Description:TECHNICAL FIELD
The present disclosure relates to the field of optical fibers and, in particular, relates to an apparatus and method for constraining an optical fiber in a draw tower.
BACKGROUND
Optical fibers are usually drawn from a glass preform, which is a cylindrical body made up of glass. The optical fibers while being drawn from the draw tower must be maintained at their central position. If we are not centring the optical fiber in the draw tower, the optical fiber goes in contact with the wall of a draw tower which can break the optical fiber. Further, the quality of the coating decreases for example thickness, concentricity, geometric shape (ovality), etc. The centring of the optical fiber minimizes physical damage of the optical fiber by preventing the contact of optical fiber to the neighbour walls of the draw tower.
There are various techniques to draw optical fiber from the draw tower. For example, the reference US5500493A discloses an acoustic levitation apparatus and method to levitate a glass object in a centre position along a vertical axis of the glass object, by generating non-standing wave acoustic beams using acoustic transducers. The reference US8973408B2 discloses a non-contact centring device having two tapered side walls in which high-pressure fluid is delivered to the non-contact centring device. The non-contact centring device acts as a fluid bearing to prevent an optical fiber from touching the mechanical surface of the walls. The high-pressure fluid is forced into the vicinity of the optical fiber region such that the optical fiber remains centered within the tapered-shaped side walls before entering into the coating process. The reference EP2096628A1 discloses an acoustic levitation system comprising an emitter and a reflector. An object which is placed between the emitter and reflector is levitated due to a standing acoustic pressure wave generated by both the emitter and the reflector.
None of the prior art references disclose an efficient way to maintain a central position of the optical fiber during the fiber draw process. The prior techniques talk about levitating a large-diameter glass object against gravity using an acoustic beam which cannot be applied to a small diameter (generally between 80 to 250 microns) optical fiber. In conventional technique, centring of the optical fiber is done by using a pneumatic based centring element wherein the high-pressure fluid provides a centering force , which requires constant flow of fluids in the vicinity of the optical fiber. In general, fluids have some impurities which impact the quality of the optical fiber.
In light of the above stated discussion, there is a need for an efficient and effective apparatus and method to constrain the optical fiber that overcomes the above stated disadvantages.
OBJECTIVE OF THE DISCLOSURE
As mentioned there remains a need to maintain a central vertical position for an optical fiber in a draw tower without contacting the optical fiber. Accordingly, the present disclosure provides an acoustic centering apparatus to stabilize or center a lateral position of the optical fiber in the draw tower.
SUMMARY
In an aspect of the present disclosure, a method for constraining an optical fiber in a draw tower is disclosed. The method includes trapping the optical fiber in a central position along a vertical axis by an arrangement of a one or more acoustic waves in the vicinity of the optical fiber such that the movement of the optical fiber is constrained within 1 milli-meter from the vertical axis. The vertical axis is one of parallel to a draw tower axis and coinciding with the draw tower axis.
In another aspect of the present disclosure, an acoustic centering apparatus is disclosed. The acoustic centering apparatus includes a transducer holder and a plurality of transducers. The plurality of transducers are held in the transducer holder such that first set of transducers of the plurality of transducers are adapted to generate one or more first waves and second set of transducers of the plurality of transducers are adapted to generate one or more second waves. The one or more first and second waves are adapted to generate a plurality of standing waves such that a combination of the plurality of standing waves generates an acoustic radiation pressure. The acoustic radiation pressure traps an optical fiber in a central position along a vertical axis of a draw tower such that a movement of the optical fiber in a direction perpendicular to the vertical axis is constrained within 1 milli-meter (mm) from the vertical axis.

BRIEF DESCRIPTION OF DRAWINGS
Having thus described the disclosure in general terms, reference will now be made to the accompanying figures, wherein:
FIG. 1A illustrates a block diagram of a draw tower.
FIG. 1B illustrates a block diagram of another draw tower.
FIG. 2A illustrates a schematic view of the draw tower of FIG. 1A.
FIG. 2B illustrates a schematic view of the draw tower of FIG. 1B.
FIG. 2C illustrates an exemplary representation of one or more acoustic waves.
FIG. 3 illustrates a block diagram of a control unit for an acoustic centering apparatus of the draw tower of FIG. 1A, FIG. 1B, FIG. 2A, and FIG. 2B.
FIG. 4 illustrates a ring-shaped acoustic centering apparatus.
FIG. 5 illustrates a concave-shaped acoustic centering apparatus.
FIG. 6 illustrates a rectangular-shaped acoustic centering apparatus.
FIG. 7 illustrates a flowchart that depicts a method for constraining an optical fiber in the draw tower of FIG. 1A, FIG. 1B, FIG. 2A, and FIG. 2B.
It should be noted that the accompanying figures are intended to present illustrations of exemplary embodiments of the present disclosure. These figures are not intended to limit the scope of the present disclosure. It should also be noted that accompanying figures are not necessarily drawn to scale.
DEFINITIONS
The term “optical fiber” as used herein refers to a light guide that provides high-speed data transmission. The optical fiber comprises one or more glass core regions and a glass cladding region. The light moving through the one or more glass core regions of the optical fiber relies upon the principle of total internal reflection, where the glass core region has a higher refractive index (n1) than the refractive index (n2) of the cladding region of the optical fiber.
The term “transducer” as used herein refers to a device that converts variations in a physical quantity, such as pressure, into an electrical signal, or vice-versa.
The term “standing wave” as used herein refers to two identical waves that move in opposite directions along a line such that the two identical waves form the standing wave. The standing wave does not travel through space.
The term “external disturbance” as used herein refers to the disturbances that are coming from main parts of a draw tower. The main parts of the draw tower include a cooling unit and spool winding take-up section. The optical fiber is drawn at a high speed from the draw tower, which leads to turbulence in incoming air that is entering into a cooling tube in the draw tower. The turbulence in the incoming air causes vibrations that lead to the disturbances in the draw tower.
The term “acoustic radiation pressure” as used herein refers to an acoustic radiation force that is acting on an object in a sound field/acoustic field. The acoustic radiation force is the total time-averaged force on the object in the acoustic field.
The term “plurality of transducers” as used herein refers to a number of elements (plurality of phased transducers) that are pulsed in unison to direct sound waves (acoustic waves) in a specific direction.
The term “amplitude” as used herein refers to a maximum distance or distance moved by a point on an acoustic wave (vibrating wave) measured from its mean position.
The term “phase” as used herein refers to a position of a wave at a point in time (instantaneous) on a waveform cycle. In other words, the term “phase” as used herein refers to an instantaneous position of the wave on the waveform cycle.
The term “phase delay” as used herein refers to a time delay for any two transducers of the set of transducers. The time delay depends on the relative position of the two transducers of the set of transducers.
The term “coating ovality” as used herein refers to a percentage of coating by which the shape of a coating layer deviates from a circle. The coating ovality affects both transmission and strength owing to a build-up of non-uniformly distributed stresses on an optical fiber.
The term “coating concentricity error” as used herein refers to an error of an optical fiber that is the offset between the center of the two concentric circles that specify the coating of the coated optical fiber and the bare optical fiber.

DETAILED DESCRIPTION
The detailed description of the appended drawings is intended as a description of the currently preferred aspects of the present disclosure, and is not intended to represent the only form in which the present disclosure may be practiced. It is to be understood that the same or equivalent functions may be accomplished by different aspects that are intended to be encompassed within the spirit and scope of the present disclosure.
Moreover, although the following description contains many specifics for the purposes of illustration, anyone skilled in the art will appreciate that many variations and/or alterations to said details are within the scope of the present technology. Similarly, although many of the features of the present technology are described in terms of each other, or in conjunction with each other, one skilled in the art will appreciate that many of these features can be provided independently of other features. Accordingly, this description of the present technology is set forth without any loss of generality to, and without imposing limitations upon, the present technology.
FIG. 1A illustrates a block diagram of a draw tower 100. The draw tower 100 may be adapted to receive a preform 102 (as shown later in FIG. 2A and FIG. 2B) in order to draw an optical fiber 104 (as shown later in FIG. 2A and FIG.2B) from the preform 102. In some aspects of the present disclosure, the preform 102 may be a made up of a glass material (i.e., a glass preform) and thus may be a pure glass cylinder. The glass preform may be made up of very high purity (5N) chemicals, which may improve a quality of the optical fiber 104. In some aspects of the present disclosure, the preform 102 may be one of a single layer preform and a multi-layer preform. In some aspects of the present disclosure, the preform 102 may be doped with a suitable dopant. The preform 102 is designed to have a desired refractive index profile for the optical fiber 104. In some aspects of the present disclosure, as the optical fiber 104 is made up of a glass material, the glass material may have a density that may lie in a range between 2.19 gram per cubic-centimeter (g/cc) and 2.20 g/cc.
The draw tower 100 may have a main furnace 106, an annealing unit 108, a cooling unit 110, an acoustic centering apparatus 112, a coating unit 114, an ultra-violet (UV) curing unit 116. Specifically, the acoustic centering apparatus 112 may be disposed below the cooling unit 110 in the draw tower 100. The annealing unit 108 may have one or more annealing furnaces 118 of which first and second annealing furnaces 118a and 118b (hereinafter collectively referred to and designated as "the annealing furnaces 118") are shown. The acoustic centering apparatus 112 may have a transducer holder 120 and a plurality of transducers 122 (hereinafter collectively referred to and designated as “the transducers 122” and individually referred to and designated as “the transducer 122a”) of which first and second set of transducers 124 and 126 are shown. The draw tower 100 may extend along a draw tower axis (Y’-Y’) of the draw tower 100. In other words, the main furnace 106, the annealing unit 108, the cooling unit 110, the acoustic centering apparatus 112, the coating unit 114, the UV curing unit 116 may be arranged along the draw tower axis (Y’-Y’).
In some aspects of the present disclosure, the optical fiber 104 may have a movement in the draw tower 100. The movement of the optical fiber 104 in the draw tower 100 is not the same in all sections (such as cooling unit 110, main furnace 106, annealing unit 108) in the draw tower 100. Some sections of the draw tower 100 may have higher amplitude range up to 1mm which can be reduced to 500 micro-meters range.
The main furnace 106 may be adapted to receive the preform 102 to heat the preform 102 such that the optical fiber 104 is drawn out from the main furnace 106. Specifically, the optical fiber 104 may be a bare optical fiber (i.e., a melted optical fiber) that may be drawn out from the main furnace 106. Specifically, the main furnace 106 may be adapted to heat the preform 102 at a temperature of about 1500 – 2200 Degree Celsius (°C) to melt the preform 102. The preform 102 may be melted to obtain the optical fiber 104. In some aspects of the present disclosure, the preform 102 may be inserted into the main furnace 106 at a predefined speed (generally between 1 milimeter per minute (mmpm) to 5 mmpm). Upon insertion of the preform 102 in the main furnace 106, the preform 102 may be adequately positioned in the main furnace 106. For example, upon insertion of the preform 102 in the main furnace 106, the preform 102 may be attached to a top end of the main furnace 106 to hang the preform 102 at the top end of the main furnace 106.
In some aspects of the present disclosure, the main furnace 106 may be provided with a plurality of induction coils (not shown) that may be disposed within the main furnace 106. The plurality of induction coils may be adapted to melt the preform 102. In one aspect of the present disclosure, the main furnace 106 may be maintained at a temperature of 2200 °C to melt the preform 102. The main furnace 106 may be further provided with one or more inert gases (such as Helium, Argon, Nitrogen etc).
In some aspects of the present disclosure, the preform 102 may be melted at a temperature of 1500°C. In some aspects of the present disclosure, the optical fiber 104 may have a diameter that may be less than 150 micrometers (µm) (generally 125 µm with a tolerance of 1 µm).
The annealing unit 108 may be coupled to the main furnace 106. Specifically, the annealing unit 108 may be disposed below the main furnace 106. Upon the optical fiber 104 being drawn out from the main furnace 106, the optical fiber 104 may be cooled in the annealing furnaces 118. The annealing furnaces 118 may gradually cool the optical fiber 104. The annealing furnaces 118 may be adapted to gradually cool the optical fiber 104 in one or more stages by passing the optical fiber 104 through the annealing furnaces 118. Specifically, the annealing furnaces 118 may bring down the temperature of the optical fiber 104 to 450°C.
The cooling unit 110 may be coupled to the annealing unit 108. Specifically, the cooling unit 110 may be disposed below the annealing unit 108. The cooling unit 110 may be adapted to cool the optical fiber 104. The cooling unit 110 may use one or more cooling gases to cool the optical fiber 104. Specifically, the one or more cooling gases may carry away heat of the optical fiber 104 to bring down the temperature of the optical fiber 104 to 50°C.
In some aspects of the present disclosure, the one or more cooling gases may include, but not limited to, Argon, Helium, and the like. Aspects of the present disclosure are intended to include and/or otherwise cover any kind of gas that is to be used in the cooling unit 110, without deviating from the scope of the present disclosure.
The acoustic centering apparatus 112 may be coupled to the cooling unit 110. Specifically, the acoustic centering apparatus 112 may be disposed below the cooling unit 110. The acoustic centering apparatus 112 may be adapted to trap the optical fiber 104 in a central position i.e., along a vertical axis (Y-Y) (as shown later in Fig. 2A and Fig. 2B). The vertical axis (Y-Y) may be one of parallel to a draw tower axis (Y’-Y’) and coinciding with the draw tower axis (Y’-Y’). While the acoustic centering apparatus 112 traps the optical fiber 104, there may be no net force that may act on the optical fiber 104. The acoustic centering apparatus 112 may be adapted to hold the optical fiber 104 at the vertical axis (Y-Y) against other external disturbances in the draw tower 100. The transducers 122 may be held in the transducer holder 120. The transducers 122 may be adapted to generate one or more acoustic waves (hereinafter interchangeably referred to as “the acoustic waves”) such that the acoustic waves have a predefined amplitude and a predefined phase. The acoustic wave may further have a predefined frequency. Each of the first and second set of transducers 124 and 126 may have a number of transducers. Aspects of the present disclosure are intended to include and/or otherwise cover any number of transducers in the first and second set of transducers 124 and 126, without deviating from the scope of the present disclosure. The first set of transducers 124 of the transducers 122 may be adapted to generate one or more first waves in a first direction. The second set of transducers 126 of the transducers 122 may be adapted to generate one or more second waves in a second direction. The one or more first and second waves may have the predefined amplitude and the predefined frequency. The acoustic centering apparatus 112 may be disposed in vicinity of the optical fiber 104 such that the one or more first and second waves (i.e., one or more acoustic waves) are generated in the vicinity of the optical fiber 104. The first direction may be opposite to the second direction such that the one or more first and second waves generate a plurality of standing waves. The plurality of standing waves may be a combination of two waves that may move in opposite direction to each other such that each of the two waves has the same amplitude and frequency. The plurality of standing waves may, in combination to each other, generate an acoustic radiation pressure. The acoustic radiation pressure may provide a strong trapping force such that the acoustic radiation pressure traps the optical fiber 104 in the central position i.e., along the vertical axis (Y-Y). The acoustic radiation pressure may provide support to the optical fiber 104 against inherent change in an axis of the optical fiber 104 due to external disturbances in the draw tower 100. The acoustic radiation pressure may be adapted to trap the optical fiber 104 in the central position without contacting the optical fiber 104. This way, the acoustic radiation pressure may maintain the optical fiber 104 in a designated position i.e., along the vertical axis (Y-Y).
In some aspects of the present disclosure, movement of the optical fiber 104 may be constrained within 1 milli-meter from the vertical axis (Y-Y).
In some aspects of the present disclosure, each transducer of the transducers 122 may be, but not limited to, a bolt-clamp Langevin-type lead-zirconate-titanate transducer. Aspects of the present disclosure are intended to include and/or otherwise cover any kind of known or later developed transducer, without deviating from the scope of the present disclosure.
In some aspects of the present disclosure, each transducer of the transducers 122 may have a diameter that may lie in a range between 15 milli-meters (mm) and 40 mm. Aspects of the present disclosure are intended to include and/or otherwise cover any dimension for each transducer of the transducers 122, without deviating from the scope of the present disclosure.
In some aspects of the present disclosure, each transducer of the transducers 122 may have a frequency range that may lie between 50 Kilo-hertz (kHz) and 200 kHz. Aspects of the present disclosure are intended to include and/or otherwise cover any frequency range for each transducer of the transducers 122, without deviating from the scope of the present disclosure.
In some aspects of the present disclosure, two adjacent transducers from the first and second set of transducers 124 and 126 may have a distance that may lie in a range such that a wavelength at which the optical fiber 104 oscillates is out of phase.
In some aspects of the present disclosure, the acoustic centering apparatus 112 may have a plurality of reflectors 128a-128n (hereinafter collectively referred to and designated as “the reflectors 128” and individually referred to and designated as “the reflector 128a”). The reflectors 128 may be disposed opposite to the transducers 122. Specifically, the reflectors 128 may be disposed opposite to one of, the first set of transducers 124 and the second set of transducers 126. The reflectors 128 may be adapted to reflect one of the one or more first and second waves. The reflectors 128 may have low absorptivity and may reflect majority of the one or more first and second waves. In some examples of the present disclosure, each reflector of the reflectors 128 may be a concave mirror reflector. In some examples of the present disclosure, each reflector of the reflectors 128 may have a diameter that may lie in a range between 15 mm and 40 mm . Preferably, each reflector of the reflectors 128 may have the diameter of 20 mm. Aspects of the present disclosure are intended to include and/or otherwise cover any dimension for each reflector of the reflectors 128, without deviating from the scope of the present disclosure. Each reflector of the reflectors 128 may have a focal length that may lie in a range between 15 mm and 25 mm. Preferably, each reflector of the reflectors 128 may have the focal length of 20 mm. Aspects of the present disclosure are intended to include and/or otherwise cover any value of the focal length for each reflector of the reflectors 128, without deviating from the scope of the present disclosure.
While using the reflectors 128, the acoustic centering apparatus 112 may use either the first set of transducers 124 or the second set of transducers 126. In one example, the reflectors 128 may be used at a place of the second set of transducers 126 in the acoustic centering apparatus 112. In such a scenario, the first set of transducers 124 may be adapted to generate the one or more first waves in the first direction. The one or more first waves may reflect from the reflectors 128 that may be disposed opposite to the first set of transducers 124 (i.e., at the place of the second set of transducers 126). The reflectors 128, upon reflecting the one or more first waves may be adapted to generate a reflected version of the one or more first waves such that the reflected version of the one or more first waves may travel in the second direction. The reflected version of the one or more first waves may now act as the one or more second waves (as described hereinabove). The one or more first waves and the reflected version of the one or more first waves may have the predefined amplitude and the predefined frequency. The one or more first waves and the reflected version of the one or more first waves may generate the plurality of standing waves. The plurality of standing waves may generate the acoustic radiation pressure. The acoustic radiation pressure may force the optical fiber 104 in one of, a forward direction and a backward direction to align the optical fiber 104 along the vertical axis (Y-Y). The acoustic radiation pressure may provide a strong trapping force such that the acoustic radiation pressure traps the optical fiber 104 in the central position i.e., along the vertical axis (Y-Y). In another example, the reflectors 128 may be used at a place of the first set of transducers 124 in the acoustic centering apparatus 112. In such a scenario, the second set of transducers 126 may be adapted to generate the one or more second waves in the second direction. The one or more second waves may reflect from the reflectors 128 that may be disposed opposite to the second set of transducers 126 (i.e., at the place of the first set of transducers 124). The reflectors 128, upon reflecting the one or more second waves may be adapted to generate a reflected version of the one or more second waves such that the reflected version of the one or more second waves may travel in the first direction. The reflected version of the one or more second waves may now act as the one or more first waves (as described hereinabove). The one or more second waves and the reflected version of the one or more second waves may have the predefined amplitude and the predefined frequency. The one or more second waves and the reflected version of the one or more second waves may generate the plurality of standing waves. The plurality of standing waves may generate the acoustic radiation pressure. The acoustic radiation pressure may provide the strong trapping force such that the acoustic radiation pressure traps the optical fiber 104 in the central position i.e., along the vertical axis (Y-Y). The vertical axis (Y-Y) may be one of parallel to the draw tower axis (Y’-Y’) and/or coinciding with the draw tower axis (Y’-Y’).
In some aspects of the present disclosure, the transducers 122 may have a flat surface such that the transducers 122 may act as the reflectors 128. In such a scenario, the flat surface of the transducers 122 may reflect one of the one or more first and second waves.
In some aspects of the present disclosure, a distance between the transducers 122 and the reflectors 128 may lie in a range between 50 mm and 200 mm. Aspects of the present disclosure are intended to include and/or otherwise cover any value for the distance between the transducers 122 and the reflectors 128, without deviating from the scope of the present disclosure.
Although FIG. 1A illustrates that one acoustic centering apparatus, (i.e., the acoustic centering apparatus 112), it will be apparent to a person skilled in the art that the scope of the present disclosure is not limited to it. In various other aspects of the present disclosure, the draw tower 100 may have a number of acoustic centering apparatuses without deviating from the scope of the present disclosure. In such a scenario, each acoustic centering apparatus of the number of acoustic centering apparatuses are configured to serve one or more functionalities in a manner similar to the functionalities as being served by the acoustic centering apparatus 112 as described herein. Further, the number of acoustic centering apparatuses may be disposed throughout a running path of the optical fiber 104, while the optical fiber 104 is being drawn from the draw tower 100.
The coating unit 114 may be coupled to the acoustic centering apparatus 112. Specifically, the coating unit 114 may be disposed below the acoustic centering apparatus 112. The coating unit 114 may be adapted to apply one or more coating layers (hereinafter referred to as “the coating layers”) to generate a coated optical fiber 105 (as shown later in FIG. 2A and FIG. 2B). The coating layers may protect the coated optical fiber 105 such that the coating layers maintain mechanical characteristics and improve optical performance.
In some aspects of the present disclosure, the coating layers may be primary and secondary coatings that may be applied on the optical fiber 104 to form the coated optical fiber 105. The primary coating may have a coating concentricity value that may be less than 20 micro-meters. In some aspects of the present disclosure, the secondary coating may have a coating concentricity value that may be less than 12 micro-meters. In some aspects of the present disclosure, each coating layer of the coating layers may have a coating ovality that may be less than 4%.
In some aspects of the present disclosure, the coating layers may have two layers i.e., an inner layer and an outer layer. The inner layer may be a soft layer that may adhere to the optical fiber 104. The outer layer may be a hard layer that may surround the inner layer. The coating unit 114 may therefore apply and cure two different separate resins that may result in the inner and outer coatings.
The UV curing unit 116 may be coupled to the coating unit 114. Specifically, the UV curing unit 116 may be disposed below the coating unit 114. The UV curing unit 116 may be adapted to cure the coated optical fiber 105. The UV curing unit 116 may provide protection, flexibility, and strength to the coated optical fiber 105. The UV curing unit 116, by way of ultraviolet inks (hereinafter referred to as “the UV inks”) may provide color code to the coated optical fiber 105 and may protect the coated optical fiber 105 against decomposition caused by gels of an optical cable, specifically while manufacturing of multi-fiber optical cables.
Although FIG. 1A illustrates that the acoustic centering apparatus 112 is disposed below the cooling unit 110 i.e., below the cooling unit 110 in the draw tower 100, it will be apparent to a person skilled in the art that the scope of the present disclosure is not limited to it. In various other aspects of the present disclosure, the acoustic centering apparatus 112 is disposed above the cooling unit 110 in the draw tower 100 without deviating from the scope of the present disclosure. In such a scenario, the cooling unit 110 and the acoustic centering apparatus 112 are configured to serve one or more functionalities in a manner similar to the functionalities as being served by the cooling unit 110 and the acoustic centering apparatus 112 as described herein.
In some aspects of the present disclosure, the acoustic centering apparatus 112 may be disposed or placed in any position along the draw tower axis (Y’-Y’) of the draw tower 100. In an example, the acoustic centering apparatus 112 may be disposed below the main furnace 106. In another example, the acoustic centering apparatus 112 may be disposed below the annealing unit 108. In another example, the acoustic centering apparatus 112 may be disposed below the coating unit 114. In another example, the acoustic centering apparatus 112 may be disposed below the UV-curing unit 116.
FIG. 1B illustrates a block diagram of another draw tower 101. The draw tower 101 may be substantially similar to the draw tower 100 with similar elements referred with similar reference numerals. However, the acoustic centering apparatus 112 in the draw tower 101 is disposed above the cooling unit 110 in the draw tower 101. For example, when the acoustic centering apparatus 112 in the draw tower 101 is disposed above the cooling unit 110, the optical fiber 104 may be prevented from getting in contact with walls of the cooling unit 110. The optical fiber 104 may go through a glass abrasion phenomena when the optical fiber 104 touches the walls of the cooling unit 110. When the optical fiber 104 touches the walls of the cooling unit, the quality of drawn optical fiber may be degraded till a longer length which may lead to increase more optical fiber wastage. Further, the draw tower 101 may be configured to serve one or more functionalities in a manner similar to the functionalities as being served by the draw tower 100 as described herein.
FIG. 2A illustrates a schematic view of the draw tower 100 of FIG. 1A. The draw tower 100 may further have first and second laser micrometers 202a and 202b (hereinafter collectively referred to and designated as “the laser micrometers 202”) and a take up unit 204. The laser micrometers 202 and the take up unit 204 may be arranged along the draw tower axis (Y’-Y’) of the draw tower 100. The draw tower 100 may further have a capstan (not shown) and a dancer pulley (not shown) that may be placed before the take up unit 204.
The main furnace 106 may have a chamber 206. The chamber 206 may have an upper end 208, a lower end 210, an inlet hole 212, and an outlet hole 214. The inlet hole 212 may be disposed at the upper end 208. The outlet hole 214 may be disposed at the lower end 210. The inlet and outlet holes 212 and 214 may be provided with an iris frame (not shown). The chamber 206 may be adapted to receive the preform 102 from the inlet hole 212. The iris frame may allow an operator to control flow of the one or more inert gases in the main furnace 106.
In some aspects of the present disclosure, the inlet and outlet holes 212 and 214 may have a cylindrical shape. Aspects of the present disclosure are intended to include and/or otherwise cover any shape for the inlet and outlet holes 212 and 214, without deviating from the scope of the present disclosure.
The first laser micrometer 202a may be disposed beneath the main furnace 106. The second laser micrometer 202b may be disposed beneath the coating unit 114. The laser micrometers 202 may be adapted to conduct non-contact inspection of the optical fiber 104 and the coated optical fiber 105. The laser micrometers 202 may allow measurement of a physical property of the optical fiber 104 and the coated optical fiber 105, including but not limited to, such as one or more dimensions, a shape, and a uniformity of the optical fiber 104 and the coated optical fiber 105. Aspects of the present disclosure are intended to include and/or otherwise cover any other physical property that is being measured by the laser micrometers 202, without deviating from the scope of the present disclosure. Aspects of the present disclosure are intended to include and/or otherwise cover any number of laser micrometers (i.e., 2, 3, 4, 5), without deviating from the scope of the present disclosure.
The coating unit 114 may have a funnel 216, a pair of rollers 218 (hereinafter collectively referred to and designated as “the rollers 218”) of which first and second rollers 218a and 218b are shown. The rollers 218 may be disposed within the funnel 216 such that the rollers 218 rotate within the funnel 216. The funnel 216 may hold a coating solution 220 such that the rollers 218 are immersed in the coating solution 220. The coating solution 220 may facilitate the coating unit 114 to apply the coating layers on the optical fiber 104 to generate the coated optical fiber 105. Specifically, the rollers 218, upon rotation, may be adapted to apply the coating layers on the optical fiber 104 to generate the coated optical fiber 105. Aspects of the present disclosure are intended to include and/or otherwise cover any number of rollers (i.e., 2, 3, 4, 5, 6), without deviating from the scope of the present disclosure.
The take up unit 204 (i.e., take up spool) may be coupled to the UV curing unit 116. Specifically, the take up unit 204 may be disposed below the UV curing unit 116. The take up unit 204 may have a drum 222. The drum 222 may be a motorized drum such that a motor (not shown) may be adapted to rotate the drum 222. Upon rotation of the drum 222, the coated optical fiber 105 may be wrapped around the drum 222. Specifically, upon rotation of the drum 222, the coated optical fiber 105 may be wrapped around the drum 222.
FIG. 2B illustrates a schematic view of the draw tower 101 of FIG. 1B. The draw tower 101 may be substantially similar to the draw tower 100 with similar elements referred with similar reference numerals. However, the acoustic centering apparatus 112 in the draw tower 101 is disposed above the cooling unit 110 in the draw tower 101. Further, the draw tower 101 may be configured to serve one or more functionalities in a manner similar to the functionalities as being served by the draw tower 100 as described herein.
FIG. 2C illustrates an exemplary representation 200 of the one or more acoustic waves. The transducer 122a may be disposed opposite to the reflector 128a. The transducer 122a may be adapted to generate the acoustic waves that may be reflected from the reflector 128a. The reflector 128a may be adapted to provide reflected versions of the acoustic waves. The acoustic waves may have the wavelength (?). The optical fiber 104 may have a center (C). The center (C) of the optical fiber 104 may be shifted by a distance (?Z) (generally less than 1000 µm) from the vertical axis (Y-Y). The optical fiber 104 may exhibit one or more inherent vibrations. The one or more inherent vibrations of the optical fiber 104 may be anchored in the acoustic waves, and thereby preventing a lateral motion of the optical fiber 104. The acoustic waves may therefore ensure centring of the optical fiber 104 along the vertical axis (Y-Y). The one or more acoustic waves may trap the optical fiber 104 for at least 3 mm vertical length of the optical fiber 104 in the draw tower 100 and 101. Specifically, the one or more acoustic waves may trap the optical fiber 104 between 3 mm to 10 mm vertical length of the optical fiber 104 in the draw tower 100 and 101. The vertical length of the optical fiber 104 which may be trapped by the one or more acoustic waves depends on a beam spread of the transducers 122 (i.e., an aperture of the transducers 122).
FIG. 3 illustrates a block diagram of a control unit 300 for the acoustic centering apparatus 112 of the draw tower 100 and 101 of FIG. 1A, FIG. 1B, FIG. 2A, and FIG. 2B. The control unit 300 may be coupled via any transmission medium to the acoustic centering apparatus 112 to control the transducers 122 of the acoustic centering apparatus 112. Specifically, the control unit 300 may be adapted to one of, activate and deactivate one or more transducers of the transducers 122. The control unit 300 may further be adapted to one of, activate and deactivate the transducers 122. The control unit 300 may further be adapted to one of, activate and deactivate the reflectors 128. The one or more transducers of the transducers 122, upon activation may generate the acoustic waves and the one or more transducers of the transducers 122, upon deactivation may not generate the acoustic waves.
The control unit 300 may have a control device 302 and a printed circuit board (PCB) 304. The PCB 304 may have an input/output port 306 (hereinafter referred to and designated as “the I/O port 306”), a programming circuit 308, and a driver circuit 310.
In some aspects of the present disclosure, the programming circuit 308 may be any or a combination of microprocessor, microcontroller, Arduino Uno, At mega 328, Raspberry Pi or other similar processing unit, and the like. In yet another embodiment, the programming circuit 308 may include one or more processors coupled with a memory (not shown) such that the memory storing computer-readable instructions executable by the one or more processors.
In some aspects of the present disclosure, the programming circuit 308 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, logic circuitries, and/or any devices that manipulate data based on operational instructions stored in a memory. The computer-readable instructions or routines stored in the memory may be fetched and executed to create or share the data units over a network service. The memory may include any non-transitory storage device including, for example, volatile memory such as RAM, or non-volatile memory such as EPROM, flash memory, and the like.
In some aspects of the present disclosure, the programming circuit 308 may be implemented as a combination of hardware and programming (for example, programmable instructions) to implement one or more functionalities of the programming circuit 308. In examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the programming circuit 308 may be processor executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the programming circuit 308 may include a processing resource (for example, one or more processors), to execute such instructions. In the present examples, the machine-readable storage medium may store instructions that, when executed by the processing resource, implement the programming circuit 308. In such examples, the programming circuit 308 may include the machine-readable storage medium storing the instructions and the processing resource to execute the instructions, or the machine-readable storage medium may be separate but accessible to the programming circuit 308 and the processing resource. In other examples, the programming circuit 308 may be implemented by an electronic circuitry.
The control device 302 may facilitate the operator to enter a co-ordinate point (hereinafter referred to and designated as “the co-ordinates”) of the one or more transducers of the transducers 122. Specifically, to control the one or more transducers of the transducers 122, the operator may enter the co-ordinates of the one or more transducers of the transducers 122. The one or more transducers of the transducers 122 may be controlled to control the predefined amplitude and the predefined phase of the acoustic wave. Specifically, the one or more transducers of the transducers 122 may be one of, activated and deactivated to independently control the predefined amplitude and the predefined phase of the acoustic wave. The one or more transducers of the transducers 122 may upon one of, activation and deactivation, undergo a phase delay. The one or more transducers of the transducers 122 may upon one of, activation and deactivation, cause delay in the predefined phase of the acoustic wave that may control the predefined amplitude and the predefined phase of the acoustic wave. In some preferred examples, the one or more transducers of the transducers 122 may be one of, activated and deactivated at different intervals of time to control the predefined amplitude and the predefined phase of the acoustic wave. By independently controlling the predefined amplitude and the predefined phase of the acoustic wave, the predefined frequency of the acoustic wave may be controlled. By controlling the predefined frequency of the acoustic wave, the acoustic radiation pressure may be varied such that no net force acts on the optical fiber 104 and the optical fiber 104 is maintained along the vertical axis (Y-Y).
In some aspects of the present disclosure, the predefined amplitude and the predefined phase may be independently controlled by changing the relative position of the one or more transducers of the transducers 122. However, upon disposing the acoustic centering apparatus 112 in the draw tower 100 and 101, to change the relative position of the one or more transducers of the transducers 122 may not be viable. Therefore, upon disposing the acoustic centering apparatus 112 in the draw tower 100 and 101, the predefined amplitude and the predefined phase of the acoustic wave may be controlled by activating and deactivating the one or more transducers of the transducers 122.
The control device 302 may be coupled to the PCB 304. The I/O port 306 may facilitate the control device 302 to couple to the PCB 304 through a network interface (not shown). The I/O port 306 is the mediums to send data from internal logic to external sources and receive data from external sources. The programming circuit 308 may be a Field Programmable Gate Array (FPGA) that may be an integrated circuit. The FPGA is an IC that may be programmed to perform a customized operation for a specific application. The FPGA provides better performance than a general CPU as they are capable of handling parallel processing. The programming circuit 308 may, upon the operator enters the co-ordinates of the one or more transducers of the transducers 122, may generate one of, an activation and deactivation signal. The activation signal may activate the one or more transducers of the transducers 122. The deactivation signal may deactivate the one or more transducers of the transducers 122. The driver circuit 310 may, upon generation of the activation signal and the deactivation signal, activates and deactivates the one or more transducers of the transducers 122. Specifically, the driver circuit 310, upon generation of the activation signal, may transmit the activation signal to the one or more transducers of the transducers 122 to activate the one or more transducers of the transducers 122. The driver circuit 310, upon generation of the deactivation signal, may transmit the deactivation signal to the one or more transducers of the transducers 122 to deactivate the one or more transducers of the transducers 122.
FIG. 4 illustrates a ring-shaped acoustic centering apparatus 400 (hereinafter referred to and designated as “the ring-shaped ACA 400”). The ring-shaped ACA 400 may be substantially similar to the acoustic centering apparatus 112 with similar elements referred with similar reference numerals. However, the ring-shaped ACA 400 may have a ring 402 (i.e., the transducer holder 120) of the acoustic centering apparatus 112. The ring 402 may be adapted to hold the transducers 122 and the reflectors 128 such that the transducers 122 are disposed opposite to the reflectors 128. In other words, the transducers 122 and the reflectors 128 may be disposed in form of the ring 402. Specifically, one portion of the ring 402 may be adapted to hold the first set of transducers 124 and another portion of the ring 402 may be adapted to hold the second set of transducers 126. The ring-shaped ACA 400 may be disposed anywhere in the draw tower 100 and 101. The ring 402 of the ring-shaped ACA 400 consumes less space in the draw tower 100 and 101. To generate the plurality of standing waves, the first and second set of transducers 124 and 126 may be adapted to generate the one or more first and second waves. The plurality of standing waves may further generate the acoustic radiation pressure. Specifically, the ring-shaped ACA 400 may be adapted to generate the acoustic radiation pressure in a horizontal direction with respect to the draw tower 100 and 101 i.e., a direction perpendicular to the vertical axis (Y-Y) to maintain the optical fiber 104 along the vertical axis (Y-Y). The acoustic radiation pressure may force the optical fiber 104 to move in one of, the forward direction and the backward direction to align the optical fiber 104 along the vertical axis (Y-Y). The acoustic radiation pressure may provide the strong trapping force such that the acoustic radiation pressure traps the optical fiber 104 in the central position i.e., along the vertical axis (Y-Y).
In some aspects of the present disclosure, the ring-shaped ACA 400 may have the transducer 122a and the reflector 128a that are positioned along a circumference of the ring 402 of the ring-shaped ACA 400. The transducer 122a may be disposed opposite to the reflector 128a. The ring-shaped ACA 400 may have two adjacent transducers 122a such that a distance between the two adjacent transducer 122a may be defined by an equation 2pRn where, R is radius of ring 402, and n is number if transducers 122a.
In some aspects of the present disclosure, to generate the plurality of standing waves, the one or more first and second waves may be reflected back by the reflectors 128 to generate the reflected versions of the one or more first and second waves, respectively. The one or more first and second waves and the reflected versions of the one or more first and second waves may together generate the plurality of standing waves.
In some aspects of the present disclosure, the ring 402 may have a diameter that may lie in a range between 50 mm and 200 mm. Aspects of the present disclosure are intended to include and/or otherwise cover any value for the diameter of the ring 402, without deviating from the scope of the present disclosure.
Although FIG. 4 illustrates one ring-shaped ACA (i.e., the ring-shaped ACA 400), however, the aspects of the present disclosure are not limited to it. Aspects of the present disclosure are intended to include and/or otherwise cover any number of ring-shaped ACAs (i.e., 2, 3, 4, 5, 6) to be used in the draw tower 100 and 101 without deviating from the scope of the present disclosure. In such a scenario, the number of ring-shaped ACAs may be stacked one above the other to form a multiple ring structure.
FIG. 5 illustrates a concave-shaped acoustic centering apparatus 500 (hereinafter referred to and designated as “the concave-shaped ACA 500”). The concave-shaped ACA 500 may be substantially similar to the acoustic centering apparatus 112 with similar elements referred with similar reference numerals. However, the concave-shaped ACA 500 may have first and second hemi-spherical shells 502a and 502b (hereinafter collectively referred to and designated as “the shells 502” and individually referred to and designated as “the first shell 502a” and “the second shell 502b”) in place of the transducer holder 120 of the acoustic centering apparatus 112. The shells 502 may be disposed opposite to each other. The transducers 122 and the reflectors 128 may be disposed in the shells 502 such that the transducers 122 are disposed opposite to the reflectors 128. The transducers 122 and the reflectors 128 may be disposed concurrently to a center of the shells 502. Specifically, the first set of transducers 124 may be disposed in the first shell 502a and the second set of transducers 126 may be disposed in the second shell 502b such that the first and second set of transducers 124 and 126 may be disposed opposite to each other. The concave-shaped ACA 500 may be disposed anywhere in the draw tower 100 and 101. To generate the plurality of standing waves, the first and second set of transducers 124 and 126 may be adapted to generate the one or more first and second waves. The plurality of standing waves may further generate the acoustic radiation pressure. Specifically, the concave-shaped ACA 500 may be adapted to generate the acoustic radiation pressure in one of, the horizontal direction and a vertical direction with respect to the draw tower 100 and 101 i.e., the direction perpendicular to the vertical axis (Y-Y) and a direction along the vertical axis (Y-Y), respectively to maintain the optical fiber 104 along the vertical axis (Y-Y). The acoustic radiation pressure may force the optical fiber 104 to move in one of, the forward direction and the backward direction to align the optical fiber 104 along the vertical axis (Y-Y). The acoustic radiation pressure may provide the strong trapping force such that the acoustic radiation pressure traps the optical fiber 104 in the central position i.e., along the vertical axis (Y-Y).
In some aspects of the present disclosure, the concave-shaped acoustic ACA 500 may have the transducer 122a and the reflector 128a that are disposed along a surface of the first and second shells 502a and 502b. The transducer 122a may be disposed opposite to the reflector 128a. Further, the transducer 122a and the reflector 128 may be concurrent to the center of the shells 502.
In some aspects of the present disclosure, to generate the plurality of standing waves, by way of the concave-shaped ACA 500, the one or more first and second waves may be reflected back by the reflectors 128 to generate the reflected versions of the one or more first and second waves, respectively. The one or more first and second waves and the reflected versions of the one or more first and second waves may together generate the plurality of standing waves.
In some aspects of the present disclosure, the concave-shaped ACA 500 may be oriented in one of, the horizontal direction and the vertical direction with respect to the draw tower 100 and 101.
In some aspects of the present disclosure, a distance between the first and second shells 502a and 502b may lie in a range between 10 centimeters (cm) and 30 cm. Aspects of the present disclosure are intended to include and/or otherwise cover any value for the distance between the first and second shells 502a and 502b, without deviating from the scope of the present disclosure.
Although FIG. 5 illustrates one concave-shaped ACA (i.e., the concave-shaped ACA 500), however, the aspects of the present disclosure are not limited to it. Aspects of the present disclosure are intended to include and/or otherwise cover any number of concave-shaped ACAs (i.e., 2, 3, 4, 5, 6) to be used in the draw tower 100 and 101 without deviating from the scope of the present disclosure.
FIG. 6 illustrates a rectangular-shaped acoustic centering apparatus 600 (hereinafter referred to and designated as “the rectangular-shaped ACA 600”). The rectangular-shaped ACA 600 may be substantially similar to the acoustic centering apparatus 112 with similar elements referred with similar reference numerals. However, the rectangular-shaped ACA 600 may have first and second plates 602a and 602b (hereinafter collectively referred to and designated as “the plates 602”) in place of the transducer holder 120 of the acoustic centering apparatus 112. The plates 602 may be disposed opposite to each other. The transducers 122 and the reflectors 128 may be disposed on the plates 602. The transducers 122 may be disposed concurrently to a center of the first and second plates 602a and 602b. Specifically, the first set of transducers 124 may be disposed on the first plate 602a and the second set of transducers 126 may be disposed on the second plate 602b such that the first and second set of transducers 124 and 126 may be disposed opposite to each other. The rectangular-shaped ACA 600 may be disposed anywhere in the draw tower 100 and 101. To generate the plurality of standing waves, the first and second set of transducers 124 and 126 may be adapted to generate the one or more first and second waves. The plurality of standing waves may further generate the acoustic radiation pressure. Specifically, the rectangular-shaped ACA 600 may be adapted to generate the acoustic radiation pressure in the vertical direction with respect to the draw tower 100 and 101 i.e., the direction along the vertical axis (Y-Y) to maintain the optical fiber 104 along the vertical axis (Y-Y). The acoustic radiation pressure may force the optical fiber 104 to move in one of, the forward direction and the backward direction to align the optical fiber 104 along the vertical axis (Y-Y). The acoustic radiation pressure may provide the strong trapping force such that the acoustic radiation pressure traps the optical fiber 104 in the central position i.e., along the vertical axis (Y-Y).
In some aspects of the present disclosure, the transducers 122 and the reflectors 128 may be disposed on the first and second plates 602a and 602b such that the first and second plates 602a and 602b lie on adjacent planes. The adjacent planes may be opposite to each other such that the transducers 122 are opposite to the reflectors 128.
In some aspects of the present disclosure, the rectangular-shaped ACA 600 may be oriented in the vertical direction with respect to the draw tower 100 and 101.
In some aspects of the present disclosure, to generate the plurality of standing waves, by way of the rectangular-shaped ACA 600, the one or more first and second waves may be reflected back by the reflectors 128 to generate the reflected versions of the one or more first and second waves, respectively. The one or more first and second waves and the reflected versions of the one or more first and second waves may together generate the plurality of standing waves.
In some aspects of the present disclosure, a distance between the first and second plates 602a and 602b may lie in a range between 10 centimeters (cm) and 30 cm. Aspects of the present disclosure are intended to include and/or otherwise cover any value for the distance between the first and second plates 602a and 602b, without deviating from the scope of the present disclosure.
In some aspects of the present disclosure, at least two transducers of the first set of transducers 124 may be disposed in a single plane to superimpose with a counter transducer on the same plane.
Although FIG. 6 illustrates one rectangular-shaped ACA (i.e., the rectangular-shaped ACA 600), however, the aspects of the present disclosure are not limited to it. Aspects of the present disclosure are intended to include and/or otherwise cover any number of rectangular-shaped ACAs (i.e., 2, 3, 4, 5, 6) to be used in the draw tower 100 and 101 without deviating from the scope of the present disclosure.
In some aspects of the present disclosure, the rectangular-shaped ACA 600 may have a reflector plate (not shown) in place of one of, the first and second plate 602a and 602b. In one example, the reflector plate may be replaced with the first plate 602a such that the reflector plate is disposed opposite to the second plate 602b. The second set of transducers 126 of the second plate 602b may be adapted to generate the one or more second waves such that the one or more second waves reflect from the reflector plate. The reflector plate may be adapted to generate the reflected version of the one or more second waves such that the one or more second waves and the reflected version of the one or more second waves generate the plurality of standing waves. The plurality of standing waves may further generate the acoustic radiation pressure to maintain the optical fiber 104 along the vertical axis (Y-Y). In another example, the reflector plate may be replaced with the second plate 602b such that the reflector plate is disposed opposite to the first plate 602a. The first set of transducers 124 of the first plate 602a may be adapted to generate the one or more first waves such that the one or more first waves reflect from the reflector plate. The reflector plate may be adapted to generate the reflected version of the one or more first waves such that the one or more first waves and the reflected version of the one or more first waves generate the plurality of standing waves. The plurality of standing waves may further generate the acoustic radiation pressure to maintain the optical fiber 104 along the vertical axis (Y-Y).
In some aspects of the present disclosure, the ring-shaped ACA 400 may have a smaller number of transducers when compared with the concave-shaped ACA 500 and the rectangular-shaped ACA 600, therefore, the ring-shaped ACA 400 is easy to calibrate.
FIG. 7 illustrates a flowchart that depicts a method 700 for constraining the optical fiber 104 in the draw tower 100 and 101 of FIG. 1A, FIG. 1B, FIG. 2A, and FIG. 2B. The method 700 may include following steps to constrain the optical fiber 104 in the draw tower 100 and 101.
At step 702, the draw tower 100 and 101, by way of the main furnace 106, may be adapted to receive the preform 102 and melt the preform 102 such that the optical fiber 104 is drawn out from the main furnace 106. Specifically, the optical fiber 104 may be the bare optical fiber that may be drawn out from the main furnace 106. For example, the main furnace 106 may be adapted to heat the preform 102 at the temperature of about 2000°C to melt the preform 102. The preform 102 may be melted to obtain the optical fiber 104 from the preform 102. The preform 102 may be hung at the top end of the main furnace 106. The preform 102 may be inserted into the main furnace 106 at the predefined speed. The preform 102 may be adequately positioned while being feeding to the main furnace 106. Aspects of the present disclosure are intended to include and/or otherwise cover any value for the temperature to melt the preform 102, without deviating from the scope of the present disclosure.
In some aspects of the present disclosure, the main furnace 106 may be provided with the plurality of induction coils (not shown) that may be disposed within the main furnace 106. The plurality of induction coils may be adapted to melt the preform 102. Preferably, the main furnace 106 may be maintained at the temperature of 2200°C to melt the preform 102. The main furnace 106 may be further provided with the one or more inert gases. The one or more inert gases may include, but not limited to, argon, helium, nitrogen and the like.
In some aspects of the present disclosure, the preform 102 may be melted at the temperature of 1500°C. The optical fiber 104 may have the diameter that may be less than 150 micrometers (µm).
At step 704, the draw tower 100 and 101, by way of the annealing unit 108, may be adapted to anneal (slowly cool) the optical fiber 104. Specifically, the annealing furnaces 118, upon the optical fiber 104 being drawn out from the main furnace 106, may be adapted to cool the optical fiber 104. The annealing furnaces 118 may gradually cool the optical fiber 104 in one or more stages by passing the optical fiber 104 through the annealing furnaces 118. Specifically, the annealing furnaces 118 may bring the temperature of the optical fiber 104 to 450°C.
At step 706, the draw tower 100 and 101, by way of the cooling unit 110, may be adapted to cool the optical fiber 104. The cooling unit 110 may use one or more cooling gases to cool the optical fiber 104. Specifically, the one or more cooling gases may carry away heat of the optical fiber 104 to bring temperature of the optical fiber 104 to 50°C.
In some aspects of the present disclosure, the one or more cooling gases, may include, but not limited to, argon, helium, and the like. Aspects of the present disclosure are intended to include and/or otherwise cover any kind of gas that is to be used in the cooling unit 110, without deviating from the scope of the present disclosure.
At step 708, the acoustic centering apparatus 112 may be deployed in the draw tower 100 and 101. Specifically, the acoustic centering apparatus 112 may be deployed in the vicinity of the optical fiber 104 such that the one or more first and second waves are generated in the vicinity of the optical fiber 104. The acoustic centering apparatus 112 may be deployed one of, above the cooling unit 110 and below the cooling unit 110.
At step 710, the draw tower 100 and 101, by way of the acoustic centering apparatus 112, may be adapted to generate the one or more first waves in the first direction. Specifically, the first set of transducers 124 of the transducers 122 may be adapted to generate the one or more first waves in the first direction.
At step 712, the draw tower 100 and 101, by way of the acoustic centering apparatus 112, may be adapted to generate the one or more second waves in the second direction. Specifically, the second set of transducers 126 of the transducers 122 may be adapted to generate the one or more second waves in the second direction. The one or more first and second waves may have the predefined amplitude and the predefined frequency. The first direction may be opposite to the second direction such that the one or more first and second waves generate the plurality of standing waves. The plurality of standing waves may in combination to each other, generate an acoustic radiation pressure. The acoustic radiation pressure may provide a strong trapping force such that the acoustic radiation pressure traps the optical fiber 104 in the central position i.e., along the vertical axis (Y-Y). The acoustic radiation pressure may provide support to the optical fiber 104 against inherent change in an axis of the optical fiber 104 due to external disturbances in the draw tower 100. The acoustic radiation pressure may be adapted to trap the optical fiber 104 in the central position without contacting the optical fiber 104. This way, the acoustic radiation pressure may maintain the optical fiber 104 in a designated position i.e., along the vertical axis (Y-Y). The vertical axis (Y-Y) may be one of parallel to the draw tower axis (Y’-Y’) and coinciding with the draw tower axis (Y’-Y’).
At step 714, the draw tower 100 and 101, by way of the acoustic centering apparatus 112, may be adapted to trap the optical fiber 104 in the central position i.e., along the vertical axis (Y-Y) of the draw tower 100. Specifically, the optical fiber 104 may be trapped by the acoustic radiation pressure that may be generated by the transducers 122. While the acoustic centering apparatus 112 traps the optical fiber 104, there may be no net force that may act on the optical fiber 104. The acoustic centering apparatus 112 may be adapted to hold the optical fiber 104 at the vertical axis (Y-Y) against other external disturbances in the draw tower 100.
In some aspects of the present disclosure, movement of the optical fiber 104 may be constrained within 1 milli-meter from the vertical axis (Y-Y).
At step 716, the draw tower 100 and 101, by way of the coating unit 114, may be adapted to apply the coating layers on the optical fiber 104 to generate the coated optical fiber 105. The coating layers may protect the coated optical fiber 105 such that the coating layers maintain mechanical characteristics and improve optical performance.
In some aspects of the present disclosure, the coating layers may be primary and secondary coatings that may be applied on the optical fiber 104 to generate the coated optical fiber 105. The primary coating may have a coating concentricity value that may be less than 20 micro-meters. In some aspects of the present disclosure, the secondary coating may have the coating concentricity value that may be less than 12 micro-meters. In some aspects of the present disclosure, each coating layer of the coating layers may have a coating ovality that may be less than 4%. In some aspects of the present disclosure, the secondary coating may be a colored secondary coating.
In some aspects of the present disclosure, the coating layers may have two layers i.e., the inner layer and the outer layer. The inner layer may be the soft layer that may adhere to the optical fiber 104. The outer layer may be the hard layer that may surround the inner layer. The coating unit 114 may therefore apply and cure two different separate resins that may result in the inner and outer coatings.
Thus, the acoustic centering apparatus 112 minimizes physical damage to the optical fiber 104 by non-contact stabilization of the optical fiber 104 along the vertical axis (Y-Y). The non-contact stabilization (entrapment) of the optical fiber 104 along the vertical axis (Y-Y) avoids touching the optical fiber 104 to any wall of the draw tower 100 and 101, which subsequently reduces optical fiber scrap. The acoustic centering apparatus 112 further improves the coating concentricity. The acoustic centering apparatus 112 improves dimensional quality such as thickness, concentricity, and geometric (ovality) of the optical fiber 104.
The foregoing descriptions of specific embodiments of the present technology have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present technology to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present technology and its practical application, to thereby enable others skilled in the art to best utilize the present technology and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present technology.
While several possible embodiments of the invention have been described above and illustrated in some cases, it should be interpreted and understood as to have been presented only by way of illustration and example, but not by limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments. , Claims:I/We Claim:
A method (700) for constraining an optical fiber (104) in a draw tower (100, 101), the method (700) comprising:
trapping (714) the optical fiber (104) along a vertical axis (Y-Y) by an arrangement of a one or more acoustic waves in the vicinity of the optical fiber (104), wherein the vertical axis (Y-Y) is one of parallel to a draw tower axis (Y’-Y’) and coinciding with the draw tower axis (Y’-Y’), wherein movement of the optical fiber (104) is constrained within 1 milli-meter from the vertical axis (Y-Y), wherein a coating ovality of a coated optical fiber (105) is less than 4%.

The method (700) of claim 1, wherein trapping the optical fiber (104) comprising generating an acoustic radiation pressure by the one or more acoustic waves.

The method (700) of claim 1, wherein the one or more acoustic waves traps the optical fiber (104) for at least 3 mm vertical length of the optical fiber (104) in the draw tower (100, 101).

The method (700) of claim 1, wherein prior to the trapping (714) of the optical fiber (104), the method (700) comprising, at least one of:
generating (710), by way of an acoustic centering apparatus (112), one or more first waves of the one or more acoustic waves in a first direction; and
generating (712), by way of the acoustic centering apparatus (112), one or more second waves of the one or more acoustic waves in a second direction that is opposite to the first direction to generate a plurality of standing waves such that a combination of the plurality of standing waves generates the acoustic radiation pressure for trapping the optical fiber (104) in a central position along the vertical axis (Y-Y).
The method (700) of claim 1, comprising coating (716) the optical fiber (104) to generate the coated optical fiber (105).

The method (700) of claim 1, wherein the optical fiber (104) has a diameter less than 150 micrometer.

The method (700) of claim 1, wherein a glass density of the optical fiber (104) lies in a range of 2.19 gram per cubic-centimeter (g/cc) to 2.20 g/cc.

A draw tower (100, 101) comprising:
an acoustic centering apparatus (112) that is adapted to generate one or more acoustic waves to trap an optical fiber (104) in a central position along a vertical axis (Y-Y) such that a movement of the optical fiber (104) in a direction perpendicular to the vertical axis (Y-Y) is constrained within 1 milli-meter (mm) from the vertical axis (Y-Y), wherein the vertical axis (Y-Y) is one of parallel to a draw tower axis (Y’-Y’) and coinciding with the draw tower axis (Y’-Y’); and
a coating unit (114) that is adapted to coat the optical fiber (104) to generate a coated optical fiber (105), wherein a coating ovality of the coated optical fiber (105) is less than 4%.

The draw tower (100, 101) of claim 8, wherein the acoustic centering apparatus (112) is adapted to generate one or more first waves of the one or more acoustic waves in a first direction and one or more second waves of the one or more acoustic waves in a second direction that is opposite to the first direction to generate a plurality of standing waves such that a combination of the plurality of standing waves generates an acoustic radiation pressure that traps the optical fiber (104) in a central position along the vertical axis (Y-Y).

The draw tower (100, 101) of claim 8, wherein the acoustic centering apparatus (112) is one of, a ring-shaped acoustic centering apparatus (400), a concave-shaped acoustic centering apparatus (500), and a rectangular-shaped acoustic centering apparatus (600).

The draw tower (100, 101) of claim 10, wherein the ring-shaped acoustic centring apparatus (400) comprising:
a ring (402); and
at least one transducer (122a) and at least one reflector (128a) that is positioned along a circumference of the ring (402), wherein the at least one transducer (122a) is disposed opposite to the at least one reflector (128a).

The draw tower (100, 101) of claim 10, wherein the ring-shaped acoustic centering apparatus (400) generates an acoustic radiation pressure in a horizontal direction with respect to the draw tower (100, 101) to maintain the optical fiber (104) along the vertical axis (Y-Y).

The draw tower (100, 101) of claim 10, wherein the concave-shaped acoustic centering apparatus (500) comprising first and second hemispherical shells (502a, 502b), at least one transducer (122a), and at least one reflector (128a) such that the at least one transducer (122a) and the at least one reflector (128a) is disposed along a surface and concurrent to a centre of the first and second hemispherical shells (502a, 502b), wherein the at least one transducer (122a) is disposed opposite to the at least one reflector (128a).

The draw tower (100, 101) of claim 10, wherein, the concave shaped acoustic centering apparatus (500) generates an acoustic radiation pressure in one of, a horizontal direction and a vertical direction with respect to the draw tower (100, 101) to maintain the optical fiber (104) along the vertical axis (Y-Y).

The draw tower (100, 101) of claim 10, wherein the rectangular-shaped acoustic centering apparatus (600) comprising first and second plates (602a, 602b), a plurality of transducers (122), and a plurality of reflectors (128) such that the plurality of transducers (122) and the plurality of reflectors (128) are disposed on the first and second plates (602a, 602b) that are on adjacent planes, wherein a distance between the first and second plates (602a, 602b) is in a range of 10 cm to 30 cm, wherein the plurality of transducers are disposed opposite to the plurality of reflectors (128).

The draw tower (100, 101) of claim 10, wherein the rectangular shaped acoustic centering apparatus (600) generates an acoustic radiation pressure in a vertical direction with respect to the draw tower (100, 101) to maintain the optical fiber (104) along the vertical axis (Y-Y).

The draw tower (100, 101) of claim 8, wherein the acoustic centering apparatus (112) is disposed above a cooling unit (110).

The draw tower (100, 101) of claim 8, wherein the acoustic centering apparatus (112) is disposed below a cooling unit (110).