SU1667642A3 - Multicore light conduit - Google Patents

Abstract

PURPOSE:To obtain brightness which is sufficient in practical use by decreasing a refractive index distribution gently in the section from the center part of a rod to the radius part and steeply in the section from the radius part to the surface part. CONSTITUTION:The radius of the core rod is 6.5mm, and the difference DELTAn between the refractive index n1 of the center part of the rod and the refractive index n2 of the surface part of the rod, i.e. n1-n2 is 0.02, where n1 is the maximum refractive index of the rod and n2 is the minimum refractive index. The refractive index distribution of the core rod decreases gently in the section from the center f0 of the rod to the radius r1, i.e. 0.65r and steeply in the section from the radius r1 of the rod to a radius (r), i.e. external surface. This core rod is easily formed by controlling the supply amount of dopant, which can use Ge, P, etc.

Description

Fig.Z

The invention relates to optical fibers, in particular to optical multicore optical fibers made of quartz glass, which can be used as image transmitters for various image indicators used in industry and other fields, especially as image transmitters for medical image indicators.

The aim of the invention is to increase the clarity and brightness of image transmission while reducing the diameter of the fiber.

FIG. 1 shows schematically a cross section of two adjacent fibers of a multicore fiber with a single-layer cladding; figure 2 - the same, a three-layer sheath; FIG. 3 shows the change in the refractive index of the fiber strand.

In Fig.1 and 2 marked vein 1, a single-layer sheath 2, the first 3, the second 4 and the third 5 layers of a three-layer sheath.

In the drawings and in the text, the following letter designations are accepted: Dc - core diameter 1; Df is the fiber diameter; T0 is the thickness of the single-layer shell 2; Ti, T2 and Tz-thickness, respectively, of the first3, second A and third 5 layers, A is the curve of the change in the refractive index of the material of the core 1 for the case of the invention; B - parabolic curve; po - index of refraction in the center of the core 1; yi, too, on its border; and is the radius of the core 1; Г2 - value, equal to 0.65 n: П2 - index of refraction at the distance Г2 from the center of the core.

The fiber contains 102 - 107 optic fibers melted together.

The core 1, which occupies at least 20% of the fiber cross section, the sheath 2 and the layers 3-5 are made of activated quartz glass and fused together. The values of the refractive indices П2, ni and Po are chosen from the ratio

about

P2 S ni + 0.65 (n0-ni),

Such a distribution of the refractive index can be implemented, for example, with the aid of germanium or phosphorus additives in the regulation of axial vapor deposition or in a similar process. The difference between the refractive indices (gm-Po) is chosen in the range of 0.015-0.040. For single-clad fibers 2, the Df and T0 values are 3-16 µm and C, 5-5 µm, respectively.

For fibers with a three-layer sheath, the first layer 3 is made of silica glass doped with fluorine and / or

boron, the second layer 4 is also made of pure silica glass doped with fluorine and / or boron, with a refractive index exceeding the refractive index of the first layer 3 by not less than 0.02; and the third layer 5 is made of quartz glass with a temperature of drawing at least 1800 ° C. In this case, Df is in the range of 3.0-8 microns, Ti - in the range of

0.02-0.7 microns; T2 - in the range of 0.1-1.5 microns and Tz - in the range of 0.02-0.6 microns.

Stranded fiber operates as follows.

When a luminous flux transferring the image is fed to its input end, each of the fibers perceives and transmits some of it in accordance with the cross-sectional area of its core 1. High brightness and clarity of image transmission with a small diameter of the fiber is ensured by the presence of a smooth and at the same time rather steep the distribution of the refractive index of core 1 at small thicknesses of both core 1 and

shell 2 (layers 3-5).

The application for the third layer 5 of quartz glass with a high temperature of drawing provides a high-quality structure of the light guide, even with high flowability of the core 1 and the inner layers 3, 4 of the cladding, which also contributes to the high-contrast image transmission.

Claims (4)

1. A multicore light guide consisting of 10-10 optical fibers fused together, having an envelope made of activated quartz glass and a core occupying at least 20% of the fiber cross section, characterized in that. in order to increase the clarity and luminance of the image while reducing the diameter the fiber, each core is made with a distribution of the refractive index satisfying the relation ni + 0.65 (n0-gi), where Po is the index of refraction in the center of the core: u - the refractive index of the outer part of the vein; ng is the refractive index at a distance from the center of the core equal to 0.65 of the core radius. 2. The light guide according to claim 1, which distinguishes between so-that the difference between the refractive index n0 in the center of the core and the refractive index of the outer part of the core is chosen in the range of 0.015-0.040. 3. The fiber according to claim 1, about tl and h and y and d so that the shell is made of three layers, the first of which is made of pure quartz glass doped with fluorine and / or boron, the second layer is made of pure silica glass doped with fluorine and / or boron, having a refractive index greater than the refractive index of the first layer less than 0.002, and the third layer is made of quartz glass with a temperature of drawing not less than 1800 ° C 4. Light guide according to Clause 3, characterized in that the diameter of the optical fiber is selected within 3.0-8.0 μm, the thickness of the first shell layer is selected within 0.02-0.7 μm, the thickness of the second shell layer is selected within 0.1-1.5 μm, and the thickness of the third shell layer is selected in the range of 0.02-0.6 μm. Fia1