axis thereof, the variations in concentrations of said high refractive index cations and said low refractive index cations within the glass filament producing said distribution of refractive index.

Claim 9

A method of continuous production of a light-conducting glass filament having a distribution of refractive index wherein said index decreases continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the axis, which comprises: a. providing a bath of molten glass containing cations and anions which can diffuse within the molten glass, said glass being so selected that, when the cations and the anions are selectively removed from it, it will have a smaller refractive index than that of the original glass; b. drawing molten glass continuously out of a surface of the bath of molten glass to form a glass filament which is gradually cooled; c. positioning a first and a second electrode means in contact with the molten glass of said bath, one of said electrode means surrounding an area of the surface of the bath of molten glass out of which the filament is drawn, said area being a continuation of and near the surface of the glass filament, the glass of the area being to produce the outer surface of the glass filament after having moved by the drawing of said filament, said electrode means being arranged concentrically and the first electrode means and the second electrode means respectively being capable of selectively extRacting out of the glass the anions and the cations which collect there; d. applying a unidirectional electrical voltage across the first and the second electrode means, the application of said electric voltage being effected so that the polarity of the first electrode means is positive with respect to the second electrode means to cause an electric current to flow through the body of the molten glass from the first electrode means to the second electrode means thereby to cause the cations and the anions within the glass nearer said surface area to transfer to a greater extent toward the second electrode means and the first electrode means, respectively, the cations and anions which have reached the electrode means being extracted out of the glass; e. whereby the concentrations of the cations and the anions within the part of the glass nearer said surface area are lowered to a greater extent and the refractive index of the part of the glass nearer said surface area is thus reduced to a greater extent whereby concentrations within the glass filament of said cations and said anions both decrease continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the center axis thereof, the variations in concentrations of cations and anions within the glass filament producing said distribution of refractive index.

Claim 10

A method of continuous production of a light-conducting glass filament having a distribution of refractive index wherein said index decreases continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the axis, which comprises: a. providing a bath of molten glass containing cations and anions which can diffuse within the molten glass, said glass being so selected that, when the cations and the anions are selectively removed from it, it will have a smaller refractive index than that of the original glass; b. drawing molten glass continuously out of a surface of the bath of molten glass to form a glass filament which is gradually cooled; c. positioning a first and a second electrode means in contact with the molten glass of said bath, one of said electrode means surrounding an area of the surface of the bath of molten glass out of which the filament is drawn, said area being a continuation of and near the surface of the glass filament, the glass of the area being to produce the outer surface of the glass filament after having moved by the drawing of said filament, said electrode means being arranged concentrically and the first electrode means and the second electrode means respectively being capable of selectively extRacting out of the glass the anions and the cations which collect there; d. applying a unidirectional electrical voltage across the first and the second electrode means, the application of said electric voltage being effected so that the polarity of the first electrode means is positive with respect to the second electrode means to cause an electric current to flow through the body of the molten glass from the first electrode means to the second electrode means thereby to cause the cations and the anions within the glass nearer said surface area to transfer to a greater extent toward the second electrode means and the first electrode means, respectively, the cations and anions which have reached the electrode means being extracted out of the glass; e. whereby the concentrations of the cations and the anions within the part of the glass nearer said surface area are lowered to a greater extent and the refractive index of the part of the glass nearer said surface area is thus reduced to a greater extent whereby concentrations within the glass filament of said cations and said anions both decrease continuously from the center axis toward the outer surface of the filament in any cross section thereof perpendicular to the center axis thereof, the variations in concentrations of cations and anions within the glass filament producing said distribution of refractive index.