JPS593416B2 - Method for manufacturing metal coated optical fiber - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a metal coated optical fiber.

Metal coating has already been proposed as the primary coating for optical fibers from the viewpoints of heat resistance, waterproofness, mechanical strength, etc. However, when metal coating is performed using a casting method, the resulting metal coating is hard to solidify after being cooled. Since the fabrication structure is 15 weaves, it is microscopically porous, and therefore, unless the film thickness is increased, sufficient metal coating cannot be obtained.

On the other hand, the vacuum plating method is quite effective as a metal coating method for optical fibers, but when attempting to perform the optical fiber spinning '0 process and the vacuum plating process continuously,
The spinning process, which is carried out under normal pressure, and the vacuum plating process, which is carried out in a vacuum atmosphere, were not compatible, and in the vacuum plating process, there were problems with the seals at the points where the optical fibers entered and exited. 5 It is becoming impossible to obtain a constant degree of vacuum.

Furthermore, even if this problem is removed, the vacuum plating method cannot be effective for optical fibers, which are long bodies with a circular cross section, unless uniform metal coating is achieved from the circumferential direction. Another issue that remains is the lack of ingenuity. The present invention aims to address the above-mentioned problems and improves the manufacturing method of this type of metal-coated optical fiber so that each process from spinning to metal coating can be carried out satisfactorily. This will be explained using an illustrated example.

In the figure, 1 is the upper stage vacuum chamber, 2 is the lower stage vacuum chamber, and the outlet 3 is at the bottom of vacuum chamber 1.
and the inlet 4 at the top of the vacuum chamber 2 is connected to the sealing flange 5.
are interconnected through.

A spinning furnace 6 is arranged in one vacuum chamber 1 in the above, and a coil 7 for high frequency discharge, a metal shielding tube 8, and a through hole 10 in the center are arranged in the other vacuum chamber 2 made of a bell gear or the like. The crucibles 9 are arranged at predetermined relative positions.

That is, within the vacuum chamber 2, the coil 7 is supported vertically via the support 11, and the shielding tube 8 is also vertically supported within the coil r via the support 12. A crucible 9 is disposed below the shielding tube 8 via a support 13, and a sealing die 14 is provided at the exit portion of the bottom 1tc of the vacuum chamber 2. The crucible 9VC further contains molten metal 15 therein.
．． is connected to the power supply 16 for resistance heating, while the coil 7
A high frequency power source 17 is connected to.

In the figure, 18 is the bleed system of the vacuum chamber 2, 19 is the leak valve of the same chamber 2, 20A is the base material for optical fiber such as quartz, and 20
B is an optical fiber and 20C is a metal coated optical fiber.

In the method of the present invention, which is carried out using the apparatus shown in FIGS. 1 and 2, a spinning process is carried out to produce an optical fiber 20B in a vacuum chamber 1, and further, in the vacuum chamber 2, a metal is attached to the optical fiber 20B. The coating is applied to make the metal-coated optical fiber 20C. First, in the vacuum chamber 1, the optical fiber base material 20A is inserted into the spinning furnace 6, and its molten end (
Optical fiber 2 with a desired fiber diameter is formed by stretching the lower end).
0B, and then the optical fiber 20B is introduced into the vacuum chamber 2 via the outlet 3 of the vacuum chamber 1, the seal flange 5, and the inlet 4 of the vacuum chamber 2.

The molten metal 15 in the crucible 9 is resistively heated and evaporated in the vacuum chamber 2, which is vacuum-suctioned through the extraction system 18, and the evaporated metal is excited by the high-frequency discharge from the coil 7. While the optical fiber 20A introduced into the vacuum chamber 2 passes through the axes of the coil 7, shielding tube 8, and crucible 9, an evaporated metal coating is formed on the outer periphery of the optical fiber. It is. At this time, the shielding tube 8 prevents the evaporated metal from adhering to the outer periphery of the optical fiber 20B.
Only the evaporated metal excited by the coil 7 adheres to the outer periphery of the coil 7 as a uniform, high-quality coating.

By the way, during the above metal coating, the evaporated metal will also adhere to the shielding tube 8, but if this shielding tube 8 is made of the same material as the molten metal 15, the shielding tube 8 can also be used as evaporated metal. become.

Of course, during metal coating at this time, since the space between both vacuum chambers 1 and 2 is sealed by the seal flange 5, the evaporated metal in one vacuum chamber 2 will not intrude into the other vacuum chamber 1. .

The optical fiber 18B after the metal coating was formed by such high-frequency ion plating becomes a predetermined metal-coated optical fiber 18C, and the metal-coated optical fiber 18C passes through the sealing die 14 of the vacuum chamber 2 and exits the same chamber 2. rear,
It is wound up by a winding machine (not shown).

Next, examples will be described.

Example 1 In the vacuum chamber 1, the mudness of the spinning furnace 6 was set to about 1800° C., and the quartz-based optical fiber base material 20A was spun into optical fibers 20BIIC with a diameter of 125 μm.

In the vacuum chamber 2, the high frequency power source 17 is set to 400W, and the shielding tube 8
is an aluminum tube with an inner diameter of 0.2 to 0.51n7n1 and a thickness of 0.5mm or less, the crucible 9 has a through hole 10 in the center with a diameter of 171tm, and aluminum is used as the molten metal 15, Then, the spun optical fiber 20B is introduced into the vacuum chamber 2, and the metal-coated optical fiber 20B is
It was set to 0C.

In the above embodiment, a metal coating with a uniform thickness adheres to the outer periphery of the optical fiber 20B due to the high-frequency discharge from the coil 17, and since metal adhesion immediately after evaporation is prevented by the effect of the shielding tube 8, the metal coating is The quality has also improved.

Although the evaporated metal adhered to the shielding tube 8, since the tube 8 and the molten metal 14 were made of the same material, the shielding tube 8 could also be used as evaporated metal, improving the yield of metal materials. did.

Of course, since the spinning process and the metal coating process are tandem, manufacturing efficiency is greatly improved, and each vacuum chamber 1, 2
The sealing effect was also sufficient.

Example 2 In this example, a plurality of optical fiber base materials 20A were prepared under substantially the same conditions as those in the previous example.
, 20A, . . . are held in a parallel state and simultaneously spun.
A metal coating was formed on the outer periphery of...

For this reason, the spinning furnace 6, coil 7, etc. were of large diameter, and the number of through holes 10 of the crucible 9 and shielding tubes 8 were increased in accordance with the number of optical fibers. In this embodiment, metal-coated optical fibers 20C, 20C... having the same effect as in the previous embodiment are used.
・Manufacturing efficiency was greatly improved because a large number of bottles could be obtained at the same time.

As explained above, in the method of the present invention, the spinning process of the optical fiber and the vacuum plating process of the optical fiber are performed in tandem, and these two processes are performed in each vacuum chamber that is relatively connected to each other while being independent of each other. Because I am trying to implement it,
Metal-coated optical fibers with uniform thickness by vacuum plating can be manufactured with high efficiency in synchronization with optical fiber spinning.

[Brief explanation of the drawing]

The drawing is a cross-sectional explanatory view schematically showing one embodiment of the method of the present invention together with its apparatus. 1, 2... Vacuum chamber, 5... Sealing flange, 6... Spinning furnace, 7... Coil,
8... Shielding pipe, 9... Crucible, 10.
...Through hole, 15... Molten metal, 16...
...Power supply, 17...High frequency power supply, 20A.
... Optical fiber base material, 20B... Optical fiber 20C... Metal-coated optical fiber.

Claims (1)

[Scope of Claims] 1. An optical fiber spinning process is arranged in the first stage and a vacuum plating process of the optical fiber is arranged in the second stage to form a tandem process, and the above two processes are performed in respective vacuum chambers that are relatively connected in a mutually independent state. A method of manufacturing a metal-coated optical fiber, characterized in that the method is carried out. 2. The method for manufacturing a metal-coated optical fiber according to claim 1, wherein the vacuum plating step is performed by a high-frequency ion plating method. 3. The method for manufacturing a metal-coated optical fiber according to claim 1, wherein both vacuum chambers are connected to each other by a sealing means that allows the optical fiber to pass therethrough, and the optical fiber passes through the sealing means. 4 In the vacuum chamber for carrying out the vacuum plating process, a coil for high frequency discharge and a crucible for molten metal are arranged along the traveling direction of the optical fiber, and the optical fiber passes through these coils and the crucible. A method for manufacturing a metal-coated optical fiber according to claim 1 or 2, wherein the metal-coated optical fiber is passed through. 5. The method of manufacturing a metal-coated optical fiber according to claim 4, wherein a shielding tube is disposed in the optical fiber passage part within the coil, and the optical fiber passes through the inside of the shielding tube. 6. The method for manufacturing a metal-coated optical fiber according to claim 5, wherein the shielding tube is made of a material similar to that of the molten metal, and the optical fiber passes through the shielding tube in which the metal has been evaporated.