Glass material manufacturing method

Abstract

To provide a method for manufacturing a glass material, capable of preventing the loss of a laser beam in a non-vessel floating method and manufacturing the glass material having desired characteristics.SOLUTION: A method for manufacturing a glass material comprises the steps of: obtaining molten glass having at least a part of glass raw material lump heated and melted by irradiating a glass raw material lump in a floating state with a laser beam; and obtaining a glass material by cooling the molten glass. The spot diameter of the laser beam is controlled according to the change of size when the glass raw material lump becomes the molten glass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a glass material by a containerless levitation method. [Background technology]

[0002] In recent years, research has been conducted on the containerless levitation method as a method for producing glass materials. For example, Patent Document 1 describes a method for vitrifying a barium-titanium-based ferroelectric sample by irradiating the sample with laser light, heating and melting it while levitating it in a gas levitation furnace, and then cooling it. In this way, the containerless levitation method can suppress the progression of crystallization due to contact with the container wall, and therefore may be able to vitrify materials that could not be vitrified using conventional manufacturing methods using containers. Therefore, the containerless levitation method is noteworthy as a method capable of producing glass materials with novel compositions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-248801 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have found that in a containerless levitation method such as that described in Patent Document 1, when glass frit lump is irradiated with laser light to heat and melt it, laser light loss may occur due to a change in size of the glass frit lump as it becomes molten glass. When laser light loss occurs, the glass frit lump may not be sufficiently melted unless the laser light output is increased. Furthermore, the lost laser light that was not irradiated onto the glass frit lump and molten glass may damage surrounding components. On the other hand, if the initial laser light spot diameter is reduced or other adjustments are made to prevent laser light loss, only a portion of the glass frit lump may be heated, which may result in a longer melting time or increased evaporation due to localized heating. In this case, a glass material with the desired properties may not be obtained.

[0005] An object of the present invention is to provide a method for manufacturing a glass material in a containerless levitation method, which can reduce the loss of laser light and enable the production of a glass material having desired properties. [Means for solving the problem]

[0006] The method for producing a glass material according to the present invention includes a step of irradiating a glass raw material lump with a laser beam in a floating state to heat and melt at least a part of the glass raw material lump to obtain molten glass, and a step of cooling the molten glass to obtain a glass material, and is characterized in that the spot diameter of the laser beam is adjusted in accordance with a change in size of the glass raw material lump when it becomes the molten glass.

[0007] In the present invention, it is preferable to adjust the spot diameter of the laser beam so that the spot diameter of the laser beam is within a range of 0.5 to 1.5 times the diameter of the glass frit lump or the molten glass when viewed from the direction of irradiation of the laser beam, from the start of heating and melting at least a part of the glass frit lump to the end of cooling the molten glass. In this case, it is more preferable to adjust the spot diameter of the laser beam so that the spot diameter of the laser beam is within a range of 0.8 to 1.0 times the diameter of the glass frit lump or the molten glass.

[0008] In the present invention, it is preferable to adjust the spot diameter of the laser beam so that the ratio of the spot diameter of the laser beam irradiated onto the molten glass to the spot diameter of the laser beam irradiated onto the glass raw material lump is within a range of 0.5 to 1.5.

[0009] In the present invention, it is preferable to adjust the spot diameter of the laser beam so that the spot diameter of the laser beam irradiated onto the molten glass is smaller than the spot diameter of the laser beam irradiated onto the glass raw material lump.

[0010] In the present invention, it is preferable to adjust the spot diameter of the laser beam so that, when viewed from the direction of irradiation of the laser beam, 80% or more of the spot area of ​​the laser beam is irradiated onto the glass raw material mass or the molten glass, and the spot diameter of the laser beam is within a range of 0.5 to 1.5 times the diameter of the molten glass.

[0011] In the present invention, it is preferable to adjust the spot diameter of the laser light while observing the glass raw material lump and the molten glass with an imaging device. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for manufacturing a glass material in a containerless levitation method, which can reduce the loss of laser light and enable the production of a glass material having desired properties. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a glass material manufacturing apparatus used in a glass material manufacturing method according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic plan view of a portion of the molding surface of the glass material manufacturing apparatus of FIG. [Figure 3] FIG. 3 is a schematic diagram illustrating the relationship between the size of each of the glass raw material chunks and the molten glass and the size of the spot diameter of the laser light in the method for producing a glass material according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram comparing the sizes of the glass raw material lump and the molten glass with the size of the spot diameter of the laser light when the laser light is irradiated with a spot diameter that can heat the entire glass raw material lump. [Figure 5] FIG. 5 is a schematic diagram comparing the size of the glass raw material lump and the molten glass with the size of the spot diameter of the laser beam when the initial spot diameter of the laser beam is reduced. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a glass material manufacturing apparatus used in a glass material manufacturing method according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[0015] (First embodiment) In this embodiment, a method for producing a glass material by a containerless levitation method will be described. The containerless levitation method can produce glass materials having compositions that do not contain network-forming oxides and that cannot be vitrified by a melting method using a container. The containerless levitation method can also suitably produce, for example, barium titanate-based glass materials, lanthanum-niobium composite oxide-based glass materials, lanthanum-tungsten composite oxide-based glass materials, lanthanum-titanium composite oxide-based glass materials, lanthanum-tantalum composite oxide-based glass materials, lanthanum-gallium composite oxide-based glass materials, lanthanum-aluminum composite oxide-based glass materials, lanthanum-boron composite oxide-based glass materials, terbium-boron composite oxide-based glass materials, europium-boron composite oxide-based glass materials, aluminum-silicon composite oxide-based glass materials, tantalum-aluminum composite oxide-based glass materials, and tantalum-aluminum composite oxide-based glass materials.

[0016] FIG. 1 is a schematic cross-sectional view showing a glass material manufacturing apparatus used in a glass material manufacturing method according to a first embodiment of the present invention.

[0017] The glass material manufacturing apparatus 1 shown in Fig. 1 has a molding die 2. The molding die 2 has a molding surface 2a and a plurality of gas ejection holes 2b opening in the molding surface 2a. The molding surface 2a is a curved surface. Specifically, the molding surface 2a is spherical.

[0018] The forming mold 2 has gas ejection holes 2b that open to the forming surface 2a. As shown in Fig. 2, the glass material manufacturing apparatus 1 is provided with a plurality of gas ejection holes 2b. Specifically, the plurality of gas ejection holes 2b are arranged radially from the center of the forming surface 2a.

[0019] Casting die 2 may be made of a porous body having continuous pores, in which case gas ejection holes 2b are made of continuous pores.

[0020] The gas ejection holes 2b are connected to a gas supply mechanism 3 such as a gas cylinder. Gas is supplied from the gas supply mechanism 3 to the forming surface 2a via the gas ejection holes 2b. This allows the object to be levitated 4, such as a glass raw material lump, to be levitated.

[0021] The type of gas is not particularly limited, and may be, for example, air or oxygen, a reducing gas such as a nitrogen-hydrogen mixed gas, or an inert gas such as nitrogen gas, argon gas, or helium gas.

[0022] Next, a method for manufacturing a glass material using the glass material manufacturing apparatus 1 will be described. In this embodiment, a glass frit lump as a floating object 4 is floated on the molding surface 2a by ejecting gas from gas ejection holes 2b that open on the molding surface 2a of the forming mold 2. That is, the glass frit lump as a floating object 4 is held in a state where it is not in contact with the molding surface 2a.

[0023] Examples of the glass raw material lump include a glass raw material powder integrated by press molding or the like, a sintered body obtained by integrating a glass raw material powder by press molding or the like and then sintering it, an aggregate of crystals having a composition equivalent to a target glass composition, etc. In the present embodiment, the shape of the glass raw material lump is not particularly limited, and may be, for example, a lens shape, a sphere shape, a cylinder shape, a polygonal column shape, a rectangular parallelepiped shape, an ellipsoid shape, or the like.

[0024] Next, in a levitated state, the glass raw material lump as the levitation object 4 is irradiated with laser light from the laser light irradiation device 5. This heats and melts the glass raw material lump to obtain molten glass (melt). Next, the molten glass is cooled in a levitated state to obtain a glass material.

[0025] The feature of this embodiment is that the spot diameter of the laser beam is adjusted in accordance with the change in size of the glass frit lump when it becomes molten glass. Specifically, the spot diameter of the laser beam is adjusted in accordance with the change in size of the glass frit lump when it becomes molten glass so that the spot diameter of the laser beam irradiated on the molten glass is smaller than the spot diameter of the laser beam irradiated on the glass frit lump.

[0026] In this embodiment, the spot diameter of the laser beam is adjusted in accordance with the change in size of the glass raw material lump as it becomes molten glass, so that the loss of the laser beam is less likely to occur and a glass material having the desired properties can be obtained. This point can be explained with reference to Figures 3 to 5. In Figures 3 to 5, the area irradiated with the laser beam is indicated by diagonal lines.

[0027] As shown in Figures 3 to 5, when glass frit lump 11 is heated and melted to form molten glass 12, the size of molten glass 12 is usually smaller than the size of the original glass frit lump 11. In this case, as shown in Figure 4, if a laser beam is irradiated with a spot diameter that can heat the entire glass frit lump 11, a large amount of laser beam is lost when molten glass 12 is formed. If a loss of laser beam occurs, it may be necessary to increase the output of the laser beam to completely melt the glass frit lump 11. Furthermore, the lost laser beam that could not be irradiated to the glass frit lump 11 and molten glass 12 may damage surrounding components.

[0028] On the other hand, as shown in Fig. 5, if the initial laser beam spot diameter is reduced in order to prevent laser beam loss, only a portion of the glass raw material lump 11 can be heated, which may result in a long time for melting or a large amount of evaporation due to localized heating, which may result in a problem that a glass material having the desired properties cannot be obtained.

[0029] In contrast, in the manufacturing method of this embodiment, as shown in FIG. 3, the spot diameter of the laser beam is adjusted (reduced) in accordance with the change in size of the glass frit lump 11 as it becomes molten glass 12. This makes it difficult for laser beam loss to occur even when the size of the molten glass 12 becomes smaller than the size of the original glass frit lump 11. Furthermore, since the spot diameter of the laser beam can be adjusted so as not to become excessively small, the glass frit lump 11 can be sufficiently melted. Therefore, according to the manufacturing method of this embodiment, the glass frit lump 11 can be sufficiently melted without increasing the output of the laser beam, and a glass material having the desired properties can be reliably obtained. Furthermore, since laser beam loss is difficult to occur, damage to peripheral components can be suppressed.

[0030] In the present invention, it is preferable to adjust the spot diameter of the laser light while observing the sizes of the glass raw material lump and the molten glass with an imaging device. In this case, the sizes of the glass raw material lump and the molten glass can be reliably recognized, and the laser light can be irradiated more efficiently. In addition, as the imaging device, for example, a camera or a thermograph can be used.

[0031] The adjustment of the spot diameter of the laser light may be performed after the irradiation of the laser light is temporarily stopped, or the spot diameter may be adjusted while the laser light is being irradiated.

[0032] In the present invention, it is preferable to adjust the spot diameter of the laser beam so that the spot diameter of the laser beam is within a range of 0.5 to 1.5 times the diameter of the glass raw material lump or the molten glass from the start of heating and melting at least a part of the glass raw material lump to the end of cooling the molten glass. In this case, it is possible to further reduce the loss of the laser beam, and it is possible to more reliably obtain a glass material having desired properties.

[0033] The spot diameter of the laser light is more preferably adjusted to within a range of 0.5 to 1.5 times the diameter of the glass raw material lump or molten glass, and even more preferably adjusted to within a range of 0.8 to 1.0 times.

[0034] The spot diameter of the laser light can be, for example, 1 mm or more and 22 mm or less. The diameter of the glass raw material lump can be, for example, 2 mm or more and 15 mm or less. The diameter of the molten glass can be, for example, 1 mm or more and 15 mm or less.

[0035] The spot diameter of the laser light refers to the spot diameter when viewed from the direction of irradiation of the laser light. When comparing with the spot diameter of the laser light, the diameters of the frit lump and the molten glass refer to the diameters when viewed from the direction of irradiation of the laser light. In this case, the planar shapes of the frit lump and the molten glass may or may not be circular. When the planar shapes of the frit lump and the molten glass are not circular, the diameters of the frit lump and the molten glass refer to the average equivalent diameters of the frit lump and the molten glass, respectively.

[0036] In the present invention, it is preferable to adjust the irradiation area of ​​the laser beam so that the irradiation area of ​​the laser beam is within a range of 0.25 to 2.5 times the area of ​​each of the glass raw material lump and the molten glass from the start of heating and melting at least a part of the glass raw material lump to the end of cooling the molten glass. In this case, it is possible to further reduce the loss of the laser beam, and more reliably obtain a glass material having desired properties.

[0037] The irradiation area of ​​the laser light is more preferably adjusted to within a range of 0.5 to 1.5 times the area of ​​the glass raw material lump and the molten glass, and even more preferably adjusted to within a range of 0.6 to 1.0 times the area of ​​each.

[0038] The irradiation area of ​​the laser light is, for example, 0.8 mm2 Above, 380mm 2 The area of ​​the glass raw material mass can be, for example, 3 mm 2 Above, 180mm 2 The area of ​​the molten glass can be, for example, 0.8 mm 2 Above, 180mm 2 It can be as follows:

[0039] The irradiation area of ​​the laser beam refers to the area when viewed from the direction of irradiation of the laser beam. When comparing with the irradiation area of ​​the laser beam, the areas of the glass raw material mass and the molten glass each refer to the area when viewed from the direction of irradiation of the laser beam.

[0040] In the present invention, it is preferable to adjust the spot diameter of the laser beam so that the ratio of the spot diameter of the laser beam irradiated on the molten glass to the spot diameter of the laser beam irradiated on the glass raw material lump is within a range of 0.5 to 1.5. It is more preferable to adjust the spot diameter of the laser beam so that the above spot diameter ratio is within a range of 0.6 to 1.2. When the above spot diameter ratio is within the above range, it is possible to further reduce the occurrence of laser beam loss, and it is possible to more reliably obtain a glass material having desired properties.

[0041] As described above, when a glass frit lump is heated and melted to form molten glass, the size of the molten glass is usually smaller than the size of the original glass frit lump. Therefore, in the present invention, as in the above embodiment, it is preferable to adjust the spot diameter of the laser light so that the spot diameter of the laser light irradiated on the molten glass is smaller than the spot diameter of the laser light irradiated on the glass frit lump. However, depending on the shape of the glass frit lump, when the glass frit lump is heated and melted to form molten glass, the size of the molten glass may be larger than the size of the original glass frit lump. In this case, it is sufficient to adjust the spot diameter of the laser light so that the spot diameter of the laser light irradiated on the molten glass is larger than the spot diameter of the laser light irradiated on the glass frit lump.

[0042] In the present invention, it is preferable to adjust the spot diameter of the laser beam so that 80% or more of the spot area of ​​the laser beam is irradiated onto an object such as a glass raw material lump or molten glass, and the spot diameter of the laser beam is within a range of 0.5 to 1.5 times the diameter of the molten glass. In this case, it is possible to further reduce the occurrence of loss of the laser beam, and more reliably obtain a glass member having the desired properties.

[0043] In the present invention, it is preferable to adjust the spot diameter of the laser beam so that 50% or more of the spot area of ​​the laser beam is irradiated onto the target such as a glass frit lump or molten glass, and it is more preferable to adjust the spot diameter of the laser beam so that 80% or more of the spot area of ​​the laser beam is irradiated onto the target such as a glass frit lump or molten glass. It is even more preferable to adjust the spot diameter of the laser beam so that 100% of the spot area of ​​the laser beam is irradiated onto the target such as a glass frit lump or molten glass.

[0044] The spot diameter of the laser light is preferably adjusted to be within a range of 0.5 to 1.5 times the diameter of the molten glass, and more preferably adjusted to be within a range of 0.7 to 1.0 times the diameter of the molten glass.

[0045] (Second embodiment) Fig. 6 is a schematic cross-sectional view showing a glass material manufacturing apparatus used in a glass material manufacturing method according to a second embodiment of the present invention. As shown in Fig. 6, the glass material manufacturing apparatus 21 has a first laser light source 21a and a second laser light source 21b. The first and second laser light sources 21a and 21b irradiate laser beams 21A and 21B, respectively, onto a floating object 24, such as a glass raw material lump or molten glass, from obliquely above.

[0046] In the second embodiment, the spot diameter of the laser beam is adjusted in accordance with the change in size of the glass frit lump when it becomes molten glass. Specifically, the spot diameters of the laser beams 21A and 21B irradiated onto the molten glass are adjusted so that the spot diameters of the laser beams 21A and 21B irradiated onto the glass frit lump are smaller than the spot diameters of the laser beams 21A and 21B irradiated onto the glass frit lump. Therefore, in the second embodiment, it is possible to reduce the loss of the laser beam and obtain a glass material having desired properties.

[0047] In addition, when a plurality of laser beams 21A and 21B are irradiated as in the second embodiment, the spot diameter of the laser beam is adjusted for each of the plurality of laser beams 21A and 21B in accordance with the change in size when the glass raw material lump becomes molten glass.

[0048] For example, it is preferable to adjust the spot diameter of the laser beam 21A so that the spot diameter of the laser beam 21A is within a range of 0.5 to 1.5 times the diameter of the glass frit lump or the molten glass from the start of heating and melting at least a part of the glass frit lump to the end of cooling the molten glass. It is also preferable to adjust the spot diameter of the laser beam 21B so that the spot diameter of the laser beam 21B is within a range of 0.5 to 1.5 times the diameter of the glass frit lump or the molten glass.

[0049] In this case, the spot diameter of the laser beam 21A refers to the spot diameter when viewed from the direction of irradiation of the laser beam 21A. When comparing with the spot diameter of the laser beam 21A, the diameters of the glass raw material lump and the molten glass refer to the diameters when viewed from the direction of irradiation of the laser beam 21A.

[0050] The spot diameter of the laser beam 21B refers to the spot diameter when viewed from the direction of irradiation of the laser beam 21B. When comparing with the spot diameter of the laser beam 21B, the diameters of the glass raw material lump and the molten glass refer to the diameters when viewed from the direction of irradiation of the laser beam 21B.

[0051] Other points are the same as those in the first embodiment.

[0052] In the method for producing a glass material of the present invention, as explained in the first and second embodiments, a glass material having desired properties can be produced.

[0053] The glass material obtained by the manufacturing method of the present invention is preferably an optical glass material, although not particularly limited thereto. The refractive index of the glass material is preferably 1.800 or more, more preferably 1.900 or more, even more preferably 2.000 or more, and preferably 2.400 or less, more preferably 2.350 or less. The refractive index is indicated by a measurement value for the d-line (587.6 nm) of a helium lamp.

[0054] The present invention will be described in more detail below based on specific examples, but the present invention is not limited to the following examples and can be implemented with appropriate modifications within the scope that does not change the gist of the present invention.

[0055] Example 1 First, raw material powders were mixed so that the glass composition was 30La2O3-70Nb2O5-10B2O3 in molar ratio.

[0056] Next, 0.35 g of the prepared raw material powder was press-molded and sintered at 800° C. to 1000° C. for 1 hour to 6 hours to obtain a cylindrical glass raw material lump.

[0057] Using the glass frit lump obtained above, a roughly spherical glass material was produced by a containerless levitation method using an apparatus similar to that shown in FIG. 1. Specifically, while the glass frit lump was levitated above the forming surface, a carbon dioxide laser with an output of 200 W was irradiated to heat and melt the glass frit lump. Next, the laser irradiation was stopped, and the glass frit lump was cooled to obtain a glass material. In Example 1, the spot diameter of the laser light was adjusted in accordance with the change in size of the glass frit lump as it became molten glass, while observing with an imaging device during the period from the start of heating and melting at least a part of the glass frit lump to the end of cooling of the molten glass (3 minutes). Specifically, the diameter of the glass frit lump was 8 mm (area 50.2 mm 2 ) and the laser spot diameter is 7 mm (irradiation area 38.5 mm 2 ) and the diameter of the molten glass is 5 mm (area 19.6 mm 2 ) and the laser spot diameter is 4 mm (irradiation area 12.6 mm 2 ) In this case, the spot diameter of the laser light was 0.9 times the diameter of the glass frit lump. The spot diameter of the laser light was 0.8 times the diameter of the molten glass. The ratio of the spot diameter of the laser light irradiated on the molten glass to the spot diameter of the laser light irradiated on the glass frit lump was 0.6. In addition, 100% of the spot area of ​​the laser light was irradiated on the glass frit lump and the molten glass.

[0058] (Comparative Example 1) In Comparative Example 1, the diameter of the glass raw material lump was 8 mm (area 50.2 mm) during laser irradiation. 2 ) and the laser spot diameter is 7 mm (irradiation area 38.5 mm 2 ), and thereafter, the spot diameter of the laser beam was not adjusted. Except for this, a glass material was obtained in the same manner as in Example 1. In this case, 100% of the spot area of ​​the laser beam was irradiated onto the glass raw material mass, and 51% of the spot area of ​​the laser beam was irradiated onto the molten glass.

[0059] (Comparative Example 2) In Comparative Example 2, the diameter of the glass raw material lump was 8 mm, and the spot diameter of the laser light was 4 mm (irradiation area 12.6 mm). 2 ), and thereafter, the spot diameter of the laser light was not adjusted. Except for this, a glass material was obtained in the same manner as in Example 1. At this time, 100% of the spot area of ​​the laser light was irradiated onto the glass raw material lump and the molten glass.

[0060] (result) In Example 1, the glass raw material lump could be heated and melted while maintaining the output at 80 W. On the other hand, in Comparative Example 1, the glass raw material lump could not be completely heated and melted unless the output was increased to 120 W.

[0061] The refractive index (nd) of the glass materials obtained in Example 1 and Comparative Example 2 was also measured. The refractive index was measured using a Shimadzu KPR-2000 after bonding the glass material to a 5 mm thick soda plate substrate and polishing it at a right angle. The refractive index was evaluated using measurements taken at the d-line (587.6 nm) of a helium lamp. As a result, the refractive index of the glass material obtained in Example 1 was 2.224, which was almost the same as the target value (refractive index 2.224). On the other hand, the refractive index of the glass material obtained in Comparative Example 2 was 2.226, which was 0.002 off the target value (refractive index 2.224). [Explanation of symbols]

[0062] 1, 21...Glass material manufacturing equipment 2…Molding mold 2a…molding surface 2b...Gas vent 3...Gas supply mechanism 4,24...Floating objects 5...Laser light irradiation device 11...Glass raw material lump 12...Molten glass 21a, 21b...First and second laser light sources 21A, 21B...Laser light

Claims

1. a step of irradiating a laser beam to the glass raw material lump in a floating state to heat and melt at least a part of the glass raw material lump to obtain molten glass; a step of obtaining a glass material by cooling the molten glass; Equipped with In the step of obtaining the molten glass, when viewed from the direction of irradiation of the laser light, a spot diameter of the laser light irradiated onto the glass frit lump is larger than a diameter of the molten glass after the glass frit lump is heated and melted, a spot diameter of the laser beam irradiated onto the molten glass being adjusted in accordance with a change in size of the glass raw material lump when the glass raw material lump is turned into the molten glass, so that the spot diameter of the laser beam irradiated onto the molten glass is smaller than the spot diameter of the laser beam irradiated onto the glass raw material lump.

2. From the start of heating and melting at least a part of the glass raw material mass to the end of cooling the molten glass, 2. The method for producing a glass material according to claim 1, wherein a spot diameter of the laser beam is adjusted so that the spot diameter of the laser beam is within a range of 0.5 to 1.5 times a diameter of the glass raw material lump or the molten glass when viewed from a direction of irradiation of the laser beam.

3. 3. The method for producing a glass material according to claim 2, wherein a spot diameter of the laser beam is adjusted so that the spot diameter of the laser beam is within a range of 0.8 to 1.0 times a diameter of the glass raw material lump or the molten glass when viewed from a direction of irradiation of the laser beam.

4. 4. The method for producing a glass material according to claim 1, wherein a spot diameter of the laser beam irradiated to the glass raw material lump is adjusted so that a ratio of a spot diameter of the laser beam irradiated to the molten glass is 0.5 or more and less than 1.

5. When viewed from the direction of irradiation of the laser light, 80% or more of the spot area of ​​the laser light is irradiated onto the glass raw material mass or the molten glass, 5. The method for producing a glass material according to claim 1, wherein a spot diameter of the laser beam is adjusted to be within a range of 0.5 to 1.5 times a diameter of the molten glass.

6. The method for manufacturing a glass material according to any one of claims 1 to 5, wherein the spot diameter of the laser light is adjusted while the glass raw material lump and the molten glass are observed with an imaging device.

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