JPS63147134A - Medical image scope - Google Patents

Abstract

PURPOSE:To increase the resolution of a transmitted image and the quantity of light incident on a core and to obtain a sharp image by allowing respective optical fibers in the multiple photoconductor of an image transmission line to meet specific requirements. CONSTITUTION:Many optical fibers 7 each consist of a core 71, a 1st clad layer 72 provided right above it, and a 2nd clad layer 73, and are welded mutually by welding mutually adjacent 2nd clad layers. Here, the thickness T1 of the 1st clad layer 72 and the thickness T2 of the 2nd clad layer 73 are 0.01-5mum. The respective optical fibers 7 are preferably at least 20% in the occupation rate of the core 71 in the optical fiber section, and various kinds of quartz-based glass such as pure glass are used. The 1st clad layer 72 is at least 0.005 lower in refractive index than the outermost part of the core 71 and 0.002 lower than the 2nd clad layer 73 on it. Consequently, the transmitted image is sharp and the multiple photoconductor can be reduced in diameter for the number of the optical fibers in the photoconductor.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a medical image scope suitable for observing blood vessels, the stomach, the uterus, the bladder, or other internal parts of the human body or animals, particularly the stomach.

Conventional Technology With recent advances in medical technology, medical imaging scopes with excellent flexibility and mechanical strength and as small a diameter as possible are required for the purpose of directly observing the insides of human bodies and animals in detail. ing.

Conventionally, medical image scopes have been used that have multiple fibers formed by bundling a large number of multi-component glass optical fibers as image transmission paths. Although this multiple fiber has the advantage of excellent flexibility, in order to manufacture multiple fibers with even smaller diameters using this method, it is necessary to bundle optical fibers with minute outer diameters in an orderly manner, which is extremely difficult. Therefore, there is a natural limit to reducing the diameter of multiple fibers.

On the other hand, multi-light guides obtained by drawing a required number of bundles of small-diameter silica glass-based optical fibers have a dense cross-sectional structure because adjacent optical fibers are fused together. It has the advantage of being easy to manufacture and use small diameter multi-light guides.

By the way, the multi-light guide obtained by the above method is
The individual optical fibers that make up the optical fibers have a structure in which adjacent fibers are fused to each other, so it is perfect from the standpoint of dense arrangement, but conversely, the individual optical fibers are fused to each other, so they are adjacent to each other. There is a phenomenon of light leakage between optical fibers, which tends to make transmitted images unclear. In order to reduce light leakage between adjacent optical fibers, the cladding layer is formed using doped silica glass with a low refractive index, in which a larger amount of dopants that lower the refractive index of silica glass, such as fluorine and boron, are added than before. There have been proposals to reduce light leakage, but such doped silica glass also has an excessive coefficient of thermal expansion, which causes cracks to form if a temperature change occurs while it is in contact with the core glass.

In view of the above circumstances, there is a demand for a medical image scope that does not have the above-mentioned problems and has a quartz glass multi-light guide as an image transmission body, which is as small as possible and capable of transmitting clear images.

5. The present invention for adjusting the refractive index is aimed at meeting the above-mentioned requirements, and has a refractive index of at least 0. It has a first cladding layer having a refractive index as low as .005 and an average thickness of 0.01 to 5 μm, and further has a first cladding layer having a refractive index at least 0.002 higher than the first cladding layer and an average thickness of 0.01 to 5 μm.
Image transmission is performed using a multi-light guide having a structure in which a large number of silica glass optical fibers having a second landing layer of 01 to 5 μm and having a space factor of at least 20% in the optical fiber cross-sectional area of the core are fused together. It is an object of the present invention to provide a medical image scope characterized by being equipped with a light beam.

■ The resolution of the transmitted image and the amount of light introduced into the core are sufficient so that each optical fiber in the multi-light guide, which functions as an image transmission path, satisfies the following requirements (1) to (3). A clear image will be obtained. Furthermore, since it is not necessary to use a glass material added to an excessive amount of dopant as the constituent glass of the first cladding layer and the second cladding layer, there is no problem of cracking caused by the above-mentioned temperature change.

il+ immediately above the core, having a refractive index at least 0.005 lower than that of the outermost part of the core and having an average thickness of 0.0
(2) a first land layer having a thickness of 1 to 5 μm;
On the cladding layer, at least 0 more than the first cladding layer.
．． (3) The core has a space factor of at least 20% in the cross-sectional area of the optical fiber.

Implementation ■ The present invention will be explained below with reference to the drawings. FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view of a multi-light guide used in FIG. 1, and FIG. 3 is a partially enlarged sectional view of FIG. 2.

In FIG. 1, l is a multi-light guide serving as an image transmitting body, 2 is an objective lens attached to the tip of the multi-light guide 1, 3 is an eyepiece detachably attached to the rear end of the multi-light guide, 31 4 is a cutting lens installed in the eyepiece 3, and 4 is a light guide for illumination. A fixed length of the tip of the light guide 4 is made of a protective tube 5 made of a flexible organic polymer, such as polyvinyl chloride, nylon, polyethylene, polypropylene, etc., which is attached to the multi-light guide 1 and protects the entire length of the multi-light guide. The remaining rear part is branched and is housed in a flexible polymer protective tube 6. Inside the protection tube 5, in addition to the light guide 4, a water pipe, an air pipe, forceps, a balloon, a tip swinging device, a laser fiber, an electric coagulator, or other devices are installed as necessary.

In FIGS. 2 and 3, 1 is a multi-light guide, and 7 is an optical fiber constituting the multi-light guide l. A large number of optical fibers 7 each consist of a core 71 and a first cladding layer 72 and a second cladding layer 73 provided directly above the core, and are fused together by fusion of adjacent second cladding layers. There is. 8 is a skin layer provided on the outermost side of the multi-light guide l, and 9 is a protective layer.

In FIG. 3, Dt is the diameter of the optical fiber 7, and De is the diameter of the optical fiber 7.
1, T represents the average thickness of the first cladding layer 72, and T2 represents the average thickness of the second cladding layer 73, respectively. In the present invention, the thickness T1 of the first cladding layer 72 is 0.0
The thickness T2 of the second cladding layer 73 is 0.01 to 5 μm, preferably 0.02 to 3 μm.

The diameter Dr of the optical fiber 7 and the diameter De of the core 71 are automatically determined once the values of T and T described above and the space factor of the core 71 described below are determined, but the diameter Dt of the optical fiber 7
The preferred value of is 3.0 to 6.0 μm, especially 3.5 to 5 μm.
．． It is 5 μm.

In the present invention, each optical fiber 7 has a core 71 space factor of at least 20% in a cross section of the optical fiber.
If the core space factor is preferably less than 20%, the amount of light transmitted through the core 71 is insufficient, making it difficult to transmit a bright image. Note that if the core space factor is excessive, the cladding layer becomes too thin unless flexibility is sacrificed, causing a bleeding phenomenon in the transmitted image, making it difficult to obtain a clear image.

Therefore, the core space factor is 70% or less, especially 25 to 60%.
% is particularly preferable.

In the present invention, the core 71, the first cladding layer 72, and the second cladding layer 73 are all made of various silica-based glasses, such as pure silica glass or pure silica glass whose refractive index is adjusted with a dopant. . Since multi-component glass contains a large amount of impurities, it is difficult to draw a bundle of its optical fibers into a thin wire.However, the above-mentioned silica glass has a small content of impurities in -a, so it is difficult to draw its optical fiber into a thin bundle. Since it is easy to draw a bundle into a thin wire, it becomes possible to manufacture a multi-light guide with a small diameter.

The core 71 may be made of pure silica glass in a step index shape, or may be made in a graded index shape using a dopant that increases the refractive index of pure silica glass, such as germalam or phosphorus. As the pure silica glass mentioned above, a synthetic product having a purity of 99.99% by weight or more, particularly a purity of 99.9999% by weight or more is preferable.

In the present invention, the first cladding layer 72 not only has a refractive index lower than that of the outermost portion of the core 71 by at least 0.005, preferably at least 0.008, but also lower than that of the second cladding layer 73 thereon. at least 0.002,
Preferably it has a refractive index as low as at least 0.004. By providing such a refractive index difference between the layers, leakage of light transmitted to the core 71 is reduced, resulting in a clear transmitted image. When the core 71 is made of pure quartz glass or pure quartz glass doped with germalum or phosphorus, the first cladding layer 72 is made of pure quartz glass doped with fluorine and/or boron, and Second
Preferably, each of the cladding layers 73 is made of pure silica glass.

In the present invention, the first cladding layer and the first cladding layer each have two layers having different refractive indexes, as long as the above-mentioned requirements for the refractive index difference and average thickness are satisfied.
It may consist of multiple layers or more.

The multi-light guide 1 is made of a large number of optical fiber base materials each having a circular cross section and having the same structure and cross-sectional space factor ratio as the optical fiber 7, for example, 500~soo, ooo wood made of natural quartz glass or synthetic quartz glass, Preferably a skin pipe made of synthetic quartz glass (forming material of the skin layer 8 in FIG. 3)
It can be manufactured by filling the skin pipe in an aligned state, drawing the skin pipe together, and immediately after drawing, applying a thermoplastic organic polymer or a thermosetting polymer to form the protective N layer 9.

The medical image scope of the present invention provides clear transmitted images and can be made smaller in diameter compared to the number of optical fibers included in the multiple optical fibers. By adjusting the number of fibers as appropriate, it is useful as an angioscope, blueprint, hysteroscope, cystoscope, arthroscope, etc.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view of a multi-light guide used in FIG. 1, and FIG. 3 is a partially enlarged sectional view of FIG. 2. , l is a multi-light guide as an image transmitting body, 2 is an objective lens, 3 is an eyepiece, 4 is a light guide for illumination, and 5 and 6 are protective tubes 5 made of flexible organic polymer layers. 2 and 3, 1 is a multi-light guide, 7 is an optical fiber constituting the multi-light guide 1, 71 is a core of the multi-light guide, 72 is a first cladding layer, 73 is a second clad layer, and 8 is an optical fiber that constitutes the multi-light guide 1. 9 is a skin layer, 9 is a protective layer, DC is a core diameter, D is an optical fiber diameter, T1 is a first cladding layer thickness, and T2 is a second cladding layer thickness.

Claims (1)

[Scope of Claims] 1. Immediately above the step-index type or graded-index type core, the refractive index is at least 0.005 lower than the refractive index of the outermost part of the core, and the average thickness is 0.01 to 0.01.
The core optical fiber has a first cladding layer having a thickness of 5 μm, and further has a second cladding layer having a refractive index higher than the first cladding layer by at least 0.002 and an average thickness of 0.01 to 5 μm. Space factor in cross-sectional area is at least 20%
1. A medical image scope comprising a multi-light guide having a structure in which a large number of quartz glass optical fibers are fused together as an image transmission path. 2. The medical image scope according to claim 1, wherein the multi-light guide includes at least 500 optical fibers. 3. The medical image scope according to claim 1, wherein the core is a step index type made of pure silica glass or a graded index type made of pure quartz glass doped with Ge. 4. The medical image scope according to claim 1, wherein the first cladding layer is made of quartz glass doped with a dopant containing fluorine and/or boron, or at least one thereof as a main component. 6. The medical image scope according to claim 1, wherein the second cladding layer is made of pure silica glass.