CN116462403A - A device and method for preparing a large-diameter core layer preform - Google Patents

Abstract

The invention discloses a device and a method for preparing a large-diameter core layer preform, and belongs to the technical field of glass fiber preforms. The device comprises a deposition cavity, a first core lamp, a wrapping lamp and a rotary suspender, wherein a second core lamp is arranged between the wrapping lamps through the first core lamp, so that the density of the outer region of the core layer is improved. The method not only solves the limit of the sintering furnace core tube on the whole size of the loose core rod body. The improved VAD production process of the present invention increases the size of the core portion of the prepared mandrel without increasing or relatively increasing the cladding size. The method not only solves the limit of the sintering furnace core tube on the whole size of the loose core rod body, but also can draw optical fibers with larger length by wrapping the stretched core rod in an OVD or sleeve mode.

Description

A device and method for preparing a large-diameter core layer preform

technical field

The invention relates to the related technical field of glass fiber prefabricated rods, in particular to a device and method for preparing large-diameter core layer prefabricated rods.

Background technique

With the rapid development of communication technology, the use of optical fiber in communication is increasing day by day. More and more optical cable manufacturers extend the industrial chain to optical fiber drawing, and further extend to the production of optical fiber preform.

At present, the manufacture of optical fiber preform mainly adopts a two-step method, that is, the core rod is manufactured first, and then the cladding is deposited outside the core rod. There are four main manufacturing technologies for mandrels: the external vapor deposition process OVD (Outside Vapor Deposition) developed by Corning Corporation of the United States, the improved chemical vapor deposition process MCVD (Modified Chemical Vapor Deposition) developed by Bell Laboratories of the United States, the axial vapor deposition process VAD (VaporAxial Deposition) developed by Japan NTT, and the plasma chemical vapor deposition process PCVD (Plasma Chemical Vapor Deposition) developed by Philips of the Netherlands. ition). Outer cladding manufacturing technologies mainly include: direct external vapor deposition process OVD, plasma external spraying process APVD, and casing method.

With the increasing competition in the industry, how to reduce the manufacturing cost of optical fiber preforms has become a hot topic in the industry. Reducing the manufacturing cost of optical fiber preform mainly starts from the following aspects: ① Increase the size of preform; ② Improve the pass rate of preform and reduce scrap; ③ Reduce the cost of raw and auxiliary materials. In this field, the core layer and cladding are mostly prepared at one time. Due to the limitation of the size of the liner in the MCVD and PCVD processes, it is difficult to increase the size of the mandrel; the VAD and OVD processes are limited by the size of the sintering furnace, and the size of the soot deposited on the mandrel is also limited, and the core layer in the mandrel only accounts for about 1/4.

In view of the above problems, if the core-clad ratio (d core layer/D cladding layer) of the core rod can be increased, that is, the size of the core layer part of the core rod can be increased without increasing or relatively little increase in the cladding size. After the core rod is stretched, it can be outsourced by OVD or sleeve, and longer optical fibers can be drawn. Therefore, based on the above ideas, the present invention provides a method for increasing the ratio of the core layer diameter of the VAD mandrel.

Contents of the invention

In order to solve the existing technical problems, the present invention provides a device for preparing a large-diameter core layer preform, which includes: a deposition chamber, a first core lamp, a second core lamp, a wrapping lamp, and a rotating suspender. The hole structure includes a central nozzle hole, a first annular nozzle hole, a second annular nozzle hole, a third annular nozzle hole, a fourth annular nozzle hole, a fifth annular nozzle hole, a sixth annular nozzle hole and a seventh annular nozzle hole from inside to outside.

Preferably or optionally, the device further includes an air intake assembly and an exhaust assembly, both of which are disposed inside the deposition chamber; the air intake system is disposed adjacent to the same side of the core lamp, and the exhaust assembly is disposed away from the core lamp.

Preferably or optionally, the device further includes a control system, which is used to set the gas flow rate of the core lamp to deposit at the end of the target rod to form a core layer, and control the gas flow rate of the clad lamp to deposit at the end of the core layer to form a cladding layer.

Preferably or optionally, in the first wick lamp,

The central nozzle hole has a preset flow rate of SiCl4 gas of 0.15-0.6slpm and _H2 of a preset flow rate of 0.1-0.8slpm;

The first annular nozzle hole has GeCl ₄ with a preset flow rate of 0.06-0.2 slpm and H ₂ with a preset flow rate of 3-5.5 slpm;

The second annular nozzle hole has Ar with a preset flow rate of 2-5 slpm;

The third annular nozzle hole has a preset flow rate of 17-24slpm O ₂ ;

The fourth annular nozzle hole has Ar with a preset flow rate of 2-5 slpm;

The fifth annular nozzle hole has H ₂ with a preset flow rate of 17-24 slpm;

The sixth annular nozzle hole has Ar with a preset flow rate of 2-6 slpm;

The seventh annular orifice is vented with O ₂ at a preset flow rate of 17-24 slpm.

Preferably or optionally, in the second wick lamp,

There is any gas in the center nozzle hole;

H ₂ with a preset flow rate of 1.5-5 slpm is passed through the first annular nozzle hole;

The second annular nozzle hole has Ar with a preset flow rate of 2-5 slpm;

The third annular nozzle hole has a preset flow rate of 5-18slpm O ₂ ;

The fourth annular nozzle hole has Ar with a preset flow rate of 2-5 slpm;

The fifth annular nozzle hole has H ₂ with a preset flow rate of 5-18 slpm;

The sixth annular nozzle hole has Ar with a preset flow rate of 2-6 slpm;

The seventh annular nozzle hole is vented with O ₂ at a preset flow rate of 5-18 slpm.

Preferably or optionally, in the package lamp,

The central nozzle hole has SiCl ₄ with a preset flow rate of 3-7 slpm and O ₂ with a preset flow rate of 0.8-2.2 slpm;

The first annular nozzle hole has H ₂ with a preset flow rate of 9-12 slpm and CF ₄ with a preset flow rate of 0.2-0.6 slpm;

The second annular nozzle hole has Ar with a preset flow rate of 2-5 slpm;

The third annular nozzle hole has a preset flow rate of 28-45slpm O ₂ ;

The fourth annular nozzle hole has Ar with a preset flow rate of 3-8 slpm;

The fifth annular nozzle hole has H ₂ with a preset flow rate of 90-120 slpm;

The sixth annular nozzle hole has Ar with a preset flow rate of 3-8 slpm;

The seventh annular orifice is vented with O ₂ at a preset flow rate of 30-55 slpm.

A method for preparing a large-diameter core layer preform, using the device for preparing a large-diameter core layer preform described in any one of the above, comprising the following steps:

Ⅰ. Install the cleaned VAD deposition core lamp and wrap lamp on the corresponding core lamp lamp holder and wrap lamp holder, adjust the cross laser to determine the installation surface of the core lamp/wrap lamp, ensure that the core lamp/wrap lamp installed on the core lamp/wrap lamp holder are in the same plane, and ensure that the position of the wick lamp/wrap lamp mounting seat is in the middle of the base;

Ⅱ. Ignite the core lamp and the bag lamp, and spray to the target rod according to the flow rate setting value. The silicon dioxide and germanium dioxide produced by hydrolysis begin to deposit on the target rod. As the deposition continues, the diameter of the core layer at the lower end of the target rod gradually increases. When the diameter of the core layer is greater than the preset value, the target rod is lifted at a constant speed with the rotating boom until the deposition is completed, and the core rod loose body is obtained;

Ⅲ. Dehydrating and sintering the obtained mandrel loose body to obtain a transparent mandrel.

Preferably or optionally, the angle of the core lamp is 51°±1°, the laser distance is required to be 20mm±2mm, and the axial distance is required to be 60mm±5mm; the angle of the wrapping lamp is 38°±1°, the laser distance is required to be 120mm±5mm, and the axial distance is required to be 160mm±10mm.

After adopting the above-mentioned device and process, the present invention has the following beneficial effects: the present invention deviates the central axis of the core lamp and the loose body to be prepared by a certain angle in the VAD process, so that the loose body grows in a spiral manner, and the lifting rate of the loose body will slow down, but the core layer size of the mandrel will increase, thereby increasing the weight of a single mandrel and the core-to-pack ratio. Simultaneously, in order to control the density and uniformity of the mandrel, the present invention further arranges a second core lamp between the first core lamp and the envelope lamp, so as to increase the density of the outer area of the core layer. The method not only solves the limitation of the sintering furnace core tube on the overall size of the mandrel loose body. The improved VAD production process of the present invention increases the size of the core layer part of the prepared mandrel without increasing or relatively little increasing the cladding layer size. This method not only solves the limitation of the overall size of the mandrel loose body by the sintering furnace core tube, but also outsources the stretched mandrel by OVD or sleeve, which can draw a longer optical fiber.

Description of drawings

The present invention is described in detail below in conjunction with accompanying drawing and specific embodiment:

Fig. 1 is the schematic diagram of the device structure of embodiment 2 of the present invention;

Fig. 2 is a schematic diagram of the deposition state of the core layer according to an embodiment of the present invention;

Reference numerals are a deposition chamber 1 , a first core lamp 2 , a second core lamp 3 , a package lamp 4 , a rotating boom 5 , and a target rod 6 .

Detailed ways

In the following description, numerous specific details are given in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without one or more of these details. In other examples, some technical features known in the art are not described in order to avoid confusion with the present invention.

In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.

The present invention will be further described below in conjunction with the embodiments, and the examples of the described embodiments are intended to explain the present invention, but should not be construed as limiting the present invention. Those that do not indicate specific techniques and reaction conditions in the examples can be carried out according to techniques or conditions described in documents in this field or product instructions. All reagents, instruments or equipment not indicated by the manufacturer can be obtained commercially.

The invention provides a device and method for preparing a large-diameter core layer prefabricated rod. The core lamp in the VAD process is deviated from the central axis of the soot body to be prepared by a certain angle, so that the soot body grows in a spiral manner, and the lifting rate of the soot body will be slowed down, but the core layer size of the mandrel will increase, thereby increasing the weight of a single mandrel rod and the core-to-package ratio. At the same time, in order to control the density and uniformity of the core rod, a second core lamp is installed between the core lamp and the wrapping lamp to increase the density of the outer area of the core layer and solve the limitation of the overall size of the core rod loose body by the sintering furnace core tube. The improved production process of the present invention increases the size of the core layer part of the prepared mandrel without increasing or relatively little increasing the size of the cladding layer. It not only solves the limitation of the overall size of the core rod loose body by the sintering furnace core tube, but also outsources the stretched core rod through OVD or sleeve, which can draw longer optical fibers.

The method for preparing a large-diameter core layer prefabricated rod includes the following steps: After installing the cleaned core lamp and the wrapped lamp on the corresponding core lamp lamp holder and the wrapped lamp lamp holder, install the target rod on the rotating suspender and place it in the deposition chamber, rotate the target rod, and place the H₂and SiCl₄into the central orifice of the wick lamp, H₂and GeCl₄It passes into the first annular nozzle hole of the core lamp, the isolation gas Ar passes into the second, fourth and sixth annular nozzle holes of the core lamp, and the combustion-supporting gas O₂The third and seventh annular nozzle holes leading to the wick lamp, the combustion-supporting gas H₂Pass into the fifth nozzle of the core lamp, and ignite in the deposition chamber to generate a flame, and the gas phase raw material SiCl₄、GeCl₄, O₂Reacts in a flame to produce SiO₂、GeO₂Dust, SiO₂、GeO₂The dust is deposited on the end of the target rod to form a core layer; the H₂and SiCl₄Into the first nozzle of the package lamp, the combustion gas H₂Pass into the second nozzle of the package lamp, the isolation gas Ar passes into the third, fifth and seventh nozzles of the package lamp, and the combustion-supporting gas O₂Into the fourth and eighth nozzles of the bag lamp, combustion-supporting gas H₂Pass into the sixth nozzle of the package lamp, and ignite in the deposition chamber to generate a flame, and the gas phase raw material SiCl₄, O₂Reacts in a flame to produce SiO₂Dust, SiO₂Dust adheres to the outer periphery of the core layer to form an optical cladding; driven by the lifting of the rotating boom, the target rod rises gradually, and the deposition surface is always kept at the end of the target rod, so that the dust is continuously deposited at the end of the target rod to form a loose body of the mandrel.

Example 1

This embodiment is a conventional VAD method preparation process. After installing the cleaned core lamp and wrapped lamp on the corresponding core lamp lamp holder and wrapped lamp holder, install the target rod on the rotating boom and place it in the deposition chamber, rotate the target rod, pass _H2 and _SiCl4 into the central nozzle hole of the core lamp, _H2 and _GeCl4 into the first annular nozzle hole of the core lamp, the insulating gas Ar into the second, fourth and sixth annular nozzle holes of the core lamp, and the combustion-supporting gas O2 into the third and seventh nozzle holes of the core lamp In the annular nozzle hole, the combustion-supporting gas _{H 2 passes} into the fifth nozzle of the core lamp, and is ignited in the deposition chamber to generate a flame.

Among them, SiCl4 gas with a preset flow rate of 0.25 slpm and H2 gas with a preset flow rate of 0.3 slpm are passed through the center nozzle hole of the wick lamp.₂Gas; the first annular orifice has GeCl4 with a preset flow rate of 0.12 slpm and H with a preset flow rate of 4.4 slpm₂Gas, Ar gas with a preset flow rate of 3 slpm is passed through the second annular nozzle hole, and O gas with a preset flow rate of 18 slpm is passed through the third annular nozzle hole₂Gas, Ar gas with a preset flow rate of 4 slpm is passed through the fourth annular nozzle hole, and H gas with a preset flow rate of 19 slpm is passed through the fifth annular nozzle hole₂Gas, Ar gas with a preset flow rate of 4 slpm is passed through the sixth annular nozzle hole, and O gas with a preset flow rate of 20 slpm is passed through the seventh annular nozzle hole.₂gas.

The gas and flow rate of each nozzle hole of the package lamp from the inside to the outside are set as follows: the center nozzle hole has SiCl4 gas with a preset flow rate of 6 slpm and O gas with a preset flow rate of 1.8 slpm₂Gas, the first annular nozzle hole has a preset flow rate of 10.8slpm H₂Gas with CF at preset flow rate of 0.44slpm₄Gas, Ar gas with a preset flow rate of 4 slpm is passed through the second annular nozzle hole, and O gas with a preset flow rate of 35 slpm is passed through the third annular nozzle hole₂Gas, Ar gas with a preset flow rate of 6 slpm is passed through the fourth annular nozzle hole, and H gas with a preset flow rate of 100 slpm is passed through the fifth annular nozzle hole₂Gas, Ar gas with a preset flow rate of 6 slpm is passed through the sixth annular nozzle hole, and O gas with a preset flow rate of 45 slpm is passed through the seventh annular nozzle hole.₂gas.

The lifting speed of the loose body is 1.2mm/min.

The transparent mandrel of this embodiment is obtained after dehydration and sintering of the mandrel loose body obtained by the above method.

Example 2

Compared with Embodiment 1, the main changes of this embodiment are that the second core lamp 3 is added, and the Y-axis coordinate of the first core lamp 2 is adjusted to move about 0.6mm in the positive direction of the Y-axis. Because the Y-axis position of the first core lamp 2 is moved to the positive direction, the position of the current flame injection position deviates from the central axis of the soot body, so the core layer of the soot body grows spirally, which is the same as the flow rate of the raw material in Example 1. However, due to the spiral growth of the core layer, the diameter of the existing core layer is larger than that of the core layer in Example 1, and the relative density of the core layer is much smaller. The mismatch between the density of the core layer and the cladding layer will cause the core rod sintered in the subsequent sintering process. . Therefore, in this embodiment, a second core lamp 3 is added between the first core lamp 2 and the wrapping lamp, and the structure schematic diagram of the improved device is shown in Fig. 1 . The device includes a deposition chamber 1 , a first core lamp 2 , a second core lamp 3 , a cover lamp 4 , a rotating boom 5 , a target rod 6 , an air inlet assembly 7 and an exhaust assembly 8 . The first core lamp 2, the second core lamp 3 and the bag lamp 4 are arranged below the inside of the deposition chamber 1, and the rotating boom 5 is arranged above the middle part of the deposition chamber 1. The rotating boom 5 rotates axially and moves up and down in the vertical direction; the target rod 6 is fixedly connected to the lower end of the rotating boom 5; the air inlet assembly 7 and the exhaust assembly 8 are all arranged inside the deposition chamber 1; .第一芯灯2、第二芯灯3与包灯4同为环状八层喷孔结构，其中第一芯灯2各环形喷孔流量配比如下：中心喷孔通有预设流量为0.25slpm的SiCl ₄气体与预设流量为0.3slpm的H ₂气体；第一环形喷孔通有预设流量为0.13slpm的GeCl4与预设流量为4.4slpm的H ₂气体，第二环形喷孔通有预设流量为3slpm的Ar气体，第三环形喷孔通有预设流量为18slpm的O ₂气体，第四环形喷孔通有预设流量为4slpm的Ar气体，第五环形喷孔通有预设流量为19slpm的H ₂气体，第六环形喷孔通有预设流量为4slpm的Ar气体，第七环形喷孔通有预设流量为20slpm的O ₂气体。

第二芯灯3要求角度为42°±0.5°，第二芯灯3中心喷孔不通有任何气体，第一环形喷孔通有预设流量为2.1slpm的H ₂气体，第二环形喷孔通有预设流量为3slpm的Ar气体，第三环形喷孔通有预设流量为8slpm的O ₂气体，第四环形喷孔通有预设流量为4slpm的Ar气体，第五环形喷孔通有预设流量为9slpm的H ₂气体，第六环形喷孔通有预设流量为4slpm的Ar气体，第七环形喷孔通有预设流量为10slpm的O ₂气体。 The function of the second core lamp 3 is to increase the density between the core layer and the core package of the loose body, and prevent the mismatch between the density of the core layer and the cladding layer from causing the white unburned condition of the core layer or the core package after sintering.

The gas and flow rate of the package lamp 4 from the inside to the outside of each nozzle hole are set as follows: the center nozzle hole has SiCl4 gas with a preset flow rate of 6.5 slpm and O gas with a preset flow rate of 2 slpm.₂Gas, the first annular nozzle hole has a preset flow rate of 11slpm H₂Gas with CF at preset flow rate of 0.48slpm₄Gas, Ar gas with a preset flow rate of 4 slpm is passed through the second annular nozzle hole, and O gas with a preset flow rate of 35 slpm is passed through the third annular nozzle hole₂Gas, Ar gas with a preset flow rate of 6 slpm is passed through the fourth annular nozzle hole, and H gas with a preset flow rate of 104 slpm is passed through the fifth annular nozzle hole₂Gas, Ar gas with a preset flow rate of 6 slpm is passed through the sixth annular nozzle hole, and O gas with a preset flow rate of 45 slpm is passed through the seventh annular nozzle hole.₂gas.

The lifting speed of the loose body is 1.1mm/min.

The transparent mandrel of this embodiment is obtained after dehydration and sintering of the mandrel loose body obtained by the above method.

Results and Tests

The optical test is carried out to the transparent mandrel that embodiment makes, and the measured parameter is shown in the following table:

Core diameter/mm Cladding diameter/mm Core-to-core ratio relative refractive index Cladding index 16.93 86.34 5.10 0.372 -0.00041 19 95.19 5.00 0.369 -0.00042

Combining the parameters obtained in the above table with the schematic diagram of the deposition state of the core layer in Figure 2, it is not difficult to see that the diameter of the core layer of the transparent mandrel prepared in Example 2 is higher than that of Example 1. At the same time, there is no obvious difference in the core-clad ratio, relative refractive index and cladding refractive index compared with Example 1. This shows that Example 2 increases the diameter of the core layer under the premise of ensuring stable optical parameters. In Example 2, by adjusting the relative positions of the first core lamp and the second core lamp and the gas flow ratio of each blowtorch, under the condition that the cross-sectional structure of the core rod remains unchanged, the uniformity of the density distribution of the deposited loose body and the transparency of the sintered core rod are ensured, and the size of the core layer of the prepared core rod is increased with a relatively small increase in the size of the cladding layer. This method not only solves the limitation of the overall size of the core rod loose body by the sintering furnace core tube, but also outsources the stretched core rod through OVD or a sleeve, so that a longer optical fiber can be drawn. In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not further described in the present invention.

Claims (9)

1. An apparatus for preparing a large diameter core preform, comprising: the deposition chamber, first core lamp, second core lamp, package lamp, rotatory jib, its characterized in that, first core lamp, second core lamp and package lamp set up in the inside below of deposition chamber, rotatory jib set up in the middle part top of deposition chamber, rotatory jib carries out axial rotation and reciprocates along vertical direction, first core lamp, second core lamp and package lamp are annular eight-layer orifice structure together, and annular eight-layer orifice structure includes central orifice, first annular orifice, second annular orifice, third annular orifice, fourth annular orifice, fifth annular orifice, sixth annular orifice, seventh annular orifice from inside to outside in proper order.

2. The apparatus for preparing a large diameter core preform according to claim 1, further comprising a target rod, an air intake assembly and an air extraction assembly; the target rod is fixedly connected to the lower bottom end of the rotary suspender; the air inlet assembly and the air draft assembly are arranged in the deposition cavity; the air inlet system is adjacently arranged on the same side of the first core lamp and the second core lamp, and the air draft assembly is far away from the first core lamp and the second core lamp.

3. The apparatus for preparing a large diameter core preform according to claim 1, further comprising a control system for setting a gas flow rate of the core lamp to deposit at an end of the target rod to form a core, and controlling a gas flow rate of the clad lamp to deposit at an end of the core to form a clad.

4. The apparatus for preparing a large diameter core preform according to claim 1, wherein the first core lamp has a central nozzle hole through which SiCl with a preset flow rate of 0.15 to 0.6slpm is introduced ₄ H with gas and preset flow rate of 0.1-0.8slpm ₂ ；

The first annular spray hole is communicated with GeCl with preset flow of 0.06-0.2slpm ₄ H with preset flow rate of 3-5.5slpm ₂ ；

Ar with the preset flow rate of 2-5slpm is communicated with the second annular spray hole;

the third annular spray orifice is communicated with O with preset flow of 17-24slpm ₂ ；

Ar with the preset flow rate of 2-5slpm is communicated with the fourth annular spray hole;

the fifth annular spray hole is communicated with H with preset flow of 17-24slpm ₂ ；

Ar with the preset flow rate of 2-6slpm is communicated with the sixth annular spray hole;

the seventh annular spray hole is communicated with O with preset flow of 17-24slpm ₂ 。

5. The apparatus for manufacturing a large diameter core preform according to claim 1, wherein, in the second core lamp,

any gas is not introduced into the central spray hole;

the first annular spray hole is communicated with H with preset flow of 1.5-5slpm ₂ ；

Ar with the preset flow rate of 2-5slpm is communicated with the second annular spray hole;

the third annular spray hole is communicated with a preset flowO of 5-18slpm ₂ ；

Ar with the preset flow rate of 2-5slpm is communicated with the fourth annular spray hole;

the fifth annular spray hole is communicated with H with preset flow of 5-18slpm ₂ ；

Ar with the preset flow rate of 2-6slpm is communicated with the sixth annular spray hole;

the seventh annular spray hole is communicated with O with preset flow of 5-18slpm ₂ 。

6. The apparatus for preparing a large diameter core preform according to claim 1, wherein, in the clad lamp,

SiCl with preset flow of 3-7slpm is communicated with the central spray hole ₄ O with preset flow rate of 0.8-2.2slpm ₂ ；

The first annular spray hole is communicated with H with the preset flow of 9-12slpm ₂ CF with preset flow rate of 0.2-0.6slpm ₄ ；

Ar with the preset flow rate of 2-5slpm is communicated with the second annular spray hole;

the third annular spray orifice is communicated with O with preset flow of 28-45slpm ₂ ；

Ar with the preset flow rate of 3-8slpm is communicated with the fourth annular spray hole;

the fifth annular spray hole is communicated with H with preset flow of 90-120slpm ₂ ；

Ar with the preset flow rate of 3-8slpm is communicated with the sixth annular spray hole;

the seventh annular spray hole is communicated with O with preset flow of 30-55slpm ₂ 。

7. A method of producing a large diameter core preform using the apparatus for producing a large diameter core preform according to any one of claims 1 to 6, comprising the steps of:

the cleaned first core lamp, the cleaned second core lamp and the cleaned package lamp are arranged on a corresponding core lamp holder and a corresponding package lamp holder, cross laser is adjusted to determine mounting surfaces of the first core lamp, the second core lamp and the package lamp, the first core lamp, the second core lamp and the package lamp which are arranged on the first core lamp, the second core lamp and the package lamp are ensured to be positioned on the same plane, and the lamp holder position is ensured to be positioned in the middle position relative to the base;

igniting the core lamp and the cladding lamp, spraying the target rod according to a flow set value, starting to deposit silicon dioxide and germanium dioxide generated by hydrolysis on the target rod, gradually increasing the diameter of a core layer at the lower end of the target rod along with the continuous progress of the deposition, and lifting the target rod along with a rotary suspender at a constant speed until the deposition is finished when the diameter of the core layer is larger than a preset value, so as to prepare a core rod loosening body;

and III, dehydrating and sintering the prepared loose core rod body to obtain the transparent core rod.

8. The method of manufacturing a large diameter core preform according to claim 7, wherein the angle of the first core lamp is 51 ° ± 1 °, the laser distance is required to be 20mm ± 2mm, and the axis distance is required to be 60mm ± 5mm; the angle of the bulb lamp is 38 degrees+/-1 degrees, the laser distance is required to be 120 mm+/-5 mm, and the axis distance is required to be 160 mm+/-10 mm.

9. The method of manufacturing a large diameter core preform according to claim 7, wherein the angle of the second core lamp is 42 ° ± 0.5 °, the laser pitch requirement is 60mm ± 5mm, and the axis pitch requirement is 90mm ± 5mm.