Abstract: A method for manufacturing an optical fiber comprises setting a heating condition for heating a glass rod, which is a parent material of the optical fiber, and an elongating speed of the glass rod based on a prescribed numerical value which changes with a progress of elongation of the glass rod; heating and elongating the glass rod to generate a preform based on the heating condition and the elongating speed which are set by the setting; and drawing the preform to a filament-like form by further heating the preform to generate the optical fiber.

Abstract: Three or more glass particle synthesizing burners are arranged to be opposed to a rotating glass rod. The glass rod and the glass particle synthesizing burners are reciprocated in parallel and relatively to deposit glass particles synthesized by the burners on the surface of the glass rod, thereby producing a soot body. The glass particle synthesizing conditions of the burners arranged at both ends are changed to have a greater deposition amount of glass particles per unit time in part or all of its movement range than other burners.

Abstract: A method of measuring the twist imparted to an optical fibre includes the steps of advancing the optical fibre in a predetermined direction and at a predetermined velocity, imparting to the optical fibre, during the step of advancing, a twist about its axis, measuring the diameter of the optical fibre during the step of advancing, to generate a time-based signal indicating the diameter, and processing this signal to find a value indicating the imparted twist. The step of processing includes the principal steps of transforming in the frequency domain the signal relating to the measurement of the diameter, calculating the power spectrum of the signal thus obtained, distinguishing in this power spectrum the signal peaks correlated with the imparted twist, determining the maximum frequency associated with these signal peaks, and dividing the value of this maximum frequency by the value of the velocity of advance of the fibre to find the value indicating the imparted twist.

Abstract: Disclosed is an optical fiber coating device for coating the outer circumference of the optical fiber with the coating material, in which the coating device is provided with and a gas provider for providing an environmental gas within the coating device, and a cooler for cooling down the environmental gas provided to the coater from the gas provider.

Abstract: An optical fiber preform (1) serving as a material of an optical fiber has a shoulder portion (12) thrusting beyond a middle portion (M) in a base end region (K) which is on the upper side when the optical fiber preform is suspended for a drawing process. The optical fiber preform (1) of this configuration can be easily produced by appropriately setting the heating condition, etc. for the sintering step in the production process. Thus, it is possible to omit the elongating step after the sintering step, thereby simplifying the production process. Further, in the prior-art technique, turbulence is generated in the gas flow in the furnace of the drawing apparatus toward the end of the drawing step, making it impossible to draw in a stable manner.

Abstract: A method for manufacturing an optical fiber preform includes a process A of applying flame polishing to a center glass rod, a process B of determining a ratio ra/rb, which is a ratio of a radius ra of the center glass rod expressed in millimeters with respect to a radius rb of a target optical fiber preform expressed in millimeters, based on a refractive index profile of a target optical fiber preform, and a process C of determining an amount of fine glass particles to be deposited on the center glass rod so that a ratio ra/rb/c falls within a range from 0.002 to 0.01, where “c” is a maximum value of hydroxyl group concentration expressed in ppm in the vicinity of a boundary between the center glass rod and an outer layer, which is formed by depositing fine glass particles on the center rod and by being vitrified.

Abstract: Methods for modifying preform core ovality during and subsequent to the formation of an optical fiber preform. Prior to MCVD deposition on a starting tube, the outer diameter of the starting tube is altered by etching or a like process to modify its ovality. Additionally, after MCVD deposition forms the core rod, but prior to overcladding of the core rod, the code rod may be etched to change its ovality. Both methods may be used independently or in combination to modify the ovality and reduce PMD of optical fiber drawn from the core rod. An additional method includes etching the cladding material of a core rod having an oval or elliptical core such that the cladding material mirrors the shape of the oval core. During drawing, the perform created there from is placed under a surface tension, or pulled in a manner to generate a circular or near perfect circular optical fiber having desired ovality and low PMD.

Abstract: When an optical fiber 3 is formed by drawing a preform 1, twisting is generated in the optical fiber 3. An outer diameter of the optical fiber 3 is continuously measured along a longitudinal direction of the optical fiber 3 from two different directions in a plane perpendicular to the advancing direction of the optical fiber 3 by a device for measuring twisting 4, thus twisting of the optical fiber 3 is measured.

Abstract: A method for processing a preform supported with a stationary chuck and a movable chuck of a glass-working lathe comprises providing a burner of a type which is able to create flame-controlled conditions by controlling flow rates of a flammable gas and a supporting gas wherein the supporting gas is discharged from at least one group of discharge pipes co-axially classified into plural groups that are, respectively, controllable with respect to a gas flow rate. The preform is processed under the flame-controlled conditions. A burner system and a preform processing apparatus comprising the burner system, both suited for realizing the method, are also described.

Abstract: A method for manufacturing an optical fiber comprises setting a heating condition for heating a glass rod, which is a parent material of the optical fiber, and an elongating speed of the glass rod based on a prescribed numerical value which changes with a progress of elongation of the glass rod; heating and elongating the glass rod to generate a preform based on the heating condition and the elongating speed which are set by the setting; and drawing the preform to a filament-like form by further heating the preform to generate the optical fiber.

Abstract: An apparatus and method for fabricating an optical fiber, an optical fiber preform, and an optical fiber core rod are disclosed herein. In particular, the process of fabricating an optical fiber preform involves, during a modified chemical vapor deposition process, collapsing the substrate tube into an optical fiber preform, and compressing the optical fiber preform in the longitudinal direction. An optical fiber preform that is shorter, but larger in diameter is thus formed. The optical fiber preforms therefore can be stacked during the optical fiber fabrication process, which is useful in drawing longer optical fibers with comparable outer diameter and core diameter to that used as the industry standard.

Abstract: The deposition of glass particulate material on a glass rod having a core is performed using a multi-burner multi-layer deposition in the following manner. The distribution of target jacketing ratios (the ratios of diameter of a consolidated optical fiber preform to diameter of the glass rod) of an optical fiber preform, whereby optical fibers of desired characteristics can be produced, is determined in the longitudinal direction of the glass rod. Based on the target ratio distribution in the longitudinal direction of the glass rod, the amount of the glass particulate material supplied from each burner to each point is adjusted to make a porous preform. Thus, an optical fiber preform obtained by clarifying the porous preform has a small variation in divergence ratio in the longitudinal direction, the divergence ratio being defined as the ratio of target jacketing ratio to jacketing ratio of the resulting preform.

Abstract: The method is designed to be implemented in an installation provided with means enabling a preform held between two points by supporting end-pieces to be rotated and to be moved in translation. Heater means for heating the preform by means of a plasma torch are associated with material supply means, so as to enable the preform to be manufactured in layers. Preform/torch relative displacements, with or without material being supplied, lead either to a new layer of material being deposited on the preform, or to the most recent layer deposited being glazed. Said method interposes a one-ended reduction in layer length, starting from one of the intermediate layers, while a succession of concentric layers are being deposited on the preform in a manner such that the lengths of the layers are progressively reduced so that the preform tapers towards it ends. The one-ended reduction leads to a limitation of the thickness of a determined segment at the level of the layer deposited immediately prior to the reduction.

Abstract: A method capable of stably drawing an optical fiber with a gas-seal system and an apparatus for implementing the method. The method produces an optical fiber 40b by drawing the optical fiber preform 30 by heating and softening the leading-end portion of it while feeding it into a drawing furnace 20. The drawing furnace 20 allows a gas 15 to blow against the optical fiber preform 30. The inside of the drawing furnace 20 is sealed with a seal ring 14U and a shutter 14L located at the top and bottom portions of it, respectively. While the gas 15 is fed, the inner diameter of the seal ring 14U is adjusted according to the diameter of the optical fiber preform 30. Consequently, even when the preform diameter varies, the clearance between the seal ring 14U and the optical fiber preform 30 can be maintained constant, thereby enabling a stable drawing operation.

Abstract: A glass composition to be softened is fed to a heating zone and is shaped continuously into a cylindrical component in a deformation zone, and the cross-sectional geometry of the component is determined. A feed device, a heating device, and a take-off device are provided, and a glass composition is supplied continuously by the feed device to the heating device, where it is softened, the component being formed from the softened glass composition by means of the take-off device under formation of a deformation zone. To produce a component with only slight deviations from the desired cross-sectional geometry and to provide a flexible apparatus suitable for this purpose, the glass composition is locally heated or cooled in at least one deformation area, which extends over only a part of the circumference of the deformation zone, as a function of a determined deviation of the cross-sectional geometry from a nominal geometry.

Abstract: Methods and apparatuses estimate and control optical fiber primary coating diameter for wet-on-wet optical fiber manufacturing. The primary coating diameter for a particular length of optical fiber is calculated based upon a measurement of the weight of primary and/or secondary coating material consumed during optical fiber manufacturing. Control of the primary coating diameter is effected by a coating controller which can increase or decrease the primary coating diameter through control of glass temperature, coating viscosity and/or other parameters during wet-on-wet fiber manufacture.

Abstract: In method of making an optical fiber and an apparatus, an optical fiber coated with UV curable resin is drawn at a drawing speed of 1000 m/min or more so that the optical fiber 5 has predetermined coating diameter from 235 &mgr;m to 265 &mgr;m. A transit time from an exit of a UV curing furnace to an entrance portion of a capstan for pulling the optical fiber downstream is set to be 0.5 seconds or more.

Abstract: A glass base material manufacturing apparatus for manufacturing a glass base material comprising: a plurality burners, arranged in a row at a predetermined intervals along the longitudinal direction of a starting base material of the glass base material, for forming a deposit, which is a base material of the glass base material by depositing glass soot on the starting base material while moving reciprocatory over a section of the entire length of the starting base material along the longitudinal direction of the starting base material; a plurality of flow rate regulators, at least one of which is connected to the plurality of burners, respectively, for regulating a flow rate of raw material gas of the glass soot, which is supplied to the plurality of burners; and a control unit connected to each of the plurality of flow rate regulators for controlling individually the plurality of flow rate regulators.

Abstract: The specification describes a VAD method for dynamically controlling the growth rate of both the core soot and the cladding soot in response to separate growth monitors.

Abstract: A method of fabricating a fused-type directional coupler that can be made in a simple manner. The present invention is characterized in that a pair of optical fibers satisfying a particular phase match condition are previously selected to form a fused-type directional coupler. The two optical fibers are prepared by respectively tapering and etching two identical optical fibers. The present invention can be applied to fabrication of mode-selective directional couplers utilizing symmetrical high-degree modes such as LP02 mode as well as fabrication of mode-selective directional couplers utilizing asymmetrical high-degree modes such as LP11 mode.

Abstract: Disclosed is a method for controlling a heat treatment in the process of fabricating a high purity silica glass via a sol-gel process using a low temperature heater having an inhalation line and an exhaust line. Accordingly, the method includes the steps of (a) identifying whether or not the diameter of the exhaust line is varied; (b) controlling the mass flow of the process gas according to the changed diameter of the exhaust line in step (a); (c) measuring an exhaust gas velocity discharged through the exhaust line; (d) comparing the exhaust gas velocity measured in the step (c) with the exhaust gas velocity after the scale of the exhaust line is varied; and, (e) repeating steps (b)-(d) if the comparison result in step (d) is different.

Abstract: An object of the present invention is to provide a method and apparatus for producing a glass particles deposit in which a soot body having less fluctuation in the outer diameter in a longitudinal direction can be produced without increasing an ineffective portion formed at an end portion of the soot body.

Abstract: Disclosed is a multi-line optical fiber drawing equipment, wherein at least two strands of optical fibers can be simultaneously drawn by the single draw tower, thereby maximizing an effectiveness of an installation space for a draw tower and the productivity in drawing the optical fiber. The optical fiber multi-line drawing equipment has at least two lines for drawing optical fibers from preforms. Each of the lines has a chuck, a furnace, a cooling unit, a coating unit, a curing unit, and a capstan, which are arranged in sequence in a draw tower. Processes for drawing optical fibers from preforms respectively along the lines are simultaneously performed.

Abstract: A silica-based core rod is traversed by a heat source along its longitudinal axis, to provide heated, softened regions. During the traverse, compressive or tensile movements are provided along the rod's longitudinal axis, these movements inducing, respectively, increases or decreases in the core diameter at the softened regions. By providing selective core diameter increases and/or decreases across the entire length of the core rod, a desired core diameter profile is attained. It is possible to attain a substantially uniform core diameter, or a varying core diameter profile that provides particular properties, such as systematically varying dispersion. In addition, due to the ability to increase core diameter and core rod diameter in a controlled manner, it is possible to make larger core rods, and in turn larger fiber preforms, than presently possible.

Abstract: The refractive index profile of a multimode optical preform, fabricated by MCVD for example, is modified in the longitudinal direction by removing selected amounts of core material from the wall of a central hole through the preform prior to collapse. The amount of core material to be removed is determined by measuring the refractive index profiles of optical fibers drawn from a number of precursor preforms at various locations along the length of the drawn fibers, averaging their profiles, and then comparing those averages with a desired profile. The refractive index profile is indirectly measured by bandwidth measurements, which are related to the alpha value a selected parameter (e.g., bandwidth) at various locations along the length of a fiber drawn from a previously fabricated preform. This parameter is then compared with desired values of that parameter at the various locations, and the differences are used to calculate the amount of core material that needs to be removed.

Abstract: A method of drawing an optical fiber which can improve the efficiency in manufacture without deforming resin coatings is provided.

Abstract: A method for manufacturing optical fiber with enhanced photosensitivity comprising the step of: forming a molten layer of glass and drawing a fiber from the molten layer of glass at a temperature of between about 1900° C. and 1995° C. Draw tension can be adjusted to attain the desired draw speed.

Abstract: A tube-encased fiber grating includes an optical fiber 10 having at least one Bragg grating 12 impressed therein which is embedded within a glass capillary tube 20. Light 14 is incident on the grating 12 and light 16 is reflected at a reflection wavelength &lgr;1. The shape of the tube 20 may be other geometries (e.g., a “dogbone” shape) and/or more than one concentric tube may be used or more than one grating or pair of gratings may be used. The fiber 10 may be doped at least between a pair of gratings 150,152, encased in the tube 20 to form a tube-encased compression-tuned fiber laser or the grating 12 or gratings 150,152 may be constructed as a tunable DFB fiber laser encased in the tube 20. Also, the tube 20 may have an inner region 22 which is tapered away from the fiber 10 to provide strain relief for the fiber 10, or the tube 20 may have tapered (or fluted) sections 27 which have an outer geometry that decreases down to the fiber 10 and provides added fiber pull strength.

Abstract: In a known method for the manufacture of a tube made of a vitreous material, especially of quartz glass, a hollow cylindrical semifinished product made of a vitreous material is carried essentially vertically to a heating zone, wherein it is heated and drawn off downwards—without the use of tools—to the tube by forming a transitional area from semifinished product to tube, while diameter and wall thickness of the tube are continuously measured, and the tube's measured geometrical data being used to generate a control signal with the aid of which a pressure difference is regulated between pressure P1 in the interior space of the semifinished product, the transitional area and the tube, as well as pressure P2 in the heating chamber which is regulated in the heating zone at least in the transitional area from semifinished product to tube and its adjacent tube area.

Abstract: A method and an apparatus for producing a glass preform having a uniform J ratio by adjusting the weight of glass particles to be deposited on a starting glass rod. The method uses an OVD method by which glass particles are successively deposited on an external cylindrical surface of a starting glass rod to create a growing soot layer thereon and the soot layer is then vitrified into a transparent glassy body, wherein the glass particle deposition is conducted by adjusting an amount of glass particles to be deposited based on data of J ratio fluctuations (where the J ratio is a ratio of an outer diameter of a glass preform to an outer diameter of a starting glass rod) of a previously produced glass preform in its longitudinal direction so that the glass preform to be produced can attain a uniform J ratio in its longitudinal direction.

Abstract: After the start of the control operation of a drawing apparatus, the operation control of a line speed being the drawing-in speed of an optical fiber is performed by a line speed control unit (19), and an optical-fiber feed speed control is performed by a preform feed speed control unit (22), in order that an optical fiber outside diameter measured by an optical-fiber outside diameter measurement unit (8) may become a target outside diameter. By way of example, in a case where the distal end of an optical fiber preform is not in a shape steadily melted in a heating furnace, the preform speed control unit (22) controls the feed speed of the optical fiber preform in the three stages of an optical-fiber-preform initial feed speed control, an acceleration-associated preform feed speed control and a line speed-associated preform feed speed control.

Abstract: The present invention relates to a sizing composition for a glass yarn, consisting of a solution whose solvent content is less than 5% by weight, this solution comprising at least 60% by weight of polymerizable components, at least 60% by weight of these polymerizable components being components with a molecular mass of less than 750 and these polymerizable components comprising at least one mixture capable of polymerizing: of component(s) containing at least one reactive acrylic function and/or at least one reactive methacrylic function, and of component(s) containing at least one reactive primary amine function and/or at least one reactive secondary amine function, at least 20% of the polymerizable components containing at least two reactive functions chosen from acrylic, methacrylic, primary amine and secondary amine functions.

Abstract: The present invention relates to an optical fiber fabrication method by which an optical fiber having an objective chromatic dispersion characteristic can be obtained readily. In an optical fiber fabrication method, a cutoff wavelength is measured in an optical fiber with a fixed length obtained by first drawing a part of an optical fiber preform. A target glass diameter for yielding an objective chromatic dispersion characteristic is then determined based on the cutoff wavelength thus measured. Then the rest of the optical fiber preform is drawn so that the glass diameter becomes the target glass diameter thus determined, thereby fabricating the optical fiber.

Abstract: The present invention relates to an optical fiber fabrication method by which an optical fiber having an objective chromatic dispersion characteristic can be obtained readily. In an optical fiber fabrication method, a cutoff wavelength is measured in an optical fiber with a fixed length obtained by first drawing a part of an optical fiber preform. A target glass diameter for yielding an objective chromatic dispersion characteristic is then determined based on the cutoff wavelength thus measured. Then the rest of the optical fiber preform is drawn so that the glass diameter becomes the target glass diameter thus determined, thereby fabricating the optical fiber.

Abstract: A manufacturing method of an optical fiber, which enables to precisely manufacture the optical fiber having a desired chromatic dispersion, comprising: (1) preparing an optical fiber preform having a longitudinally uniform refractive index, (2) measuring the chromatic dispersion of a predetermined length of the optical fiber obtained at the beginning of the drawing, (3) according to the results of such measurement, estimating the chromatic dispersion characteristic of the optical fiber obtained by drawing the optical fiber preform, and commencing the drawing of the optical fiber preform. To achieve the target chromatic dispersion diameter of the optical fiber is determined according to the chromatic dispersion that is measured with respect to a predetermined length of an optical fiber obtained at the beginning of the drawing of an optical fiber preform. Then, the remainder of the optical fiber preform is drawn to produce an optical fiber having the desired chromatic dispersion.

Abstract: A method of measuring the twist imparted to an optical fiber comprises the steps of advancing the optical fiber in a predetermined direction and at a predetermined velocity, imparting to the optical fiber, during the step of advancing, a twist about its axis, measuring the diameter of the optical fiber (210) during the step of advancing, to generate a time-based signal indicating the diameter, and processing this signal to find a value indicating the imparted twist. The step of processing comprises the principal steps of transforming in the frequency domain (240) the signal relating to the measurement of the diameter, calculating the power spectrum (250) of the signal thus obtained, distinguishing in this power spectrum the signal peaks correlated with the imparted twist (270), determining the maximum frequency (280) associated with these signal peaks, and dividing the value of this maximum frequency by the value of the velocity of advance of the fiber to find the value indicating the imparted twist (290).

Abstract: A plurality of glass deposition targets are rotated simultaneously and a first plasma torch, having a coil diameter larger than the sum of the target diameters, deposits glass simultaneously on the plurality. After the diameter of the targets reaches a threshold a second plasma torch is used. The diameter of the second plasma torch can provide for simultaneous deposition. In a further embodiment, after the target diameter reaches a second threshold a third plasma torch is used. In a further embodiment the spacing between the axes of rotation of the targets is widened as the target diameter increases. In a still further embodiment a single plasma torch includes movable concentric tubes within its coil to selectively operate as any of a plurality of different diameter plasma torches.

Abstract: The method includes axially modulating at least one plasma build-up pass in order to improve the opto-geometrical properties of the preform. The modulation preferably takes place during the final passes of plasma build-up and takes place by modulating the build-up grain flow rate. The diameter of the preform is evaluated (6), and a build-up control device (8) regulates grain flow rate (11, 5) in application of the above method.

Abstract: There are disclosed a method for producing an optical fiber base material ingot comprising depositing a soot on a starting core member, and subjecting the soot to dehydration, vitrification by sintering, and then cylindrical grinding, wherein the cylindrical grinding is performed while a core portion central axis is brought into line with a rotation axis of cylindrical grinding machine, and an optical fiber base material ingot produced by the method. According to the present invention, there are provided an optical fiber base material ingot having excellent ingot roundness and excellent core portion eccentricity, and a production method capable of producing the optical fiber base material ingot in a short period of time.

Abstract: In a elongating process, diameter gauges 20, 25 are provided at two locations of upstream measurement position P1 and downstream measurement position P2 which are in a taper portion 1b of an optical fiber preform 1, and fixed target diameters D10, D20 are set for the respective positions. Then a feed speed V1 of starting preform 1a is controlled based on a deviation (D1−D10) of measured diameter D1 at the measurement position P1, while a take-up speed V2 of elongated preform 1c is controlled based on a deviation (D2−D20) of measured diameter D2 at the measurement position P2. This decreases a time lag of control over the outside diameter of the elongated preform 1c and it thus becomes feasible to control the outside diameter in good response and with accuracy. Accordingly, an optical fiber preform elongating method and elongating apparatus are substantiated with improved elongating accuracy of the optical fiber preform and with improved productivity thereof.

Abstract: A method and apparatus for assembling optical components and a substrate. A glass coating is located at the inner base between the optical component and the substrate. The assembly of the component, substrate and glass coating can be used in the field of imaging and in particular for endoscopy.

Abstract: In a method of elongating a glass preform comprising the steps of holding both ends of the glass preform 1a with a first holding section 2 and a second holding section 3, respectively; moving the first holding section 2 and the second holding section 3 in a longitudinal direction of the glass preform 1a with the moving speed of the first holding section 2 faster than that of the second holding section 3 and, at the same time, heating and softening the glass preform 1a by a heating section 4 successively; and elongating the glass preform 1a by a tensile force applied thereto, so as to form an elongated body 1c; an electric furnace is employed in the heating section 4; and said method further comprising the steps of setting a reference value R1 with respect to an outside diameter at a specific position 1d in a tapered region 1b in the glass preform 1a in the process of elongating; acquiring an actually measured value R2 at the specific position 1d; and controlling the moving speed of the first holding section 2

Abstract: Making a polymer-clad optical fiber comprising a step of determining at a plurality of temperatures the delamination resistance of the polymer coating from fiber. The delamination resistance at ambient temperature can be compared with a predetermined target value for delamination resistance in use. The delamination resistance at elevated temperature can be compared with a predetermined lower target value for ease of strippability. Coated optical fiber having delamination resistances outside the predetermined ranges will typically be rejected.

Abstract: A method for producing an optical fiber preform is provided in which the variation of the outer diameter in the longitudinal direction is minimized and a target quantity of glass is accumulated as a whole. Based on a predetermined relationship between three variables: the outer diameter of a starting rod being a first variable, the outer diameter of an optical fiber preform a second variable, and the timing for ending the glass particles depositing process a third variable, the starting rod and burners are subjected to relative reciprocating movement so as to deposit glass particles on the starting rod until the timing for ending the depositing process, and then the resulting deposit body is vitrified. The third variable may be the traverse velocity, the glass particles deposition time, or the weight of a soot glass deposit body.

Abstract: There is provided robust diameter-controlled optical fiber during optical fiber drawing process and an optical fiber drawing process which comprises drawing the optical fiber from a perform therefor under tension to form the optical fiber while heating and melting the preform, wherein an outer diameter of the preform is measured (at a safe position immediately) above the furnace, an outer diameter of the optical fiber on which no coating has been provided is measured at one process position or two process positions before coating, and drawing conditions are robustly controlled based on the deviation of the measured optical fiber diameter data and the measured preform diameter data from a preselected outer diameter of the optical fiber and a preselected outer diameter of the preform.

Abstract: A method for manufacturing an optical fiber comprises setting a heating condition for heating a glass rod, which is a parent material of the optical fiber, and an elongating speed of the glass rod based on a prescribed numerical value which changes with a progress of elongation of the glass rod; heating and elongating the glass rod to generate a preform based on the heating condition and the elongating speed which are set by the setting; and drawing the preform to a filament-like form by further heating the preform to generate the optical fiber.

Abstract: A method and apparatus for controlling the shape and position of a deformable object are described. At least a portion of an object is heated to a temperature sufficient to render the heated portion deformable by a force. An image profile of the heated portion of the object is obtained. A controller compares the image profile to a reference profile and produces an error image signal. Based on the error image signal, an instruction signal is generated. A force applicator responsive to the instruction signal applies a radial force to at least one distinct predetermined location on the heated portion of the object in response to the instruction signal to cause the heated portion of the object to conform to the reference profile. The invention is particularly useful in controlling the shape of an optical fiber preform.

Abstract: An apparatus for grinding a glass base material having a core and a clad comprising: a grinding wheel for grinding the clad; a measuring unit for measuring an eccentricity between a center position of the glass base material and a center position of the core at a plurality of positions along a longitudinal direction of the glass base material; a design unit for calculating target diameters substantially continuous throughout the longitudinal direction of the glass base material so that the eccentricity becomes substantially zero for each of the plurality of positions; and a control unit for controlling the grinding wheel to grind the clad so that a diameter of the glass base material to be the target diameter substantially continuous throughout the longitudinal direction of the glass base material based on the target diameters calculated by the design unit.

Abstract: Method for winding a fiber element onto a support. The fiber element having at least two longitudinal portions (Pi) with different characteristics. The method including the steps of supplying the fiber element to the support and associating with each longitudinal portion a respective value of the winding pitch (pi) which is different from the values associated with the portions adjacent thereto. The winding pitch associated with each portion being modulated in accordance with a periodic function.

Abstract: A test optical fiber section (F) that resides under tensile stress (F) is heated in at least one longitudinal location so that a constriction (&Dgr;d) of its outside circumference forms thereat. This constriction (&Dgr;d) is acquired and utilized for setting welding parameters.