JPS5968709A - Production of image guide - Google Patents

Abstract

PURPOSE:To obtain an image guide which is free from intrusion of foam over a long length and permits excellent transmission of an image by melt sticking and spinning an optical fiber bundle by heating in a gaseous atmosphere of He having a small atomic radius. CONSTITUTION:An optical fiber bundle 2 is fed from the upper to lower part of a furnace core tube 3, and gaseous He is flowed from the upper to lower part of the tube 3 as shown by an arrow. The fiber bundle is melt stuck and spun by heating with a heater 5 provided along the tube 3 in an optical fiber drawing furnace 4. Helium has an atomic radius smaller than conventional gaseous N2 and Ar, and it is extremely smaller as compared to the network structure of the glass constituting optical fibers 1; therefore He has substantiall fluidity in a melt stuck part 7 and when the fibers 1 are melt stuck, the spacing 6 between the fibers 1 is thoroughly eliminated. An image guide which enables the excellent transmission of an image over a long length without forming foam is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an image guide, and more particularly to a method of manufacturing an image guide for image transmission.

A conventional method for manufacturing an image guide involves heating and fusing an optical fiber bundle made up of several thousand to tens of thousands of optical fibers in an atmosphere inertized with argon or nitrogen gas, and then spinning the fibers together. However, this is because the atomic radius of the argon or nitrogen gas that creates an inert atmosphere in the heating fusion spinning furnace is relatively large, so during heating fusion, the optical fibers become trapped between the optical fiber bundles and remain as bubbles, causing image disturbances. It has been difficult to manufacture long image guides because of the occurrence of

The present invention has been made in view of the above points, and its object is to provide a method for manufacturing an image guide that enables good image transmission over a long length.

That is, the present invention collects a plurality of optical fiber bundles,
This method is characterized in that the assembled optical fiber bundle is heated, fused and spun in a helium gas atmosphere.

The present invention will be explained below based on the illustrated embodiments. An embodiment of the invention is shown in FIGS. 1 and 2. FIG. In this example, a plurality of optical fibers 1 were assembled, and the assembled optical fiber bundle 2 was heat-fused and spun in a helium gas atmosphere. That is, the optical fiber bundle 2 is inserted into an optical fiber drawing furnace 4 having a furnace core tube 3, and helium gas is caused to flow from the top to the bottom of the furnace core tube B as shown by the solid arrow in the figure. The optical fiber bundle 2 was heat-fused and spun so that a helium gas atmosphere was always around the fiber bundle 2. In this process of heating and fusing the optical fiber bundle 2, the optical fiber bundle 2 is continuously fed into the high temperature area near the heater 5 without delay, so that the optical fiber bundle 2 is fused from the bottom to the top. do. In other words, the cross section of the gap 6 between the optical fibers 1 of the optical fiber bundle 2 gradually decreases at the fused portion to take a sharp tip shape, and disappears at the fused portion 7.

By doing so, the atmosphere around the optical fiber bundle 2 is helium gas, the atomic radius of which is smaller than that of argon or nitrogen gas, and the size of the mesh of the glass network structure constituting the optical fiber 1 is smaller than that of argon or nitrogen gas. Because it is very small
Even the welded part 7, which forms a sharp tip as described above, has sufficient fluidity, so that helium gas does not remain and become bubbles during welding, and good image transmission over a long length is achieved. You can get an image guide that makes it possible.

As described above, in the present invention, the optical fiber bundle is heated and fusion-spun in a helium gas atmosphere, so that the heating and fusion-spinning is performed in a helium gas atmosphere, eliminating the inclusion of air bubbles and increasing the length. A method for manufacturing an image guide that enables good image transmission over a length can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an optical fiber drawing furnace showing the manufacturing state of an embodiment of the image guide manufacturing method of the present invention, and FIG. 2 is a sectional view showing the fusion state of optical fibers in the same embodiment. be. 1: Optical fiber, 2: Optical fiber bundle, 6: Furnace tube, 4: Optical fiber drawing furnace, 5: Heater, 6: Gap between optical fibers, 7: Fusion part.

Claims (1)

[Claims] 1. A method for manufacturing an image guide, which comprises assembling a plurality of optical fibers and heating and fusing the assembled optical fiber bundle in a helium gas atmosphere.