JP2004284868A - Apparatus and method of manufacturing primary coated optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing of a primary coated optical fiber and a method manufacturing the same which enable the primary coated optical fiber having excellent hydrogen characteristic to be stably manufactured by improving an annealing method of a bare optical fiber after melt-spinning in a manufacturing process of the primary coated optical fiber. <P>SOLUTION: The approach temperature and the receding temperature of the bare optical fiber passing through an annealing apparatus 4 are measured by installing an optical fiber temperature measuring thermometer 15 and an optical fiber temperature measuring thermometer 16 respectively arranged on the upper part of the annealing apparatus 4 and the lower part of the annealing apparatus 4. The bare optical fiber 3 is annealed at an optimum temperature by vertically moving the annealing apparatus 4 based on the approach temperature of the bare optical fiber 3 and controlling the temperature in the annealing apparatus 4 based on the receding temperature of the bare optical fiber 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４０】
【発明の効果】
以上説明したように、本発明に係る光ファイバ素線の製造装置及び光ファイバ素線の製造方法においては、徐冷装置の上部及び下部で光ファイバ裸線の温度を測定し、徐冷装置の上部で測定された光ファイバ裸線の進入温度に基づいて徐冷装置を上下に移動し、徐冷装置の下部で測定された光ファイバ裸線の退出温度に基づいて徐冷装置内の温度を調節することで、任意の温度で光ファイバ裸線を徐冷することができる。そのため、徐冷装置を通過する光ファイバ裸線に最適な進入温度及び最適な温度分布を見出して、常に最適な温度で光ファイバ裸線を徐冷することができる。これにより、光ファイバ中のＮＢＯＨＣを含むガラス欠陥の再結合を促進し、結果として、優れた水素特性を持つ光ファイバ素線を得ることができる。
【図面の簡単な説明】
【図１】本発明の光ファイバ素線製造装置の一例を示す概略図である。
【図２】従来の光ファイバ素線製造装置の一例を示す概略図である。
【図３】本発明の光ファイバ素線製造装置における徐冷装置の一例を示す概略図である。
【図４】本発明の光ファイバ素線製造装置における徐冷装置の一例を示す概略図である。
【図５】光ファイバ裸線の徐冷装置への進入温度と水素特性との関係を示す図表である。
【図６】光ファイバ裸線の徐冷装置への進入温度と出口温度の差と水素特性との関係を示す図表である。
【符号の説明】
２・・・紡糸炉、３・・・光ファイバ裸線、４・・・徐冷装置、５・・・冷却装置、１０・・・光ファイバ素線、１５、１６・・・光ファイバ温度測定器、[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for manufacturing an optical fiber, and more particularly, to an apparatus and a method for manufacturing an optical fiber capable of obtaining an optical fiber with improved hydrogen characteristics.
[0002]
[Prior art]
FIG. 2 is a schematic view showing an example of a conventional optical fiber manufacturing apparatus. The bare optical fiber 3 melt-spun from the optical fiber preform 1 in the spinning furnace 2 is cooled by the slow cooling device 4 and the cooling device 5. Next, a resin is applied to the bare optical fiber 3 by a resin coating device 6 and then cured by a curing device 7 to form a primary coating layer. Further, a resin is applied to the primary coating layer by a resin coating device 8 and the resin is cured by a curing device 9 to form a secondary coating layer. The optical fiber 10 thus manufactured has its pass line changed by a turn pulley 11, passes through a take-up machine 12, a dancer 13, and is taken up by a take-up machine 14.
[0003]
With the increase in the drawing speed of the optical fiber in order to improve productivity in recent years, a decrease in hydrogen characteristics has become a problem. Hydrogen characteristics refer to the properties of hydrogen diffused in glass reacting with defects in the glass and affecting the transmission loss of the optical fiber.If the hydrogen characteristics decrease, the transmission loss of the optical fiber increases. Say. In the step of drawing the optical fiber, the non-crosslinked oxygen hole center (NBOHC) in the optical fiber is obtained by rapidly cooling the heated and melted optical fiber bare wire. It is considered that the glass defects containing γ are less likely to recombine, and as a result, the hydrogen characteristics are reduced. As a countermeasure, as described in JP-A-2002-160946, the molten optical fiber bare wire is gradually cooled by using a slow cooling device provided between the spinning furnace and the cooling device, so that glass defects are recombined. Solutions have been reported to facilitate this. When drawing an optical fiber by such a method, it is important to set the temperature of the bare optical fiber at the time of slow cooling. It is necessary to gradually cool the bare fiber.
[0004]
[Patent Document 1]
JP-A-2002-160946 [0005]
[Problems to be solved by the invention]
However, in the conventional technology, the temperature of the bare optical fiber when entering the slow cooling device changes depending on drawing conditions such as the thickness of the preform and the drawing speed. There is a problem that the bare optical fiber cannot be gradually cooled, and as a result, the hydrogen characteristics of the optical fiber do not improve.
[0006]
Accordingly, an object of the present invention is to promote recombination of glass defects containing NBOHC in an optical fiber by gradually cooling the bare optical fiber at an optimum temperature at all times in accordance with the drawing conditions, thereby achieving excellent hydrogen characteristics. An object of the present invention is to provide a manufacturing apparatus and a manufacturing method for stably manufacturing an optical fiber.
[0007]
[Means for Solving the Problems]
In such a situation, the present inventor, when performing the drawing of the optical fiber, regardless of the drawing conditions at that time, in order to always cool the bare optical fiber at an optimum temperature, the upper part of the slow cooling device and An optical fiber temperature measuring device was installed at the bottom, and a device was developed in which the position of the slow cooling device could be moved up and down and the temperature of the slow cooling device could be adjusted.
By using such a device, the entry temperature of the bare optical fiber being drawn into the slow cooling device is measured, and the position of the slow cooling device is moved upward or downward depending on the temperature, so that the approach temperature is reduced. Can be controlled. Further, by measuring the exit temperature and adjusting the temperature in the slow cooling device thereby, an arbitrary temperature distribution can be given to the bare optical fiber passing through the slow cooling device. Thus, the bare optical fiber being drawn can be gradually cooled at an optimum temperature without depending on the spinning conditions, and thus a stable optical fiber having excellent hydrogen characteristics can be obtained.
[0008]
That is, the first invention of the present invention is a means for cooling a bare optical fiber melt-spun in a spinning furnace with a cooling device, and applying a resin on the bare optical fiber, curing the resin, and sequentially curing the primary coating layer. Means for forming a secondary coating layer, wherein in the apparatus for producing an optical fiber, in which a slow cooling device is installed between the spinning furnace and the cooling device, an optical fiber is provided above the slow cooling device. An apparatus for manufacturing an optical fiber, comprising a temperature measuring device.
[0009]
The second invention of the present invention is the apparatus for manufacturing an optical fiber according to claim 1, wherein the optical fiber temperature measuring device and the slow cooling device can be interlocked in a vertical direction.
[0010]
A third aspect of the present invention is the apparatus for manufacturing an optical fiber according to claim 1 or 2, wherein an optical fiber temperature measuring device is provided below the slow cooling device.
[0011]
The fourth invention of the present invention is the apparatus for manufacturing an optical fiber according to any one of claims 1 to 3, wherein the temperature of the slow cooling device is adjustable.
[0012]
The fifth invention of the present invention is that the bare optical fiber melt-spun from the optical fiber preform is cooled with a slow cooling device and a cooling device, and then a resin is applied on the bare optical fiber, cured, and sequentially. In the method for manufacturing the optical fiber element forming the primary coating layer and the secondary coating layer, the entry temperature of the bare optical fiber passing through the slow cooling device is measured, and the slow cooling device is moved up and down based on the measured temperature. The method is for controlling the temperature of entry of the bare optical fiber into the slow cooling device.
[0013]
In a sixth aspect of the present invention, the bare optical fiber melt-spun from the optical fiber preform is cooled by a slow cooling device and a cooling device, and then a resin is applied on the bare optical fiber, cured, and sequentially. In the method for producing an optical fiber strand forming a temporary coating layer and a secondary coating layer, the exit temperature of the bare optical fiber passing through the slow cooling device is measured, and the temperature of the slow cooling device is adjusted based on the measured temperature. Thus, there is provided a method for manufacturing an optical fiber, wherein the temperature distribution of the bare optical fiber passing through the slow cooling device is controlled.
[0014]
The seventh invention of the present invention is that the bare optical fiber melt-spun from the optical fiber preform is cooled by a slow cooling device and a cooling device, and then a resin is applied on the bare optical fiber, cured and sequentially cured. In the method for producing an optical fiber strand forming a primary coating layer and a secondary coating layer, the entrance temperature and exit temperature of the bare optical fiber passing through the slow cooling device are measured, and the slow cooling device is measured based on both temperatures. A method for producing an optical fiber, characterized by controlling a temperature distribution of a bare optical fiber passing through a slow cooling device by adjusting a position and a temperature.
[0015]
In the method for manufacturing an optical fiber of the present invention, the entrance temperature and the exit temperature of the bare optical fiber passing through the slow cooling device are measured, and only the position of the slow cooling device is adjusted based on both temperatures. This makes it possible to control the temperature distribution of the bare optical fiber passing through the slow cooling device.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings.
[0017]
FIG. 1 shows an example of an apparatus for manufacturing an optical fiber according to the present invention, and the same components as those described in FIG. 2 are denoted by the same reference numerals.
[0018]
The spinning furnace 2 is a device for heating and melting the optical fiber preform 1 at a temperature of 1000 ° C. or higher and spinning. A slow cooling device 4 is provided below the spinning furnace 2.
[0019]
The slow cooling device 4 is a device for cooling the bare optical fiber without quenching in order to promote the recombination of glass defects into the bare optical fiber 3 melt-spun from the optical fiber preform 1. The slow cooling device 4 is movable in the vertical direction, and can control the temperature at which the bare optical fiber enters the slow cooling device 4. Furthermore, since the temperature inside the slow cooling device 4 can be adjusted, an arbitrary temperature distribution can be given to the bare optical fiber passing through the slow cooling device 4.
[0020]
Here, the position where the slow cooling device 4 is provided may be anywhere between the spinning furnace 2 and the cooling device 5. In some cases, the lower part of the spinning furnace 2 may be extended to form the slow cooling device 4.
[0021]
The external shape of the slow cooling device 4 includes a cylindrical shape and a polygonal shape, but is not particularly limited. The internal shape of the slow cooling device 4 through which the bare optical fiber passes may be cylindrical, polygonal, corrugated, or the like, but is not particularly limited.
[0022]
Further, the length of the slow cooling device 4 is required to be 100 mm or more in order to slowly cool the bare fiber 3 melted in the spinning furnace 2, and the preferable length is appropriately determined according to the spinning speed. . If the length is less than 100 mm, the defects including the NBOHC of the bare optical fiber 3 cannot be sufficiently cooled to recombine.
[0023]
The mechanism for vertically moving the slow cooling device 4 is not particularly limited. For example, the slow cooling device may be vertically moved by electric power.
The temperature in the slow cooling device 4 can be adjusted in a range of about 50 to 1200 ° C. by a heater or the like. In addition, the slow cooling device 4 may be divided into several parts from the side closer to the spinning furnace 2 so that the temperature can be adjusted.
The periphery of the slow cooling device 4 is covered with a heat insulating material, so that the temperature inside the slow cooling device 4 does not change the entry temperature and the exit temperature of the bare optical fiber 3.
[0024]
An optical fiber temperature measuring device 15 is mounted on the upper part of the slow cooling device 4, and an optical fiber temperature measuring device 16 is mounted on the lower portion of the slow cooling device 4. The optical fiber temperature measuring device 15 is a device for measuring the entry temperature of the bare optical fiber 3, and the optical fiber temperature measuring device 16 is a device for measuring the exit temperature of the bare optical fiber 3. The optical fiber temperature measuring devices 15 and 16 do not come into contact with the bare optical fiber 3, but measure the temperature near the bare optical fiber 3. Therefore, strictly speaking, the entry temperature of the bare optical fiber 3 refers to the temperature near the bare optical fiber 3 measured by the temperature measuring device 15 attached to the upper part of the slow cooling device 4. Strictly speaking, the exit temperature of the wire 3 refers to a temperature near the bare optical fiber 3 measured by a temperature measuring device 16 attached to a lower part of the slow cooling device 4.
[0025]
When the optical fiber temperature measuring device 15 is attached to the upper part of the slow cooling device 4 and the optical fiber temperature measuring device 16 is attached to the lower portion of the slow cooling device 4, the optical fiber temperature measuring devices 15 and 16 are sufficiently close to the slow cooling device 4. More specifically, it is preferable that the cooling device is attached within a range of 0 cm to 20 cm from the end of the slow cooling device 4. This makes it possible to more accurately measure the entry temperature and the exit temperature of the bare optical fiber 3.
When the slow cooling device 4 moves up and down, the optical fiber temperature measuring devices 15 and 16 can move up and down in conjunction therewith.
[0026]
The temperature measuring mechanism of the optical fiber temperature measuring devices 15 and 16 is not particularly limited, and may be, for example, a mechanism for electronically measuring the temperature. The optical fiber temperature measuring devices 15 and 16 are preferably the same type of measuring devices.
The data of each temperature measured by the optical fiber temperature measuring devices 15 and 16 is sent to the control device 17.
[0027]
The control device 17 inputs the entry temperature of the bare optical fiber 3 measured by the optical fiber temperature measuring device 15 attached to the upper part of the slow cooling device 4, and controls the slow cooling device 4 based on the approach temperature. It has a function of moving upward or downward. Further, the control device 17 inputs the exit temperature of the bare optical fiber 3 measured by the optical fiber temperature measuring device 16 attached to the lower part of the slow cooling device 4, and based on the exit temperature, the slow cooling device It has a function of adjusting the temperature inside the slow cooling device 4 by adjusting the output of the heater and the like in the inside 4.
[0028]
Further, when the desired entry temperature is set in advance, the control device 17 calculates the difference from the entry temperature measured by the optical fiber temperature measuring device 15, thereby moving the slow cooling device 4 upward, or You can also move it down. For example, if the measured entry temperature is lower than the set temperature, the controller 17 can move the slow cooling device 4 upward.
Further, when a desired exit temperature is set in advance, the controller 17 calculates the difference between the exit temperature measured by the optical fiber temperature measuring device 16 and adjusts the temperature in the slow cooling device 4. You can also. For example, if the measured exit temperature is lower than the set temperature, the control device 17 can increase the output of the heater or the like in the slow cooling device 4 to increase the temperature in the slow cooling device 4.
[0029]
A cooling device 5 is provided below the slow cooling device 4. The cooling device 5 is a device that cools the bare optical fiber 3 until the temperature becomes appropriate for applying the resin. A resin coating device 6 is provided below the cooling device 5. The resin coating device 6 is a device for uniformly coating a resin on the bare optical fiber 3. A curing device 7 is provided below the resin coating device 6. The curing device 7 is a device for curing the resin applied to the bare optical fiber 3 in the resin application device 6. A resin coating device 8 is provided below the curing device 7. The resin coating device 8 is a device for uniformly coating another resin layer on the resin applied by the resin coating device 6. A curing device 9 is provided below the resin coating device 8. The curing device 9 is a device that cures the resin applied in the resin application device 8.
[0030]
Next, a method of manufacturing an optical fiber by the above-described optical fiber manufacturing apparatus will be described.
The bare optical fiber 3 melt-spun from the optical fiber preform 1 in the spinning furnace 2 is sent to a slow cooling device 4 and further sent to a cooling device 5 where it is cooled and sent to a resin coating device 6. Here, a resin is applied to the bare optical fiber 3, and then the resin is cured by a curing device 7 to form a primary coating layer. Further, a resin is applied on the primary coating layer by a resin application device 8 and the resin is cured by a curing device 9 to form a secondary coating layer. The optical fiber 10 thus manufactured has its pass line changed by a turn pulley 11, passes through a take-up machine 12 and a dancer 13 in this order, and is taken up by a take-up machine 14.
[0031]
In the manufacturing method of the present invention, the temperature at which the bare optical fiber 3 is being drawn into the slow cooling device 4 is measured by the optical fiber temperature measuring device 15, and the control device 17 controls the slow cooling device 4 based on the measured temperature. The entry temperature can be controlled by moving the position upward or downward. For example, if it is desired to increase the entry temperature, the control device 17 can move the slow cooling device 4 upward. Further, the exit temperature is measured by the optical fiber temperature measuring device 15, and the controller 17 adjusts the temperature inside the annealing device 4 based on the exit temperature. Temperature distribution can be given. For example, if it is desired to increase the exit temperature, the controller 17 can increase the output of a heater or the like in the slow cooling device 4 to increase the temperature in the slow cooling device 4.
[0032]
The optical fiber bare wire 3 gradually cooled by the slow cooling device 4 is cooled by the cooling device 5 to a temperature at which the resin to be the primary coating layer can be applied. Next, a resin is applied to the bare optical fiber 3 by a resin coating device 6, and then the resin is cured by a curing device 7 to form a primary coating layer. Further, a resin coating device 8 is formed on the primary coating layer. Is applied, and the resin is cured by the curing device 9 to form a secondary coating layer, and the optical fiber 10 is obtained. As the resin used for the coating layer, an ultraviolet curable resin is preferable.
[0033]
The apparatus and method for manufacturing an optical fiber of the present invention can be applied to any type of optical fiber such as a single mode optical fiber, a dispersion shift, a cutoff shift, and a dispersion compensation optical fiber. It is suitable for an optical fiber having a large loss, that is, absorption by NBOHC.
[0034]
As described above, the optical fiber manufacturing apparatus of the present invention measures the entry temperature of the bare optical fiber 3 passing through the slow cooling device 4 by the optical fiber temperature measuring device 15, and the control device 17 By moving the slow cooling device 4 upward or downward, the entry temperature of the bare optical fiber 3 can be controlled. In the optical fiber manufacturing apparatus according to the present invention, the exit temperature of the bare optical fiber 3 passing through the slow cooling device 4 is measured by the optical fiber temperature measuring device 16, and based on the measured temperature, the control device 17 gradually cools. An arbitrary temperature distribution can be given to the bare optical fiber passing through the slow cooling device 4 by adjusting the temperature inside the slow cooling device 4 by adjusting the output of the heater and the like in the device 4.
[0035]
Therefore, the optical fiber bare wire manufacturing apparatus according to the present invention can give the optimum entry temperature and the optimum temperature distribution to the bare optical fiber passing through the slow cooling device, and always provide the bare optical fiber 3 at the optimum temperature. Can be cooled slowly. For this reason, this optical fiber element manufacturing apparatus does not rapidly cool the heated and melted optical fiber bare wire, but promotes the recombination of glass defects including NBOHC in the optical fiber, and as a result, the hydrogen characteristic is reduced. The optical fiber 10 excellent in the above can be stably provided.
[0036]
Similarly, if the method for producing an optical fiber in the present invention is used, by finding the optimal entry temperature and the optimal temperature distribution for the bare optical fiber passing through the slow cooling device, the optical fiber is always kept at the optimal temperature. The bare fiber 3 can be gradually cooled. For this reason, if this method for producing an optical fiber is used, the hot-melted bare optical fiber is not rapidly cooled, and the recombination of glass defects including NBOHC in the optical fiber is promoted. The optical fiber 10 having excellent hydrogen characteristics can be stably provided.
[0037]
【Example】
Hereinafter, specific examples will be described.
(Example 1)
An optical fiber (SM fiber; outer diameter 250 μm, coating material: urethane acrylate ultraviolet curable resin) was drawn at a drawing speed of 500 m / min. At this time, a slow cooling device 4 as shown in FIG. 3 and an optical fiber temperature measuring device 15 were provided between the spinning furnace and the cooling device, and the entry temperature A of the bare optical fiber 3 during spinning was measured. The temperature inside the slow cooling device 4 is 1000 ° C., and the length of the slow cooling device 4 is 1500 mm. Further, the slow cooling device 4 can move up and down in conjunction with the optical fiber temperature measuring device 15. The hydrogen characteristics were measured for the optical fiber wires obtained by moving the slow cooling device up and down and changing the entry temperature A to 700 to 1200 ° C. The hydrogen characteristics were evaluated based on the increase in transmission loss at a wavelength of 1.38 μm after being left in a 1% hydrogen atmosphere for one week. FIG. 5 shows the relationship between the measured temperature A at which the bare optical fiber enters the slow cooling device and the hydrogen characteristics. From this result, it was found that when the entry temperature was around 1000 ° C., an optical fiber with the best hydrogen characteristics could be obtained, and it was found that there was an optimal entry temperature of the bare optical fiber.
[0038]
(Example 2)
Next, as shown in FIG. 4, a fiber temperature measuring device 15 was also provided immediately below the slow cooling device 4, and the exit temperature of the bare optical fiber 3 was measured. The position of the slow cooling device 4 is fixed at a position where the entry temperature is 1000 ° C., and the temperature of the slow cooling device 4 is changed such that the difference between the entry temperature and the exit temperature is −300 to 300 ° C. The hydrogen characteristics of the optical fiber obtained in the above were measured. Table 1 shows the measured entry temperature A, exit temperature (outlet temperature) B, and their difference (AB), and FIG. 6 shows the relationship between the temperature difference (AB) and the hydrogen characteristics. From this result, it was found that the smaller the absolute value of the temperature difference (AB), that is, the more constant the temperature of the optical fiber, the more an optical fiber having excellent hydrogen characteristics can be obtained. It has been found that there is an optimal temperature distribution for the bare fiber.
The temperature distribution of the bare optical fiber, the temperature of the slow cooling device, the length of the slow cooling device, and the like described herein are not limited, and may be appropriately determined according to the material and dimensions of the preform and the drawing conditions. What is necessary is just to select an appropriate value.
[0039]
[Table 1]

[0040]
【The invention's effect】
As described above, in the optical fiber manufacturing apparatus and the optical fiber manufacturing method according to the present invention, the temperature of the bare optical fiber is measured at the upper and lower portions of the slow cooling device, and the temperature of the slow cooling device is measured. The annealing device is moved up and down based on the entry temperature of the bare optical fiber measured at the upper portion, and the temperature in the annealing device is determined based on the exit temperature of the bare optical fiber measured at the lower portion of the cooling device. By adjusting the temperature, the bare optical fiber can be gradually cooled at an arbitrary temperature. Therefore, it is possible to find the optimum entry temperature and the optimum temperature distribution for the bare optical fiber passing through the slow cooling device, and to gradually cool the bare optical fiber at the optimum temperature. Thereby, recombination of glass defects including NBOHC in the optical fiber is promoted, and as a result, an optical fiber having excellent hydrogen characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an optical fiber manufacturing apparatus of the present invention.
FIG. 2 is a schematic view showing an example of a conventional optical fiber manufacturing apparatus.
FIG. 3 is a schematic view showing an example of a slow cooling device in the optical fiber manufacturing apparatus of the present invention.
FIG. 4 is a schematic view showing an example of an annealing device in the optical fiber manufacturing apparatus of the present invention.
FIG. 5 is a table showing a relationship between a temperature at which a bare optical fiber enters a slow cooling device and hydrogen characteristics.
FIG. 6 is a chart showing a relationship between a difference between a temperature at which an optical fiber bare wire enters a slow cooling device and an outlet temperature, and hydrogen characteristics.
[Explanation of symbols]
2 ... spinning furnace, 3 ... bare optical fiber, 4 ... slow cooling device, 5 ... cooling device, 10 ... optical fiber wire, 15, 16 ... optical fiber temperature measurement vessel,

Claims (7)

A means for cooling the bare optical fiber melt-spun in the spinning furnace with a cooling device, and a means for applying a resin on the bare optical fiber, curing and forming a primary coating layer and a secondary coating layer sequentially. In the apparatus for manufacturing an optical fiber which is provided with a slow cooling device between the spinning furnace and the cooling device, an optical fiber temperature measuring device is provided above the slow cooling device. Equipment for producing optical fiber. 2. The apparatus for manufacturing an optical fiber according to claim 1, wherein the optical fiber temperature measuring device and the annealing device can be interlocked in a vertical direction. 3. The apparatus for manufacturing an optical fiber according to claim 1, wherein an optical fiber temperature measuring device is provided below the slow cooling device. The apparatus for producing an optical fiber according to any one of claims 1 to 3, wherein the slow cooling device is capable of adjusting the temperature. The bare optical fiber melt-spun from the optical fiber preform is cooled by a slow cooling device and a cooling device, and then a resin is applied on the bare bare optical fiber and cured to form a primary coating layer and a secondary coating layer sequentially. In the method for producing an optical fiber to be formed, the entrance temperature of the bare optical fiber passing through the slow cooling device is measured, and the slow cooling device is moved in the vertical direction based on the measured temperature. A method for manufacturing an optical fiber, comprising controlling an entry temperature of a bare optical fiber. The bare optical fiber melt-spun from the optical fiber preform is cooled by a slow cooling device and a cooling device, and then a resin is applied on the bare optical fiber, and then cured to form a temporary coating layer and a secondary coating layer sequentially. In the method for manufacturing an optical fiber to be formed, the exit temperature of the bare optical fiber passing through the slow cooling device is measured, and the temperature of the slow cooling device is adjusted based on the measured temperature, so that the temperature passes through the slow cooling device. A method for manufacturing an optical fiber, comprising controlling a temperature distribution of the bare optical fiber. The bare optical fiber melt-spun from the optical fiber preform is cooled by a slow cooling device and a cooling device, and then a resin is applied on the bare bare optical fiber and cured to form a primary coating layer and a secondary coating layer sequentially. In the manufacturing method of the optical fiber to be formed, by measuring the entrance temperature and the exit temperature of the bare optical fiber passing through the slow cooling device, by adjusting the position and temperature of the slow cooling device based on both temperatures, A method for manufacturing an optical fiber, comprising controlling a temperature distribution of a bare optical fiber passing through a slow cooling device.

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