JP2000007367A - Apparatus and method for manufacturing glass preform for optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain porous glass preform of the tapered part reduced with high sedimentation efficiency and no bubble formation by providing a burner- moving mechanism that enables individual burners to move along the circumferential direction of the porous preform. SOLUTION: Figure (a) gives its longitudinal section, while Figure (b) shows its plan view. This production apparatus is equipped with a chamber 1, target 2, a porous glass preform 3, the core part 4, the second burner for clad 5, the first burner for clad 6, the burner for core 7, the burner-moving mechanism 8 and an exhaustion tube. The burner-moving mechanism 8 is for allowing the burners set in the chamber to move in the circumferential direction of the porous glass preform, equipped with a rail in the same distance from the soot-accumulating center and a jig for fixing the burner is fixed onto the rail. The jig for fixing the burner is allowed to slide along the rail whereby the burner becomes possible to move in the circumferential direction of the burner. In the figure, three burners are spirally arranged in the chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for manufacturing an optical fiber glass preform.

[0002]

2. Description of the Related Art Production of a porous glass preform for an optical fiber by the VAD method is performed by an apparatus as shown in FIG. Referring to the drawing, an exhaust pipe 19, a core burner 17, and a clad burner are provided in a closed chamber 11.
Using an apparatus in which 15, 16 and a target 12 are arranged, glass particles generated by a flame hydrolysis reaction of a glass source gas containing silicon halide as a main component are sprayed and deposited on a rotating target 12, and this is axially deposited. It is done in a growing way. At this time, glass particles not deposited on the porous glass base material, hydrochloric acid generated by the reaction, and the like are exhausted from the inside of the chamber through the exhaust pipe 19.

[0003]

However, when the size of the porous glass base material increases and the amount of fine glass particles generated by a plurality of burners increases, the flames of adjacent burners interfere with each other due to an increase in the heat of the burners. Then, the flow of gas in the chamber is disturbed, and the generated glass particles scatter,
These are not exhausted from the exhaust pipe and flow into the chamber as soot, which adheres to the porous glass base material and causes bubbles and inclusions, etc., and further reduces the deposition efficiency of glass fine particles. Although the distance between the burners is increased by moving in the axial direction to prevent interference between the flames, this method has a problem that the obtained tapered portion of the glass base material for an optical fiber becomes long, and the productivity is deteriorated.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an apparatus for manufacturing a glass preform for an optical fiber comprising a chamber having a plurality of burners, an exhaust pipe and a target. It is characterized in that each burner can move in the circumferential direction of the porous glass base material, which also deposits glass particles synthesized in the flames of a plurality of burners on a target, and axially deposits them. In a method of manufacturing a glass preform for an optical fiber in which a porous glass preform is formed by growing the glass preform, each burner is moved and arranged in a circumferential direction of the porous glass preform to reduce flame interference between the burners. And depositing glass fine particles. According to the present invention, flame interference between burners can be prevented without increasing the tapered portion of the porous glass base material, and since there is no disturbance in the gas flow in the reaction chamber, bubbles are generated in the glass base material. And the inclusion is not generated, and the deposition efficiency of the glass particles can be improved.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIGS. 1A and 1B show an apparatus for manufacturing a glass preform for an optical fiber according to the present invention, wherein FIG. 1A is a longitudinal sectional view and FIG. 1B is a plan view. In the figure, reference numeral 1 denotes a chamber, 2 denotes a target, 3 denotes a porous glass base material, 4
Represents a core portion, 5 represents a second burner for cladding, 6 represents a first burner for cladding, 7 represents a burner for core, 8 represents a burner moving mechanism, and 9 represents an exhaust pipe. The burner moving mechanism 8 is a device for moving the burner mounted in the chamber in the circumferential direction of the porous glass base material. The structure is such that a rail is provided at an equal distance from the deposition center of the device, and the burner is placed on the rail. It consists of fixing a fixing jig. By sliding the burner fixing jig on the rail along the rail, the burner can be moved in the circumferential direction. FIG. 1 shows an example in which three burners are spirally arranged with respect to a porous glass base material in a chamber by a burner moving mechanism, and FIG. 2 shows an example in which the burners are staggered.

Next, a method for manufacturing a glass preform for an optical fiber according to the present invention will be described in detail with reference to FIG. First, in the chamber 1 provided with the burner moving mechanism 8 capable of moving each burner in the circumferential direction of the porous glass base material, the distance between adjacent burners is adjusted by the burner moving mechanism 8 in order to suppress interference of flames between the burners. It is necessary to. The larger the distance is, the less the flame interference between the burners is, but the problem is that the apparatus becomes large and the tapered portion of the obtained glass base material becomes long. Next, the core burner 7, the cladding first burner 6, and the cladding second burner 5 rotate the core glass fine particles and the cladding glass fine particles generated by the flame hydrolysis reaction of the glass raw material gas. The porous glass base material 3 is generated by depositing on the target 2 and growing it in the axial direction. The present invention solves the above problem by arranging the burner in a three-dimensional manner with the moving direction of the burner being the circumferential direction of the porous glass base material.

[0007]

EXAMPLES Examples and comparative examples of the present invention will be shown below, but the present invention is not limited to these examples. (Example 1) In the manufacturing apparatus of FIG. 1, a quadruple tube with an outer diameter of 15 mm and a first burner 6
As the second burner 5 for cladding, a quintuple tube with an outer diameter of 20 mm is used, and each burner can move in the circumferential direction of the porous glass preform at an angle of 120 ° with respect to the target. Using an apparatus provided with a moving mechanism 8, the second burner 5 for cladding is arranged in front of the exhaust pipe 9, and the first burner 6 for cladding and the burner 7 for core are shifted by 15 ° at a time, and are placed in the chamber as shown in FIG. Helically arranged as shown. Each burner interval is 6mm, 5mm, 5 and 6 are
There was no interference between the burners at 50mm. Next, while rotating the target at 30 RPM with this apparatus, the core burner 7 was supplied with 200 SCCM of silicon tetrachloride gas, 60 SCCM of germanium tetrachloride gas, 10 SLM of hydrogen gas, 12 SLM of oxygen gas and 12 SLM of Ar gas.
The gas 3SLM, the first burner 6 for cladding is 400 SCCM of silicon tetrachloride gas, the hydrogen gas 20SLM, the 20SLM of oxygen gas, and the 5SLM of Ar gas. The second burner 5 for cladding is 800 SCCM of silicon tetrachloride gas, 40SLM of hydrogen gas. Oxygen gas 25SLM
, Ar gas 7SLM are respectively supplied to generate glass fine particles, which are deposited, grown in the axial direction, and have a diameter of 10 mm.
A porous glass preform having a length of 0 mm and a length of 1,000 mm was produced. The length of the tapered portion of the porous glass base material was about 60 mm. Next, the porous glass base material is dehydrated at 1,000 ° C.
Ten optical fiber preforms having a diameter of 45 mm and a length of 500 mm were produced as sintered glass at 1,400 ° C., but no bubbles or inclusions were observed.

(Embodiment 2) As shown in FIGS. 2 (a) and 2 (b), a core burner 7, a clad first burner 6 and a clad second burner 5 are arranged in a zigzag manner in a chamber. When a porous glass preform having a diameter of 100 mm and a length of 1,000 mm was manufactured under the same conditions as in Example 1 except that the burner interval was adjusted, the length of the tapered portion of the porous glass preform was about 60 mm. Next, the porous glass base material is dehydrated at 1,000 ° C. and sintered at 1,400 ° C. as a sintered glass having a diameter of 45 mm and a length of 500 mm.
Five optical fiber preforms were produced, but no bubbles or inclusions were observed.

Comparative Example As shown in FIGS. 3A and 3B, a core burner 17, a clad first burner 16, and a clad second burner 15 are arranged linearly in the axial direction. A porous glass preform having a diameter of 100 mm and a length of 1,000 mm was manufactured under the same conditions as in Example 1 except that the intervals between the burners were adjusted. The length of the tapered portion was 150 mm, which was more than twice that of the Example. It became size.

[0010]

According to the present invention, a glass base material for an optical fiber having a small taper portion, a high deposition efficiency and a bubble-free efficiency can be obtained even if the interval between the burners is increased in order to reduce the interference of the flame of the burner. Can be

[Brief description of the drawings]

FIG. 1 is a view showing an example of an apparatus for manufacturing a glass preform for an optical fiber of the present invention, wherein (a) is a longitudinal sectional view and (b) is a plan view.

FIGS. 2A and 2B show another example of the apparatus for manufacturing a glass preform for an optical fiber of the present invention, wherein FIG. 2A is a longitudinal sectional view and FIG. 2B is a plan view.

3A and 3B are views showing a conventional apparatus for manufacturing a glass preform for optical fibers, wherein FIG. 3A is a longitudinal sectional view and FIG. 3B is a plan view.

[Explanation of symbols]

 1, 11 ... chamber 2, 12 ... target 3, 13 ... porous glass base material 4, 14 ... core part 5, 15 ... second burner for cladding 6, 16 ... first burner for cladding 7, 17 ... core burner 8 Burner moving mechanism 9 19 Exhaust pipe

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[Procedure amendment]

[Submission date] August 12, 1999 (1999.8.1)
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an apparatus for manufacturing a glass preform for an optical fiber comprising a chamber having a plurality of burners, an exhaust pipe and a target. , A burner moving mechanism that allows each burner to move in the circumferential direction of the porous glass base material
Characterized in that it has a, which also glass particles synthesized in the plurality of burners flames is deposited on the target, which is grown in the axial direction the optical fiber to form a porous glass preform In the method of manufacturing a glass preform for use, each burner is provided with a bar in a circumferential direction of the porous glass preform.
The method is characterized in that glass particles are deposited by moving and arranging them by a ker moving mechanism to reduce flame interference between the burners. According to the present invention, flame interference between burners can be prevented without increasing the tapered portion of the porous glass base material, and since there is no disturbance in the gas flow in the reaction chamber, bubbles are generated in the glass base material. And the inclusion is not generated, and the deposition efficiency of the glass particles can be improved.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIGS. 1A and 1B show an apparatus for manufacturing a glass preform for an optical fiber according to the present invention, wherein FIG. 1A is a longitudinal sectional view and FIG. 1B is a plan view. In the figure, reference numeral 1 denotes a chamber, 2 denotes a target, 3 denotes a porous glass base material, 4
Represents a core portion, 5 represents a second burner for cladding, 6 represents a first burner for cladding, 7 represents a burner for core, 8 represents a burner moving mechanism, and 9 represents an exhaust pipe. The burner moving mechanism 8 is a device for moving the burner mounted in the chamber in the circumferential direction of the porous glass base material. The structure is such that a rail is provided at an equal distance from the deposition center of the device, and the burner is placed on the rail. It consists of fixing a fixing jig. By sliding the burner fixing jig on the rail along the rail, the burner can be moved in the circumferential direction. The burner moving mechanism, FIG. 1 also examples were helically arranged, the three burners relative to the porous glass preform in the chamber 2, a multi
This is an example in which the porous glass base material is arranged in a zigzag pattern in the circumferential direction .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

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[0007]

EXAMPLES Examples and comparative examples of the present invention will be shown below, but the present invention is not limited to these examples. (Example 1) In the manufacturing apparatus of FIG. 1, a quadruple tube with an outer diameter of 15 mm and a first burner 6
20 mm outer diameter quintuple pipe, 20 mm outer diameter quintuple pipe as the second burner 5 for cladding, target each burner
At an angle relative to the axis 120 °, equidistant from the deposition center point
Using a device provided with a moving mechanism 8 capable of moving the porous glass base material in the circumferential direction along the rail provided in the above , the second burner 5 for cladding is arranged in front of the exhaust pipe 9 and the first burner for cladding is used. Burner 6 and core burner 7 as target axes
It was helically arranged in the chamber as shown in FIG. Each burner interval is 6,
7 was 5 mm, 5 and 6 were 50 mm, and there was no interference between burners. Then, while rotating the target at 30 RPM with this device, 200 SC of silicon tetrachloride gas was added to the core burner 7.
CM, germanium tetrachloride gas 60SCCM, hydrogen gas 10SLM,
12 SLM for oxygen gas, 3 SLM for Ar gas, 400 SCCM silicon tetrachloride gas for the first burner 6 for cladding, 20 SLM for hydrogen gas, 20 SLM for oxygen gas, 5 SLM for Ar gas, and 800 SCCM for the second burner 5 for cladding. , Hydrogen gas 40SL
M, oxygen gas 25SLM, and Ar gas 7SLM were respectively supplied to generate glass fine particles, which were deposited and grown in the axial direction to produce a porous glass base material having a diameter of 100 mm and a length of 1,000 mm. . The length of the tapered portion of the porous glass base material was about 60 mm. Next, this porous glass preform is
Dehydrated at 1,000 ° C, 45m in diameter as sintered glass at 1,400 ° C
m, 10 optical fiber preforms with a length of 500 mm were made.
No bubbles or inclusions were observed.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

(Embodiment 2) As shown in FIGS. 2A and 2B, a core burner 7, a clad first burner 6, and a clad second burner 5 are placed in a chamber, and a porous glass base material.
The diameter was 100 mm and the length was 1,000 mm under the same conditions as in Example 1 except that the distance between each burner was adjusted by arranging in a staggered fashion in the circumferential direction.
When the porous glass preform was manufactured, the length of the tapered portion of the porous glass preform was about 60 mm. Next, the porous glass preform was dehydrated at 1,000 ° C., and five optical fiber preforms having a diameter of 45 mm and a length of 500 mm were produced as sintered glass at 1,400 ° C., but no bubbles or inclusions were observed.

Continuation of the front page (72) Inventor Hideo Hirasawa 2-13-1, Isobe, Annaka-shi, Gunma F-term in Shin-Etsu Kagaku Kogyo Co., Ltd. Precision Functional Materials Laboratory 4G021 EA01 EB14

Claims (5)

[Claims] An apparatus for manufacturing a glass preform for an optical fiber comprising a plurality of burners, an exhaust pipe, and a chamber having a target, wherein each burner can move in a circumferential direction of the porous glass preform. Equipment for manufacturing glass preforms for fibers. 2. A rail is provided at an equal distance from a deposition center of the apparatus, a jig for fixing a burner is fixed on the rail, and a jig for fixing a burner is slid along the rail on the rail. The apparatus for producing a glass preform for an optical fiber according to claim 1, further comprising a burner moving mechanism comprising: 3. The apparatus for manufacturing a glass preform for an optical fiber according to claim 1, wherein each burner is spirally disposed in the chamber with respect to the porous glass preform. 4. The apparatus for manufacturing a glass preform for an optical fiber according to claim 1, wherein each burner is arranged in a staggered manner with respect to the porous glass preform in the chamber. 5. A method of manufacturing a glass preform for an optical fiber, comprising depositing glass fine particles synthesized in a plurality of burner flames on a target and growing the same in an axial direction to form a porous glass preform. A method for producing a glass base material for optical fibers, wherein each burner is moved and arranged in the circumferential direction of the porous glass base material to reduce the interference of flame between the burners and deposit glass fine particles.