JP3010082B2 - Image fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image fiber and, more particularly, to an image fiber having an extremely small diameter suitable for observation of the inside of a blood vessel.

[0002]

2. Description of the Related Art Recently, an ultrafine image fiber has been desired for use in the medical field, in particular, for local observation and treatment of small diameters such as blood vessels, ureters, and pancreatic ducts. For this reason, for example, an outer diameter of 1 m
For practical use of an ultra-small diameter image fiber of m or less, the pixel diameter must be extremely small, for example, 4 μm or less.

Generally, in order to reduce the pixel diameter, the core diameter of the fiber constituting the image fiber must be reduced. To reduce the core diameter, the relative refractive index difference of the core clad of the fiber is increased. There is a need. Therefore, in order to obtain an ultra-fine diameter image fiber, it is necessary to increase the relative refractive index difference of the fiber constituting the image fiber as much as possible.

[0004] By the way, as a very small diameter image fiber of the past, from the core is SiO ₂ -GeO _2-based glass,
One using a fiber whose cladding is made of fluorine-doped silica glass is known. The core preform serving as the core of the fiber is made by the VAD method, and the cladding preform serving as the cladding is made by the plasma CVD method. With such a fiber preform, the relative refractive index difference of the fiber can be made up to 4% at maximum, but if it is made larger than this, at the present time, in consideration of the next step of drawing work, image drawing work, etc. Impossible.

That is, if the doping amount of germanium oxide is increased in the core base material, the refractive index is increased, while if the doping amount of fluorine is increased in the cladding base material, the refractive index is reduced, and the relative refractive index difference is increased. can do. However, it is known that germanium oxide and fluorine decrease the viscosity of silica glass when it is melted when the doping amount to silica glass is increased, and fluorine in particular has a large reduction ratio. For this reason, the viscosity of the core preform and the viscosity of the clad preform greatly differ during melt spinning, and spinning is not performed normally.

Accordingly, in a fiber having a relative refractive index difference of 4%, the core diameter is 1.5 μm at the minimum, and in an image fiber using this fiber, the minimum pixel diameter is 0.3 μm.
μm is the limit.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the core diameter of a fiber constituting an image fiber to 1 μm or less so that an image fiber having an extremely small diameter can be obtained.

[0008]

Means for Solving the Problems] Such problem is the core of the fiber constituting the image fiber configured from a single piece germanium oxide (GeO _2), silicon oxide cladding -
Boron oxide - with fluorine _{(SiO 2 -B 2 O 3 -F} ), oxide
Boron doping amount of 10 to 20% by weight, fluorine doping
Of 2 to 7% by weight and a viscosity at 1200 ° C. of 5
Glass or oxide oxide of × 10 ^{4 to} 5 × 10 ⁵ poise
Lee containing - phosphorus - fluorine _{(SiO 2 -P 2 O 5 -F} ) based
And the doping amount of phosphorus oxide is 5 to 10% by weight, and the doping amount of fluorine is
5 to 10% by weight and a viscosity at 1200 ° C.
Constructed from glass with a degree of 5 × 10 ^{4 to} 5 × 10 ⁵ poise
The relative refractive index difference between the core and the clad must be 7% or more.
And can be solved.

Hereinafter, the present invention will be described in detail. In the image fiber of the present invention, the cores of many fibers constituting the image fiber are made of germanium oxide alone. The cladding of the fiber has a relative refractive index difference of 7% or more from the core and a viscosity at 1200 ° C. of 5 × 10 ^4.
Made from glass that is ~ 5 x 10 ⁵ poise.

When the core of the fiber is composed of germanium oxide alone, the refractive index of the core can be extremely increased to 1.62, which is advantageous in increasing the relative refractive index difference. On the other hand, the glass forming the clad has a refractive index difference of 7% or more with respect to the core of germanium oxide alone, and has a melt viscosity at 1200 ° C. of 5 × 10 5.
^The reason why the glass having ^{4 to} 5 × 10 ⁵ poise is selected is that the core diameter cannot be sufficiently reduced unless the relative refractive index difference is 7% or more, and the meaning of using germanium oxide alone having a high refractive index for the core is used. Is also lost. Further, if the viscosity at 1200 ° C. is in the range of 5 × 10 ^{4 to} 5 × 10 ⁵ poise, the viscosity of germanium oxide alone as a core at the same temperature is almost in the range, and the melt spinning of the fiber is excellent. Done.

As a specific example of the cladding glass satisfying such conditions, silicon oxide-boron oxide-fluorine (S
iO ₂ -B ₂ O ₃ -F) based is glass. The doping amount of boron oxide is 10 to 20% by weight, and the doping amount of fluorine is 2 to 20%.
In the range of 7% by weight.
This glass has a refractive index of 1.42, a relative refractive index difference of about 10% in combination with a core made of germanium oxide alone, and a viscosity at 1200 ° C. of about 2 × 10 ⁵ poise, which is an oxide forming the core. It has about the same viscosity as germanium.

In addition, as the cladding glass satisfying the above conditions, silicon oxide-phosphorus oxide-fluorine (SiO _2-
P ₂ O ₅ -F) glass, and the doping amount of phosphorus oxide is 5
10 to 10% by weight, and the doping amount of fluorine is 5 to 10% by weight. This glass has a refractive index of 1.44, and the relative refractive index difference can be similarly set to 11%. The viscosity at 1200 ° C. is about 10 ⁵ poise.

In such a fiber, the relative refractive index difference is 1
0% or more, and the core diameter can be as fine as 0.5 μm. For this reason, the image fiber obtained from this fiber can have a pixel diameter of 2 μm or less, and can have an extremely small diameter.

Next, a method of manufacturing the image fiber will be described. First, a core base material is prepared. This includes V
The AD method is used. Germanium chloride (Ge
Using Cl ₄ ), glass microparticles made of only GeO ₂ are deposited and made vitrified by a conventional method to produce a rod-shaped core base material made of germanium oxide alone. On the other hand, the clad base material is externally mounted (OV
According to the method D), silicon oxide-boron oxide-fluorine or
Is a soot having a composition of silicon oxide-phosphorus oxide-fluorine , and after vitrification, a support rod is extracted, a pipe-shaped glass body is formed, and the inner surface thereof is polished to form a pipe-shaped clad base material. I do.

Next, using the pipe-shaped cladding base material and the rod-shaped core base material, a spinning temperature of about 10 is obtained by a rod-in-tube method (Rod in Tube method).
The fiber is prepared by melt spinning at 00 ° C. Next, this fiber is aligned and packed in a pipe having the same composition as that of the cladding base material to form an image fiber preform rod, and image spinning is performed using this image preform rod to obtain a target image fiber. can get.

As another manufacturing method, a soot of a cladding glass having the above-described composition is deposited on the periphery of a rod-shaped core base material made of germanium oxide alone obtained by the VAD method by an external method. Then, there is a method of simultaneously performing the vitrification of the soot and the melt spinning.

(Example) A rod-shaped core base material having a diameter of 10 mm made of germanium oxide alone was prepared by the VAD method. On the other hand, a pipe-shaped cladding base material having an outer diameter of 40 mm and an inner diameter of 11 mm having a composition of 80% by weight of silicon oxide, 17% by weight of boron oxide and 3% by weight of fluorine was prepared by an external method. Using the core base material and the clad base material, a spinning temperature of 125 is obtained by a rod-in-tube method.
The fiber was spun at 0 ° C. to obtain a core-clad fiber having a diameter of 0.2 mm. The relative refractive index difference of this fiber was 10%.

Next, 10,000 fibers of this fiber were aligned and filled in a pipe made of glass having the same composition as the cladding base material and having an inner diameter of 21 mm and an outer diameter of 23 mm.
Image spinning was performed at ℃ to obtain an image fiber having an effective diameter of 0.3 mm. The fiber core diameter of this image fiber was 0.5 μm, and the minimum pixel diameter was 2 μm.

[0019]

As described above, in the image fiber of the present invention, the core of the fiber constituting the image fiber is made of germanium oxide alone, and the relative refractive index difference from this core is 7%. % Or more and a viscosity at 1200 ° C. of 5 × 10 ^{4 to} 5 × 10 ⁵ poise.
Boron (10-20% by weight) -Fluorine (2-7% by weight)
Glass or silicon oxide-phosphorus oxide (5 to 10 weight
%)- A fiber having a cladding made of fluorine (5 to 10% by weight) glass ,
The core diameter of the fiber can be very small, 1 μm or less, and the resulting image fiber can also be very small. Therefore, compared with the conventional image fiber, can be significantly reduced pixel size, it is possible to obtain a clear images even in very narrow locally. Also take
Excellent production of ultra-fine diameter image fiber
You.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-252342 (JP, A) JP-A-56-121002 (JP, A) JP-A-63-313103 (JP, A) 57602 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 6/04-6/08

Claims (2)

(57) [Claims] 1. A image fiber comprising bundling the plurality of core-clad fiber, the core of said fiber is made of germanium oxide alone cladding of said fiber
Is silicon oxide-boron oxide-fluorine and boron oxide
The doping amount is 10 to 20% by weight, and the fluorine doping amount is 2 to
7% by weight and a viscosity at 1200 ° C. of 5 × 10 ⁴
Made of glass of ~ 5 × 10 ⁵ poise,
An image fiber having a relative refractive index difference of at least 7% from an optical fiber. 2. A image fiber comprising bundling the plurality of core-clad fiber, the core of said fiber is made of germanium oxide alone cladding of said fiber
The silicon oxide-phosphorus oxide-fluorine system is phosphorus oxide
5 to 10% by weight, fluorine doping amount 5 to 10
% And a viscosity at 1200 ° C. of 5 × 10 ^{4 to} 5
× 10 ⁵ poise made of glass, core and clad
An image fiber having a relative refractive index difference of 7% or more .