Holding member, glass manufacturing apparatus using the same, and glass manufacturing method

Abstract

This invention provides a method for manufacturing optical glass using a laser levitation furnace, which allows glass samples to be stably levitated by a suspended gas. [Solution] A holding member used in a glass manufacturing apparatus that manufactures glass by cooling glass raw materials that have been suspended and heated and melted by gas, wherein the holding member has a gas injection surface having a plurality of injection ports for injecting gas, the gas injection surface has a first region P1 having a first injection port 1024x which is a part of the plurality of injection ports, and a second region P2 having a second injection port 1024y which is different from the first injection port, the first region is located inside the second region when viewed from above the gas injection surface, and the area of ​​the injection ports per unit area of ​​the first region is smaller than the area of ​​the injection ports per unit area of ​​the second region.

Description

Technical Field

[0001] The present invention relates to a holding member, a glass manufacturing apparatus using the same, and a method for manufacturing glass. The present invention claims the priority of Japanese Patent Application No. 2020-202124 filed on December 4, 2020, and for designated countries where incorporation by reference is recognized, the content described in that application is incorporated herein by reference.

Background Art

[0002] For example, Patent Document 1 discloses a method for manufacturing optical glass using a laser floating furnace. In such a laser floating furnace, it is required to stably float a glass sample with a floating gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A first aspect of the present invention is a holding member used in a glass manufacturing apparatus for producing glass by cooling glass raw materials that are suspended by gas and heated and melted, wherein the holding member has a gas injection surface having a plurality of injection ports for injecting the gas, the gas injection surface having a first region having first injection ports which are some of the plurality of injection ports, and a second region having second injection ports which are different from the first injection ports, the first region is located inside the second region when viewed from above the gas injection surface, the area of ​​the injection ports per unit area of ​​the first region is smaller than the area of ​​the injection ports per unit area of ​​the second region, the area of ​​the injection ports per unit area of ​​the first region is the ratio of the sum of the cross-sectional areas of the first injection ports to the area of ​​the first region when viewed from above the gas injection surface, and the area of ​​the injection ports per unit area of ​​the second region is the ratio of the sum of the cross-sectional areas of the second injection ports to the area of ​​the second region when viewed from above the gas injection surface.

[0005] A second aspect of the present invention is a holding member used in a glass manufacturing apparatus for producing glass by cooling glass raw materials that are suspended by gas and heated and melted, wherein the holding member has a gas injection surface having a plurality of injection ports for injecting the gas, the gas injection surface has a first region having first injection ports which are some of the plurality of injection ports, and a second region having second injection ports which are different from the first injection ports, the first region is located inside the second region when viewed from above the gas injection surface, the number of injection ports per unit area of ​​the first region is less than the number of injection ports per unit area of ​​the second region, and the number of injection ports per unit area of ​​the first region is the ratio of the number of first injection ports to the area of ​​the first region when viewed from above the gas injection surface. The number of injection ports per unit area of ​​the second region is the ratio of the number of second injection ports to the area of ​​the second region when the gas injection surface is viewed from above.

[0006] A third aspect of the present invention is a holding member used in a glass manufacturing apparatus for producing glass by cooling glass raw materials that are suspended by gas and heated and melted, the holding member having a gas introduction surface having an inlet for introducing the gas, and a gas injection surface having a plurality of injection ports for injecting the gas introduced from the gas introduction surface, the gas injection surface having a first region having a first injection port which is a portion of the plurality of injection ports, and a second region having a second injection port which is different from the first injection port among the plurality of injection ports, the first region being located inside the second region in a top view of the gas injection surface, and the gas introduction surface having a convex shape.

[0007] A fourth aspect of the present invention is a holding member used in a glass manufacturing apparatus for producing glass by cooling glass raw materials that are suspended by gas and heated and melted, the holding member having a gas introduction surface having an inlet for introducing the gas, and a gas injection surface including a first region having a plurality of injection ports for injecting the gas introduced from the gas introduction surface and a second region having injection ports for injecting the gas, wherein the first region is located inside the second region in a top view of the gas injection surface, and the holding member comprises a first portion surrounded by a plane including a straight line drawn perpendicularly from the first region to the gas introduction surface and a second portion surrounded by a plane including a straight line drawn perpendicularly from the second region to the gas introduction surface, wherein the thickness of the first portion, which is the length of a straight line drawn in the direction of gravity from a point in the first region to the gas introduction surface, is greater than the thickness of the second portion, which is the length of a straight line drawn in the direction of gravity from a point in the second region to the gas introduction surface.

[0008] A fifth aspect of the present invention is a holding member used in a glass manufacturing apparatus for producing glass by cooling glass raw materials that are suspended by gas and heated and melted, the holding member having a gas introduction surface having an inlet for introducing the gas, and a gas injection surface including a first region having a plurality of injection ports for injecting the gas introduced from the gas introduction surface and a second region having injection ports for injecting the gas, wherein the first region is located inside the second region in a top view of the gas injection surface, and the average thickness (K1) of the holding member between the first region and the gas introduction surface is greater than the average thickness (K2) of the holding member between the second region and the gas introduction surface.

[0009] A sixth aspect of the present invention is a glass manufacturing apparatus that includes the holding member described above.

[0010] A seventh aspect of the present invention is a method for manufacturing glass, comprising: a flotation step of blowing gas onto the glass raw material from the nozzle of the holding member described above to levitate the glass sample; a melting step of irradiating the levitated sample with laser light to melt the glass raw material; and a cooling step of cooling the molten glass raw material. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a glass manufacturing apparatus equipped with a floating furnace including a holding member according to this embodiment. [Figure 2] Figure 1 is a schematic diagram (cross-sectional view) showing the state in which a sample suspended above the holding member is heated. [Figure 3] This is a schematic diagram (cross-sectional view) of the retaining member according to this embodiment. [Figure 4] This is a schematic diagram (top view) (part 1) of the concave surface 1020 of the retaining member 102 according to this embodiment. [Figure 5] This is a schematic diagram (cross-sectional view) illustrating the shape of the concave surface 1020 of the retaining member 102 according to this embodiment. [Figure 6] This is a schematic diagram (top view) (part 1) illustrating the relationship between the concave surface and the nozzle according to this embodiment. [Figure 7] It is a schematic diagram (top view) (part 2) for explaining the relationship between the concave surface and the injection port according to this embodiment. [Figure 8] It is a schematic diagram (top view) (part 3) for explaining the relationship between the concave surface and the injection port according to this embodiment. [Figure 9] It is a partial schematic diagram (top view) (part 2) of the concave surface of the holding member according to this embodiment. [Figure 10] It is a schematic diagram (cross-sectional view) (part 1) of the holding member in the second embodiment. [Figure 11] It is a schematic diagram (cross-sectional view) (part 2) of the holding member in the second embodiment. [Figure 12] It is a schematic diagram (cross-sectional view) (part 3) of the holding member in the second embodiment. [Figure 13] It is a schematic diagram (cross-sectional view) (part 4) of the holding member in the second embodiment. [Figure 14] It is a schematic diagram (top view and cross-sectional view) (part 1) of the holding member in the third embodiment. [Figure 15] It is a schematic diagram (top view and cross-sectional view) (part 2) of the holding member in the third embodiment. [Figure 16] It is a schematic diagram (top view and cross-sectional view) (part 3) of the holding member 123 in the third embodiment. [Figure 17] It is a schematic diagram (top view and cross-sectional view) (part 4) of the holding member 124 in the third embodiment.

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described. The following present embodiment is an exemplification for explaining the present invention and is not intended to limit the present invention to the following contents.

[0013] In the drawings, the same reference numerals are assigned to the same elements, and redundant descriptions are omitted. Also, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[0014] Also, terms with "approximate" attached indicate the meaning of the terms without "approximate" within the scope of the common technical knowledge of those skilled in the art, and include the meaning itself without "approximate". And vice versa. For example, the term "circle" does not have "approximate" attached, but naturally includes the meaning of "approximate circle" as long as it does not conflict with the gist of the invention.

[0015] Also, the "top view" or "top view" refers to the view from the direction of the upper surface of the holding member 10 when the concave surface 1020 of the holding member 102 described later is placed upward and stationary on a horizontal plane perpendicular to the gravitational direction.

[0016] Furthermore, the "cross-sectional view" or "cross-sectional view" refers to the cross-section passing through the center or centroid of the concave surface 1020 when the concave surface 920 of the holding member 102 is placed upward and stationary on a horizontal plane perpendicular to the gravitational direction.

[0017] <The holding member 102 and floating furnace of the first embodiment>

[0018] FIG. 1 is a schematic view of a glass manufacturing apparatus 1 including a floating furnace including a holding member 102 according to the present embodiment, FIG. 2 is a schematic view (cross-sectional view) showing a state of heating a sample M floating on the holding member 102 in FIG. 1, and FIG. 3 is a schematic view (cross-sectional view) of the holding member 102 according to the present embodiment.

[0019] As shown in Figure 1, the glass manufacturing apparatus 1 is an optical glass manufacturing apparatus equipped with a gas jet type levitation furnace. The glass manufacturing apparatus 1 manufactures glass by heating and melting the glass raw material while the glass raw material is suspended by gas. The glass manufacturing apparatus 1 includes a levitation furnace that includes a holding member 102 that blows gas onto a sample M containing the glass raw material to levitate it, a laser light source 103 that irradiates the suspended sample M with laser light L, a radiation thermometer 106 that measures the temperature of the suspended sample M, a computer 107 that controls the output of the laser light source 103 based on the temperature information from the radiation thermometer 106, and a gas flow rate regulator 110 that adjusts the flow rate of gas supplied to the holding member 102.

[0020] In the glass manufacturing apparatus 1, a sample M floating above a holding member 102 placed on a stage 101 is non-contact heated by irradiation with laser light L. As a result, the sample M melts and becomes a molten material in a roughly spherical or roughly ellipsoidal shape due to its own surface tension, and floats in that state. Then, the sample M solidifies as it cools to become optical glass.

[0021] Non-contact heating of sample M is performed by irradiating sample M with laser light L emitted from laser light source 103 via mirrors 104 and 105. The temperature of sample M, heated by the irradiation of laser light L, is monitored by radiation thermometer 106. Based on the temperature information of sample M monitored by radiation thermometer 106, the output of laser light source 103 is controlled by computer 107. In addition, the state of sample M is imaged by CCD camera 108 and output to monitor 109. The laser light source 103 is not particularly limited and examples include carbon dioxide lasers, semiconductor lasers, fiber lasers, and YAG lasers.

[0022] The flow rate of the gas supplied to the holding member 102 is controlled by the gas flow regulator 110. The type of gas is not particularly limited, and any known gas can be used as appropriate. Specific examples include oxygen, carbon dioxide, nitrogen, argon, and air. Furthermore, the shape of the nozzle (not shown) connected to the holding member 102 is not particularly limited, and any known method can be used as appropriate.

[0023] After non-contact heating of the stably suspended sample M, the laser light L is blocked. This cools and solidifies the molten material (sample M), yielding optical glass.

[0024] As shown in Figure 2, the holding member 102 comprises a first surface S1 facing the sample M and having a concave surface (gas injection surface) 1020, and a second surface S2 on the opposite side of the first surface S1, which is a gas introduction surface. The second surface S2 has an inlet 1022 into which gas is introduced, and the concave surface 1020 of the first surface S1 has an injection port 1024 for injecting gas. The inlet 1022 supplies gas to the injection port 1024 on the concave surface 1020.

[0025] Furthermore, as shown in Figure 3, the nozzle 1024 consists of a nozzle 1024a located in the center of the first surface S1 and nozzles 1024b, c, and d located in the periphery. The number, shape, and arrangement of the nozzles 1024 are not particularly limited, and suitable conditions can be selected as appropriate. By blowing gas onto the sample M from the nozzles 1024, the sample M can be stably suspended above the holding member 102.

[0026] Furthermore, it is preferable that the holding member 102 includes a through hole 1026 that connects the inlet 1022 and the injection port 1024. The through hole 1026 efficiently directs the gas supplied from the inlet 1022 on the second surface S2 toward the injection port 1024 on the concave surface 1020 of the first surface S1. As an example, the cross-section of the surface of the through hole 1026 parallel to the direction of gravity is rectangular.

[0027] In addition, the inlet 1022 can be described as an inlet for introducing gas, and the injection port 1024 can be described as an injection port for injecting gas. In this embodiment, for example, the multiple injection ports 1024 of the concave surface 1020 are each in communication with one inlet 1022.

[0028] In Figure 3, through holes 1026a connecting the inlet 1022a and the nozzle 1024a, through holes 1026b connecting the inlet 1022b and the nozzle 1024b, through holes 1026c connecting the inlet 1022c and the nozzle 1024c, and through holes 1026d connecting the inlet 1022d and the nozzle 1024d are formed.

[0029] In this embodiment, not all inlets 1022 and all nozzles 1024 are necessarily connected by through holes 1026; only some of them may be connected by through holes 1026.

[0030] Next, the arrangement of the nozzle 1024 of the holding member 102 will be further explained.

[0031] <Example 1 of the concave surface 1020>

[0032] Figure 4 is a schematic diagram (top view) of a portion of the concave surface 1020 of the retaining member 102 according to this embodiment.

[0033] In the example shown in Figure 4, the concave surface 1020 is a circle with center O and radius R when viewed from above. The first circle C1 is a circle with radius R1 from center O, and the second circle C2 is a circle with radius R2. Specifically, the "center point" refers to the center of the circle when the shape of the concave surface 1020 of the first surface S1 viewed from above is circular, and the centroid is the center when the shape when viewed from above is elliptical or a polygon such as a rectangle.

[0034] That is, the concave surface 1020 has, in a top view, the region of the first circle C1 and the region of the second circle C2 having a radius R2 that is greater than or equal to the radius R1 of the first circle C1, and they are concentric and adjacent. The concave surface 1020 has a first region P1 that is the region of the first circle C1 and a second region P2 that is an annular region obtained by excluding the region of the first circle C1 from the region of the second circle C2. The first region P1 is a region that includes the center or the centroid in the top view of the concave surface 1020. In other words, the first region P1 is located closer to the inside (closer to the center or the centroid) of the concave surface 1020 than the second region P2. Note that the radius R2 of the second circle C2 may be equal to the radius R of the concave surface 1020. That is, the concave surface 1020 may be composed of the first region P1 and the second region P2.

[0035] The first region P1 is at least a part of a substantially circular region having a radius of r or less from the center point O in the top view of the concave surface 1020. Note that r < R. Also, the second region P2 is at least a part of a substantially annular region having an inner peripheral radius of r or more in the top view of the concave surface 1020.

[0036] In the top view, the first region P1 is preferably a substantially circular region having a radius of 0.2R (0.2 times the radius R) or less from the center point O with respect to the radius R of the concave surface 1020, and more preferably 0.1R or less. Also, the radius R1 is preferably 1 to 3 mm. The lower limit value of the radius R1 is more preferably 1.5 mm, and the upper limit value is more preferably 2.5 mm.

[0037] In the top view, for the second region P2, the radius R2 corresponding to the outer peripheral radius of the annular region may be equal to the radius R of the concave surface 1020, and is more preferably 0.9R (0.9 times the radius R) or less, and even more preferably 0.8R or less. Also, the radius R2 is preferably 3 to 8 mm. The lower limit value of the radius R2 is more preferably 4 mm, and the upper limit value is more preferably 7 mm.

[0038] The second region P2 only needs to be outside the first region P1, and it may or may not be adjacent to the first region P1. The case where they are not adjacent will be discussed later.

[0039] When viewed from above, if the concave surface 1020 is circular, the radius R of the concave surface 1020 is preferably 5 to 10 mm. The lower limit of the radius R of the concave surface 1020 is more preferably 5.5 mm, and even more preferably 6.5 mm. The upper limit of the radius R of the concave surface 1020 is more preferably 9.5 mm, and even more preferably 8.5 mm. By having the radius R of the concave surface 1020 within the above range, the sample M can be suspended more stably, and as a result, larger glass gobs and optical glass can be produced. Here, a glass gob refers to a block of glass directly formed from molten glass.

[0040] In this embodiment, the case where the shape of the concave surface 1020 of the first surface S1 when viewed from above is circular has been described, but it is not limited to this. For example, the shape of the concave surface 1020 of the first surface S1 when viewed from above may be elliptical, or it may be a polygon such as a rectangle. In the case of a shape that is not a perfect circle, "radius" refers to the shortest diameter from the centroid.

[0041] Figure 5 is a schematic diagram (cross-sectional view) illustrating the shape of the concave surface 1020 of the retaining member 102 according to this embodiment.

[0042] In a cross-sectional view of the concave surface 1020, the maximum depth H of the concave surface 1020 is preferably 4 to 10 mm. Here, the maximum depth H of the concave surface 1020 refers to the distance from the opening of the concave surface 1020 to the deepest point of the concave surface 1020. The lower limit of the maximum depth H of the concave surface 1020 is more preferably 5 mm, and even more preferably 5.5 mm. The upper limit of the maximum depth H of the concave surface 1020 is more preferably 6.5 mm, and even more preferably 6 mm. By having the maximum depth H of the concave surface 1020 within the above range, the sample M can be suspended more stably, and as a result, a larger glass gob can be manufactured.

[0043] Furthermore, while the cross-sectional shape of the concave surface 1020 is not particularly limited, it is preferable that it be a semicircle or a semiellipse from the viewpoint of more stably suspending the sample M.

[0044] The holding member 102 is formed from a non-porous material such as metal. The material of the holding member 102 is not particularly limited, but it is preferable that at least a part or all of the member contains at least one selected from the group consisting of stainless steel (SUS), silicon carbide (SiC), alumina (Al2O3), zirconia (ZrO2), duralumin, copper (Cu), and carbon (C). These materials have excellent thermal shock resistance and wear resistance even at high temperatures, so that gas can be blown onto the sample M with higher precision even at the high temperatures under which laser heating is performed, and the sample M can be stably suspended.

[0045] <Example 1 of the configuration of nozzle 1024>

[0046] Figure 6 is a schematic diagram (top view) (part 1) illustrating the relationship between the concave surface 1020 and the nozzle 1024 according to this embodiment. The nozzle 1024 provided in the first region P1 will be described as nozzle 1024x (first nozzle), and the nozzle 1024 provided in the second region P2 will be described as nozzle 1024y (second nozzle), which is different from 1024x. Let W1 be the area of ​​nozzle 1024x per unit area in the first region P1, and let W2 be the area of ​​nozzle 1024y per unit area in the second region P2. Note that the area of ​​nozzle 1024 refers to the area of ​​the space as an opening surrounded by the member of the concave surface 1020 having nozzle 1024.

[0047] The method for determining the area W1 of the nozzles 1024x per unit area of ​​the first region P1 is as follows. The area of ​​the first region P1 refers to the area of ​​the first region P1 when the concave surface 1020 is viewed from above, as shown in Figure 4. Furthermore, the area of ​​the nozzles 1024x included in the first region P1 refers to the sum of the cross-sectional areas of the nozzles 1024x included in the first region P1 in the cross section of the holding member 102 perpendicular to the direction of gravity (plane AA' in Figure 3). For example, in the case of Figure 3, It is the sum of the cross-sectional areas of the three injection nozzles 1024a and b. Therefore, W1 is given by the following equation (1). The area W1 of the nozzles 1024x per unit area in the first region P1 = Sum of the cross-sectional areas of the nozzles 1024x included in the first region P1 / Area of ​​the first region P1 when viewed from above... (1)

[0048] Furthermore, the method for calculating the area W2 of the nozzle 1024y per unit area of ​​the second region P2 is the same as for W1. The area of ​​the second region P2 refers to the area of ​​the second region P2 when the concave surface 1020 is viewed from above, as shown in Figure 4. Also, the area of ​​the nozzle 1024y included in the second region P2 refers to the sum of the cross-sectional areas of the nozzles 1024y included in the second region P2 in the cross section of the holding member 102 perpendicular to the direction of gravity (plane AA' in Figure 3). For example, in the case of Figure 3, it is the sum of the cross-sectional areas of the four nozzles 1024, namely nozzles 1024c and d. Therefore, W2 is given by the following equation (2). The area of ​​the nozzle 1024y per unit area in the second region P2 W2 = Sum of the areas of the nozzle 1024y included in the second region P2 / Area of ​​the second region P2 when viewed from above ... (2)

[0049] Furthermore, it is preferable that the AA' section is the section at the lowest position when the concave surface 1020 is viewed from the side.

[0050] Furthermore, the area of ​​the nozzle 1024x·1024y may also be as follows: The area of ​​the nozzle 1024x·1024y may be the area of ​​the nozzle 1024x·1024y when the concave surface is viewed from above.

[0051] In the example shown in Figure 6, the area W1 of the injection nozzles 1024x per unit area in the first region P1 is smaller than the area W2 of the injection nozzles 1024y per unit area in the second region P2. That is, W1 <W2 ···(3) That is the case.

[0052] Furthermore, the ratio (W1 / W2) of the area W1 of the injection nozzle 1024x per unit area in the first region P1 to the area W2 of the injection nozzle 1024y per unit area in the second region P2 is preferably 0.05 to 0.7. The lower limit of W1 / W2 is more preferably 0.1, and the upper limit is more preferably 0.4.

[0053] In this example, by configuring the nozzle 1024 of the concave surface 1020 as described above, the gas flow rate per unit time from the nozzle 1024y in the second region P2 becomes greater than the gas flow rate per unit time from the nozzle 1024x in the first region P1. This allows the sample M to be kept stably suspended near the irradiation target position of the laser beam L (stable levitation).

[0054] Conventionally, in methods for manufacturing optical glass using containers such as crucibles (sometimes called the container method), it was necessary to include a large amount of network-forming oxides such as SiO2, B2O3, P2O5, and GeO2 to enhance the glass-forming ability. Therefore, when a glass composition is made that contains a large amount of materials other than network-forming oxides and has a low content of the aforementioned network-forming oxides, crystallization (heterogeneous nucleation) occurs starting from the container-melt interface, leading to problems such as difficulty in vitrification.

[0055] Furthermore, in conventional floating furnace methods, the holding member used blows gas from below the sample, but it is difficult to keep the sample stably floating above the holding member (stable levitation). This makes precise laser irradiation heating difficult, and there are problems such as the inability to produce large glass gobs.

[0056] Regarding these issues, by using the holding member 102 according to this embodiment, the conditions for blowing gas onto the sample M can be controlled with high precision. As a result, a stable floating state can be maintained to a degree that was not possible with conventional methods (high floating stability), and larger glass gobs can be produced. In other words, high stable floating performance contributes to precise irradiation heating with laser light, larger optical glass (glass gobs) obtained, and homogenization of the component composition.

[0057] Glass gobs are sometimes used as optical lens materials for various optical instruments, such as objective lenses for microscopes and lenses for cameras, but there is a need for a way to stably manufacture large glass gobs. The holding member according to this embodiment can meet this requirement.

[0058] Furthermore, let T1 be the number of injection nozzles 1024x per unit area in the first region P1, and T2 be the number of injection nozzles 1024y per unit area in the second region P2.

[0059] The multiple nozzles 1024 in the concave surface 1020 shown in Figure 6 are arranged at approximately equal intervals. That is, the distance L1 from the center of each nozzle 1024 to the center of another nozzle 1024 adjacent to that nozzle 1024 is approximately equal. In other words, the number T1 of nozzles 1024x per unit area of ​​the first region P1 in the example shown in Figure 6 is equal to the number T2 of nozzles 1024y per unit area of ​​the second region P2.

[0060] To stably suspend the sample M, the radius of the nozzle 1024x is preferably 0.05 mm to 0.2 mm. More preferably, the lower limit of the radius of 1024x is 0.1 mm, and the upper limit is more preferably 0.15 mm. The radius of the nozzle 1024y is preferably 0.2 mm to 0.5 mm. More preferably, the lower limit of the radius of 1024y is 0.3 mm, and the upper limit is more preferably 0.4 mm.

[0061] Note that the number of nozzles 1024 in this example is not limited to this. The area W1 of nozzles 1024x per unit area in the first region P1 is small compared to the area W2 of nozzles 1024y per unit area in the second region P2. For example, the number T1 of nozzles 1024x per unit area in the first region P1 may be greater than the number T2 of nozzles 1024 per unit area in the second region P2.

[0062] Furthermore, one nozzle 1024x that is larger than one nozzle 1024y in the second region P2 may exist in the first region P1. Similarly, one nozzle 1024y that is smaller than one nozzle 1024x in the first region P1 may exist in the second region P2.

[0063] <Example 2 of the configuration of nozzle 1024>

[0064] Figure 7 is a schematic diagram (top view) (part 2) illustrating the relationship between the concave surface 1020 and the injection nozzle 1024 according to this embodiment. In the example shown in Figure 7, the number of injection nozzles 1024x per unit area T1 in the first region P1 is less than the number of injection nozzles 1024y per unit area T2 in the second region P2. That is, T1 <T2 ···(4) That is the case.

[0065] Furthermore, the ratio (T1 / T2) of the number of injection nozzles 1024x per unit area in the first region P1 to the number of injection nozzles 1024y per unit area in the second region P2 (T2) is preferably 0.05 to 0.5. The lower limit of T1 / T2 is more preferably 0.1, and the upper limit is more preferably 0.3.

[0066] For example, when the retaining member 102 is viewed in cross-section, the first region P1 including the center point O of the concave surface 1020 can be arranged such that the spacing of the through holes is sparse, and the spacing of the through holes becomes denser as it approaches the end of the concave surface 1020. By configuring it in this way, the relationship expressed by equation (4) can be satisfied.

[0067] In this example, a number of nozzles 1024 satisfying equation (4) are provided in the concave surface 1020, and the nozzles 1024 are formed such that the area W1 of the nozzles 1024x per unit area in the first region P1 is smaller than the area W2 of the nozzles 1024y per unit area in the second region P2. That is, in this example as well, similar to the example shown in Figure 6, the gas flow rate per unit time from the nozzles 1024 provided in the second region P2 is greater than the gas flow rate per unit time from the nozzles 1024 provided in the first region P1. Therefore, the sample M can be kept stably suspended near the irradiation target position of the laser beam L.

[0068] When sample M is heated by laser and becomes molten, its viscosity and surface tension decrease with increasing temperature, making it more susceptible to deformation and vibration when subjected to gas pressure. Furthermore, as the volume and total weight of sample M increase, it becomes more susceptible to the effects of its own weight and gas flow, resulting in more pronounced deformation and vibration of the molten material. Consequently, it was difficult to stably levitate large samples M. However, with the configuration of this embodiment, the gas flow rate per unit time in the second region is greater than the gas flow rate per unit time in the first region, allowing even large samples M to be stably suspended.

[0069] In the example shown in Figure 7, the area of ​​each nozzle 1024x in the first region P1 is equal to the area of ​​each nozzle 1024y in the second region P2. However, the area of ​​each nozzle 1024 in this example is not limited to this. <Example 3 of the configuration of nozzle 1024>

[0070] Figure 8 is a schematic diagram (top view) (part 3) illustrating the relationship between the concave surface 1020 and the nozzle 1024 according to this embodiment. In the example shown in Figure 8, the area W1 of the nozzles 1024x per unit area in the first region P1 is smaller than the area W2 of the nozzles 1024y per unit area in the second region P2. Also, in the example shown in Figure 8, the number T1 of the nozzles 1024x per unit area in the first region P1 is less than the number T2 of the nozzles 1024y per unit area in the second region P2.

[0071] In other words, the example shown in Figure 8 satisfies equations (3) and (4) described above.

[0072] In this example, as with the other examples described above, the gas flow rate per unit time from the nozzle 1024 in the second region P2 is greater than the gas flow rate per unit time from the nozzle 1024 in the first region P1. That is, the sample M can be kept stably suspended near the irradiation target position of the laser beam L.

[0073] The arrangement of the nozzles 1024 is not limited to the positions shown above and in Figures 6 to 8. In order to stably levitate the sample M, it is preferable that the arrangement of the nozzles 1024 in a top view of the concave surface 1020 has symmetry such as point symmetry or line symmetry with respect to the center point O (or centroid) of the concave surface 1020 in either the first region P1 or the second region P2.

[0074] <Example 2 of the concave surface 1020>

[0075] Figure 9 is a schematic partial view (top view) (part 2) of the concave surface 1020 of the retaining member 102 according to this embodiment. In the schematic partial view shown in Figure 4, the first region P1 and the second region P2 are adjacent. In the example shown in this figure, the first region P1 and the second region P2 are not adjacent.

[0076] In a top view, the concave surface 1020 has concentrically arranged regions: the region of a first circle C1, the region of a second circle C2 having a radius R2 greater than or equal to the radius R1 of the first circle C1, and the region of a third circle C3 having a radius R3 greater than the radius R2 of the second circle C2. The first region P1 is the region of the first circle C1, and the second region P2 is the annular region obtained by subtracting the region of the second circle C2 from the region of the third circle C3.

[0077] In this example, the first region P1 preferably has a radius R1 from the center point O of 3 mm or less when viewed from above the concave surface 1020. Furthermore, the radius R1 is preferably between 1 and 3 mm, with a lower limit of 1.5 mm being more preferable and an upper limit of 2.5 mm being more preferable.

[0078] In the second region P2, when viewed from above the concave surface 1020, the radius R2 corresponding to the inner circumference radius of the annular region is preferably 3 to 5 mm. The lower limit of radius R2 is more preferably 3.5 mm, and the upper limit of radius R2 is more preferably 4.5 mm. The radius R3 corresponding to the outer circumference radius of the annular region is preferably 5 to 9 mm. The lower limit of radius R3 is more preferably 5.5 mm, and the upper limit of radius R3 is even more preferably 8 mm. Furthermore, radius R2 is preferably 1 to 3 times radius R1, and radius R3 is preferably 3.5 to 6 times R1.

[0079] Furthermore, the concave surface 1020 is circular in shape with radius R when viewed from above.

[0080] The first region P1 is preferably a circular region in which, when viewed from above the concave surface 1020, the radius R1 from the center point O is 0.2R (0.2 times the radius R) or less with respect to the radius R of the concave surface 1020.

[0081] In the second region P2, when viewed from above the concave surface 1020, it is preferable that the radius R2 from the center point O is 0.4R (0.4 times the radius R) or more, and more preferably 0.5R (0.5 times the radius R) or more, with respect to the radius R of the concave surface 1020. Furthermore, it is preferable that the radius R3 from the center point O is 0.9R (0.9 times the radius R) or less, and even more preferably 0.8R (0.8 times the radius R) or less.

[0082] As shown in this example, even when the first region P1 and the second region P2 are not adjacent, the concave surface 1020 can be configured such that the gas flow rate per unit time from the injection port 1024 in the second region P2 is greater than the gas flow rate per unit time from the injection port 1024 in the first region P1. This makes it possible to maintain high buoyancy stability.

[0083] Up to this point, a holding member 102 has been described as an example, in which through-holes for allowing gas to pass through are provided to extend vertically within the member. However, the holding member according to this embodiment is not limited to this configuration and may be configured in other ways.

[0084] <Example 1 of the configuration of the holding member (holding member 111) of the second embodiment>

[0085] Figure 10 is a schematic diagram (cross-sectional view) (part 1) of the retaining member 111 in the second embodiment. The differences from the first embodiment will be explained below. In the second embodiment, the retaining member 111 is porous in at least a portion of it.

[0086] By including porous materials, the gas supplied to the inlet 1112 can be blown onto the sample M from the injection port 1114 through the internal pore structure. Thus, the through-holes described above may be pores in a porous material. In other words, the pores in the porous body of the holding member 111 can be considered one form of the through-holes described above. Figure 10 illustrates a case where all the components constituting the holding member 111 are porous. Specific examples of porous materials include stainless steel (SUS), silicon carbide (SiC), alumina (Al2O3), zirconia (ZrO2), and carbon (C).

[0087] If the pore diameter of the porous material constituting the retaining member 111 is too small, the pressure loss will be large, and gas will not be able to pass through sufficiently. Conversely, if the pore diameter is too large, the surface shape, including the concave surface 1110, will become rough. Therefore, the pore diameter of the porous material constituting the retaining member 111 is preferably 1 to 100 μm. The lower limit of the pore diameter is more preferably 5 μm, and even more preferably 9 μm. The upper limit of the pore diameter is more preferably 50 μm, and even more preferably 20 μm.

[0088] By having pore diameters within the above range for the porous material constituting the holding member 111, it is possible not only to allow gas to pass through appropriately but also to suppress the influence on the surface shape of the concave surface 1110.

[0089] By creating density variations in the internal arrangement of the pore structure of the retaining member 111, gas can be blown in such a way that it satisfies the relationship expressed by equation (3) or equation (4). Here, the portion of the retaining member 111 having pores that supply gas to the injection port 1114 in the first region P1 is denoted as portion Q1, and the portion of the retaining member 111 having pores that supply gas to the injection port 1114 in the second region P2 is denoted as Q2. For example, let V1 be the porosity of portion Q1 of the retaining member 111 corresponding to the first region P1 which includes the center point O of the concave surface 1110 of the first surface S1, and let V2 be the porosity of portion Q2 of the retaining member 111 corresponding to the second region P2 which is located outside the first region P1. Here, porosity refers to the ratio of the volume of space to the total volume of a substance.

[0090] In this embodiment, the porosity V1 of portion Q1 of the retaining member 111 corresponding to the first region P1 including the center point O of the concave surface 1110 of the first surface S1 is lower than the porosity V2 of portion Q2 of the retaining member 111 corresponding to the second region P2 located outside the first region P1. That is, V1 <V2 ···(5) That is the case.

[0091] As a result of setting the porosity V1 of part Q1 to be lower than the porosity V2 of part Q2, the area W1 of the nozzles 1114 per unit area in the first region P1 is smaller than the area W2 of the nozzles 1114 per unit area in the second region P2. That is, equation (3) above is satisfied, and the gas flow rate per unit time from the nozzles 1024y in the second region P2 is greater than the gas flow rate per unit time from the nozzles 1024x in the first region P1. This makes it possible to keep the sample M stably suspended near the irradiation target position of the laser beam L (stable suspension). Furthermore, the number T1 of nozzles 1114 per unit area in the first region P1 can be less than the number T2 of nozzles 1114 per unit area in the second region P2.

[0092] As a result of forming the holding member 111 from a porous material, at least one of the multiple injection ports 1114 of the concave surface 1110 communicates with the multiple inlet ports 1112. Part Q1 of the holding member 111 corresponds to the multiple injection ports 1114 provided in the first region P1 and includes pores and inlet ports 1112 that communicate with the injection ports 1114. Similarly, part Q2 of the holding member 111 corresponds to the multiple injection ports 1114 provided in the second region P2 and includes pores and inlet ports 1112 that communicate with the injection ports 1114.

[0093] In this embodiment, the inlet 1112 is not limited to being provided on the second surface S2. For example, gas may be introduced from the side surface of the holding member 111. In other words, the gas introduction surface having the inlet 1112 may be at least one of the side surface S3 of the holding member 111 and the second surface S2 which is opposite to the concave surface 1110.

[0094] Furthermore, the retaining member 111 in this embodiment can be formed by combining a porous body located in part Q1 and a porous body located in part Q2, which is different from part Q1. As another example, the retaining member 111 can consist of a single porous body, and this porous body can be formed so that the porosity differs between part Q1 and part Q2.

[0095] According to the holding member 111 of this embodiment, the gas flow rate per unit time from the nozzle 1114 in the second region P2 is greater than the gas flow rate per unit time from the nozzle 1114 in the first region P1. This allows the sample M to be kept stably suspended near the irradiation target position of the laser beam L (stable levitation).

[0096] <Example 2 of the configuration of the holding member (holding member 112) of the second embodiment>

[0097] Figure 11 is a schematic diagram (cross-sectional view) (part 2) of the retaining member 112 in the second embodiment. The retaining member 112 shown in this figure includes a member made of a porous material and a member made of a non-porous material.

[0098] The holding member 112 has an inlet 1122 and an injection port 1124, and is composed of a non-porous portion 1126 and a porous portion 1128, with a through hole located between the non-porous portion 1126 and the porous portion 1128. That is, the concave surface 1120 of the first surface S1 has both a porous region and a non-porous region, thereby allowing control of the gas flow rate. As the non-porous portion 1126, a non-porous material can be used, such as stainless steel (SUS), silicon carbide (SiC), alumina, zirconia (ZrO2), duralumin, copper (Cu), carbon (C), and various other metals.

[0099] The non-porous portion 1126 corresponds to a first region P1 including the center of the concave surface 1120, and the porous portion 1128 corresponds to a second region P2 located outside the first region P1. Furthermore, the through-hole between the non-porous portion 1126 and the porous portion 1128 is treated as being located in the second region P2. In the holding member 112, the gas flow rate per unit time from the injection port 1124 provided in the second region P2 is greater than the gas flow rate per unit time from the injection port 1124 provided in the first region P1.

[0100] In this example configuration, the inlet 1122 is not limited to being located on the second surface S2, but gas may also be introduced from the side surface S3 of the holding member 112.

[0101] <Example 3 of the configuration of the holding member (holding member 113) in the second embodiment>

[0102] Figure 12 is a schematic diagram (cross-sectional view) (part 3) of the holding member 113 in the second embodiment. In the holding member 113 shown in this figure, at least a portion of the injection nozzle 1134 in the second region P2 injects gas in a substantially horizontal direction substantially perpendicular to the direction of gravity.

[0103] The retaining member 113 includes member 1136 and member 1138. The material of member 1136 is not particularly limited. Member 1136 may be formed of a porous material having a nozzle 1134, or of a non-porous material having a nozzle 1134, or of a non-porous material without a nozzle 1134. Member 1136 is provided at a position corresponding to a first region P1 that includes the center point O of the concave surface 1130.

[0104] Member 1138 has an injection port 1134, and injects gas introduced from the inlet 1132 through the injection port 1134. Member 1138 injects gas in a substantially horizontal direction. Member 1138 is provided at a position corresponding to the second region P2 outside the first region P1. The inlet 1132 for introducing gas to the injection port 1134 may be located on the side of the holding member 113, or it may be located below the holding member 113 and introduce gas to the injection port 1134 via a curved hollow member.

[0105] In the holding member 113, the gas flow rate per unit time in the second region P2 is greater than the gas flow rate per unit time in the first region P1.

[0106] With this configuration, gas is blown onto the sample M from a nearly horizontal direction, allowing the sample M to be suspended more stably.

[0107] <Example 4 of the configuration of the holding member (holding member 114) in the second embodiment>

[0108] Figure 13 is a schematic diagram (part 4) of the retaining member 114 in the second embodiment. The retaining member 114 shown in this figure has a member 1141 and a member 1149.

[0109] Member 1141 is a member having a concave surface 1140, and the concave surface 1140 has a first region P1 and a second region P2. Member 1141 may be any of the holding members 102, 111, or 112 described above. In member 1141, the area W1 of the nozzle 1134 per unit area of ​​the first region P1 and the area W2 of the nozzle 1134 per unit area of ​​the second region P2 satisfy the above formula (3).

[0110] Member 1149 is located on the upper part of the concave surface 1140 and has an injection nozzle 1149a that injects gas in a substantially horizontal direction substantially perpendicular to the direction of gravity. By having an injection nozzle 1149a that ejects gas in a substantially horizontal direction, in addition to member 1141, the sample M can be suspended more stably.

[0111] Although not shown in the diagram, in a gas levitation furnace, the process of levitating the sample by blowing gas onto it and then melting the sample by laser irradiation is preferably carried out in a chamber that can be depressurized. Blowing gas onto the sample under reduced pressure makes it easier for the gas to pass through the porous material and through-holes of the holding member. As a result, high levitation stability can be obtained even when the gas flow rate is low, and the generation of turbulence can be suppressed. The gas may also be heated, which can also suppress turbulence. Furthermore, the laser beam L may be defocused or scanned. This allows the sample to be heated uniformly and improves levitation stability.

[0112] <Example 1 of the configuration of the holding member (holding member 121) of the third embodiment>

[0113] Figure 14 is a schematic diagram (top view and cross-sectional view) (Part 1) of the retaining member 121 in the third embodiment. The upper part of Figure 14 is a top view of the retaining member 121, and the lower part of Figure 14 is a cross-sectional view of the retaining member 121. The differences from the first and second embodiments will be described below.

[0114] In the third embodiment, the retaining member 121 has a convex shape on the second surface S2, which is the gas introduction surface, and has a portion J1 enclosed by a plane containing a straight line drawn from the first circle C1 to the second surface S2 (or side surface S3) in the direction of gravity (perpendicular), and a portion J2 enclosed by a plane containing a straight line drawn from the second circle C2 to the second surface S2 (or side surface S3) in the direction of gravity. The thickness of portion J1, which is the length of the straight line drawn from a point in the first circle C1 to the second surface S2 (or side surface S3) in the direction of gravity, is thicker than the thickness of portion J2, which is the length of the straight line drawn from a point in the second circle C2 to the second surface S2 (or side surface S3) in the direction of gravity. As will be described in detail later, portion J2 does not include portion J1. For example, the second surface S2 is approximately horizontal near the center and has a tapered shape that gradually narrows downwards toward the center. In Figure 14, the surface that forms the tapered shape that gradually narrows toward the center is defined as side surface S3. In other words, the second surface S2 can be described as having a roughly frustoconical shape that gradually widens upwards.

[0115] In this example, the retaining member 121 is made of a porous material. By changing the thickness of the retaining member 121, the buoyancy stability of the sample M can be improved.

[0116] Here, of the retaining member 121, the portion enclosed by the plane containing the straight line drawn perpendicularly from the first circle C1 to the second surface S2 (or side surface S3) is defined as portion J1, and the portion enclosed by the plane containing the straight line drawn perpendicularly from the second circle C2 to the second surface S2 (or side surface S3), excluding portion J1, is defined as portion J2. Portion J1 is the portion of the retaining member 121 corresponding to the first region P1 which includes the center point O of the concave surface 1210 of the first surface S1, and portion J2 is the portion of the retaining member 121 corresponding to the second region P2 which is located outside the first region P1.

[0117] In this example, "vertical" refers to the vertical direction when the retaining member 121 is placed on a horizontal plane perpendicular to the direction of gravity, with its concave surface 1210 facing upwards. For example, if the second surface S2 is substantially flat, it refers to the direction perpendicular to the second surface S2.

[0118] For example, let K1 be the average thickness of section J1, and K2 be the average thickness of section J2. The average thickness here refers to a value obtained by measuring the thickness of several predetermined points in a cross-sectional view and calculating the average value of those measurements. The thickness represents the distance from a predetermined point on the concave surface 1210 as the starting point, to the point where a straight line extended perpendicularly from that point intersects the second surface S2 (or side surface S3) as the ending point.

[0119] In this embodiment, the average thickness K1 of portion J1 of the retaining member 121 in cross-sectional view is greater than the average thickness K2 of portion J2 of the retaining member 121. That is, K1 > K2 ... (6)

[0120] In other words, in this embodiment, the average thickness K1 of the retaining member 121 between the first region P1 and the second surface S2, which is the gas introduction surface, is greater than the average thickness K2 of the retaining member 121 between the second region P2 and the second surface S2 (or side surface S3).

[0121] Furthermore, the ratio of the average thickness K2 of part J2 to the average thickness K1 of part J1 (K2 / K1) is preferably 0.5 to 0.95. The lower limit of K2 / K1 is more preferably 0.6, and the upper limit is more preferably 0.9.

[0122] In this embodiment, the thickness of the retaining member 121 at the center point O in a cross-sectional view is denoted as D1, and the thickness of the retaining member 121 at any point on the second region P2 is denoted as D2. The shortest D2 is configured to be shorter than D1. The longest D1 is configured to be longer than D2.

[0123] This configuration creates a difference in the length of the gas paths between the first region P1 (part J1) and the second region P2 (part J2), with the path through part J1 being longer than the path through part J2. As a result, the gas flow rate through part J2 is greater than the gas flow rate through part J1, allowing the sample M to be stably suspended near the center point O, and enabling the creation of a larger glass gob.

[0124] Furthermore, the retaining member 121 in the third embodiment can also be configured to satisfy the above-described formula (3) or formula (4), similar to the retaining members in the first and second embodiments.

[0125] <Example 2 of the configuration of the holding member (holding member 122) of the third embodiment>

[0126] Figure 15 is a schematic diagram (top view and cross-sectional view) (part 2) of the retaining member 122 in the third embodiment. The upper part of Figure 15 is a top view of the retaining member 122, and the lower part of Figure 15 is a cross-sectional view of the retaining member 122. The retaining member 122 in this figure is made of a non-porous material.

[0127] Similar to the retaining member 121, the retaining member 122 has a convex shape on its second surface S2. That is, the second surface S2, including the side surface S3, is a roughly frustoconical shape that gradually widens upward. In the retaining member 122, similar to the retaining member 121, the average thickness K1 in a cross-sectional view of the portion J1 of the retaining member 121 corresponding to the first region P1 including the center point O of the concave surface 1220 of the first surface S1 is greater than the average thickness of the portion J2 of the retaining member 121 corresponding to the second region P2 located outside the first region P1.

[0128] Furthermore, similar to the retaining member 121, when the thickness of the retaining member 122 at the center point O in a cross-sectional view is D1, and the thickness of the retaining member 122 at any point on the second region P2 is D2, the shortest D2 is configured to be shorter than D1.

[0129] In this configuration as well, the gas flow rate through section J2 is greater than the gas flow rate through section J1, allowing the sample M to be stably suspended near the center point O, and enabling the creation of larger glass gobs.

[0130] In addition, the retaining member 122 in this example can also be configured to satisfy the above-described formula (3) or formula (4), similar to the retaining members in the first and second embodiments.

[0131] <Example 3 of the configuration of the holding member (holding member 123) of the third embodiment>

[0132] Figure 16 is a schematic diagram (top view and cross-sectional view) (part 2) of the retaining member 123 in the third embodiment. The upper part of Figure 16 is a top view of the retaining member 123, and the lower part of Figure 16 is a cross-sectional view of the retaining member 123. In this figure, the retaining member 123 is made of a porous material. However, the retaining member 123 may be made of a non-porous material, or it may be made of both a porous material and a non-porous material.

[0133] The retaining member 123, like the retaining members 121 and 122, has a convex shape on its second surface S2. More specifically, the second surface S2 of the retaining member 123 has a projection. The area near the center of the second surface S2 is approximately horizontal. The surfaces of the second surface S2 other than those near the center are designated as side surfaces S3.

[0134] For example, a protrusion can be formed by making the portion directly below the first region P1 approximately horizontal and the other portions recessed. Similar to the example above, the portion of the retaining member 123 corresponding to the first region P1, including the center point O of the concave surface 1230 of the first surface S1, is defined as portion J1, and the portion of the retaining member 123 corresponding to the second region P2, located outside the first region P1, is defined as portion J2. The average thickness K1 in the cross-sectional view of portion J1 is greater than the average thickness of portion J2.

[0135] Furthermore, in the case of the retaining member 123, if the thickness of the retaining member 123 at the center point O in a cross-sectional view is D1, and the thickness of the retaining member 123 at any point on the second region P2 is D2, then the shortest D2 is configured to be shorter than D1, similar to the retaining members 121 and 122.

[0136] In this configuration as well, the gas flow rate through section J2 is greater than the gas flow rate through section J1, so the sample M can be stably suspended near the center point O, and a larger glass gob can be created. The holding member 123 in this example can also be configured to satisfy the above-described equation (3) or equation (4), similar to the holding members in the first and second embodiments.

[0137] <Example 4 of the configuration of the holding member (holding member 124) of the third embodiment>

[0138] Figure 17 is a schematic diagram (top view and cross-sectional view) (4) of the retaining member 124 in the third embodiment. The upper part of Figure 17 is a top view of the retaining member 124, and the lower part of Figure 17 is a cross-sectional view of the retaining member 124. In this figure, the retaining member 124 is made of a porous material. However, the retaining member 124 may be made of a non-porous material, or it may be made of both a porous material and a non-porous material.

[0139] Like the retaining members 121, 122, and 123, the retaining member 124 has a convex shape on its second surface S2. More specifically, the second surface S2 of the retaining member 124 is bowl-shaped, with the longest point being where a straight line extending perpendicularly from the center point O intersects with the second surface S2. In other words, in cross-sectional view, the retaining member 124 traces a roughly parabolic curve with the second surface S2 convex downwards.

[0140] In this example, the average thickness K1 of the retaining member 124 in cross-sectional view of portion J1 is greater than the average thickness of portion J2 of the retaining member 123.

[0141] Furthermore, similar to the retaining members 121, 122, and 123, when the thickness of the retaining member 124 at the center point O in a cross-sectional view is D1, and the thickness of the retaining member 124 at any point on the second region P2 is D2, the shortest D2 is configured to be shorter than D1.

[0142] In this configuration as well, the gas flow rate through section J2 is greater than the gas flow rate through section J1, so the sample M can be stably suspended near the center point O, and a larger glass gob can be created. The holding member 124 in this example can also be configured to satisfy the above-described equation (3) or equation (4), similar to the holding members in the first and second embodiments.

[0143] <Manufacturing method>

[0144] The method for manufacturing optical glass according to this embodiment includes the steps of: blowing gas onto a sample M from the gas injection part of the holding member described above in a gas levitation furnace to levitate the sample M, melting the sample M by irradiating the levitated sample M with laser light L, and cooling the molten sample M.

[0145] According to the optical glass manufacturing method of this embodiment, by using the above-described holding member, there is no contact between the container and the molten material (sample M), and heterogeneous nucleation can be suppressed to the greatest extent possible. Therefore, even compositions with a low or no network-forming oxide content, which are impossible to manufacture using the container method (crucible melting), can be vitrified. By adopting this manufacturing method, it is possible to manufacture optical glass with compositions that could not be vitrified conventionally. Therefore, it is also possible to manufacture optical glass with a high refractive index and a high Abbe number.

[0146] In addition, because the gas injection flow rate is greater in the peripheral area than in the center relative to the molten material, the molten material can be stably suspended near the central point O, and a large glass gob can be produced. Specifically, its diameter is preferably 6 mm or more, more preferably 6.5 mm or more, and even more preferably 7 mm or more.

[0147] The optical glass obtained by the manufacturing method according to this embodiment has many advantages, and can therefore be applied as a high-refractometer, low-dispersion glass material or a broadband transmission material. Specific examples will be described below.

[0148] <Examples>

[0149] Next, the following embodiments will be described, but the present invention is not limited in any way by these embodiments.

[0150] (Fabrication of optical glass in each example) The optical glass in each embodiment was manufactured using a glass manufacturing apparatus 1 equipped with a gas jet type levitation furnace as shown in Figure 1, and a holding member 121 as shown in Figure 14. In Examples 1 to 19, the structure of the holding member 121 had a concave surface 1210 radius (R) = 5.5 mm, a maximum depth (H) of the concave surface 1210 = 4.5 mm, and was made of a porous stainless steel material with a pore diameter of 10 μm. Furthermore, the radius R1 of the first region P1 of the holding member 121 was 2.1 mm from the center point O, and the radius R2 of the outer circumference of the second region P2 was 5.5 mm from the center point O. In addition, in Examples 20 to 24, the structure of the holding member 121 had a concave surface 1210 radius (R) = 8.5 mm, a maximum depth (H) of the concave surface 1210 = 6.8 mm, and was made of a porous stainless steel material with a pore diameter of 10 μm. Furthermore, the radius R1 of the first region P1 of the holding member 121 is 5 mm from the center point O, and the radius R2 of the outer circumference of the second region P2 is 8.5 mm from the center point O.

[0151] Gas was supplied from the gas flow regulator 110 connected to the holding member 121 at a rate of 2-3 L / min. As a result of using the holding member 121, the average thickness K1 in the cross-sectional view of portion J1 of the first region P1 was thicker than the average thickness K2 of portion J2 of the second region P2.

[0152] Next, optical glass was fabricated according to the following procedure. First, raw materials selected from oxides, hydroxides, carbonates, nitrates, sulfates, etc., were weighed to achieve a predetermined chemical composition and then mixed in an alumina mortar. This raw material was uniaxially pressed at 20 MPa to form cylindrical pellets. The obtained pellets were fired in an electric furnace at 1000-1300°C in air for 6-12 hours to produce a sintered body. The obtained sintered body was roughly crushed, and 500-600 mg was taken and placed in the nozzle of the holding member. Then, the raw material was melted by irradiating it from above with a carbon dioxide laser while spraying oxygen gas. The melted raw material became spherical or ellipsoidal due to its own surface tension and was suspended by the pressure of the sprayed gas. By cutting off the laser output when the raw material was completely melted, the raw material was cooled to obtain a roughly spherical glass gob with a diameter of 6 mm or more. In all of the examples, no visible volatilization was observed during melting of the glass, nor were any bubbles or devitrification observed.

[0153] (Creating a glass goblin) In each example, if a roughly spherical glass gob with a diameter of 6 mm or more was produced, it was described as "vitrified."

[0154] (Measurement of refractive index and Abbe number) The refractive index of the glass was measured using a prism coupler (Metricon, model "2010 / M"). The glass sample was polished, and the polished surface was placed in close contact with a single-crystal rutile prism. The refractive index was determined by measuring the total reflection angle when light of the measurement wavelength was incident on the sample. Five measurements were taken at each of the three wavelengths: 473 nm, 594.1 nm, and 656 nm, and the average value was used as the measured value. Furthermore, the obtained measured values ​​were fitted using the least squares method with the following Drude-Voigt dispersion formula to determine the refractive index at the d line (587.562 nm), F line (486.133 nm), and C line (656.273 nm), and the Abbe number (ν d ) was calculated.

[0155]

number

[0156] (n: refractive index, m: electron mass, c: speed of light, e: elementary charge, N: number of molecules per unit volume, f: oscillator intensity, λ0: intrinsic resonance wavelength, λ: wavelength)

[0157] Also, the Abbe number (ν d ) is defined by the following formula.

[0158]

number

[0159] (n d :Refractive index at line d, n F :Refractive index in the F line, n C (Refractive index at line C)

[0160] Each table shows the composition and physical properties of each example. Unless otherwise specified, the content of each component is expressed in cation percentages.

[0161] [Table 1]

[0162] [Table 2]

[0163] [Table 3]

[0164] [Table 4]

[0165] Based on the above, it was confirmed that large glass gobs can be stably produced according to the manufacturing method of each embodiment, and that the resulting optical glass possesses a high level of high refractive index, low dispersion, and resistance to devitrification. [Explanation of Symbols]

[0166] 1…Glass manufacturing equipment, 101…Stage, 102·111·112·113·114·121·122·123·124:Holding member, 103…Laser light source, 104·105…Mirror, 106…Infrared thermometer, 107…Computer, 108…CCD camera, 109…Monitor, 110…Gas flow regulator, 1020·1110·1120·1130·1140·1210·1220·1230·1240:Concave surface, 1022·1022a·1022b·1022c·1022d·1112·1122·1132·1142…Inlet, 1 024·1024a·1024b·1024c·1024d·1024x·1024y·1114·1124·1134·1144·1149a·1224… Nozzle, 1126: Non-porous part, 1128: Porous part, 1136·1138·1141·1149: Components, H: Maximum depth, S1… First surface, S2… Second surface, S3… Side surface, L… Laser beam, M… Sample, O… Center point, C1… First circle, C2… Second circle, C3… Third circle, P1: First region, P2: Second region, J1·J2·Q1·Q2: Part, R·R1·R2·R3: Radius

Claims

1. A holding member used in a glass manufacturing apparatus that produces glass by cooling glass raw materials that have been suspended by gas and heated and melted, The holding member has a gas injection surface having a plurality of injection ports for injecting the gas, The gas injection surface has a first region having a first injection port which is a part of the plurality of injection ports, and a second region having a second injection port which is different from the first injection port among the plurality of injection ports. The first region is located inside the second region in a top view of the gas injection surface. The area of ​​the nozzle per unit area of ​​the first region is smaller than the area of ​​the nozzle per unit area of ​​the second region. The area of ​​the nozzle per unit area of ​​the first region is the ratio of the sum of the cross-sectional areas of the first nozzle to the area of ​​the first region when the gas injection surface is viewed from above. The area of ​​the injection nozzle per unit area of ​​the second region is the ratio of the sum of the cross-sectional areas of the second injection nozzle to the area of ​​the second region when the gas injection surface is viewed from above. Retaining member.

2. A holding member used in a glass manufacturing apparatus that produces glass by cooling glass raw materials that have been suspended by gas and heated and melted, The holding member has a gas injection surface having a plurality of injection ports for injecting the gas, The gas injection surface has a first region having a first injection port which is a part of the plurality of injection ports, and a second region having a second injection port which is different from the first injection port among the plurality of injection ports. The first region is located inside the second region in a top view of the gas injection surface. The number of injection ports per unit area of ​​the first region is less than the number of injection ports per unit area of ​​the second region. The number of injection ports per unit area of ​​the first region is the ratio of the number of first injection ports to the area of ​​the first region when the gas injection surface is viewed from above. The number of injection ports per unit area of ​​the second region is the ratio of the number of second injection ports to the area of ​​the second region when the gas injection surface is viewed from above. Retaining member.

3. The area of ​​the nozzle per unit area of ​​the first region is smaller than the area of ​​the nozzle per unit area of ​​the second region. The area of ​​the nozzle per unit area of ​​the first region is the ratio of the sum of the cross-sectional areas of the nozzles in the first region to the area of ​​the first region when the gas injection surface is viewed from above. The area of ​​the nozzle per unit area of ​​the second region is the ratio of the sum of the cross-sectional areas of the nozzles in the second region to the area of ​​the second region when the gas injection surface is viewed from above. The retaining member according to claim 2.

4. The ratio (W1 / W2) of the area of ​​the nozzle per unit area of ​​the first region (W1) to the area of ​​the nozzle per unit area of ​​the second region (W2) is 0.05 to 0.

7. The retaining member according to claim 1 or 3.

5. The ratio (T1 / T2) of the number of injection nozzles per unit area of ​​the first region (T1) to the number of injection nozzles per unit area of ​​the second region (T2) is 0.05 to 0.

5. The retaining member according to any one of claims 2 to 4.

6. A holding member used in a glass manufacturing apparatus that produces glass by cooling glass raw materials that have been suspended by gas and heated and melted, The holding member has a gas introduction surface having an inlet for introducing the gas, and a gas injection surface having a plurality of injection ports for injecting the gas introduced from the gas introduction surface. The gas injection surface has a first region having a first injection port which is a part of the plurality of injection ports, and a second region having a second injection port which is different from the first injection port among the plurality of injection ports. The first region is located inside the second region in a top view of the gas injection surface. The gas introduction surface is a retaining member having a convex shape.

7. The holding member comprises a first portion surrounded by a plane including a straight line drawn perpendicularly from the first region to the gas introduction surface, and a second portion surrounded by a plane including a straight line drawn perpendicularly from the second region to the gas introduction surface. The thickness of the first portion, which is the length of a straight line drawn from a point in the first region to the gas introduction surface in the direction of gravity, has a portion that is thicker than the thickness of the second portion, which is the length of a straight line drawn from a point in the second region to the gas introduction surface in the direction of gravity. The retaining member according to claim 6.

8. The ratio (K2 / K1) of the average thickness of the second portion (K2) to the average thickness (K1) of the first portion is preferably 0.5 to 0.

95. The retaining member according to claim 7.

9. The average thickness (K1) of the retaining member between the first region and the gas introduction surface is greater than the average thickness (K2) of the retaining member between the second region and the gas introduction surface. The retaining member according to claim 6.

10. The ratio (K2 / K1) of the average thickness (K2) of the retaining member between the second region and the gas introduction surface to the average thickness (K1) of the retaining member between the first region and the gas introduction surface is 0.5 to 0.

95. The retaining member according to claim 9.

11. A holding member used in a glass manufacturing apparatus that produces glass by cooling glass raw materials that have been suspended by gas and heated and melted, The holding member has a gas introduction surface having an inlet for introducing the gas, and a gas injection surface including a first region having a plurality of injection ports for injecting the gas introduced from the gas introduction surface, and a second region having injection ports for injecting the gas. The first region is located inside the second region in a top view of the gas injection surface. The holding member comprises a first portion surrounded by a plane including a straight line drawn perpendicularly from the first region to the gas introduction surface, and a second portion surrounded by a plane including a straight line drawn perpendicularly from the second region to the gas introduction surface. A retaining member having a portion in which the thickness of the first portion, which is the length of a straight line drawn from a point in the first region to the gas introduction surface in the direction of gravity, is greater than the thickness of the second portion, which is the length of a straight line drawn from a point in the second region to the gas introduction surface in the direction of gravity.

12. The ratio (K2 / K1) of the average thickness of the second portion (K2) to the average thickness (K1) of the first portion is preferably 0.5 to 0.

95. The retaining member according to claim 11.

13. A holding member used in a glass manufacturing apparatus that produces glass by cooling glass raw materials that have been suspended by gas and heated and melted, The holding member has a gas introduction surface having an inlet for introducing the gas, and a gas injection surface including a first region having a plurality of injection ports for injecting the gas introduced from the gas introduction surface, and a second region having injection ports for injecting the gas. The first region is located inside the second region in a top view of the gas injection surface. A retaining member wherein the average thickness (K1) of the retaining member between the first region and the gas introduction surface is greater than the average thickness (K2) of the retaining member between the second region and the gas introduction surface.

14. The ratio (K2 / K1) of the average thickness (K2) of the retaining member between the second region and the gas introduction surface to the average thickness (K1) of the retaining member between the first region and the gas introduction surface is 0.5 to 0.

95. The retaining member according to claim 13.

15. The area of ​​the nozzle per unit area of ​​the first region of the gas injection surface is smaller than the area of ​​the nozzle per unit area of ​​the second region in a top view of the gas injection surface. The retaining member according to any one of claims 6 to 14.

16. The area of ​​the nozzle per unit area of ​​the first region is the ratio of the sum of the cross-sectional areas of the nozzles in the first region to the area of ​​the first region when the gas injection surface is viewed from above. The area of ​​the nozzle per unit area of ​​the second region is the ratio of the sum of the cross-sectional areas of the nozzles in the second region to the area of ​​the second region when the gas injection surface is viewed from above. The retaining member according to claim 15.

17. The ratio (W1 / W2) of the area of ​​the nozzle per unit area of ​​the first region (W1) to the area of ​​the nozzle per unit area of ​​the second region (W2) is 0.05 to 0.

7. The retaining member according to claim 15 or 16.

18. The number of nozzles per unit area of ​​the first region of the gas injection surface is less than the number of nozzles per unit area of ​​the second region in a top view of the gas injection surface. The first region has a first injection port which is a part of the plurality of injection ports, The second region has a second injection port which is different from the first injection port among the plurality of injection ports, The number of injection ports per unit area of ​​the first region is the ratio of the number of first injection ports to the area of ​​the first region when the gas injection surface is viewed from above. The number of injection ports per unit area of ​​the second region is the ratio of the number of second injection ports to the area of ​​the second region when the gas injection surface is viewed from above. The retaining member according to any one of claims 6 to 17.

19. The ratio (T1 / T2) of the number of injection nozzles per unit area of ​​the first region (T1) to the number of injection nozzles per unit area of ​​the second region (T2) is 0.05 to 0.

5. The retaining member according to claim 18.

20. At least a portion of the retaining member is made of stainless steel (SUS), silicon carbide (SiC), alumina (Al ２ O ３ ), Zirconia (ZrO ２ ), including at least one selected from the group consisting of duralumin, copper (Cu), and carbon (C), The retaining member according to any one of claims 1 to 19.

21. The radius of the nozzle in the first region is 0.2 mm or less. The radius of the nozzle in the second region is 0.5 mm or less. The retaining member according to any one of claims 1 to 20.

22. At least a portion of the retaining member is porous. The retaining member according to any one of claims 1 to 19.

23. The holding member has a porous material, and the porosity of the porous material in the portion corresponding to the first region is lower than the porosity of the porous material in the portion corresponding to the second region. The retaining member according to any one of claims 1 to 22.

24. The retaining member includes, at least in part, a member made of a porous material and a member made of a metal material. The retaining member according to claim 22 or 23.

25. The pore size of the porous material is 100 μm or less. The retaining member according to any one of claims 22 to 24.

26. Gas is injected in a nearly horizontal direction, approximately perpendicular to the direction of gravity. The retaining member according to any one of claims 1 to 25.

27. The holding member has an injection nozzle above the gas injection surface that injects gas in a substantially horizontal direction substantially perpendicular to the direction of gravity. The retaining member according to any one of claims 1 to 26.

28. The gas injection surface is a substantially circular region when viewed from above the holding member. The retaining member according to any one of claims 1 to 27.

29. The first region is the region that includes the center or centroid in a top view of the gas injection surface. The retaining member according to any one of claims 1 to 28.

30. The first region is at least a part of a substantially circular region whose radius from the center point is r (r < R, where R is the radius of the gas injection surface when viewed from above), The second region is at least a part of a substantially annular region in which the radius of the inner circumference is greater than or equal to r when viewed from above the gas injection surface. The retaining member according to any one of claims 1 to 29.

31. The first region is at least a part of a substantially circular region in which, when viewed from above the gas injection surface, the radius from the center point is 0.2R or less with respect to the radius (R) of the gas injection surface. The second region is, in a top view of the gas injection surface, at least a portion of a substantially annular region. The radius of the inner circumference of the aforementioned substantially annular region is 0.2R or greater than the radius (R) of the gas injection surface. The retaining member according to any one of claims 1 to 30.

32. The radius of the outer circumference of the substantially annular region is 0.9R or less with respect to the radius (R) of the gas injection surface. The retaining member according to claim 31.

33. The first region is at least a part of a substantially circular region in a top view of the gas injection surface, where the radius from the center point is 0.2R or less relative to the radius (R) of the gas injection surface. The retaining member according to any one of claims 1 to 30.

34. The second region is, in a top view of the gas injection surface, at least a portion of a substantially annular region. The radius of the inner circumference of the aforementioned substantially annular region is 0.4R or greater than the radius (R) of the gas injection surface. The radius of the outer circumference of the substantially annular region is 0.9R or less with respect to the radius (R) of the gas injection surface. The retaining member according to any one of claims 1 to 31.

35. The first region is at least a part of a substantially circular region with a radius of 3 mm or less from the center point, as viewed from above the gas injection surface. The retaining member according to any one of claims 1 to 34.

36. The second region is, in a top view of the gas injection surface, at least a portion of a substantially annular region. The radius of the inner circumference of the aforementioned substantially annular region is 3 mm or more. The radius of the outer circumference of the aforementioned substantially annular region is 9 mm or less. The retaining member according to any one of claims 1 to 35.

37. The gas injection surface, when viewed from above, has a first circular region, a second circular region having a radius greater than or equal to the radius of the first circle, and a third circular region having a radius greater than the radius of the second circle, arranged concentrically. The first region is at least a portion of the region of the first circle, The second region is at least a part of the substantially annular region obtained by subtracting the region of the second circle from the region of the third circle. The retaining member according to any one of claims 1 to 36.

38. The second region is not adjacent to the first region. The retaining member according to any one of claims 1 to 37.

39. The gas introduction surface having an inlet for introducing the gas is provided on the side of the holding member or on the opposite side of the gas injection surface. The retaining member according to any one of claims 1 to 38.

40. Each of the multiple injection ports on the gas injection surface is in communication with one inlet. The retaining member according to claim 39.

41. At least one of the multiple injection ports of the gas injection surface is in communication with a plurality of inlet ports. The retaining member according to claim 39.

42. The radius (R) of the gas injection surface is 5 to 10 mm when viewed from above. The retaining member according to any one of claims 1 to 41.

43. The maximum depth (H) of the gas injection surface is 4 to 10 mm in cross-sectional view of the gas injection surface. The retaining member according to any one of claims 1 to 42.

44. A glass manufacturing apparatus comprising a holding member according to any one of claims 1 to 43.

45. A flotation step in which gas is blown onto the glass raw material from the nozzle of the holding member according to any one of claims 1 to 43 to suspend the glass raw material, A melting step in which the suspended glass raw material is melted by irradiating it with laser light, A method for manufacturing glass, comprising a cooling step of cooling the molten glass raw material.

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