JPS6146415B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a method for manufacturing an optical fiber bundle for image transmission, and in particular to an optical fiber bundle for image transmission that has a large pixel space factor and can manufacture a long optical fiber bundle for image transmission. Relating to a manufacturing method.

An optical fiber bundle for image transmission is a bundle of optical fibers (for example, 10,000 to 20,000 fibers) that are bundled, welded, or fused together, and each optical fiber has a core that transmits light and a cladding that surrounds it. Become. The core part of each optical fiber is also called a pixel, and the more pixels there are, the more
The image becomes clearer, and the larger the proportion of pixels in the unit cross-sectional area of the optical fiber bundle (that is, the pixel space factor), the clearer the image becomes. Furthermore, the presence of voids and foreign matter between the optical fibers constituting the bundle at both ends of the bundle also makes the image unclear. Furthermore, what is important for image transmission is that the arrangement of the optical fibers constituting the optical fiber bundle, and therefore the arrangement of the pixels, must be exactly the same at both ends of the optical fiber bundle.

Incidentally, multi-component glass, which is inexpensive, has a low processing temperature, and is easy to process, is generally used as a material for optical fiber bundles for image transmission, but optical fiber bundles made of multi-component glass usually have a ~
Although only a length of about 3 m is practical, if an optical fiber bundle made of quartz-based optical fibers with low transmission loss is realized, long image transmission will become possible.

Conventionally, there are various methods for producing optical fiber bundles, but there is a method suitable for obtaining long optical fiber bundles, and a method for producing optical fiber bundles that is considered to be applicable to the production of quartz-based optical fibers. The following method is considered to be the only one.

That is, this is a method in which a plurality of optical fibers are housed in a glass pipe, and a composite body of the optical fibers and the glass pipe is sequentially melt-drawn from one end.
Usually, in order to obtain an optical fiber bundle with a large number of pixels,
A plurality of the melt-drawn composites are placed in a glass pipe again, and the process of melt-drawing them as a new composite of the composite and the glass pipe is repeated.

However, in this method, there is a part of the glass pipe that does not contribute to image transmission at all, which is not only wasteful, but also requires repeating melt-drawing of the composite in order to increase the number of pixels. There is a problem that the pipe portion occupies a larger proportion of the cross-sectional area of the optical fiber bundle, and as a result, the space factor of the pixel decreases.

The present invention improves the above-mentioned drawbacks of conventionally known manufacturing methods, and provides a method for manufacturing an optical fiber bundle that has a large pixel space factor and can produce a long optical fiber bundle.

The gist of this invention is to provide an optical fiber for image transmission, characterized in that a plurality of optical fibers are bundled, each optical fiber is fixed at one end of the bundle, and the bundle of optical fibers is heated and drawn from the fixed end side. This is a method for manufacturing bundles.

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1a and 1b are illustrative views showing an example of the manufacturing method of the optical fiber bundle for image transmission of the present invention, FIG. 2 is an illustrative view showing the manufacturing process of the optical fiber base material of the present invention, and FIG.
The figure is an illustrative view showing a cross section of an optical fiber bundle for image transmission according to the present invention.

In FIGS. 1a and 1b, 10 has a plurality of optical fibers 20, for example, as shown in FIG. It is a bundle of 12 pieces arranged concentrically. As shown in FIG. 1a, a glass rod 11 is welded or glued to one end of the bundle 10 to secure all optical fibers 20 together at that end of the bundle 10. The optical fibers 20 at the other end of the bundle 10 are matched with the arrangement of the optical fibers 20 at the end, and the outer periphery of the bundle 10 is clamped by a clamping member such as a glass pipe 12.
Next, as shown in FIG.
While heating at step 3, the tip of the glass rod 11 is sandwiched between take-up rolls 14, and the take-up rolls 14 are rotated at a constant speed to perform heating and wire drawing.
Optical fiber bundle 10a consisting of 19 optical fibers 20
get. The diameter of the optical fiber bundle 10a after being drawn is determined by the take-up speed of the take-up roll 14. By heating and drawing from the end of the bundle 10 fixed by the glass rod 11, all the optical fibers 20 constituting the bundle 10 are sequentially melted and welded together from the end, and the optical fiber bundle 10a after drawing is The arrangement of each optical fiber 20 on both end faces is exactly the same. Further, the optical fibers 20 are not bonded in advance over their entire length, but are welded and integrated sequentially from one end, and only the outer periphery of the other end of the bundle 10 is held between the glass pipes 12. Electric furnace 13
When the bundle 10 is heated and welded sequentially from one end side,
Air bubbles and foreign matter between the optical fibers 20 are welded and gradually escape upward through the upper opening of the pipe 12, thereby preventing air bubbles and foreign matter from remaining in the optical fiber bundle 10a. This becomes an optical fiber bundle 10a. Note that by ultrasonically cleaning the optical fibers prior to welding and integrating them, it is possible to further reduce the amount of air bubbles and foreign matter remaining. In the optical fiber bundle 10a obtained in this way, the arrangement of the optical fibers 20 on both end faces is exactly the same, and there are no air bubbles or foreign substances remaining between the optical fibers 20, and the pixel occupancy is This results in an excellent optical fiber bundle with a high resolution. Furthermore,
As described above, the optical fiber bundle 10a having a substantially hexagonal cross-sectional shape, which has been welded and integrated by melt drawing according to the manufacturing method of the present invention, is used as a new optical fiber to form one optical fiber bundle 10a as shown in FIG. 3b. 6 centered around
The fibers are assembled in a radial circle in increasing numbers by multiples of , for example, 37 fibers, and are welded and integrated by melt drawing according to the method of the present invention to form a substantially hexagonal optical fiber bundle 10b. The optical fiber bundle 10b consists of 37×19 optical fiber strands, and each strand is completely welded to each other to form an integrated state. The thus obtained optical fiber bundle 10b is further assembled into 19 fibers, bundled, melted and drawn in the same manner as described above, and welded and integrated to form an optical fiber for image transmission as shown in FIG. 3c. A bundle 10c is produced. This optical fiber bundle for image transmission consists of 19×37×19=13,357 cores, resulting in a pixel count of 13,357.

Figure 3 illustrates the case of manufacturing an optical fiber bundle for image transmission with a pixel count of 13,357. An optical fiber bundle for image transmission having the following properties is obtained.

Note that, according to the conventional manufacturing method in which a plurality of optical fibers are housed in a glass pipe at once and then drawn, the fibers are drawn several times as in the present invention in order to increase the number of pixels. If the drawing is reversed, the portion of the glass pipe that does not contribute to image transmission will increase, and the space factor of the light transmission section (core section) will become relatively low, making it impossible to perform good image transmission.

As described above, according to the present invention, the optical fibers are sequentially welded and integrated from the ends of the bundle of optical fibers even by multiple melt-drawing operations.
By appropriately selecting the drawing length, a long image transmission optical fiber can be obtained without disrupting the arrangement and leaving no bubbles or foreign matter behind. Moreover, each pixel, one pixel, is
It is possible to obtain a product in which the optical fibers of the book are accurately aligned, and the optical fiber bundle has a small diameter and a large amount of information per unit cross-sectional area of the optical fiber bundle. An optical fiber bundle for image transmission which can perform good image transmission with a large ratio is obtained.

Incidentally, the optical fiber 20 consists of a core portion for transmitting light and a cladding portion surrounding the core portion, and a method for manufacturing the base material of this optical fiber 20 will be explained with reference to FIG.
In FIG. 2, reference numeral 21 denotes a quartz glass rod serving as a core, and the rod 21 is concentrically inserted and supported in a quartz glass tube 22, which is a cladding having a lower refractive index than the rod 21. Then, both ends of the tube 22 are fixed with a fixing member such as a glass lathe, and the tube 22 is heated and reduced in diameter with an oxyhydrogen burner or the like that moves from one side of the tube 22 to the other side, so that it is brought into close contact with the rod 21. A base material 23 of the optical fiber 20 is obtained. The base material thus produced usually has a diameter of 10 to 30 mm, and the optical fiber 20 is produced by appropriately drawing the base material to a diameter of 1 to 6 mm. The rod inch tube method described above is preferable for manufacturing the optical fiber 20 with a large core diameter. Furthermore, if optical fibers made of quartz glass or pure quartz are used in the method of manufacturing optical fiber bundles for image transmission of the present invention, they will have high light transmittance, low loss, excellent flexibility in long lengths, and mechanical properties. It is possible to produce an optical fiber bundle for image transmission with excellent resolution and optical strength, chemical stability, and radiation resistance.

Note that the present invention is not limited to the use of optical fibers 20 made of quartz-based glass materials, but can be applied extremely simply and inexpensively even with optical fibers made of conventionally used multi-component glass materials. It is possible to manufacture an optical fiber bundle for image transmission in which both end faces are arranged in correspondence with each other.

[Brief explanation of the drawing]

FIG. 1 is an illustrative diagram showing an example of a method for manufacturing an optical fiber bundle for image transmission according to the present invention, FIG. FIG. 2 is an illustrative view showing a cross section of an optical fiber bundle for image transmission.

Claims (1)

[Claims] 1. An image transmission device characterized by bundling a plurality of optical fibers, fixing each optical fiber at one end of the bundle, and heating and drawing the bundle of optical fibers from the fixed end side. A method for manufacturing an optical fiber bundle. 2. The method of manufacturing an optical fiber bundle for image transmission according to claim 1, wherein the optical fibers are made of quartz glass. 3. The method of manufacturing an optical fiber bundle for image transmission according to claim 1 or 2, characterized in that the optical fibers are subjected to ultrasonic cleaning prior to the heating drawing.