The present disclosure relates to a system and methods for preheating a preform in a preheater furnace and then transferring the preheated preform to a consolidation furnace for chemical treatment and sintering the preform into a clear glass which can be drawn into optical fiber. In addition, the present disclosure relates to the preheater furnace which is configured to heat the preform per a predetermined heat-profile until the preform is uniformly heated to a temperature above 1000° C.
The traditional consolidation process utilizes a consolidation furnace to heat-up of a porous preform and sinter to form a fully dense clear preform that is capable of being drawn into optical fiber. The porous preform is typically a porous silica preform and the consolidation process typically includes drying and doping of the porous silica preform before and/or during the sintering process. Drying and doping are chemical processes that entail exposing the porous silicon preform to a drying agent (e.g. Cl2) and a doping precursor (e.g. SiCl4 or SiF4). In order for the chemical reactions accompanying drying and doping to proceed efficiently, the porous silica preform must be heated to a sufficiently high temperature. The threshold temperature for efficient reaction of common drying agents and doping precursors is a temperature above 1000° C. The threshold temperature is achieved at least at the surface of the porous silica preform and preferably is achieved throughout the volume of the porous silica preform. Due to the typical physical dimensions (e.g. 2 meters long with a diameter of 240 mm) and the low thermal conductivity (e.g. 0.1 to 0.4 W/m-K) of porous silica preforms, a time of several hours is typically needed to heat the porous silica preform uniformly to a temperature above 1000° C.
Referring to
A system, a preheater furnace, and various methods which address the aforementioned need are described in the independent claims of the present disclosure. Advantageous embodiments of the system, the preheater furnace, and the various methods are described in the dependent claims.
In one aspect, the present disclosure provides:
A system comprising:
In one aspect, the present disclosure provides:
A preheater furnace configured to heat a preform, the preheater furnace comprising:
In one aspect, the present disclosure provides:
A method of processing an optical fiber preform, comprising:
In one aspect, the present disclosure provides a system comprising a preheater furnace and a consolidation furnace. The preheater furnace is configured to receive a preform and further configured to heat the preform per a predetermined heat-profile until the preform is uniformly heated to a temperature above 1000° C. The consolidation furnace is configured to receive the preform that was heated in the preheater furnace and further configured to chemically dry, dope and sinter the preform.
In another aspect, the present disclosure provides a method comprising the steps of: (a) loading a preform into a preheater furnace; (b) heating the preform in the preheater furnace per a predetermined heat-profile until the preform is uniformly heated to a temperature above 1000° C.; (c) transferring the preform which has been uniformly heated to a consolidation furnace; and, (d) chemically drying, doping, and sintering the preform within the consolidation furnace.
In yet another aspect, the present disclosure provides a preheater furnace configured to heat a preform. The preheater furnace comprising: (a) a body having an automated door attached thereto which when opened provides access to an interior space of the body and when closed prevents access to the interior space of the body; (b) one or more heating elements and associated insulation located within the body, wherein the one or more heating elements are configured to radiate heat to heat the preform while the preform is located in the interior space of the body; (c) a box muffle configured to prevent the one or more heating elements and the insulation from contaminating an outer surface of the preform while the preform is located within the interior space of the body; (d) a rotation-translation mechanism configured to rotate the preform while the preform is located within the interior space of the body; and (e) the rotation-translation mechanism is further configured to be retracted to move the preform into the interior space of the body and further configured to be extended to move the preform out from the interior space of the body.
In still yet another aspect, the present disclosure provides a method comprising the steps of: (a) moving an automated robot into a predetermined position; (b) initiating an unload process for the automated robot in which the automated robot removes a consolidated preform from a consolidation furnace; (c) unloading the consolidated preform from the automated robot to an unload station; (d) unloading by the automated robot a heated preform from a preheater furnace and transferring the heated preform to a consolidation furnace; (e) operating the consolidation furnace to chemically dry, dope, and sinter the heated preform; (f) picking up a soot preform by the automated robot from a load station and loading the soot preform into the preheater furnace; (g) operating the preheater furnace to heat the soot preform therein per a predetermined heat-profile until the soot preform is uniformly heated to a temperature above 1000° C.; (h) moving the automated robot to a stowed position S and disengaging a cell interlock; (i) initiating a load countdown; (j) enabling an operator to enter an area associated with the preheater furnace and the consolidation furnace; (k) enabling the operator to transfer the consolidated preform from the unload station to a hot case; (1) enabling the operator to load the load station with another soot preform; and, (m) completing the consolidation of the preform located in the consolidation furnace and returning to the first moving step.
Additional aspects of the disclosure will be set forth, in part, in the detailed description, figures and any claims which follow, and in part will be derived from the detailed description, or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure as disclosed.
A more complete understanding of the present disclosure may be had by reference to the following detailed description when taken in conjunction with the accompanying drawings wherein:
The present disclosure provides systems and methods for processing preforms used to draw optical fibers. As described in further detail below, the systems and methods include placing a porous preform in a preheating furnace to heat the preform to a threshold temperature, removing the preform from the preheating furnace while the preform is at the threshold temperature, transferring the preform to a consolidation furnace, and processing the preform in the consolidation furnace. The porous preform is preferably formed of silica soot and the threshold temperature is preferably a temperature above 1000° C. and less than a temperature at which sintering occurs. Processing in the consolidation furnace includes sintering the preform and one or both of drying and doping the preform.
In the present disclosure, the following terms are used and have the following meanings:
“Porous preform” refers to a preform formed in a soot deposition process. A porous preform is a soot body that is in a state corresponding to or closely corresponding to the state at the time of deposition. When the porous preform consists of silica or primarily of silica, the bulk density of the porous preform is less than 0.70 g/cm3, or less than 0.65 g/cm3, or less than 0.60 g/cm3, or less than 0.55 g/cm3, or less than 0.50 g/cm3, or less than 0.45 g/cm3, or in the range from 0.35 g/cm3-0.70 g/cm3, or in the range from 0.40 g/cm3-0.65 g/cm3, or in the range from 0.45 g/cm3-0.60 g/cm3. When the porous preform consists of silica or primarily of silica, the surface density of the porous preform is less than 0.70 g/cm3, or less than 0.65 g/cm3, or less than 0.60 g/cm3, or less than 0.55 g/cm3, or less than 0.50 g/cm3, or less than 0.45 g/cm3, or in the range from 0.35 g/cm3-0.70 g/cm3, or in the range from 0.40 g/cm3-0.65 g/cm3, or in the range from 0.45 g/cm3-0.60 g/cm3. The porous preform has a mass greater than 10 kg, or greater than 25 kg, or greater than 40 kg, or greater than 55 kg, or in the range from 10 kg-75 kg, or in the range from 20 kg-65 kg, or in the range from 30 kg-55 kg.
“Preheated preform” refers to the preform produced by processing the porous preform in a preheating furnace operated at a temperature above 1000° C. and without exposure to a temperature of 1350° C. or greater. When the preheated preform consists of silica or primarily of silica, the preheated preform has an outer surface with a temperature greater than 1000° C. and less than 1200° C., or greater than 1050° C. and less than 1200° C., or greater than 1100° C. and less than 1200° C., or greater than 1150° C. and less than 1200° C., or in the range from 1000° C.-1200° C., or in the range from 1050° C.-1175° C. When the porous preform consists of silica or primarily of silica, the bulk density of the porous preform is less than 0.70 g/cm3, or less than 0.65 g/cm3, or less than 0.60 g/cm3, or less than 0.55 g/cm3, or less than 0.50 g/cm3, or less than 0.45 g/cm3, or in the range from 0.35 g/cm3-0.70 g/cm3, or in the range from 0.40 g/cm3-0.65 g/cm3, or in the range from 0.45 g/cm3-0.60 g/cm3. When the porous preform consists of silica or primarily of silica, the surface density of the porous preform is less than 0.70 g/cm3, or less than 0.65 g/cm3, or less than 0.60 g/cm3, or less than 0.55 g/cm3, or less than 0.50 g/cm3, or less than 0.45 g/cm3, or in the range from 0.35 g/cm3-0.70 g/cm3, or in the range from 0.40 g/cm3-0.65 g/cm3, or in the range from 0.45 g/cm3-0.60 g/cm3. In one embodiment, the surface density of the preheated preform is greater than the bulk density of the preheated preform. In another embodiment, the surface density of the preheated preform is equal to the bulk density of the preheated preform.
“Consolidated preform” refers to the preform produced by processing the preheated preform at a temperature of 1300° C. or higher. In the context of the present disclosure, a consolidated preform is formed by processing a preheated preform in a consolidation furnace. A consolidated preform is a transparent or vitrified glass body suitable for use in an optical fiber draw process. When the consolidated preform consists of silica or doped silica, the bulk density of the consolidated preform is greater than 1.90 g/cm3, or greater than 2.00 g/cm3, or greater than 2.05 g/cm3, or greater than 2.10 g/cm3, or greater than 2.15 g/cm3, or greater than 2.20 g/cm3, or greater than 2.25 g/cm3, or in the range from 1.90 g/cm3-2.35 g/cm3, or in the range from 1.95 g/cm3-2.30 g/cm3, or in the range from 2.00 g/cm3-2.25 g/cm3, or in the range from 2.05 g/cm3-2.20 g/cm3. When the consolidated preform consists of silica or doped silica, the surface density of the consolidated preform is greater than 1.90 g/cm3, or greater than 2.00 g/cm3, or greater than 2.05 g/cm3, or greater than 2.10 g/cm3, or greater than 2.15 g/cm3, or greater than 2.20 g/cm3, or greater than 2.25 g/cm3, or in the range from 1.90 g/cm3-2.35 g/cm3, or in the range from 1.95 g/cm3-2.30 g/cm3, or in the range from 2.00 g/cm3-2.25 g/cm3, or in the range from 2.05 g/cm3-2.20 g/cm3.
“Sintering” refers to heating a porous preform or a preheated preform to a temperature sufficient to induce densification. Densification corresponds to loss of porosity and a transition to a non-porous state. When the porous preform or preheated preform consists of silica or primarily of silica, sintering refers to heating the porous preform or preheated preform to a temperature above 1350° C.
“Surface density” refers to the average density of a preform in the region of the preform extending from the outer surface to a depth of 5 mm.
“Bulk density” refers to the average density of a preform throughout the entirety of its volume.
“Radial position”, “radius”, or the radial coordinate “r” refers to radial position relative to the centerline (r=0) of a preform.
The system 200 and methods 1100 and 1200 of the present disclosure address the aforementioned need of the traditional consolidation process by preheating a porous preform 208a (e.g., a porous silica preform 208a) in a preheater furnace 202 to form a preheated preform 208b and then transferring the preheated preform 208b to a consolidation furnace 206 for chemical treatment (e.g. drying and/or doping) and sintering to form a consolidated preform 208c. The system 200 and methods 1100 and 1200 involve heating of the porous preform 208a in the preheater furnace 202 to form the preheated preform 208b. The preheater furnace 202 is spaced apart from and separate from the consolidation furnace 206. More specifically, the system 200 and methods 1100 and 1200 involve the heating of the surface of porous preform 208a to a threshold temperature (e.g., above 1000° C., such as approximately 1125° C.) in the preheater furnace 202 to form the preheated preform 208b and transferring the preheated preform 208b from the preheater furnace 202 to the consolidation furnace 206 for further processing to form consolidated preform 208c.
Transfer of the preheated preform 208b from the preheater furnace 202 to the consolidation furnace 206 is accomplished with a transfer stage. The transfer stage is operatively connected to the preheater furnace 202 and the consolidation furnace 206. The transfer stage removes preheated preform 208b from the preheater furnace 202, carries and moves preheated preform 208b to the consolidation furnace 206, and inserts preheated preform 208b into consolidation furnace 206. The transfer stage is manual or automated. In one embodiment, the transfer stage includes an automated robot. Further description of the transfer process and transfer stages is given below.
The operating temperature of the preheater furnace 202 is set to a temperature at or above the threshold temperature needed for efficient reaction of drying agents and/or doping precursors. When the porous preform consists of silica or primarily of silica, the operating temperature of the preheater furnace 202 is 1000° C. or higher, or 1050° C. or higher, or 1100° C. or higher, or 1150° C. or higher, or in the range from 1000° C.-1200° C., or in the range from 1025° C.-1175° C., or in the range from 1050° C.-1150° C. To reduce system costs, it is preferable to limit the preheater furnace to a furnace having a maximum operating temperature of 1200° C. In the context of the present disclosure, preheating above 1200° C. is not preferred because it can lead to undesirable surface densification of the preheated preform. Furnaces capable of operating above 1200° C. are also more expensive.
In one embodiment, the preheater furnace 202 is operated to provide a preheated preform having a uniform temperature throughout its volume. As used herein, “uniform temperature” means that the temperature of the preheated preform deviates by less than ±5% from the average temperature of the preheated preform throughout its volume. A uniform temperature for the preheated preform can be achieved by controlling the residence time of the porous preform in the preheater furnace 202. A longer residence time leads to better uniformity of temperature at different positions within the preheated preform 208b. As shown, for example, in
Transfer of the preheated preform 208b from the preheater furnace 202 to the consolidation furnace 206 preferably occurs quickly to minimize cooling of the preheated preform. When the preheated preform 208b is removed from the preheater furnace 202, it passes through a cooler ambient and begins to cool as it is transferred to the consolidation furnace 206. As described below (see, for example,
Cooling during transfer occurs more quickly at the surface of the preheated preform than in the interior of the preheated preform. The temperature of the outer surface of the preheated preform 208b is higher at the time of removal from the preheater furnace 202 than at the time of insertion of the preheated preform 208b into the consolidation furnace. It is preferable to minimize the reduction in the temperature of the outer surface of the preheated preform 208b during transfer from the preheater furnace 202 to the consolidation furnace 206.
When the preheated preform 208b consists of silica or primarily of silica, the preheated preform 208b has an outer surface upon removal from the preheater furnace with a temperature greater than 1000° C. and less than 1200° C., or greater than 1050° C. and less than 1200° C., or greater than 1100° C. and less than 1200° C., or greater than 1150° C. and less than 1200° C., or in the range from 1000° C.-1200° C., or in the range from 1050° C.-1175° C. and the preheated preform 208b has an outer surface when inserted into consolidation furnace 206 greater than room temperature, or greater than 100° C., or greater than 400° C., or greater than 600° C., or greater than 800° C., or greater than 1000° C., or in the range from 400° C.-1100° C., or in the range from 500° C.-1050° C., or in the range from 600° C.-1000° C., or in the range from 650° C.-900° C. The decrease in the temperature of the outer surface of the preheated preform 208b during the transfer from the preheater furnace 202 to the consolidation furnace 206 is less than 600° C., or less than 500° C., or less than 400° C., or less than 300° C., or less than 200° C., or in the range from 100° C.-600° C., or in the range from 150° C.-550° C., or in the range from 200° C.-500° C.
Since, the preheating step is accomplished by the separate preheater furnace 202 in the process disclosed herein, preheating of the porous preform 208a no longer needs to be performed in the consolidation furnace 206 as occurs in the traditional processing of preforms. In the traditional processing of preforms, porous preform 208a is inserted into the consolidation furnace 206 at room temperature and preheating to temperatures required for efficient drying and doping occurs directly in the consolidation furnace 206. In the process described herein, in contrast, porous preform 208a is preheated independent of the consolidation furnace 206 to form preheated preform 208b, which is then transferred the preheater furnace 202 and inserted into the consolidation furnace 206. Insertion of preheated preform 208b into consolidation furnace 206 improves process efficiency by reducing the processing time of the preform in the consolidation furnace 206. When using a preheated preform 208b as described herein, the processing time in the consolidation furnace 206 is limited to the time needed for drying, doping, and sintering of the preheated preform 208b. In this way, the system 200 and methods 1100 and 1200 of the present disclosure results in a decreased deployment of the high capital cost consolidation furnace 206 for preheating, and a reduced overall cost of manufacturing equipment. Instead of dedicating process time of consolidation furnace 206 for preheating, utilization of consolidated furnace 206 is dedicated to the more demanding drying, doping, and/or sintering processes. As a result, overall process efficiency is improved. An exemplary system 200, an exemplary preheater furnace 202, and exemplary methods 1100 and 1200 in accordance with the present disclosure are discussed in detail below with respect to the
Referring to
Referring to
The preheater furnace 202 further includes a rotation-translation mechanism 310 which rotates the porous preform 208a or preheated preform 208b during heating to minimize or prevent azimuthal non-uniformity of temperature in the porous preform 208b during processing in the preheater furnace 202 (note: the azimuthal non-uniformity problem is discussed in detail below with respect to
The preheater furnace 202 includes one or more heating elements 316 (e.g., electrical heating elements 316) located therein which radiate heat to heat the porous preform 208a (see
The preheater furnace 202 can also have ports 326 therein to allow for an inert gas (e.g., nitrogen) to flow and create a net gas flow to purge the interior space 306 so as to avoid exposing the preform 208 to furnace materials (e.g., heating elements 316 and insulation 318) which may contaminate the surface of the porous preform 208a or preheated preform 208b and alter in an unfavorable way the viscosity of the porous preform 208a or preheated preform 208b.
Referring to
In the traditional consolidation process, the heating of the porous preform 208a to the threshold temperature in the consolidation furnace 206 occurs at the beginning of the process and does not require hazardous chemical delivery or pollution controls. Therefore, this heating step can be completed in a separate lower cost preheater furnace 202 rather than in the high capital cost consolidation furnace 206 in accordance with the present disclosure. When this is accomplished, the process time in the more expensive chemical and sintering consolidation furnace 206 can be reduced which is a marked improvement over the traditional consolidation process where the consolidation furnace 206 is utilized to heat the porous preform 208a to the threshold temperature.
An important feature of the present disclosure is to heat the porous preform 208a in a low cost separate preheater furnace 202 at about 1125° C. for about five hours or slightly longer until the porous preform 208a reaches the threshold temperature of around 1000° C. or higher, and then to quickly transfer the resulting preheated preform 208b to the more expensive consolidation furnace 206 for chemical treatment (drying and/or doping) and sintering at higher temperatures. The cost and complexity of operating the consolidation furnace 206 below 1200° C. per the new process is significantly less than when the consolidation furnace 206 had to operate above 1200° C. in order to heat the porous preform 208a to the threshold temperature of around 1000° C. or higher. Further, since the processing time for chemical treatment and sintering is several hours, the operation of the separate preheater furnace 202 can be matched with the consolidation furnace 206. In this regard, the combined processing time in both the preheater furnace 202 and the consolidation furnace 206 in the context of the present disclosure is, for example, 5-8 hours which results in a higher output or process rate than for manufacturing that involves only the consolidation furnace 206 (e.g., see discussion below with respect to
In order to improve the efficiency and repeatability of the process using the preheater furnace 202, of warehandling automation, such as the automated robot 204, can also be used so that the transfer time of the preheated preform 208b from the preheater furnace 202 to the consolidation furnace 206 is minimized and repeatable. The repeatable transfer of the preheated preform 208b from the preheater furnace 202 to the consolidation furnace 206 is important because the temperature profile of the preheated preform 208b entering the consolidation furnace 206 is an important factor in determining the required process conditions for the drying and/or doping processes.
Mitigation of cooldown effects is achieved through automation of the transfer process by the transfer stage of the preheated preform 208b from the preheater furnace 202 to the consolidation furnace 206. Automation leads to greater consistency in transfer time (thus reducing variability in manufacturing) and shorter transfer times (thus minimizing the effects of cooldown). The temperature profile of the preheated preform 208b at the time of insertion in the consolidation furnace 206 is also more predictable and the heating protocol used in consolidation furnace 206 can be adjusted accordingly to improve uniformity in drying, doping and sintering. With a repeatable transfer time, the process time in the consolidation furnace 206 can be minimized because the preheating portion of the process occurs within the preheater furnace 202 and the process conditions are simplified because movement and transfer time of the preheated preform 208b is predictable and repeatable thus the temperature profile of the preform 208 is also predictable and repeatable. In one embodiment, the automated robot 204 enables a transfer time that is consistent and less than five minutes.
In addition to the temperature profile of the preheated preform 208b, the density of the preheated preform 208b is also important because it relates to the porosity of the preheated preform 208b and accessibility of drying agents and doping precursors positions on the surface and in the interior of the preheated preform 208b. As densification occurs, porosity decreases and diffusion of drying agents and doping precursors is inhibited. Variations in density over the volume of the preheated preform 208b lead to non-uniformities in moisture and dopants in the consolidated preform 208c. It is accordingly preferably to minimize densification of porous preform 208a in the preheater furnace 202 to maintain low bulk and surface density in preheated preform 208b.
Further, if the temperature distribution in the preheater furnace 202 is not uniform, then portions of the porous preform 208a in either or both of the axial and azimuthal directions will not heat at the same rate. This could result in a preheated preform 208b with non-uniformities in temperature and/or density, which in turn may result in a consolidated preform 208c with non-uniformities in moisture or dopant concentration following treatment in the consolidation furnace 206. A lack of chemical uniformity in the azimuthal direction of the consolidated preform 208c can result in internal stresses is optical fibers drawn from consolidated preform 208c, which in turn can result in an undesirable increase in the bow or curl of the optical fiber.
One approach to minimize azimuthal non-uniformity is to rotate the porous preform 208a in the preheater furnace 202. For instance, the preheated preform 208b can be rotated at a rate of 30 revolutions per hour, or at a rate of 60 revolutions per hour, or at a rate of 90 revolutions per hour, or at a rate in the range from 30 revolutions per hour-150 revolutions per hour, or at a rate of 50 revolutions per hour-120 revolutions per hour, or at a rate of 60 revolutions per hour-90 revolutions per hour.
Referring to
Referring to
At step 1202, the system 200 (e.g., cell 200) interlock is engaged which includes locking to prevent entry of the operator 1201 during automated tasks, and the automated robot 204 moves into a predetermined operating position. At step 1204, the system 200 (e.g., cell 200) initiates the unload process for the automated robot 204 in which the automated robot 204 removes a consolidated preform 208c from the consolidation furnace 206. At step 1206, the automated robot 204 unloads the consolidated preform 208c to the unload station 209 (pick point A) (see
In view of at least the foregoing, it can be appreciated that there is described and enabled the new system 200 and new methods 1100 and 1200 for heating a porous preform 208a in a preheater furnace 202 and then transferring the preheated preform 208b to a consolidation furnace 206 for chemical treatment and sintering into a consolidated preform 208c that can be drawn into optical fiber. The new system 200 and new methods 1100 and 1200 have several advantages over the traditional consolidation process which does not involve the use of the preheater furnace 202 but only involves the use of the consolidation furnace 206. These advantages are described next.
Referring to
The graph 1400 in
The following are selected additional advantages associated with a process that combines the use of a preheater furnace and a consolidation furnace relative to prior art processes that utilize only a consolidation furnace:
Reduced time in the consolidation furnace:
Improvement in capital efficiency for new consolidation furnace installations. Inexpensive preheater furnaces paired with consolidation furnaces, result in less capital cost for an equivalent amount of consolidation output/capacity.
Adding the automation robot 204 reduces blank handling losses, improves process repeatability, and improves labor efficiency.
Clause 1 of the description discloses:
A system comprising:
Clause 2 of the description discloses:
The system of clause 1, wherein the preheater furnace is further configured to rotate the porous preform.
Clause 3 of the description discloses:
The system of clause 1 or 2, wherein the porous preform has a mass greater than 25 kg.
Clause 4 of the description discloses:
The system of any of clauses 1-3, wherein the porous preform has a bulk density in the range from 0.35 g/cm3-0.70 g/cm3.
Clause 5 of the description discloses:
The system of any of clauses 1-3, wherein the preheated preform has a surface density in the range from 0.35 g/cm3-0.70 g/cm3.
Clause 6 of the description discloses:
The system of any of clauses 1-5, wherein the consolidation furnace is further configured to dry or dope the preheated preform.
Clause 7 of the description discloses:
The system of any of clauses 1-6, wherein the first temperature is less than 1200° C.
Clause 8 of the description discloses:
The system of any of clauses 1-7, wherein the first temperature is greater than 1100° C.
Clause 9 of the description discloses:
The system of any of clauses 1-8, wherein the second temperature is greater than 400° C.
Clause 10 of the description discloses:
The system of any of clauses 1-8, wherein the second temperature is greater than 600° C.
Clause 11 of the description discloses:
The system of any of clauses 1-8, wherein the second temperature is greater than 800° C.
Clause 12 of the description discloses:
The system of any of clauses 1-11, wherein the second temperature is less than the first temperature by less than 600° C.
Clause 13 of the description discloses:
The system of any of clauses 1-11, wherein the second temperature is less than the first temperature by less than 400° C.
Clause 14 of the description discloses:
The system of any of clauses 1-13, wherein the preheated preform has a uniform temperature greater than 1000° C.
Clause 15 of the description discloses:
The system of any of clauses 1-13, wherein the preheated preform has a uniform temperature greater than 1100° C.
Clause 16 of the description discloses:
The system of any of clauses 1-15, wherein the preheater furnace comprises a maximum operating temperature of 1200° C.
Clause 17 of the description discloses:
The system of any of clauses 1-16, wherein the transfer stage comprises a robot.
Clause 18 of the description discloses:
The system of any of clauses 1-17, wherein the transfer stage is configured to complete the transfer in less than 10 min.
Clause 19 of the description discloses:
The system of any of clauses 1-18, wherein the consolidated preform has a bulk density greater than 1.90 g/cm3.
Clause 20 of the description discloses:
The system of any of clauses 1-19, wherein the preheater furnace comprises:
Clause 21 of the description discloses:
A preheater furnace configured to heat a preform, the preheater furnace comprising:
Clause 22 of the description discloses:
The preheater furnace of clause 21, wherein the box muffle is composed of fused quartz or other ceramics which would sit on a solid hearth composed of silicon carbide.
Clause 23 of the description discloses:
The preheater furnace of clause 21 or 22, further comprising at least one port located in the body where the at least one port is configured to enable an inert gas to purge the interior space within the preheater furnace.
Clause 24 of the description discloses:
The preheater furnace of any of clauses 21-23, further comprising an air blower configured to move hot air away from the rotation-translation mechanism.
Clause 25 of the description discloses:
A method of processing an optical fiber preform, comprising:
Clause 26 of the description discloses:
The method of clause 25, wherein the porous preform has a mass greater than 25 kg.
Clause 27 of the description discloses:
The method of clause 25 or 26, wherein the porous preform has a bulk density in the range from 0.35 g/cm3-0.70 g/cm3.
Clause 28 of the description discloses:
The method of clause 25 or 26, wherein the preheated preform has a surface density in the range from 0.35 g/cm3-0.70 g/cm3.
Clause 29 of the description discloses:
The method of any of clauses 25-28, wherein the first temperature is less than 1200° C.
Clause 30 of the description discloses:
The method of any of clauses 25-29, wherein the first temperature is greater than 1100° C.
Clause 31 of the description discloses:
The method of any of clauses 25-30, wherein the second temperature is greater than 400° C.
Clause 32 of the description discloses:
The method of any of clauses 25-30, wherein the second temperature is greater than 600° C.
Clause 33 of the description discloses:
The method of any of clauses 25-30, wherein the second temperature is greater than 800° C.
Clause 34 of the description discloses:
The method of any of clauses 25-33, wherein the second temperature is less than the first temperature by less than 600° C.
Clause 35 of the description discloses:
The method of any of clauses 25-33, wherein the second temperature is less than the first temperature by less than 400° C.
Clause 36 of the description discloses:
The method of any of clauses 25-35, wherein the preheated preform has a uniform temperature greater than 1000° C.
Clause 37 of the description discloses:
The method of any of clauses 25-35, wherein the preheated preform has a uniform temperature greater than 1100° C.
Clause 38 of the description discloses:
The method of any of clauses 25-37, further comprising rotating the porous preform in the preheater furnace.
Clause 39 of the description discloses:
The method of any of clauses 25-38, further comprising sintering the preheated preform in the consolidation furnace.
Clause 40 of the description discloses:
The method of clause 39, further comprising doping or drying the preheated preform in the consolidation furnace.
Clause 41 of the description discloses:
The method of any of clauses 25-40, further comprising forming a consolidated preform from the preheated preform in the consolidation furnace, the consolidated preform having a bulk density greater than 1.90 g/cm3.
Clause 42 of the description discloses:
The method of any of clauses 25-41, wherein the transferring is accomplished with an automated transfer stage.
Clause 43 of the description discloses:
The method of any of clauses 25-42, wherein the transferring occurs in less than 10 min.
Clause 44 of the description discloses:
The method of any of clauses 25-42, wherein the transferring occurs in less than 5 min.
It will be appreciated that the various disclosed embodiments may involve particular features, elements or steps that are described in connection with that particular embodiment. It will also be appreciated that a particular feature, element or step, although described in relation to one particular embodiment, may be interchanged or combined with alternate embodiments in various non-illustrated combinations or permutations.
It is also to be understood that, as used herein the terms “the,” “a,” or “an,” mean “at least one,” and should not be limited to “only one” unless explicitly indicated to the contrary. Thus, for example, reference to “an opening” includes examples having two or more such “openings” unless the context clearly indicates otherwise.
Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, examples include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
All numerical values expressed herein are to be interpreted as including “about,” whether or not so stated, unless expressly indicated otherwise. It is further understood, however, that each numerical value recited is precisely contemplated as well, regardless of whether it is expressed as “about” that value. Thus, “a dimension less than 10 mm” and “a dimension less than about 10 mm” both include embodiments of “a dimension less than about 10 mm” as well as “a dimension less than 10 mm.”
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.
While various features, elements or steps of particular embodiments may be disclosed using the transitional phrase “comprising,” it is to be understood that alternative embodiments, including those that may be described using the transitional phrases “consisting” or “consisting essentially of,” are implied. Thus, for example, implied alternative embodiments to a method comprising A+B+C include embodiments where a method consists of A+B+C, and embodiments where a method consists essentially of A+B+C.
Although multiple embodiments of the present disclosure have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it should be understood that the disclosure is not limited to the disclosed embodiments, but is capable of numerous rearrangements, modifications and substitutions without departing from the disclosure as set forth and defined by the following claims.
This application is a divisional of and claims the benefit of priority under 35 U.S.C. § 120 of U.S. application Ser. No. 16/799,185, filed on Feb. 24, 2020, which claims the benefit of priority U.S. Provisional Application Ser. No. 62/813,951 filed on Mar. 5, 2019, the content of which is relied upon and incorporated herein by reference in its entirety.
Number | Date | Country | |
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62813951 | Mar 2019 | US |
Number | Date | Country | |
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Parent | 16799185 | Feb 2020 | US |
Child | 18207376 | US |