JPS6364928A - Production of glass material having refractive index distribution - Google Patents

Abstract

PURPOSE:To obtain a glass material having a large refractive index distribution in the axial direction inexpensively and by a relatively easy method, by immersing a gelatinous glass material containing a Zr component in an eluting solution of sulfuric acid, hydrochloric acid or nitric acid at <= the boiling temperature, drying and sintering. CONSTITUTION:A raw material is hydrolyzed to give a Zr-containing gelatinous glass material having a given shape, which is partially immersed in sulfuric acid, hydrochloric acid or nitric acid and partially eluted. Then the gel is washed with water or another cleaning solution, gradually dried, sintered by an electric furnace at high temperature and made into glass. By the production of the glass material, since (1) room temperature is used as eluting temperature and desired refractive index distribution can be obtained in a relatively short time, operation efficiency can be extremely improved. (2) Since large difference in refractive index is obtained by addition of a small amount of Zr, high numerical aperture can be obtained. (3) Since a high-silica glass aqueous is obtained, weather resistance can be improved. (4) Since a large amount of samples can be treated and produced in a single, operation the production has high mass productive effects and reduction in cost can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a glass body having a refractive index distribution.

[Prior Art] Glass bodies used as optical components such as optical fiber base materials and rod lenses are provided with a refractive index distribution in the thickness direction. , CVD method, and other methods are known.

The ion exchange method is, for example, “Applied Physics (A
pplied Physics); Volume 19 No. 7 1
113 (1980) J, a borosilicate glass rod containing ion-exchangeable Te+ and Na+ was heated to 50 to 10% in KNO3 molten salt at 530 to 550°C.
It is made by processing for 0 hours, then cutting and polishing.

Further, the CVD method utilizes thermal decomposition and chemical reactions in a gas phase, and is a method for creating a glass body using a high-silica material.

[Problems to be Solved by the Invention] As described above, ion exchange methods, CVD methods, and the like are used to provide a refractive index distribution in a glass body. Among these methods, the ion exchange method requires a process in which the glass rod is held in molten salt for a long period of time, but this creates an extremely poor working environment and the materials used contain alkali, making weather resistance difficult. There are problems such as lack of reliability.

Furthermore, in the case of the CVD method, high reliability is achieved because a high-silica material is used, but since the metal element that can be added is Ge, a large amount of addition is required to obtain a large refractive index distribution, and therefore the thermal expansion coefficient There is a risk that cracks will occur during sintering due to the difference in Therefore, there is no problem when a small refractive index is sufficient, but it is inappropriate when a large refractive index is required.

In addition, because the manufacturing speed is slow, mass production is difficult, and product prices tend to increase.

An object of the present invention is to provide a method for manufacturing a glass body having a refractive index distribution that can be manufactured by a relatively easy method and at low cost.

[Means for Solving the Problems] The present invention provides a gelatinous material having a predetermined shape to which at least a zirconium component is added as a metal other than silicon, by adding at least one of sulfuric acid, hydrochloric acid, and nitric acid at a temperature below the boiling point. The method is characterized in that a part of the zirconium component is eluted by immersion at least once in an eluent consisting of The aim was to achieve this goal by making it possible to manufacture it.

[Function] In the method for manufacturing a glass body having a refractive index distribution of the present invention,
A part of a gel containing zirconium produced by hydrolyzing raw materials and having a predetermined shape is immersed in sulfuric acid, hydrochloric acid, or nitric acid to dissolve the part, and then the gel is washed with water and other cleaning solutions. After that, it is gradually dried, and then sintered and vitrified at high temperatures in an electric furnace to form a glass rod, making it possible to manufacture a glass rod with a large refractive index distribution in the axial direction using a relatively easy method. be able to.

[Example code] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory diagram of the manufacturing process of an embodiment of the method for manufacturing a glass body having a refractive index distribution according to the present invention, (a), (
The steps are performed in the order of b) and (c).

In the figure, 1 is a glass container, 2 is a wet gel created in the glass container 1, 3 is an eluent that elutes a Zr (zirconium) component, and 4 is an electric furnace that heats the wet gel 2.

In the manufacturing method of this example, 20% Zr(QCH)
6 moles of alcohol and 2 moles of a 1/1000 N--NH40H aqueous solution are added to 41 moles of Si (OCH3) containing 41 moles of Si (OCH3) for hydrolysis, and the mixture is gelatinized in a glass container 1 to create a wet gel 2.

When wet gel 2 is created, a part of it is 0 of 20CC.
．． It was immersed in a 5N-HCjl aqueous solution at room temperature for about 3 hours, then in water for washing at room temperature for about 3 hours, and then in a 1:1 mixture of methanol and water for about 1 hour at room temperature, and finally in methanol. Cleaning is completed after soaking in the water for about 1 hour.

After this, the temperature should be increased from room temperature to 120℃ so as not to exceed the boiling point of the cleaning solution.
The temperature was raised at a rate of 1°C per hour to gradually dry the product, and then it was sintered and vitrified at 1200°C using an electric furnace 4, resulting in a diameter of 2.7 mm and a length of about 10 mm. glass rods can be manufactured.

FIG. 2 shows the refractive index distribution of the manufactured glass rod, in which the glass rod was cut in a direction perpendicular to the axis and the refractive index distribution in the radial direction was measured.

The horizontal axis shows the radius r, 0 is the center of the radius, and the vertical axis shows the refractive index n
shows.

As shown by curve 5 in the figure, the refractive index n tends to be high at the center 0 of the diameter and decrease toward the periphery.

Now, if the refractive index at the center of the diameter is n, and the refractive index at the position of radius r is n (r), and a is a constant, it is clear that the characteristics shown in the figure show a distribution as shown below. .

Refractive index n. and refractive index n1, respectively, n
'= 1.55. It has been shown to have a large refractive index distribution of Nt -1.46.

Although the above-mentioned example shows the case where hydrochloric acid is used as the eluent, the same effect can be obtained by using sulfuric acid or nitric acid.

From the experimental results, once the amount of Zr added and the concentration of the eluate are determined, the diameter or thickness of the gel, the density of the gel, the amount of eluate, the elution time, the elution temperature, and the rate of elution temperature rise and fall, etc. It has become clear that the shape of the refractive index distribution can be controlled by changing each of the conditions.

Generally, the higher the concentration of sulfuric acid, hydrochloric acid, or nitric acid used in the eluate, the better;
It is desirable to keep it below the specified value.

If it is less than 0.1 normal, elution takes time and is not practical.

The elution time is determined not only by the elution concentration (but also by the density of the gel, that is, the pore diameter of the porous gel and the gel size. For example, if the pore diameter doubles, the elution time is approximately halved; On the other hand, if the gel density and size are the same, the longer the time, the larger the total elution amount will be, but the difference in refractive index between the center and peripheral areas will increase by a factor of 4. For example, in the above example, when the elution time was extended to 20 hours, there was almost no difference in refractive index. Therefore, it is not desirable to lengthen the elution time unnecessarily, and the gel size The upper limit value will be determined based on such factors.

Room temperature is sufficient for the elution temperature, but to shorten the elution time,
Temperature raising and lowering control is performed as necessary to raise the temperature to near the boiling point of the eluate or to change the shape of the refractive index distribution.

In the above embodiments, after the gel elution process, the gel was sequentially immersed in water and a mixed solution of water and methanol, and further immersed in methanol for cleaning, but this step is not always necessary. However, if the amount of elution is large or the concentration of the eluate is high, the components of the eluate or the eluate may adhere to the surface of the porous gel, causing crystallization or cracking during sintering. To prevent this, the gel is washed.Water is effective for washing the sulfuric acid component of the eluate, and methanol, ethanol, propanol, etc. are particularly effective for washing the eluted component. be. Note that if the case of immersion in water and the case of immersion in alcohol are suddenly changed, cracks tend to occur in the gel, probably because stress is generated inside the gel corresponding to the osmotic pressure of the alcohol. To alleviate this problem, it is effective to immerse it in a mixture of water and alcohol. It is also desirable to repeat the cleaning process as necessary. As with the elution time and temperature conditions, the lower limits of the washing time and washing temperature will be determined by the density and size of the gel.

In the above example, a case was explained in which a gel obtained by hydrolyzing an alkoxide was used, but in carrying out the present invention, any porous gel to which at least a Zr component is added can be used. .

Further, even if a metal other than the Z component is added at the same time, the same effect can be obtained. For example, a Ta component may be added in addition to the Zr component.

Next, as another example, a case of a glass material to which Zr component and Ta component are added will be described.

15 mol% Zr(OC4H9)4 and 5 mol% (7)
6 S t (O
8 mol of alcohol and 2 mol of 1/1000 N-NH40H aqueous solution were added to 41 mol of CHs) to hydrolyze it, and gel it in a glass container 1 with an inner diameter of 8 φ as shown in Fig. 1 to form a wet gel 2. create.

A portion of this gel was immersed in 20 cc of 0.5N-H2S04 aqueous solution for about 2 hours, followed by 20 cc of 0.1% by weight
It was immersed in a hydrofluoric acid aqueous solution at room temperature for about 4 hours, then in water for about 3 hours at room temperature, and then in a 1:1 ratio of methanol and water.
It was immersed in a mixed solution for about 1 hour at room temperature, and finally immersed in methanol for about 1 hour for cleaning. After this, at room temperature 12
Raising the temperature to 0℃ at a rate of 1℃ per hour and gradually drying.
By sintering at 1200° C. using the electric furnace 4 and vitrifying it, a glass rod having a diameter of 2.6 mmφ and a length of 1001111 mm can be obtained.

As a result of cutting this glass rod in a direction perpendicular to the axis and measuring the refractive index distribution in the radial direction, it is clear that the refractive index distribution is high at the center of the diameter and low at the periphery, similar to the first example. Became.

Note that if the hydrofluoric acid concentration is 0.01% by weight or less, the Ta component will not be effectively eluted, while if the concentration is 0.01% by weight or less, the St component will be significantly eluted and the gel will dissolve.
It is necessary to make it 1-10% by weight.

In each of the above embodiments, the case of rod-shaped glass has been described, but it is clear that by using gel in a plate-shaped glass plate, it is possible to create a plate glass having a refractive index distribution in the thickness direction of the plate.

As described above, by using the method of this embodiment, the following effects can be obtained.

(1) Since room temperature is used as the elution temperature and a desired refractive index can be obtained in a relatively short time (within several hours), work efficiency can be greatly improved compared to conventional manufacturing methods.

(2) Since a large refractive index difference can be obtained by adding a small amount of Zr, a high numerical aperture can be obtained.

(3) Since a high silica glass body is obtained, weather resistance can be improved. It also has very good heat resistance, so it can be used in high-temperature environments.

(4) Since a large number of samples can be processed and manufactured in - times, the mass production effect is large and the cost can be reduced.

[Effects of the Invention] According to the present invention, it is possible to provide a method for manufacturing a glass body having a refractive index distribution that can be manufactured by a relatively easy method and at low cost.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the manufacturing process of an embodiment of the method for manufacturing a glass body having a refractive index distribution according to the present invention, and FIG.
FIG. 3 is an explanatory diagram of the refractive index distribution of a glass rod obtained by the example shown in the figure. 1: Niglass container, 2: Nigel, 3: Eluate, 4: Electric furnace.

Claims (6)

[Claims] (1) A gel-like body of a predetermined shape to which at least a zirconium component is added as a metal other than silicon is immersed at least once in an eluate consisting of at least one of sulfuric acid, hydrochloric acid, and nitric acid at a temperature below the boiling point. A method for manufacturing a glass body having a refractive index distribution, characterized in that a part of the zirconium component is eluted, and the gel-like body is dried and sintered to form a glass body. (2) The eluate of sulfuric acid, hydrochloric acid and nitric acid is 0.1 to 1
Claim 1 consisting of a 0 normal aqueous solution
A method for manufacturing a glass body having a refractive index distribution as described in 1. (3) The gel-like body is washed at least once with a washing liquid before drying and sintering.
A method for manufacturing a glass body having a refractive index distribution according to items 1 and 2. (4) The method for manufacturing a glass body having a refractive index distribution according to claim 3, wherein the cleaning liquid uses at least one of water, methanol, ethanol, and propanol. (5) When the gel-like body is immersed in the eluate, the temperature of the eluate is raised and lowered while controlling the temperature from room temperature to near the boiling point. A method for producing a glass body having a refractive index distribution according to any one of the above items. (6) The refractive index according to any one of claims 1 to 5, wherein the drying temperature of the gel-like body is raised and lowered while controlling the temperature from room temperature to the boiling point of the cleaning liquid. A method for manufacturing a glass body having a distribution.