Abstract: Method of producing glass components and preforms for use in the method. The preform includes a primary rod having a constant outside diameter and a flat bottom portion, wherein the primary rod comprises a core rod surrounded by at least one outer cladding layer; and a cylindrical sacrificial tip having a first end attached to the flat bottom portion of the primary rod, a second end opposite the first end, and a hollow interior region extending fully from the first end to the second end, wherein the sacrificial tip is circular in cross section and the first end of the sacrificial tip has a constant inside diameter and outside diameter along its entire length from the first end to the second end, and wherein the constant outside diameter is equal to the outside diameter of the primary rod. When the preform is heated in a furnace, the sacrificial tip melts and collapses into a drawing bulb which either draws the primary rod directly into the glass fiber or results in a tapered (i.e.

Abstract: An apparatus for producing large glass preforms with minimal clad to-core waveguide distortion from a glass body having a weight, an outer surface, core rods, and a cladding surrounding and separated from the core rods by a gap. The apparatus includes collars affixed to the top and bottom of the cladding; a spacer upon which the core rods rest; a first unit holding and supporting both the bottom collar and the spacer; a second unit holding and supporting the top collar; and a frame defining a heating zone having a heating element to heat the glass body. The weight of the glass body above and below the molten glass in the heating zone is supported by the first and second units without contacting the outer surface of the glass body.

Abstract: A drawing furnace for drawing a glass element includes: a furnace body having an upper end and a lower end. The furnace body includes a top annular plate, an A/C induction coil capable of accepting electrical current and producing an oscillating electronic signal, a cylindrical susceptor capable of producing heat output, a cylindrical quartz beaker, an insulating material disposed between the susceptor and the beaker, and a bottom annular plate housing and supporting at least one of the susceptor, the beaker, and the insulating material. wherein the furnace body comprises a central longitudinal axis; A rotational drive system operably connected to the bottom annular plate by an annular rotation gear system rotates the bottom annular plate along with the susceptor, beaker, and/or insulating material at a frequency between 0.01 to 10 Hz. The electrical current and oscillation frequency determine the heat output of the susceptor.

Abstract: An automated large outside diameter preform tipping process. A zone of the preform is heated inside a furnace and softened. The preform tip is shaped and the process is controlled by the movement of the glass above and below the heating zone and by sensing the weight of the lower part of the preform, which in effect is a measure of the viscosity of the softened material. Once the correct viscosity is reached, the bottom holder is moved away from the top holder with a non-linear, accelerated velocity profile (derived from the FEM simulation of glass flow) which is precisely programmed and controlled so that the preform tip is optimally shaped (usually short and sharp tipped) with minimum waste and waveguide distortion when drawn into a fiber. The same concept of the non-linear, accelerated velocity profile can also be applied to other tipping processes such as horizontal preform tipping processes.

Abstract: Method of producing glass components and preforms for use in the method. The preform includes a primary rod having a constant outside diameter and a square bottom and a sacrificial tip having a first end attached to the bottom of the primary rod, a second end opposite the first end, and a hollow interior region extending from the first end to the second end. The sacrificial tip is circular in cross section and the first end of the sacrificial tip has an outside diameter equal to the outside diameter of the primary rod. When the preform is heated in a furnace, the sacrificial tip melts and collapses into a drawing bulb which either draws the primary rod directly into the glass fiber or results in a tapered (i.e. tipped) preform for subsequent fiber draw. Material waste as well as the drip time is reduced and the cladding-to-core ratio, crucial for waveguide properties, is maintained for the whole preform compared to a square cut preform without the sacrificial tip.

Abstract: Methods for preform and tube draw based on controlling forming zone viscosity determined by calculating a holding force exerted by the glass component in the forming zone on the strand being drawn below. The holding force may be calculated by determining a gravitational force applied to the strand and a pulling force applied to the strand by a pulling device, where the holding force is equal to the opposite of the algebraic sum of the gravitational and pulling forces. The holding force may also be calculated by measuring a stress-induced birefringence in the strand at a point between the forming zone and the pulling device, determining an amount of force applied to the strand at the point corresponding to the birefringence, and calculating the holding force by correcting the amount of force for a gravitational effect of the weight of the strand between the forming zone and the point.

Abstract: An apparatus for producing large glass preforms with minimal clad to-core waveguide distortion from a glass body having a weight, an outer surface, core rods, and a cladding surrounding and separated from the core rods by a gap. The apparatus includes collars affixed to the top and bottom of the cladding; a spacer upon which the core rods rest; a first unit holding and supporting both the bottom collar and the spacer; a second unit holding and supporting the top collar; and a frame defining a heating zone having a heating element to heat the glass body. The weight of the glass body above and below the molten glass in the heating zone is supported by the first and second units without contacting the outer surface of the glass body.

Abstract: An apparatus and related process for producing large glass preforms with minimal clad to-core waveguide distortion from a glass body having a weight, an outer surface, core rods, and a cladding surrounding and separated from the core rods by a gap. The apparatus includes collars affixed to the top and bottom of the cladding; a spacer upon which the core rods rest; a first unit holding and supporting both the bottom collar and the spacer; a second unit holding and supporting the top collar; and a frame defining a heating zone having a heating element to heat the glass body. The weight of the glass body above and below the molten glass in the heating zone is supported by the first and second units without contacting the outer surface of the glass body.

Abstract: Methods are known for producing an anti-resonant hollow-core fiber which has a hollow core extending along a fiber longitudinal axis and an inner jacket region that surrounds the hollow core, said jacket region comprising multiple anti-resonant elements. The known methods have the steps of: providing a cladding tube that has a cladding tube inner bore and a cladding tube longitudinal axis along which a cladding tube wall extends that is delimited by an interior and an exterior; forming a number of precursors for anti-resonant elements at target positions of the cladding tube wall; and elongating the primary preform in order to form the hollow-core fiber or further processing the primary preform in order to form a secondary preform from which the hollow-core fiber is drawn. The aim of the invention is to achieve a high degree of precision and an exact positioning of the anti-resonant elements in a sufficiently stable and reproducible manner on the basis of the aforementioned methods.

Abstract: Method of producing glass components and preforms for use in the method. The preform includes a primary rod having a constant outside diameter and a flat bottom portion, wherein the primary rod comprises a core rod surrounded by at least one outer cladding layer; and a cylindrical sacrificial tip having a first end attached to the flat bottom portion of the primary rod, a second end opposite the first end, and a hollow interior region extending fully from the first end to the second end, wherein the sacrificial tip is circular in cross section and the first end of the sacrificial tip has a constant inside diameter and outside diameter along its entire length from the first end to the second end, and wherein the constant outside diameter is equal to the outside diameter of the primary rod. When the preform is heated in a furnace, the sacrificial tip melts and collapses into a drawing bulb which either draws the primary rod directly into the glass fiber or results in a tapered (i.e.

Abstract: An automated large outside diameter preform tipping process. A zone of the preform is heated inside a furnace and softened. The preform tip is shaped and the process is controlled by the movement of the glass above and below the heating zone and by sensing the weight of the lower part of the preform, which in effect is a measure of the viscosity of the softened material. Once the correct viscosity is reached, the bottom holder is moved away from the top holder with a non-linear, accelerated velocity profile (derived from the FEM simulation of glass flow) which is precisely programmed and controlled so that the preform tip is optimally shaped (usually short and sharp tipped) with minimum waste and waveguide distortion when drawn into a fiber. The same concept of the non-linear, accelerated velocity profile can also be applied to other tipping processes such as horizontal preform tipping processes.

Abstract: An apparatus and a method for measurement of transparent cylindrical articles during their manufacture in high temperature furnaces having openings for viewing the articles as they pass through the furnace. The cylindrical articles may, for example, be optical fiber preforms which have at least two layers of vitreous material and from which optical fibers are made. Measurement is accomplished using a digital camera with a sensing and digital recording device and a lens, and a processor programmed with an algorithm which analyzes the images recorded by the sensing and digital recording device by eliminating noise, identifying and locating the outer edges of the transparent cylindrical article and calculating measurements of the article including the diameter and the axial center of the article.

Abstract: A method of forming a glass preform of predetermined length comprises providing a length of glass material to be separated to form a preform length and a remaining length; forming a notch in the glass material; inducing a tensile stress in excess of the tensile strength of the glass in an area adjacent to the notch; and separating the preform length from the remaining length at the notch.

Abstract: An apparatus and related process for producing large glass preforms with minimal clad to-core waveguide distortion from a glass body having a weight, an outer surface, core rods, and a cladding surrounding and separated from the core rods by a gap. The apparatus includes collars affixed to the top and bottom of the cladding; a spacer upon which the core rods rest; a first unit holding and supporting both the bottom collar and the spacer; a second unit holding and supporting the top collar; and a frame defining a heating zone having a heating element to heat the glass body. The weight of the glass body above and below the molten glass in the heating zone is supported by the first and second units without contacting the outer surface of the glass body.

Abstract: A method of forming a glass preform of predetermined length comprises providing a length of glass material to be separated to form a preform length and a remaining length; forming a notch in the glass material; inducing a tensile stress in excess of the tensile strength of the glass in an area adjacent to the notch; and separating the preform length from the remaining length at the notch.

Abstract: Method of producing glass components and preforms for use in the method. The preform includes a primary rod having a constant outside diameter and a square bottom and a sacrificial tip having a first end attached to the bottom of the primary rod, a second end opposite the first end, and a hollow interior region extending from the first end to the second end. The sacrificial tip is circular in cross section and the first end of the sacrificial tip has an outside diameter equal to the outside diameter of the primary rod. When the preform is heated in a furnace, the sacrificial tip melts and collapses into a drawing bulb which either draws the primary rod directly into the glass fiber or results in a tapered (i.e. tipped) preform for subsequent fiber draw. Material waste as well as the drip time is reduced and the cladding-to-core ratio, crucial for waveguide properties, is maintained for the whole preform compared to a square cut preform without the sacrificial tip.

Abstract: Methods for preform and tube draw based on controlling forming zone viscosity determined by calculating a holding force exerted by the glass component in the forming zone on the strand being drawn below. The holding force may be calculated by determining a gravitational force applied to the strand and a pulling force applied to the strand by a pulling device, where the holding force is equal to the opposite of the algebraic sum of the gravitational and pulling forces. The holding force may also be calculated by measuring a stress-induced birefringence in the strand at a point between the forming zone and the pulling device, determining an amount of force applied to the strand at the point corresponding to the birefringence, and calculating the holding force by correcting the amount of force for a gravitational effect of the weight of the strand between the forming zone and the point.

Abstract: A method of producing a quartz glass optical component is provided. The method includes providing a cylindrical quartz glass body made of core rod glass and cladding glass. The quartz glass body has a square cut first end having a first outer diameter. The method further includes providing a glass handle having a first end and an opposing square cut second end having a second outer diameter which is between 50% and 110% of the first outer diameter; attaching the square cut end of the glass handle to that of the quartz glass body; and using the glass handle to guide the quartz glass body through a draw furnace. A distortion in a clad-to-core ratio proximate the interface of the cylindrical quartz glass body and the glass handle is less than 5%.

Abstract: An apparatus and a method for measurement of transparent cylindrical articles during their manufacture in high temperature furnaces having openings for viewing the articles as they pass through the furnace. The cylindrical articles may, for example, be optical fiber preforms which have at least two layers of vitreous material and from which optical fibers are made. Measurement is accomplished using a digital camera with a sensing and digital recording device and a lens, and a processor programmed with an algorithm which analyzes the images recorded by the sensing and digital recording device by eliminating noise, identifying and locating the outer edges of the transparent cylindrical article and calculating measurements of the article including the diameter and the axial center of the article.