JPS60155539A - Burner for producing optical oxide powder - Google Patents

Abstract

PURPOSE:To produce a soot rod having uniform soot density, in high reproducibility, by using the titled burner composed of a mutually integrated plural unit burners, and reacting the vapor-phase raw material with the flame using said burner. CONSTITUTION:The burner 1 for the production of the powder of oxide for optical use is composed of a plurality of unit burners 2,2..., each having a multi- tube structure and integrated with each other. The burners 2,2... are divided by the outermost walls 3,3... from each other, and share the walls 3a,3a... with the adjacent burner. Polygonal paths of the raw material 4, the oxygen 5 and the hydrogen 6 are formed in the outer wall 3 of each burner 2 from the center outward. The combustion gas blasted from each burner 2 is instantaneously diffused and mixed with the adjacent combustion gas, and is homogenized before it reaches the soot deposition surface. Accordingly, the abrupt change in the surface temperature of the soot rod can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a burner for producing optical oxide powder by reaction of a gas phase raw material with a flame.

When manufacturing porous optical fiber matrix (also called soot rod), rod lens matrix, etc. by the known VAD method, OVD method, etc., an appropriate flame reaction burner such as a multi-tube concentric burner or a multi-core nozzle burner is used. For example, as shown in Figure 1, when making a soot rod (base material) S with the refractive index distribution required by the VAD method, a plurality of independent flame reaction burners B with different dopant concentrations are used. There is.

Furthermore, as shown in FIG. 2, when synthesizing the core and cladding, a flame reaction burner B for the core and two flame reaction burners C for the cladding are used.

In such a case, since the optical system oxide powder is produced using a plurality of flame reaction burners, a large core having the desired refractive index distribution or a large soot rod can be obtained by synthesizing the core and the crund.

However, in the above conventional example using a plurality of flame reaction burners, each burner is separated from each other through a space, so a discontinuous part of the soot surface temperature occurs at the boundary of each flame reaction burner, and the soot density of the part changes greatly, so
During sintering, there were problems such as generation of bubbles and uneven dopant concentration distribution.

Generally, in a method for manufacturing a porous base material (soot rod) by a soot deposition method such as an OVD method or a VAD method, soot deposition efficiency, dopant yield, etc. largely depend on the temperature of the deposition surface.

Since a rapid temperature increase on the soot surface locally changes the soot density and dopant concentration, it is preferable that there is no such phenomenon in both the diameter and the rain direction.

If multiple burners are used, the frames may interfere with each other,
If the burners are spaced close together, the temperature at the boundary will be higher than other areas, and if they are spaced apart, the temperature will be lower.

Therefore, in order to have a uniform temperature distribution and a smooth temperature gradient, it is difficult to adjust the oxyhydrogen flow rate, the burner interval, etc., and the reproducibility is poor.

The present invention has been made in view of the above-mentioned conventional circumstances, and is capable of preventing the occurrence of temperature discontinuities between a plurality of flame reaction burners, and reproducibly producing soot rods with uniform soot density. The purpose is to make it possible to produce large base materials.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

In FIG. 3 showing the first embodiment of the present invention, a burner 1 for producing an optical system oxide powder includes a plurality of unit burner parts 2, 2, etc., each having a multi-tube structure, connected adjacent to each other. The unit burner parts 2.2... are separated from each other by the outermost walls 3.3... and the outermost walls 3a, 3 between these adjacent parts.
We share a...

The outermost wall 3.3 of each unit burner section 2.2...
... Inside, from the center outward, a raw material flow 4, an oxygen injection flow 6, and a hydrogen injection flow 6 are each shaped like a polygon.

In this embodiment, each adjacent unit burner section 2.2
... is the outermost wall part 3 a s 3 between these adjacent parts
Since the unit burner portions 2, 2, .

Therefore, the combustion gas immediately after being injected from each unit burner section 2.2... diffuses and mixes with the adjacent combustion gas, and becomes uniform by the time it reaches the soot deposition surface, so that the soot rod surface temperature There is no need to adjust the burner spacing by arranging a plurality of independent burners.

FIG. 4 shows a second embodiment of the present invention, and in the burner 1 of this embodiment, each unit burner section 2.2... is the outermost wall section 3a.
, 3a..., but in the embodiment shown in Fig. 4, the outermost wall of each unit burner 2.2... has a polygonal shape. 3, a small cylindrical raw material flow 4 is provided in the center, and a plurality of small cylindrical oxygen injection flows 6.6 are provided around it, and these flows 4.6.5... (The remaining space is the hydrogen injection flow 6.

Also in the second embodiment, the unit burner parts 2 are adjacent to each other.
．． 2... By mutually sharing the outermost wall portion 3a13a..., the above-mentioned effects can be obtained.

In addition, the outermost wall 3 in FIGS. 3 and 4 may be a triangle or a polygon such as a pentagon to an octagon other than the illustrated quadrangle, and of course each circulation 4, 5, and 6 may also be a triangle to an octagon. The number of connected unit burner sections 2 is not limited to the illustrated example, and can be increased or decreased as appropriate.

Next, specific examples and comparative examples of the present invention will be explained.Specific Example (1) Using the burner 1 for producing optical system oxide powder shown in FIG. 3, each unit burner section 2.2...・S' i Ct40.05 mat/m for raw material flow 4, Ot3 L for oxygen injection flow 5/H24 L for hydrogen injection flow 6
/m respectively, synthesize the soot by the OVD method,
When the surface temperature of the soot was measured, as shown in the temperature distribution diagram of FIG. 5, no rapid temperature change was observed in the adjacent portions of each unit burner section 2.2.2.

Specific example (2) Using the optical system oxide powder production burner 1 shown in FIG. 4,
When synthesizing the soot for Gl-type optical fume/() by the VAD method, S i C1a0.05 mot/m is added to the unit burner section 2 for the high refractive index section (left end in FIG. 4) in its raw material distribution 4.
GeCl2O, 01 mot/m.

023t/m for oxygen injection flow 5, L for hydrogen injection flow 6
41/m is supplied, and 5iCtaO50 is supplied to the unit burner section 2 for the medium refractive index section (center of Fig. 4) through its raw material distribution 4.
7mal-/”s G e Ct40.005.m,
, ot/- Oxygen injection flow 6 to Ox 2.6 L/m
r, H to hydrogen injection distribution 6! 3.5 t/ decoy is supplied, and S i Ct40.07 yyioA is supplied to the raw material distribution 4 to the unit burner section 2 for the low refractive index section (right end in Fig. 4).
/ m, O12 to oxygen injection flow 6,, 2t /+++t
After synthesizing soot by supplying Hx31/hydrogen to i1 hydrogen injection flow 6 and making it transparent vitrified by a conventional method, the refractive index distribution was examined using an interference microscope, and a good pull file with no disturbance was obtained. Ta.

Comparative Example (1) Using two concentric quadruple tube burners, the first layer of each burner B1 and Bt contains S i Cl<0.05 mot/''%
Hz 3 t/m1 in the second layer A r O, 6A in the third layer
/a, a gas of Os 6 t/m is flowed into the fourth layer,
The soot was synthesized by the external method with two burners spaced apart by 20wn.

When the soot surface temperature was measured during synthesis, a low temperature area was observed in the soot between the burners, as shown in FIG.

This tendency did not change even if the space was brought closer together.

Comparative Example (2) In Comparative Example (1) above, the interval between the two burners Bs and B2 is set to 511II+1, and one is slightly tilted so that the tip of the frame slightly interferes with the surface temperature. As a result of the measurement, as shown in FIG. 7, the interfered part became high temperature.

As a result, as is clear from FIGS. 5 and 6, the low-temperature and high-temperature portions of the soot between the burners, which occurred in the comparative example using multiple burners in which each burner was separated by a space, The soot surface has a uniform temperature distribution, which is not observed in the specific example of the present invention.

As explained above, the present invention provides a burner for producing optical system oxide powder through the reaction of a gas phase raw material and a flame. It is characterized in that the burner parts are connected adjacently to each other, and each of the unit burner parts shares the outermost wall between these adjacent parts.

Therefore, when making various soot rods (for optical fibers, rond lenses, etc.) with a desired refractive index distribution by the VAD method, OVD method, etc., the temperature of the soot deposition surface corresponding to the boundary of each unit burner part is made uniform, and The doping speed will also increase, making it possible to produce larger and better quality soot rods.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams showing an example of the use of a conventional burner, FIG. 3 is a cross-sectional view showing a first embodiment of the burner according to the present invention, and FIG. 4 is a cross-sectional view showing an example of the burner according to the present invention. A cross-sectional view showing the second embodiment of the burner, FIG. 5 is a temperature distribution diagram on the soot rod surface in a specific example of the present invention, and FIG. 6 and FIG. 7 are comparative temperature distribution diagrams on the soot rod surface. It is. 1... Burner for producing optical system oxide powder 2...
・Unit burner section 3...Outermost wall 3a...Common outermost wall part 4.5.6-...Yoshio Saito, Patent Attorney, Patent Attorney, Patent Applicant, Figure 1, Figure 2r1 ! J β Fig. 3 Fig. 4 Fig. 5 Fig. 2r1! J Figure 7 IBjl

Claims (1)

[Claims] In a burner for producing optical system oxide powder by reaction between a gas phase raw material and a flame, each of the plurality of unit burner parts has a plurality of passages within the outermost wall, and most of these unit bars are adjacent to each other. A burner for producing an optical system oxide powder, in which each unit burner part shares an outermost wall part between adjacent parts.