JPS62187805A - Manufacture of light guide - Google Patents

Abstract

PURPOSE:To easily and efficiently remove a clad with efficiency by forming the clad of fluorine-containing resin and removing the clad on an incidence end side by heat decomposition. CONSTITUTION:The clad 4 is formed of fluororesin and its end part is removed by heat decomposition. The fluororesin uses vinylidene fluoride, a copolymer of fluororesin and fluororubber, etc. Each of them contains fluorine which lowers a refractive index, so the refractive index is lower than that of quartz, which is only coated to form a complete waveguide structure (optical fiber). The clad can be removed without contacting a light guide element wire mechanically, so the element wire is neither flawed nor broken in clad removing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light guide, and more particularly to a gourmet light guide for use when the incident end is exposed to high temperatures such as sunlight.

(Prior Art) Light guide wires include plastic clad optical fibers (PCFs), multicomponent optical fibers, quartz optical fibers, and plastic fibers.

A light guide is made by bundling a large number of these fibers together, attaching a cap to the end, and polishing the end face.

Recently, from the viewpoint of energy saving, sunlight is focused through a Fresnel lens l as shown in Figure 1, and it is transferred to a light guide 2.
The method of introducing and using it indoors is attracting attention.

In this case, the energy density at the input end of the light guide becomes very large, reaching a temperature of several hundred degrees Celsius, so quartz-based optical fiber or plastic laminated optical fiber (PCF) with a quartz core is used as the light guide wire. When considering both of these optical fibers from the viewpoint of fiber NA and fiber price, PCF is suitable as a light guide fiber.

(Problem to be solved by the invention) However, the heat resistance of silicone resin, which is generally used as a cladding material for PCF, is only about 200°C, so if PCF is used as it is as a light guide fiber, The silicone resin burns, producing silicon dioxide flakes that cover the core end face and prevent light from passing through.

Therefore, when using PCF as a light guide fiber, the silicone resin at the end is peeled to expose the core (quartz), which is inserted into the base 3 as shown in FIG.

Methods for removing silicone resin include mechanical removal using a stripper and chemical removal using a remover containing an alkaline amine as a main component. However, in the former method, the core may be damaged or the fiber end may be damaged, and silicone resin may remain on the surface of the core.

In the latter method, since the heat treatment is performed at a temperature of 100° C. or higher, there is a problem that the core deteriorates due to alkali and is harmful to the human body.

In addition, regardless of the former method or the latter method, processing the 100 fiber terminals required for the handle is usually difficult and the yield is low.

(Means for Solving the Problems) In order to solve these problems, the present invention is a method for manufacturing a light guide in which the cladding 4 is formed of fluorine resin and the ends thereof are removed by thermal decomposition.

As the fluororesin, vinylidene fluoride resin (for example, Kynar, a trademark of Pennwalt Co., USA), a copolymer of fluororesin and fluororubber (for example, Eight Seal, a product of Asahi Glass Co., Ltd.), etc. are used. All of these materials contain fluorine, which lowers the refractive index, so they have a lower refractive index than quartz, and simply coating the quartz (core) 6 creates a complete waveguide structure (optical fiber).

The thermal analysis results of Kynar (trade name) and Eight Seal (trade name) are shown in FIG. From this, it can be seen that thermal decomposition begins at 300°C for Kynar and around 350°C for Eight Seal, and both completely decompose at 500°C. In fact, when optical fibers clad with these resins were heated to 500° C. in an air atmosphere, a clean surface with no residue on the core surface was obtained. [For confirmation, even when laser light (He-Ne) was incident from the terminal, no scattering from the core due to residual decomposition residue was observed.

The core 6 of the light guide fiber in the present invention is preferably made of quartz, and the light guide wire according to the present invention, which is made by thermally decomposing the fluorine-containing resin at the input end, has an air cladding on the input end side and an air cladding on the output end side. Comes with fluorine-containing resin craft on the side.

(Examples) Example 1 The Kynar described above was dissolved in dimethylacetamide heated to 80°C to form a paint (resin concentration 20%). This was coated with quartz rond on a fiber drawn to an outer diameter of 150 mm using a normal method, and baked to produce a light guide wire 5. This fiber was cut into 500 mm sections every 20 m.
This was prepared, and the input terminals were put together over a length of 10 meters into an electric furnace at 500° C. for 5 minutes to completely thermally decompose the craft of the input terminals. This terminal was densely packed into the base 3 and polished to create a light guide with an air-clad entrance end.

Example 2 A quartz rod was drawn to have an outer diameter of 200 tna by a normal method, and then immediately coated with Eight Seal F-20 described above and baked to produce a light guide wire 5, which was cut into a length of 10 m. 500 pieces were prepared, and the incident side was inserted over a length of 5C11 into an electric furnace at 500° C. for 5 minutes to completely thermally decompose the cladding on the incident side. This was processed in the same manner as in Example 1 to produce a light guide with a length of 10m.

Example 3 The light guide wires 5 prepared in Example 1.2 were each cut to a length of lOm, 500 of each wire 5 was prepared, and the cladding on the incident side was sheathed without removing it by thermal decomposition. The cap was covered with a thin film, and the cap was filled with fine particles, which was then polished and used as a light guide.

When this light guide was attached to the concentrator shown in Figure 1 and sunlight was incident on it, the cladding on the incident side instantly thermally decomposed. In this case, the reduction in light transmission effect was about 5%, which did not have a significant effect in practical terms.

(Effects of the Invention) As described above, in the present invention, the cladding is formed from a fluorine-containing resin, and the cladding on the incident end side is removed by thermal decomposition, making the cladding removal work easier and faster than in the conventional method. It can be done efficiently.

Conventionally, one person needed 200 terminals to process 500 bare fibers.
I was able to do what I knew in about 10 minutes.

In addition, in the present invention, since the cladding can be removed without incidentally touching the light guide wire, the cladding removal work will not damage or break the cladding wire (therefore, the yield rate due to breakage will be reduced). It also improves.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of application of a solar light guide, FIG. 2 is an explanatory diagram showing an example of a light guide according to the present invention,
FIG. 3 is a cross-sectional view of the light guide wire. 2 is a light guide, 3 is a base 4 is a clamp, 5 is a light guide wire 6 is a core

Claims (3)

[Claims] (1) In a method for manufacturing a light guide in which the ends of a large number of light guide wires are densely packed into a base, the cladding of the light guide wires is formed of a fluorine-containing resin, and the incident end of the light guide wires is A method for producing a light guide, the method comprising: heating the side to thermally decompose and remove the fluorine-containing resin, and forming an incident end without cladding at the end. (2) The method for manufacturing a light guide according to claim 1, wherein the cladding at the end of the light guide wire is removed by thermal decomposition before the incident end of the light guide wire is densely packed into the base. (3) The method for manufacturing a light guide according to claim 1, wherein the incident end side of the light guide wire is densely packed into the base, and then the cladding at the same end is removed by thermal decomposition.