Method for producing glass, method for producing optical glass, method for producing glass set, glass set, set of optical elements, set of optical devices, glass, optical element, optical device, and levitation molten glass

Abstract

Disclosed is a method for producing a glass that contains a plurality of components, the method including: a preparation step for preparing a starting material of the glass and a liquid dispersion medium so as to have a concentration of 80% or less in terms of percentage by mass; a first mixing step for mixing the starting material and the dispersion medium, which have been prepared in the preparation step, with each other by means of a mixing member so as to obtain a first mixture of the starting material; a second mixing step for mixing the first mixture after the start of drying of the first mixture so as to obtain a second mixture that is a dried particulate material; a starting material lump formation step for obtaining a plurality of starting material lumps from the second mixture; a heating step for heating the starting material lump so as to bring the starting material lump into a melt state; and a temperature lowering step for lowering the temperature of the starting material lump in the melt state, the starting material lump being supported in a non-contact manner.

Description

Glass manufacturing method, optical glass manufacturing method, glass set manufacturing method, glass set, optical element set, optical device set, glass, optical element, optical device, and floating molten glass

[0001] The present invention relates to a method for manufacturing glass, a method for manufacturing optical glass, a method for manufacturing a glass set, a glass set, a set of optical elements, a set of optical devices, glass, an optical element, an optical device, and a floating molten glass. This invention claims priority from International Application No. PCT / JP2023 / 046451 filed on December 25, 2023, the contents of which are incorporated herein by reference in designated states where incorporation by reference of documents is permitted.

[0002] For example, Patent Document 1 discloses a method for manufacturing optical glass using a laser levitation furnace. When manufacturing glass in such a laser levitation furnace, it is necessary to suppress variations in the performance of multiple glasses.

[0003] Japanese Patent Application Laid-Open No. 2014-196236

[0004] An aspect of the present invention is, for example, a method for producing glass containing multiple components, including: a blending step of blending the glass raw materials and a liquid dispersion medium to a concentration of 80% by mass or less; a first mixing step of mixing the raw materials and the dispersion medium blended in the blending step using a mixing member to obtain a first mixture of raw materials; a second mixing step of mixing the first mixture after drying of the first mixture has begun to obtain a second mixture that is a dried powder or granular material; a raw material lump preparation step of obtaining multiple raw material lump pieces from the second mixture; a heating step of heating the raw material lump to bring it into a molten state; and a cooling step of lowering the temperature of the raw material lump in a molten state that is supported in a non-contact manner.

[0005] Another aspect of the present invention is a method for producing an optical glass, which comprises producing an optical glass using the above-described method for producing glass.

[0006] Another aspect of the present invention is a method for manufacturing a glass set including a plurality of glasses, comprising: a mixing step of mixing raw materials for the glasses to obtain a raw material mixture; a raw material lump preparation step of obtaining a plurality of raw material lump from the raw material mixture; a heating step of heating the raw material lump to form a molten liquid; and a cooling step of cooling the raw material lump in a non-contact supported molten liquid state, wherein in the mixing step, the raw materials are mixed so that the standard deviation of the refractive index for the d line of the plurality of glasses is 0.0005 or less.

[0007] Another aspect of the present invention is a glass set including a plurality of glasses having a common composition, wherein the plurality of glasses are, in mol %, B ２ O ３ , SiO ２ , P ２ O ５ and As ２ O ３ The total content of (B ２ O ３ +SiO ２ +P ２ O ５ +As ２ O ３ ): 25% or less, Li ２ O.K. ２ O, Na ２ O, P ２ O ５ and B ２ O ３ The total content of (Li ２ O+K ２ O + Na ２ O+P ２ O ５ +B ２ O ３ ): 10% or less, La ２ O ３ , BaO, CaO, MgO, Y ２ O ３ , Gd ２ O ３ , Al ２ O ３ , TiO ２ , Nb ２ O ５ , ZrO ２ and Ta ２ O ５ Total content (La ２ O ３+BaO+CaO+MgO+Y ２ O ３ +Gd ２ O ３ +Al ２ O ３ + TiO ２ +Nb ２ O ５ + ZrO ２ +Ta ２ O ５ ): 70% or more, and the standard deviation of the refractive indexes of the plurality of glasses with respect to the d line is 0.0005 or less.

[0008] Another aspect of the present invention is a glass set including a plurality of glasses having a common composition, wherein the plurality of glasses have a partial dispersion ratio (P ｇ，Ｆ ) and Abbe number (ν ｄ ) is P ｇ，Ｆ ≦−0.0042×ν ｄ +0.7193 and the wavelength (λ ８０ ) and Abbe number (ν ｄ ) is λ ８０ ≦−10.253×ν ｄ +672.5, and the glass transition temperature T ｇ ≧780° C., the difference ΔT between the crystallization onset temperature and the glass transition temperature ≦230° C., and the standard deviation of the refractive indexes of the plurality of glasses with respect to the d line is 0.0005 or less.

[0009] Another aspect of the present invention is a set of optical elements having a plurality of optical elements each including a glass included in the glass set described above.

[0010] Another aspect of the invention is a set of optical devices having a plurality of optical devices each including an optical element included in the set of optical elements described above.

[0011] Another aspect of the present invention is a glass comprising, in mole percent, B ２ O ３ , SiO ２ , P ２ O ５ and As ２ O ３ The total content of (B ２ O ３ +SiO ２ +P ２O ５ +As ２ O ３ ): 25% or less, Li ２ O.K. ２ O, Na ２ O, P ２ O ５ and B ２ O ３ The total content of (Li ２ O+K ２ O + Na ２ O+P ２ O ５ +B ２ O ３ ): 10% or less, La ２ O ３ , BaO, CaO, MgO, Y ２ O ３ , Gd ２ O ３ , Al ２ O ３ , TiO ２ , Nb ２ O ５ , ZrO ２ and Ta ２ O ５ Total content (La ２ O ３ +BaO+CaO+MgO+Y ２ O ３ +Gd ２ O ３ +Al ２ O ３ + TiO ２ +Nb ２ O ５ + ZrO ２ +Ta ２ O ５ ): 70% or more, and the difference between the reference value of the refractive index for the d line specified for the glass and the refractive index for the d line of the glass is 0.0003 or less.

[0012] Another aspect of the present invention is a glass having a partial dispersion ratio (P ｇ，Ｆ ) and Abbe number (ν ｄ ) is P ｇ，Ｆ ≦−0.0042×ν ｄ +0.7193 and the wavelength (λ ８０ ) and Abbe number (ν ｄ) is λ ８０ ≦−10.253×ν ｄ +672.5, the glass transition temperature Tg≧780°C, the difference ΔT between the crystallization onset temperature and the glass transition temperature ΔT≦230°C, and the difference between the reference value of the refractive index at the d line specified for the glass and the refractive index at the d line of the glass is 0.0003 or less.

[0013] Another aspect of the present invention is an optical element comprising the glass described above.

[0014] Another aspect of the present invention is an optical device including the optical element described above.

[0015] Another aspect of the present invention is a glass set including a plurality of floating molten glasses having a common composition, wherein the standard deviation of the refractive index of the plurality of floating molten glasses with respect to the d-line is 0.0005 or less.

[0016] Another aspect of the present invention is a floating molten glass, wherein the difference between the refractive index of the floating molten glass at the d line and the reference value of the refractive index at the d line specified for the floating molten glass is 0.0003 or less.

[0017] FIG. 1 is a schematic diagram of a glass manufacturing apparatus equipped with a levitation furnace including a holding member according to one embodiment of the present invention. FIG. 2 is a flowchart showing an example of a manufacturing process of levitated molten glass according to one embodiment of the present invention. FIG. 3 is a perspective view of an example of an optical device according to each embodiment as an imaging device. FIG. 4 is a front view of another example of an optical device according to each embodiment as an imaging device. FIG. 5 is a rear view of another example of an optical device according to each embodiment as an imaging device. FIG. 6 is a block diagram showing an example of an optical device according to each embodiment as a multiphoton microscope. FIG. 7 is a schematic view showing an example of a cemented lens according to each embodiment.

[0018] An embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described below. The present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content.

[0019] In the drawings, the same elements are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, unless otherwise specified, the positional relationships, such as up, down, left, and right, are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0020] Furthermore, terms with "abbreviation" attached indicate the meaning of the term excluding "abbreviation" within the scope of common general technical knowledge of a person skilled in the art, and also include the meaning itself excluding "abbreviation." The same is true vice versa. For example, the term "circle" does not have "abbreviation" attached, but naturally includes the meaning of "approximately circle" as long as it does not contradict the gist of the invention.

[0021] <Overview of Glass Manufacturing Apparatus 10>

[0022] 1 is a schematic diagram of a glass manufacturing apparatus 10 equipped with a levitation furnace according to this embodiment. Note that levitating a sample U by a levitation unit 21 (described later) is also referred to as supporting the sample U in a non-contact manner.

[0023] As shown in FIG. 1 , glass manufacturing apparatus 10 is an optical glass manufacturing apparatus equipped with a gas jet levitation furnace. Glass manufacturing apparatus 10 produces glass by heating and melting glass raw materials while levitating the glass raw materials using a gas. Glass manufacturing apparatus 10 includes a levitation furnace including a support member 12 that blows gas onto a sample U containing glass raw materials to levitate the sample U, a laser light source 13 that irradiates the levitated sample U with laser light L, a radiation thermometer 16 that measures the temperature of the levitated sample U, a computer 17 that has a control unit (not shown) that controls the output of laser light source 13 based on temperature information from radiation thermometer 16, and a gas flow regulator 20 that adjusts the flow rate of gas supplied to support member 12. Support member 12 and gas flow regulator 20 are included in a levitation unit 21 that levitates sample U.

[0024] In the glass manufacturing apparatus 10, a sample U is placed on a support member 12 arranged on a stage 11, and then a gas is blown onto the sample U to levitate it. The sample U is a lump of raw material formed from a glass raw material, and the levitation unit 21 levitates one or more samples U. Thereafter, the sample U floating above is heated in a non-contact manner by irradiation with laser light L. As a result, the sample U melts and becomes a molten liquid having a substantially spherical or substantially ellipsoidal shape due to its own surface tension, and floats in that state.

[0025] A known heating method can be used for non-contact heating of the sample U. In the glass manufacturing apparatus shown in FIG. 1 , this is achieved by irradiating the sample U with laser light L emitted from a laser light source 13 via mirrors 14 and 15. The temperature of the sample U heated by irradiation with the laser light L is monitored by a radiation thermometer 16. The output of the laser light source 13 is controlled by a computer 17 based on temperature information of the sample U monitored by the radiation thermometer 16. In addition, an image of the state of the sample U is captured by a CCD camera 18, and the image is output to a monitor 19. The laser light source 13 is not particularly limited, and examples thereof include a carbon dioxide laser, a semiconductor laser, a fiber laser, and a YAG laser.

[0026] The flow rate of the gas fed into the support member 12 is controlled by a gas flow regulator 20. 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. The shape of the nozzle (not shown) connected to the support member 12 is not particularly limited, and any known method can be used as appropriate.

[0027] After the stably levitated sample U is heated non-contact, the laser light L is shut off. As a result, the sample U, which is a molten lump of raw material, cools and solidifies, yielding optical glass. The glass obtained in this manner is called levitation melt glass. It can then be processed into the desired shape and polished as necessary to produce the desired optical element.

[0028] Furthermore, for example, the support member 12 may levitate the sample U using static electricity. In this case, the glass manufacturing apparatus 10 does not have the gas flow rate regulator 20, but instead has an electrostatic device (not shown) that charges the sample U. The support member 12 can levitate the sample U, for example, placed between one to multiple pairs of electrodes that constitute the electrostatic device, using static electricity. Note that the method by which the support member 12 levitates the sample U is not limited to the above example, and may be, for example, an electromagnetic method, an acoustic method, a magnetic method, or the like.

[0029] When a plurality of optical glasses are manufactured using glass manufacturing apparatus 10, variations in the composition of the raw material lump will result in individual differences in the resulting optical glasses. In this embodiment, in order to suppress variations in the performance of the plurality of optical glasses, a plurality of raw material lump is manufactured by a predetermined method.

[0030] <Float molten glass manufacturing process> FIG. 2 is a flowchart showing an example of a float molten glass manufacturing process according to one embodiment of the present invention.

[0031] First, the specified raw materials are weighed and dispersed in a liquid dispersion medium to produce a mixture, i.e., a slurry (Step S1: Blending Process). Here, combining the specified raw materials and the liquid dispersion medium is referred to as "blending." While any desired liquid, such as water or ethanol, can be used as the dispersion medium, water is preferred to avoid aggregation of the raw material powder and granular material and to account for the polarity of the oxides. Furthermore, if the concentration of the slurry produced in this process is too high, the raw materials will not disperse evenly in the dispersion medium, resulting in poor optical glass performance. Therefore, the raw material content is preferably 80% by mass or less. The raw material content may also be 78% by mass or less, or 75% by mass or less. While there is no particular lower limit for the slurry concentration, a concentration of 5% or more is desirable from the perspective of productivity. Here, "mass %" refers to the "mass of the raw materials" divided by the "sum of the mass of the raw materials and the mass of the dispersion medium." The raw materials are solids, and are those typically used as raw materials for glass, such as oxides, hydroxides, phosphate compounds (phosphates, orthophosphates, etc.), carbonates, or nitrates. Therefore, when preparing a system containing multiple components, even if multiple slurries in which raw materials and liquid dispersion media are mixed in advance are combined into one, the mass of the raw materials is calculated as the mass of the solid portion.

[0032] Next, the raw materials prepared in the blending step and the dispersion medium are mixed using a mixing element to obtain a slurry in which the raw materials are dispersed (step S2: mixing step). Because optical glass is composed of multiple components, it is necessary to mix the raw materials uniformly. The mixing element may be a separate component installed inside the container containing the slurry, or a component protruding inward from the inner wall of the container. Mixing through the mixing element causes the raw material particles to collide with the mixing element, crushing the raw material particles into smaller particles. This allows the raw materials to be more uniformly dispersed in the dispersion medium, and one of the benefits is reduced performance variation between individual pieces of optical glass. As an example, the slurry is placed in a ball mill and mixed to uniformly disperse the raw materials in the liquid. In this example, resin balls with a diameter of 10 mm or more and the slurry are placed in the ball mill, and the slurry is mixed.

[0033] As another example, the slurry is mixed using a bead mill. In this example, spherical beads with a diameter of, for example, 1 mm or less and the slurry are placed in the bead mill, and the slurry is mixed. When using a ball mill or bead mill, one of the mixing elements can be a plurality of balls. When using a plurality of balls, the diameter of the balls is not particularly limited, and an appropriate diameter can be selected from a range of 1 mm or less to 10 mm or more. As another example, the slurry is mixed using a stirrer. In this example, a stirring blade is placed in a container containing the slurry, and the slurry is mixed by driving the stirring blade. The slurry can also be mixed using a stirrer with a stirring blade attached to the inside of the container. Note that the method of mixing the slurry is not limited to this example.

[0034] In this embodiment, the inner surface of the container and the mixing member can be made of resins such as polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), nylon, polyethylene, and polypropylene, or ceramics such as alumina and zirconia. Furthermore, in the mixing process, the raw materials and the dispersion medium must be mixed for a sufficient period of time. For example, it is desirable to mix the raw materials and the dispersion medium for at least one hour. A dispersant may be added during the mixing process. The type of dispersant is not particularly limited, and an anionic or nonionic polymeric dispersant may be used. Furthermore, a dispersion aid may be added during the mixing process. After mixing, the mixing member is removed from the slurry. For example, if the slurry is mixed using a ball mill or a bead mill, the balls or beads are removed from the slurry by suction filtration. The mixing time may be 24 hours or more, 48 hours or more, or 60 hours or more, as needed.

[0035] Next, the slurry obtained in the mixing step is dried (Step S3: Drying Step). As an example, the slurry is placed in one or more containers and left to dry. As another example, the slurry is placed in a centrifuge and dried by centrifugation. As another example, the slurry is freeze-dried by freezing. As yet another example, the slurry is sprayed into hot air and instantly dried (spray drying). Note that, when the mixing members are removed by suction filtration in the mixing step, the slurry may be dried by separating the water and solids by the suction filtration. The solid obtained after the drying step is referred to as a cake. At least a portion of the cake is lumpy.

[0036] Next, the cake obtained in the drying step is pulverized (step S4: pulverization step). The method used for pulverizing the cake is not particularly limited as long as it can pulverize the cake, and any method can be used. For example, the cake is pulverized into powder particles using a pulverizing device such as a stone mill (mass colloider), a jaw crusher, an electric mortar, or a pulverizing mill having two-stage blades, horizontal blades, or screw blades. This step improves the moldability of the raw material mass and also disperses the raw material powder particles more evenly. The drying step and the pulverization step may be performed in parallel by using equipment such as a rotary evaporator.

[0037] Next, multiple raw material blocks are obtained from the powder produced by the grinding process (step S5: raw material block preparation process). Specifically, multiple units of powder corresponding to one raw material block are weighed out from the powder obtained in step S4, and the resulting mixture is pressurized to form multiple raw material blocks. Alternatively, the raw material blocks may be sintered to form multiple raw material blocks. Sintering allows gases generated during the thermal decomposition process of the compounds in the raw material to be volatilized in advance, thereby suppressing the generation of glass bubbles. Sintering also makes the raw material block harder and less likely to break, thereby suppressing weight fluctuations due to, for example, cracking or chipping of the raw material block during handling.

[0038] Alternatively, a desired amount of powder or grain may be pressed into a block and then crushed to obtain multiple raw material blocks. Alternatively, at least a portion of the block of raw material may be crystallized to obtain an aggregate of crystals having the same composition as the desired glass, which serves as the multiple raw material blocks.

[0039] Next, the raw material lump is heated to a molten state (step S6: heating step). For example, as described above, one raw material lump is placed on the support member 12, and gas is blown onto it to levitate it and support it in a non-contact manner. The non-contact supported raw material lump is heated and melted by irradiating it with laser light L. Note that when a single optical glass is obtained from multiple raw material lump, multiple raw material lump may be heated. Note that the raw material lump may be heated before or after it begins to levitate.

[0040] Next, the non-contact supported molten lump of raw material is cooled to obtain optical glass (step S7: cooling step). For example, by stopping the irradiation of the laser light L, the heating of the levitated lump of raw material is stopped and the lump of raw material is cooled. Note that in this step, the levitation of the lump of raw material may be stopped before the cooling is completed.

[0041] In this embodiment, in the raw material lump preparation process performed after the pulverization process, the powder obtained in the pulverization process is weighed, and multiple units of powder corresponding to one raw material lump are weighed out. However, the raw material lump preparation process may also be performed after the mixing process. In this case, multiple units of slurry, each equivalent to one raw material lump, are weighed out from the slurry obtained in the mixing process, and each weighed slurry is dried. Thereafter, the raw material is formed into a lump and sintered to obtain a raw material lump without going through the pulverization process of step S4. In other words, it can be said that the drying process is performed in the raw material lump preparation process. Note that the weighed slurry may be dried and then the resulting cake may be pulverized.

[0042] In addition, when melting glass raw materials by adding them to a container such as a crucible without using a levitation furnace, even if the raw materials are not completely homogenized by sufficient mixing before addition, they may be homogenized by stirring during melting. Furthermore, in the case of a composition system that requires high temperature heating, components of the container may dissolve, resulting in the incorporation of impurities. As shown in this embodiment, the incorporation of impurities can be suppressed by levitating the raw material blocks and melting them in a non-contact state. However, since the structure for levitating the raw material blocks limits the size of the raw material blocks that can be melted at one time, a technique for preventing variations in the composition among multiple raw material blocks is required. In other words, when melting using a container such as a crucible, homogenization may be possible even in the molten state. However, in this embodiment, in order to prevent variations in the composition among the raw material blocks, a technique for uniformly mixing the raw materials (e.g., in a powder state) before forming a melt is required.

[0043] This embodiment makes it possible to suppress variations in the components among a plurality of raw material chunks, thereby suppressing variations in the performance of optical glass produced using the raw material chunks.

[0044] As described above, the grinding step (step S4) results in the raw material powder particles being mixed to a more uniform state. In other words, this step can also be considered a second mixing step when using equipment for grinding and mixing raw materials. The mixture (referred to as the first mixture) obtained as a result of the mixing step (step S2) (also referred to as the first mixing step) is in a slurry state. On the other hand, the mixture (referred to as the second mixture) obtained as a result of the second mixing step is, for example, a dried powder particle. As described above, in the first mixing step, the raw materials are mixed in a slurry state using a mixing element, thereby obtaining a first mixture in a slurry state in which the raw material components are uniformly dispersed. If the obtained first mixture is subjected to static drying, for example, in a drying step, differences in the settling speed of the components may result in uneven components between the upper and lower parts of the cake after static drying. If the first mixture dried in this manner is used in the raw material block preparation step S5 without going through the second mixing step, variations in the components may occur among the prepared raw material blocks, resulting in variations in the performance of the resulting glass. By performing the second mixing step, a second mixture with uniform components can be obtained in a dry powder state, and by using the second mixture to prepare raw material blocks, the occurrence of variations in the components among the raw material blocks can be suppressed, and variations in the performance of the resulting glass can be further suppressed. Note that mixing in the second mixing step refers to the application of some kind of force for the purpose of uniformly distributing the components.

[0045] For example, after the drying step (step S3), in the second mixing step (i.e., the grinding step: step S4), the dried first mixture, which is a powder or granule, can be mixed using equipment such as a mass colloider, an (electric) mortar, or an (electric) mill to obtain a second mixture. Furthermore, for example, in the second mixing step after the drying step (step S3), a plurality of equipments with different functions may be used, such as grinding the first mixture with a jaw crusher and then stirring with an electric mill. Note that in the second mixing step, mixing may be performed using a mixing element, as in the first mixing step, or mixing may be performed without using a mixing element by rotating a container, for example.

[0046] Additionally, when using a mass colloider, (electric) mortar, (electric) mill, etc., or when placing cake or powder or granular materials in a container and shaking the container, forces are applied to the cake or powder or granular materials in directions other than the direction of crushing (the direction in which the cake or powder or granular materials are crushed or the direction in which the cake or powder or granular materials collide), and the powder or granular materials can move in the direction in which they mix, so it can be said that this is a processing method with mixing capabilities. On the other hand, a jaw crusher is a device that clamps the cake between moving teeth and crushes it sequentially, and applies force mainly in the direction in which the cake is clamped, so the crushed powder or granular materials do not move easily in the direction in which they mix, or the crushed powder or granular materials gradually escape from the moving teeth before they mix, so this is a processing method that has the ability to crush cake but not the ability to mix powder or granular materials. Even when a cake placed on a horizontal surface is crushed vertically, the crushed powder particles are unlikely to move in a direction that allows them to mix, so this processing method has the ability to crush the cake but does not have the ability to mix the powder particles. When using such a processing method that does not have the ability to mix the powder particles, the second mixing step can be carried out by also using a processing method that has the ability to mix the powder particles.

[0047] Additionally, as described above, in this embodiment, the drying step (step S3) and the second mixing step (i.e., the pulverization step: step S4) may be performed in parallel. In other words, in the second mixing step, the first mixture may be mixed after the start of drying of the first mixture to obtain the second mixture. As described above, as an example, by using a rotary evaporator for the first mixture, the drying step (step S3) and the second mixing step (step S4), which is mixing of the first mixture, may be performed in parallel. As another example, in the second mixing step, after the start of the drying step (step S3) and before the end of drying, the first mixture may be transferred to another device and mixed while drying, thereby obtaining the second mixture.

[0048] As explained above, examples of processing methods capable of mixing include a mass colloider, an (electric) mortar, an (electric) mill, a rotary evaporator, and a method of rotating a container containing a cake or powder or granular material. In other words, an example of a processing method capable of mixing is a method using equipment in which a member that comes into contact with the powder or granular material or the cake-shaped first mixture is driven to rotate. Note that the processing method in the second mixing step is not limited to the one described here, as long as the final second mixture is a dry powder or granular material in which the components are uniformly mixed.

[0049] <Glass Composition and Properties> The glasses manufactured by this embodiment have a common composition. A common composition means, for example, that the content of each component differs by within 1% in mol %. This embodiment can be applied to the manufacture of glass of a desired composition, but there are compositions that can be more suitably manufactured by this embodiment. The glasses have a composition of B in mol %. ２ O ３ , SiO ２ , P ２ O ５ and As ２ O ３ The total content of (B ２ O ３ +SiO ２ +P ２ O ５ +As ２ O ３ ): 25% or less, more preferably 20% or less, and even more preferably 15% or less. Such a composition tends to cause problems such as crystallization when melting glass raw materials in contact with a container such as a crucible, making vitrification difficult. On the other hand, in this embodiment, in which the raw material mass is suspended and melted in a non-contact state, vitrification is easier than when a container such as a crucible is used, and this composition can improve productivity.

[0050] In addition, the plurality of glasses manufactured according to this embodiment each contain Li ２ O.K. ２ O, Na ２ O, P ２ O ５ and B ２ O３ The total content of (Li ２ O+K ２ O + Na ２ O+P ２ O ５ +B ２ O ３ ): 10% or less is preferable, 5% or less is more preferable, and 3% or less is even more preferable.

[0051] La ２ O ３ , BaO, CaO, MgO, Y ２ O ３ , Gd ２ O ３ , Al ２ O ３ , TiO ２ , Nb ２ O ５ , ZrO ２ and Ta ２ O ５ Total content (La ２ O ３ +BaO+CaO+MgO+Y ２ O ３ +Gd ２ O ３ +Al ２ O ３ + TiO ２ +Nb ２ O ５ + ZrO ２ +Ta ２ O ５ ): is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. Such a composition tends to cause problems such as crystallization when melting glass raw materials in contact with a container such as a crucible, making vitrification difficult. Therefore, in this embodiment, in which the raw material mass is floated and melted in a non-contact state, vitrification is easier than when a container such as a crucible is used, and this composition can improve productivity.

[0052] The glass produced according to this embodiment contains, in mol %, Li ２ O.K. ２ O, Na ２ O, P ２ O ５ , B ２ O３ , W.O. ３ and As ２ O ３ The total content of (Li ２ O+K ２ O + Na ２ O+P ２ O ５ +B ２ O ３ +WO ３ +As ２ O ３ ) is preferably 10% or less, more preferably 5% or less, even more preferably 3% or less, and even more preferably substantially free. "Substantially free" means that the content is equal to or less than the level of an impurity, and specifically, for example, 100 ppm or less.

[0053] When melting glass, the glass raw materials can reach a temperature of around 1500°C. ２ O.K. ２ O, Na ２ O, P ２ O ５ , B ２ O ３ , W.O. ３ and As ２ O ３ The gasification of the contained components occurs by sublimation or boiling at a relatively low temperature. When the contained components gasify, the composition in the glass becomes non-uniform, which causes variations in performance (for example, striae) at different positions in a single glass. ２ O.K. ２ O, Na ２ O, P ２ O ５ , B ２ O ３ , W.O. ３ and As ２ O ３ By carrying out the manufacturing according to this embodiment with the total content within this range, it is possible to suppress not only the variation in performance between glasses but also the variation in performance within each glass. ２ O, Na ２ O, P ２ O ５are known to sublime at relatively low temperatures of 1275°C, 350°C, and 350°C, respectively. ２ O ３ , W.O. ３ , As ２ O ３ are known to reach their boiling points at relatively low temperatures of 1800°C, 1837°C, and 465°C, respectively.

[0054] Furthermore, the standard deviation of the refractive indexes of the plurality of glasses at the d line (587.56 nm) is preferably 0.0005 or less. The standard deviation of the refractive indexes of the plurality of glasses at the d line is more preferably 0.0003 or less, and even more preferably 0.0002 or less. Furthermore, the standard value can be set so that the difference in the refractive indexes of the plurality of glasses at the d line compared with the standard value indicated in a catalog, specification, or the like is 0.0003 or less.

[0055] Furthermore, the standard deviation of the Abbe numbers of the plurality of glasses is preferably 0.03 or less. The standard deviation of the Abbe numbers of the plurality of glasses is more preferably 0.01 or less. Furthermore, the standard value can be set so that the difference in the Abbe numbers of the plurality of glasses compared with the standard value indicated in a catalog, specification, or the like is equal to or less than the standard value of the Abbe numbers × 0.005.

[0056] Each of the plurality of glasses has a partial dispersion ratio (P ｇ，Ｆ ) and Abbe number (ν ｄ ) is P ｇ，Ｆ ≦−0.0042×ν ｄ It is preferable that the wavelength (λ ) at which the transmittance is 80% or less is satisfied. ８０ ) and Abbe number (ν ｄ ) is λ ８０ ≦−10.253×ν ｄ +672.5, and the glass transition temperature T ｇ≧780°C, and the difference ΔT between the crystallization onset temperature and the glass transition temperature ≦230°C. Glasses with such physical properties tend to encounter problems such as crystallization when the glass raw materials are melted in contact with a container such as a crucible, making vitrification difficult. Therefore, in this embodiment, in which the raw material mass is suspended and melted in a non-contact state, vitrification is easier than when a container such as a crucible is used, and productivity can be improved. A glass set is composed of at least three of the plurality of glasses.

[0057] Furthermore, the standard values ​​of each of the plurality of glasses are shown in a catalog, specification, or the like. The difference between the Abbe number of each of the plurality of glasses and the standard value is preferably not more than the standard value of the Abbe number × 0.005, more preferably not more than the standard value of the Abbe number × 0.003, and even more preferably not more than the standard value of the Abbe number × 0.002. The difference between the refractive index of each of the plurality of glasses and the standard value is preferably not more than 0.0003, more preferably not more than 0.0002, and even more preferably not more than 0.0001.

[0058] Examples Next, each example will be described, but the present invention is not limited to the following examples in any way.

[0059] Example 1 First, oxide raw materials described separately were weighed to achieve a predetermined chemical composition, and 100 g of raw materials and 50 g of a dispersion medium were mixed to obtain a slurry. Water was used as the dispersion medium. The slurry was then placed in a ball mill and mixed for 72 hours. Next, the mixed slurry was allowed to stand and dried, and the resulting cake was pulverized using a stone mill (mass colloider). After pulverization, powder equivalent to seven raw material blocks was weighed out, pressed, and sintered to obtain raw material blocks. The powder was weighed so that each glass block weighed 4,200 mg. Each of the seven raw material blocks was placed on the support member 12 of the glass manufacturing apparatus 10. The raw material blocks were then melted by irradiating them from above with a carbon dioxide laser while injecting air. The molten raw material blocks assumed a roughly spherical shape due to their own surface tension and were suspended in a floating state due to the gas pressure. Finally, when the raw materials were completely melted, the laser output was shut off to cool the mixture, yielding seven glasses. The refractive index of each of the seven glasses was measured by the minimum deviation method using a precision refractive index measuring instrument ("Spectro Master HR" manufactured by TRIOPTICS) (refractive index measurement precision: ±0.000001).

[0060] Example 2 The raw materials described below were weighed and mixed in the same manner as in Example 1 to obtain a slurry. The slurry was then mixed using a ball mill in the same manner as in Example 1, and the cake obtained by leaving it to dry was pulverized in an automatic mortar. After pulverization, powder equivalent to three raw material chunks was weighed out, and raw material chunks were obtained in the same manner as in Example 1. Glass was then produced in the same manner as in Example 1, and the refractive index was measured using the minimum deviation method. The Abbe number of the produced glass was calculated from the measured refractive index.

[0061] Example 3 The raw materials described below were weighed, and three pieces of glass were obtained in the same manner as in Example 2. The powder and granular materials were weighed so that the weight per piece of glass was 3,500 mg. Thereafter, the Abbe number was measured in the same manner as in Example 2. The obtained glass was processed into a 90-degree prism, and the refractive index was measured by the V-block method using a refractive index measuring instrument (KPR-3000 manufactured by Kalnew Optical Co., Ltd.) (refractive index measurement accuracy: ±0.00002).

[0062] Example 4 The raw materials described below were weighed, and six pieces of glass were obtained in the same manner as in Example 2. The powder and granules were weighed so that the weight of each piece of glass was 3,500 mg. The refractive index and Abbe number were measured in the same manner as in Example 3.

[0063] Example 5 The raw materials described below were weighed and mixed in the same manner as in Example 1 to obtain a slurry. The slurry was then placed in a bead mill and mixed for 1 hour. The mixed slurry was then placed in a rotary evaporator, where drying and cake crushing were carried out in parallel. After crushing, 10 glass pieces were obtained in the same manner as in Example 1. The powder and granules were weighed so that the weight of each glass piece was 600 mg. The refractive index and Abbe number were measured in the same manner as in Example 2.

[0064] Example 6: The oxide raw materials described below were weighed to obtain a predetermined chemical composition, and 100 g of the raw materials and 40 g of a dispersion medium were mixed to obtain a slurry. Water was used as the dispersion medium. Three pieces of glass were then obtained from the powder obtained in the same manner as in Example 2 in the same manner as in Example 1. The powder was weighed so that each piece of glass weighed 4200 mg. The refractive index and Abbe number were then measured in the same manner as in Example 3.

[0065] Example 7: The oxide raw materials described separately were weighed to achieve a predetermined chemical composition, and the raw materials and the dispersion medium were mixed at a mixing ratio of 5.4% to obtain a slurry. Water was used as the dispersion medium. The cake obtained by leaving the mixture to dry was then crushed in an automatic mortar in the same manner as in Example 2, and three pieces of glass were obtained in the same manner as in Example 1. The powder was weighed so that each piece of glass weighed 4200 mg. The refractive index and Abbe number were then measured in the same manner as in Example 3.

[0066] Comparative Example 1: The oxide raw materials described below were weighed to obtain a predetermined chemical composition, and 100 g of the raw materials and 20 g of a dispersion medium were mixed to obtain a slurry. Water was used as the dispersion medium. The slurry was then mixed using a ball mill in the same manner as in Example 1, but the slurry solidified and lost its fluidity when removed. The solidified sample was heated and melted in the same manner as in Example 1, and then cooled, but did not crystallize to form a glass.

[0067] Comparative Example 2: The oxide raw materials described separately were weighed to achieve a predetermined chemical composition. The raw materials were placed in a ball mill without adding a dispersion medium and mixed for 72 hours. Subsequently, without performing the drying and pulverization processes, powder equivalent to four raw material blocks was weighed out, pressed, and sintered to obtain raw material blocks. The powder was weighed so that each glass block weighed 4,200 mg. Four glasses were then produced using the same method as in Example 1, and their refractive indices were measured using the V-block method. The Abbe numbers of the produced glasses were also measured.

[0068] Comparative Example 3: The oxide raw materials described separately were weighed to achieve a predetermined chemical composition. The raw materials were placed in a mill without adding a dispersion medium and mixed for 72 hours. The mill used rotated the container containing the raw materials to mix the contents, and no mixing members such as balls or beads were added. Subsequently, powder equivalent to three raw material blocks was weighed out without performing the drying and grinding processes, and the powder was pressed and sintered to obtain raw material blocks. The powder was weighed so that the weight per glass block was 4200 mg. Three glasses were then produced using the same method as in Example 1, and the Abbe number and refractive index were measured using the same method as in Comparative Example 2.

[0069] Comparative Example 4 The raw materials described below were weighed and mixed in the same manner as in Example 1 to obtain a slurry. Then, the mixture was mixed for 72 hours using the same mill as in Comparative Example 3. Then, as in Example 2, the mixed slurry was left to dry to obtain a cake, which was then pulverized using an automatic mortar. After pulverization, powder equivalent to four raw material blocks was weighed out, and raw material blocks were obtained in the same manner as in Example 1. The powder was weighed so that the weight per glass block was 4200 mg. Then, four glasses were produced in the same manner as in Example 1, and the Abbe number and refractive index were measured in the same manner as in Comparative Example 1.

[0070] Comparative Example 5: The raw materials described separately were weighed and mixed to obtain a slurry in the same manner as in Example 1. The slurry was then placed in a ball mill, mixed for 72 hours, and allowed to dry to obtain a cake. Subsequently, without performing the pulverization step (i.e., the second mixing step), powder equivalent to four raw material blocks was weighed out, pressed, and sintered to obtain raw material blocks. The powder was weighed so that the weight per glass block was 4200 mg. Four glasses were then produced in the same manner as in Example 1, and the Abbe number and refractive index were measured in the same manner as in Comparative Example 1.

[0071] Comparative Example 6: The raw materials described below were weighed and mixed to obtain a slurry in the same manner as in Example 1. The slurry was then placed in a ball mill, mixed for 72 hours, and allowed to dry to obtain a cake. The cake was then crushed using a jaw crusher. The cake and powder were not mixed during the crushing process. Powder equivalent to four raw material blocks was then weighed, pressed, and sintered to obtain raw material blocks. The powder was weighed so that each glass block weighed 4200 mg. Four glasses were then produced using the same method as in Example 1, and the Abbe number and refractive index were measured using the same method as in Comparative Example 1.

[0072] The raw material compositions and physical properties of the resulting glasses in each example are shown in Tables 1 to 4. In addition, the standard deviation (σ) and the difference between the maximum and minimum values ​​were calculated for the refractive index and Abbe number of the glasses obtained in each example.

[0073]

[0074]

[0075]

[0076]

[0077] <Evaluation> According to Examples 1 to 7, by blending raw materials and a dispersion medium so that the raw materials account for 80% or less, and then producing a plurality of raw material blocks through a mixing process, a drying process, and a crushing process, it was confirmed that the standard deviation of the refractive index at the d line of the plurality of glasses produced from each of the raw material blocks was 0.0005 or less. In addition, the partial dispersion ratio (P ｇ，Ｆ) and Abbe number (ν ｄ ) is P ｇ，Ｆ ≦−0.0042×ν ｄ +0.7193 and the wavelength (λ ８０ ) and Abbe number (ν ｄ ) is λ ８０ ≦−10.253×ν ｄ +672.5, and it was confirmed that the glass transition temperature Tg≧780° C. and the difference ΔT between the crystallization onset temperature and the glass transition temperature ΔT≦230° C. It was also confirmed that the standard deviation of the Abbe numbers of the obtained glasses was 0.03 or less.

[0078] Furthermore, according to Examples 1 to 7, it was confirmed that by carrying out the second mixing step, glass having desirable physical properties can be obtained.

[0079] <Optical Elements, Optical Systems, Interchangeable Camera Lenses, Optical Devices, etc.> The optical glass obtained by the glass manufacturing apparatus 10 according to each embodiment can be suitably used, for example, as an optical element included in an optical instrument. Such optical elements include mirrors, lenses, prisms, filters, etc., and can be widely used as optical systems. The optical systems according to the present embodiments can be suitably used as interchangeable camera lenses including the optical glass. Known configurations of such optical elements, optical lenses, and interchangeable camera lenses can be used. Furthermore, the optical systems according to the present embodiments can be suitably used as optical devices including the optical systems. Optical devices including such optical systems include, but are not limited to, imaging devices such as interchangeable lens cameras and non-interchangeable lens cameras, optical microscopes, and the like. Examples of these devices are described below.

[0080] (Imaging Device) FIG. 3 is a perspective view of an example in which the optical device according to each embodiment is used as an imaging device.

[0081] The imaging device 1 is a so-called digital single-lens reflex camera (interchangeable lens camera), and the photographing lens (optical system) 103 is equipped with the cured product according to this embodiment. A lens barrel 102 is detachably attached to a lens mount (not shown) of a camera body 101. Light passing through a lens 103 of the lens barrel 102 forms an image on a sensor chip (solid-state image sensor) 104 of a multi-chip module 106 arranged on the rear side of the camera body 101. This sensor chip 104 is a bare chip such as a so-called CMOS image sensor, and the multi-chip module 106 is, for example, a COG (chip-on-glass) type module in which the sensor chip 104 is bare-chip mounted on a glass substrate 105.

[0082] FIG. 4 is a front view of another example in which the optical device according to each embodiment is used as an imaging device, and FIG. 5 is a rear view of the imaging device.

[0083] The imaging device CAM is a so-called digital still camera (non-interchangeable lens camera), and the photographing lens (optical system) WL is equipped with the cured product according to this embodiment. When the power button (not shown) of the imaging device CAM is pressed, a shutter (not shown) of the photographing lens WL is opened, and light from a subject (object) is collected by the photographing lens WL and focused on an imaging element disposed on the image plane. The subject image focused on the imaging element is displayed on an LCD monitor M disposed behind the imaging device CAM. After determining the composition of the subject image while looking at the LCD monitor M, the photographer presses the release button B1 to capture the subject image with the imaging element and record and save it in memory (not shown). The imaging device CAM is equipped with an auxiliary light emitter EF that emits auxiliary light when the subject is dark, a function button B2 used to set various conditions for the imaging device CAM, and the like.

[0084] Optical systems used in such digital cameras and the like are required to have higher resolution, lighter weight, and smaller size. To achieve these, it is effective to use optical glass with a high refractive index in the optical system. From this perspective, the optical glass according to each embodiment is suitable as a component of such optical equipment. Note that optical equipment to which each embodiment can be applied is not limited to the imaging device described above, but also includes, for example, projectors, etc. Optical elements are also not limited to lenses, but include, for example, prisms, etc.

[0085] (Multiphoton Microscope) FIG. 6 is a block diagram showing an example in which the optical device according to each embodiment is a multiphoton microscope.

[0086] The multiphoton microscope 2 includes, as optical elements, an objective lens 206, a condenser lens 208, and an imaging lens 210. The following description will focus on the optical system of the multiphoton microscope 2.

[0087] The pulsed laser device 201 emits ultrashort pulsed light, for example, with a near-infrared wavelength (approximately 1000 nm) and a pulse width in femtosecond units (e.g., 100 femtoseconds). The ultrashort pulsed light immediately after being emitted from the pulsed laser device 201 is generally linearly polarized in a predetermined direction.

[0088] The pulse splitting device 202 splits the ultrashort pulsed light, increases the repetition frequency of the ultrashort pulsed light, and emits it.

[0089] The beam adjusting unit 203 has functions such as a function to adjust the beam diameter of the ultrashort pulsed light incident from the pulse splitting device 202 to match the pupil diameter of the objective lens 206, a function to adjust the focusing and divergence angles of the ultrashort pulsed light in order to correct on-axis chromatic aberration (focus difference) between the wavelength of the multiphoton excitation light emitted from the sample S and the wavelength of the ultrashort pulsed light, and a pre-chirp function (group velocity dispersion compensation function) to impart reverse group velocity dispersion to the ultrashort pulsed light in order to correct the pulse width of the ultrashort pulsed light being broadened by group velocity dispersion while passing through the optical system.

[0090] The repetition frequency of the ultrashort pulsed light emitted from the pulsed laser device 201 is increased by the pulse dividing device 202, and the above-mentioned adjustment is performed by the beam adjusting unit 203. The ultrashort pulsed light emitted from the beam adjusting unit 203 is then reflected by the dichroic mirror 204 toward the dichroic mirror 205, passes through the dichroic mirror 205, and is collected by the objective lens 206 to be irradiated onto the sample S. At this time, the ultrashort pulsed light may be scanned over the observation surface of the sample S by using a scanning means (not shown).

[0091] For example, when observing the fluorescence of a sample S, the fluorescent dye with which the sample S is stained undergoes multiphoton excitation in the area of ​​the sample S irradiated with the ultrashort pulsed light and in its vicinity, emitting fluorescence (hereinafter referred to as "observation light") having a wavelength shorter than that of the ultrashort pulsed light, which is an infrared wavelength.

[0092] Observation light emitted from the sample S in the direction of the objective lens 206 is collimated by the objective lens 206 and is reflected by or transmitted through the dichroic mirror 205 depending on its wavelength.

[0093] The observation light reflected by the dichroic mirror 205 enters the fluorescence detection unit 207. The fluorescence detection unit 207 is composed of, for example, a barrier filter, a PMT (photomultiplier tube), etc., receives the observation light reflected by the dichroic mirror 205, and outputs an electrical signal corresponding to the amount of light. Furthermore, the fluorescence detection unit 207 detects the observation light across the observation surface of the sample S as the ultrashort pulsed light scans the observation surface of the sample S.

[0094] On the other hand, the observation light that has passed through the dichroic mirror 205 is descanned by a scanning means (not shown), passes through the dichroic mirror 204, is focused by the focusing lens 208, passes through a pinhole 209 located at a position approximately conjugate to the focal position of the objective lens 206, passes through an imaging lens 210, and enters the fluorescence detection unit 211.

[0095] The fluorescence detection unit 211 is configured with, for example, a barrier filter, a PMT, etc., receives the observation light imaged on the light receiving surface of the fluorescence detection unit 211 by the imaging lens 210, and outputs an electrical signal according to the amount of light. Furthermore, the fluorescence detection unit 211 detects the observation light across the observation surface of the sample S as the ultrashort pulsed light scans the observation surface of the sample S.

[0096] It is also possible to remove the dichroic mirror 205 from the optical path so that all of the observation light emitted from the sample S in the direction of the objective lens 206 is detected by the fluorescence detection unit 211 .

[0097] Furthermore, observation light emitted from the sample S in the direction opposite to the objective lens 206 is reflected by the dichroic mirror 212 and enters the fluorescence detection unit 213. The fluorescence detection unit 213 is composed of, for example, a barrier filter, a PMT, etc., and receives the observation light reflected by the dichroic mirror 212 and outputs an electrical signal according to the amount of light. Furthermore, the fluorescence detection unit 213 detects the observation light across the observation surface of the sample S as the ultrashort pulsed light scans the observation surface of the sample S.

[0098] The electrical signals output from the fluorescence detection units 207, 211, and 213 are input, for example, to a computer (not shown), which can generate an observation image based on the input electrical signals, display the generated observation image, and store the data of the observation image.

[0099] <Cemented Lens> Fig. 7 is a schematic diagram showing an example of a cemented lens according to each embodiment. The cemented lens 3 is a compound lens having a first lens element 301 and a second lens element 302. At least one of the first lens element and the second lens element uses the optical glass according to each embodiment. The first lens element and the second lens element are cemented together via a cementing member 303. A known adhesive or the like can be used as the cementing member 303. Note that the lenses that make up the cemented lens may be referred to as "lens elements" as described above, in order to clearly indicate that they are elements of the cemented lens.

[0100] The cemented lens according to each embodiment is useful from the viewpoint of chromatic aberration correction, and can be suitably used in the optical elements, optical systems, optical devices, etc. described above. Furthermore, optical systems including cemented lenses can be particularly suitably used in interchangeable lenses for cameras, optical devices, etc. While the cemented lens using two lens elements has been described in the above-described embodiments, this is not limiting, and a cemented lens using three or more lens elements may also be used. When a cemented lens using three or more lens elements is used, it is sufficient that at least one of the three or more lens elements is formed using the optical glass according to this embodiment.

[0101] 1...imaging device (interchangeable lens camera), 10...glass manufacturing apparatus, 11...stage, 12...support member, 13...laser light source, 14 / 15...mirror, 16...radiation thermometer, 17...computer, 18...CCD camera, 19...monitor, 20...gas flow regulator, 21...floating section, L: laser light, S / U: sample, 30...molding section, 101...camera body, 102...lens barrel, 103...lens, 104...sensor chip, 105...glass substrate, 106...multi-chip module, CAM...imaging device (non-interchangeable lens camera) camera), WL...taking lens, M...liquid crystal monitor, EF...fill-in light emitting unit, B1...release button, B2...function button, 2...multiphoton microscope, 201...pulse laser device, 202...pulse splitter, 203...beam adjusting unit, 204, 205, 212...dichroic mirror, 206...objective lens, 207, 211, 213...fluorescence detecting unit, 208...condensing lens, 209...pinhole, 210...imaging lens, 3...cemented lens, 301...first lens element, 302...second lens element, 303...cementing member

Claims

1. A method for producing glass containing multiple components, comprising: a blending step of blending glass raw materials and a liquid dispersion medium to a concentration of 80% or less by mass; a first mixing step of mixing the raw materials and the dispersion medium blended in the blending step using a mixing member to obtain a first mixture of raw materials; a second mixing step of mixing the first mixture after drying of the first mixture begins to obtain a second mixture which is a dried powder or granular material; a raw material lump preparation step of obtaining multiple raw material lump pieces from the second mixture; a heating step of heating the raw material lump to bring it into a molten state; and a cooling step of lowering the temperature of the raw material lump in a molten state supported in a non-contact manner.

2. The method for producing glass according to claim 1, wherein in the first mixing step, the raw materials and the dispersion medium are mixed for one hour or more.

3. The method for producing glass according to claim 1 or 2, wherein the mixing members are a plurality of spheres.

4. The method for producing glass according to claim 3, wherein in the first mixing step, the raw materials and the dispersion medium are mixed using a ball mill or a bead mill.

5. The method for producing glass according to claim 1 or 2, wherein the mixing member is a stirring blade.

6. A method for producing glass according to any one of claims 1 to 5, wherein the first mixing step comprises mixing the raw materials and the dispersion medium in a container, and the inner surface of the container and the mixing member are made of a material selected from the group consisting of resin and ceramics.

7. The method for producing glass according to any one of claims 1 to 6, wherein in the first mixing step, a dispersant is added and the raw materials and the dispersion medium are mixed.

8. A method for producing glass according to any one of claims 1 to 7, wherein in the second mixing step, the first mixture is dried and the dried first mixture is mixed to obtain the second mixture.

9. The method for producing glass according to claim 8, wherein in the second mixing step, the first mixture is left to dry and the dried first mixture in clump form is mixed to obtain the second mixture.

10. The method for producing glass according to any one of claims 1 to 7, wherein the second mixing step is carried out while the first mixture is dried.

11. A method for producing glass according to any one of claims 1 to 10, wherein in the second mixing step, the first mixture is mixed using a device that rotates a member that comes into contact with the first mixture.

12. The method for manufacturing glass according to any one of claims 1 to 11, wherein in the raw material lump forming step, pressure is applied to the second mixture to form the raw material lump.

13. The method for manufacturing an optical glass, which manufactures an optical glass using the method for manufacturing glass according to any one of claims 1 to 12.

14. A method for manufacturing a glass set including a plurality of glasses, the method including: a mixing step of mixing raw materials of the glasses to obtain a mixture of the raw materials; a raw material lump forming step of obtaining a plurality of raw material lumps from the mixture of the raw materials; a heating step of heating the raw material lumps to a molten state; and a cooling step of cooling the raw material lumps in a molten state supported without contact, wherein in the mixing step, the raw materials are mixed such that a standard deviation of refractive indices with respect to the d-line of the plurality of glasses is 0.0005 or less.

15. A glass set including a plurality of glasses having a common composition, wherein the plurality of glasses have, in mol%, a total content of B ２ O ３ , SiO ２ P ２ O ５ and As ２ O ３ (B ２ O ３ + SiO ２ + P ２ O ５ + As ２ O ３ ): 25% or less, a total content of Li ２ O, K ２ O, Na ２ O, P ２ O ５ and B ２ O ３ (Li ２ O + K ２ O + Na ２ O + P ２ O ５ + B ２ O ３ ): 10% or less, a total content of La ２ O ３ , BaO, CaO, MgO, Y ２ O ３ , Gd ２ O ３ , Al ２ O ３ , TiO ２ , Nb ２ O ５ , ZrO ２ and Ta ２ O ５ (La ２ O ３ + BaO + CaO + MgO + Y ２ O ３ + Gd ２ O ３ + Al ２ O ３ + TiO ２ + Nb ２ O ５ + ZrO ２ + Ta ２ O ５ ): 70% or more, and the standard deviation of the refractive index with respect to the d-line of the plurality of glasses is 0.0005 or less, a glass set.

16. A glass set including a plurality of glasses having a common composition, wherein the plurality of glasses satisfy a partial dispersion ratio (P ｇ，Ｆ ), and an Abbe number (ν ｄ ) such that P ｇ，Ｆ ≦ -0.0042 × ν ｄ + 0.7193, a wavelength (λ ８０ ) and an Abbe number (ν ｄ ) such that the transmittance is 80% or less and λ ８０ ≦ -10.253 × ν ｄ + 672.5, a glass transition temperature T ｇ ≧ 780 °C, a difference ΔT between the crystallization start temperature and the glass transition temperature is ΔT ≦ 230 °C, and the standard deviation of the refractive index with respect to the d-line of the plurality of glasses is 0.0005 or less. A glass set.

17. The glass set according to claim 15 or 16, wherein a standard deviation of refractive indices with respect to the d-line of three of the plurality of glasses is 0.0005 or less.

18. The glass set according to any one of claims 15 to 17, wherein a standard deviation of Abbe numbers of the plurality of glasses is 0.03 or less.

19. The glass set according to claim 18, wherein a standard deviation of Abbe numbers of three of the plurality of glasses is 0.03 or less.

20. The glass set according to any one of claims 15 to 19, wherein, for the plurality of glasses having a common composition, a difference in content rates of respective components of the plurality of glasses is within 1 mol%.

21. The plurality of glasses, in mol%, contains Li ２ O, K ２ O, Na ２ O, P ２ O ５ , B ２ O ３ , WO ３ and As ２ O ３ with a total content (Li ２ O + K ２ O + Na ２ O + P ２ O ５ + B ２ O ３ + WO ３ + As ２ O ３ ): 10% or less. The glass set according to any one of claims 15 to 20.

22. An optical element set having a plurality of optical elements each including the glass included in the glass set according to any one of claims 15 to 21.

23. An optical device set having a plurality of optical devices each including the optical element included in the optical element set according to claim 22.

24. Glass, in mol%, B ２ O ３ , SiO ２ P ２ O ５ and As ２ O ３ total content (B ２ O ３ + SiO ２ + P ２ O ５ + As ２ O ３ ): 25% or less, Li ２ O, K ２ O, Na ２ O, P ２ O ５ and B ２ O ３ total content (Li ２ O + K ２ O + Na ２ O + P ２ O ５ + B ２ O ３ ): 10% or less, La ２ O ３ , BaO, CaO, MgO, Y ２ O ３ Gd ２ O ３ Al ２ O ３ TiO ２ Nb ２ O ５ ZrO ２ and Ta ２ O ５ total content (La ２ O ３ + BaO + CaO + MgO + Y ２ O ３ + Gd ２ O ３ + Al ２ O ３ + TiO ２ + Nb ２ O ５ + ZrO ２ + Ta ２ O ５ ): 70% or more, and the difference between the reference value of the refractive index with respect to the d-line defined for the glass and the refractive index of the glass with respect to the d-line is 0.0003 or less.

25. Glass, with a partial dispersion ratio (P ｇ，Ｆ ), and an Abbe number (ν ｄ ), satisfying P ｇ，Ｆ ≦ -0.0042 × ν ｄ + 0.7193, and the wavelength (λ ８０ ) and the Abbe number (ν ｄ ) for which the transmittance is 80% or less satisfy λ ８０ ≦ -10.253 × ν ｄ + 672.5, a glass transition temperature Tg ≧ 780°C, a difference ΔT between the crystallization start temperature and the glass transition temperature ΔT ≦ 230°C, and the difference between the reference value of the refractive index with respect to the d-line defined for the glass and the refractive index of the glass with respect to the d-line is 0.0003 or less.

26. The glass according to claim 24 or 25, wherein a difference between a reference value of the Abbe number defined for the glass and the Abbe number of the glass is 0.005 times or less the reference value of the Abbe number.

27. The glass according to any one of claims 24 to 26, wherein the reference value is a value shown in a catalog, a specification, or the like for the glass.

28. An optical element including the glass according to any one of claims 24 to 27.

29. An optical device including the optical element according to claim 28.

30. A glass set including a plurality of float-melted glasses having a common composition, wherein a standard deviation of refractive indices with respect to the d-line of the plurality of float-melted glasses is 0.0005 or less.

31. The glass set according to claim 30, wherein a standard deviation of Abbe numbers of the plurality of float-melted glasses is 0.03 or less.

32. A float-melted glass, wherein a difference between a refractive index of the float-melted glass with respect to the d-line and a reference value of the refractive index with respect to the d-line defined for the float-melted glass is 0.0003 or less.

33. The float-melted glass according to claim 32, wherein a difference between an Abbe number of the float-melted glass and a reference value of the Abbe number defined for the float-melted glass is equal to or less than the reference value of the Abbe number × 0.005.

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