Optical glass, optical element, optical system, microscope objective, interchangeable lens for camera, endoscope device, and optical device

Abstract

An optical glass, in terms of mol%, contains SiO2 at 15% or more and 55% or less, Al2O3 at 7% or more and 42% or less, the total content of TiO2 and Nb2O5 (TiO2+Nb2O5) at 0% or more and 21% or less, the total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) at 15% or more and 55% or less, and the total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) at 32% or more and 65% or less.

Description

Technical Field

[0001] This invention relates to optical glass, optical elements, optical systems, microscope objectives, camera interchangeable lenses, endoscope devices, and optical apparatuses. The invention claims priority to Japanese Patent Application No. 2023-217061, filed December 22, 2023, and Japanese Patent Application No. 2023-218032, filed December 25, 2023. For designated countries that recognize the inclusion of content by means of documentary reference, the content described in those applications is incorporated herein by reference. Background Technology

[0002] Optical glass is used in various optical components and optical devices. For example, optical glass for various lenses is disclosed in Patent Document 1.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-219365 Summary of the Invention

[0006] The first aspect of the present invention relates to an optical glass, wherein, expressed in mole percent, the SiO2 content is 15% or more and 55% or less, the Al2O3 content is 7% or more and 42% or less, the total content of TiO2 and Nb2O5 (TiO2+Nb2O5) is 0% or more and 21% or less, the total content of La2O3, Y2O3, ZrO2 and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is 15% or more and 55% or less, and the total content of Al2O3, TiO2, ZrO2, Nb2O5 and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is 32% or more and 65% or less.

[0007] The second aspect of the present invention relates to an optical glass, wherein, in mole percent, the SiO2 content is 7% or more and 35% or less, the Al2O3 content is 5% or more and 45% or less, the total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is 30% or more and 65% or less, and the total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is 45% or more and 78% or less.

[0008] The third aspect of the present invention relates to an optical glass, wherein, in mole percent, the SiO2 content is 7% or more and 55% or less, the Al2O3 content is 5% or more and 45% or less, the total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is 15% or more and 65% or less, and the total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is 32% or more and 78% or less.

[0009] Another aspect of the present invention relates to optical elements using the aforementioned optical glass.

[0010] Another aspect of the invention relates to an optical system comprising the aforementioned optical elements.

[0011] Another aspect of the invention relates to a microscope objective lens comprising an optical system including the aforementioned optical elements.

[0012] Another aspect of the invention relates to a replaceable lens for a camera, comprising an optical system including the aforementioned optical elements.

[0013] Another aspect of the invention relates to an endoscope device comprising an optical system including the aforementioned optical elements.

[0014] Another aspect of the invention relates to an optical device comprising an optical system including the aforementioned optical elements.

[0015] Another aspect of the invention relates to a bonding lens having a first lens element and a second lens element, at least one of which is the aforementioned optical glass.

[0016] Another aspect of the invention relates to an optical system comprising the aforementioned joint lens.

[0017] Another aspect of the invention relates to a microscope objective lens comprising an optical system including the aforementioned joint lens.

[0018] Another aspect of the invention relates to a replaceable lens for a camera, comprising an optical system including the aforementioned coupling lens.

[0019] Another aspect of the invention relates to an optical device comprising an optical system including the aforementioned coupled lens. Attached Figure Description

[0020] Figure 1 This is a perspective view showing an example of using the optical device of this embodiment as a camera device.

[0021] Figure 2This is a schematic diagram showing another example of using the optical device of this embodiment as a camera device, and is a front view of the camera device.

[0022] Figure 3 This is a schematic diagram showing another example of using the optical device of this embodiment as a camera device, and is a rear view of the camera device.

[0023] Figure 4 This is a block diagram illustrating an example of the configuration of the multiphoton microscope of this embodiment.

[0024] Figure 5 This is a schematic diagram illustrating an example of the bonding lens of this embodiment.

[0025] Figure 6 This is a schematic diagram illustrating an example of the endoscopic device of this embodiment.

[0026] Figure 7 This is a schematic diagram of the overall structure of the gas-jet suspension furnace of this embodiment.

[0027] Figure 8 This is an enlarged schematic diagram of the base on the workbench of the gas-jet levitation furnace in this embodiment.

[0028] Figure 9 The optical constant values ​​(v) of Examples 1 to 32 d -P g,F The graph obtained by plotting. The dashed line represents P. g,F =-0.00204×ν d +0.657 and P g,F =-0.00204×ν d +0.640.

[0029] Figure 10 The optical constant values ​​(v) of Examples 1 to 32 d -n d The graph obtained by drawing the graph.

[0030] Figure 11 The optical constant values ​​(v) of Examples 1 to 32 d The graph obtained by plotting -λ5. The dashed line represents λ5 = -5.625 × ν. d +535 and λ5 = -5.625 × ν d +542.

[0031] Figure 12 The optical constant values ​​(ν) of Examples 33-67 d -n d The graph obtained by drawing the graph.

[0032] Figure 13The optical constant values ​​(ν) of Examples 33-67 d -P g,F The graph obtained by plotting. The dashed line represents P. g,F =-0.0028×ν d +0.5606 and P g,F =-0.0028×ν d +0.6775. Detailed Implementation

[0033] Hereinafter, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described. The following embodiments are illustrative of the present invention and are not intended to limit the present invention to the following content. The present invention can be appropriately modified and implemented within its scope.

[0034] In this specification, unless otherwise specified, the content of each component is expressed as mol% (molar percentage) relative to the total number of moles of the glass with oxide equivalent composition. It should be noted that the oxide equivalent composition referred to here means that, assuming that the oxides, complex salts, etc., used as raw materials constituting the glass of this embodiment completely decompose and transform into oxides during melting, the total number of moles of these oxides is set to 100 mol%, representing the composition of each component contained in the glass.

[0035] Furthermore, the statement "does not contain component Q" means that component Q is not substantially present, and that the content of this component is below the level of impurities. "Below the level of impurities" means, for example, less than 0.01%.

[0036] The term "resistance to devitrification stability" refers to the glass's resistance to devitrification. Here, "devitrification" refers to the loss of transparency of the glass caused by crystallization or phase separation when the glass is heated above its glass transition temperature or cooled from a molten state to below its liquidus temperature.

[0037] <Optical Glass of the First Embodiment>

[0038] The optical glass of the first embodiment is an optical glass in which, expressed in mole percent, the SiO2 content is 15% or more and 55% or less, the Al2O3 content is 7% or more and 42% or less, the total content of TiO2 and Nb2O5 (TiO2+Nb2O5) is 0% or more and 21% or less, the total content of La2O3, Y2O3, ZrO2 and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is 15% or more and 55% or less, and the total content of Al2O3, TiO2, ZrO2, Nb2O5 and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is 32% or more and 65% or less.

[0039] The optical glass of the first embodiment is a novel optical glass containing La2O3, Ta2O5, etc. as high refractive index and high transmittance components, and SiO2, Al2O3, etc. as low specific gravity stabilizing components. Furthermore, the optical glass of this embodiment can simultaneously achieve high refractive index, high ultraviolet transmittance, low specific gravity, and high thermal stability (T). x -T g Large glass droplets are stably produced in the suspension melting method.

[0040] First, the components of the optical glass in the first embodiment will be explained.

[0041] SiO2 is a component that maintains a low specific gravity and improves resistance to devitrification, as well as a component that lowers the refractive index. Furthermore, it forms a mesh-like oxide and improves melt permeability. If the SiO2 content is too low, the viscosity decreases; conversely, if it is too high, the refractive index decreases. From this perspective, the SiO2 content, expressed as a mole percent, is 15% or more and 55% or less. The lower limit of this content is preferably 18%, more preferably 22%, and even more preferably 27%. The upper limit of this content is preferably 50%, more preferably 42%, and even more preferably 35%.

[0042] Al2O3 is a component that maintains a low specific gravity and improves devitrification resistance, but it also reduces the refractive index, partial dispersion ratio, and solubility. If the Al2O3 content is too low, the solubility stability decreases; conversely, if it is too high, the refractive index decreases. From this perspective, the Al2O3 content, expressed as 7% to 42% in mol%, is preferred. Furthermore, the lower limit of this content is preferably 10%, more preferably 15%, and even more preferably 19%. The upper limit of this content is preferably 35%, more preferably 30%, and even more preferably 27%.

[0043] TiO2 can either increase the refractive index and maintain a low specific gravity, or it can decrease the transmittance. If the TiO2 content is too low, the specific gravity will be high; conversely, if it is too high, the transmittance will decrease. From this perspective, the TiO2 content, expressed as mole percent, is 0% or more and 5% or less. The upper limit of this content is preferably 3%, more preferably 2%, and even more preferably 1%.

[0044] Nb₂O₅ is a component that increases the refractive index, but it also reduces transmittance and dispersion. If the Nb₂O₅ content is too low, it leads to low refractive index; conversely, if it is too high, transmittance decreases. From this perspective, the Nb₂O₅ content, expressed as 0% to 21%, is preferred. The upper limit of this content is preferably 15%, more preferably 10%, and even more preferably 5%.

[0045] La2O3 is a component that increases refractive index and transmittance without compromising devitrification resistance, but it also increases specific gravity. If the La2O3 content is too low, transmittance decreases; conversely, if it is too high, specific gravity increases. From this perspective, the La2O3 content, expressed as 0% to 33%, is preferred. Furthermore, the lower limit of this content is preferably 5%, more preferably 9%, and even more preferably 13%. The upper limit of this content is preferably 30%, more preferably 26%, and even more preferably 22%.

[0046] Y₂O₃ is a component that improves refractive index and transmittance. However, if the content of Y₂O₃ is too low, it leads to low refractive index; conversely, if it is too high, its solubility decreases. From this perspective, the content of Y₂O₃, expressed as mole percent, is 0% or more and 10% or less. The upper limit of this content is preferably 6%, more preferably 3%, and even more preferably 1%.

[0047] ZrO2 is a component that improves refractive index and transmittance, and also enhances devitrification resistance. However, if the ZrO2 content is too low, its solubility decreases; conversely, if it is too high, its devitrification resistance decreases. From this perspective, the ZrO2 content, expressed as 0% in moles, is 0% or more and 23% or less. Furthermore, the lower limit of this content is preferably 3%, more preferably 7%, and even more preferably 11%. Additionally, the upper limit of this content is preferably 20%, more preferably 18%, and even more preferably 17%.

[0048] Ta₂O₅ is a component that improves refractive index and transmittance, but it also improves specific gravity and devitrification resistance. If the Ta₂O₅ content is too low, the refractive index decreases; conversely, if it is too high, the specific gravity increases. From this perspective, the Ta₂O₅ content, expressed as 0% to 25%, is preferred. Furthermore, the lower limit of this content is preferably 5%, more preferably 8%, and even more preferably 10%. The upper limit of this content is preferably 21%, more preferably 18%, and even more preferably 16%.

[0049] BaO is a component that reduces dispersion while maintaining the devitrification resistance of optical glass. However, if the BaO content is too low, the devitrification resistance decreases; conversely, if it is too high, the solubility decreases. From this perspective, the BaO content, expressed as mole percent, is 0% or more and 25% or less. Furthermore, the lower limit of this content is preferably 1%, more preferably 5%, and even more preferably 12%. The upper limit of this content is preferably 23%, more preferably 19%, and even more preferably 15%.

[0050] B2O3 is a component used to form the oxide that contributes to the mesh structure. However, B2O3 is highly volatile, so excessive addition can alter the glass composition during manufacturing, sometimes making the corrugations more pronounced. From this perspective, the B2O3 content, expressed as a molar percentage, is 0% to 5%. The upper limit of this content is preferably 3%, more preferably 2%, and even more preferably 1%. Most preferably, it does not contain B2O3.

[0051] The total content of TiO2 and Nb2O5 (TiO2+Nb2O5) is 0% or more and 21% or less. The upper limit of this total content is preferably 15%, more preferably 10%, and even more preferably 5%. By making the total content of TiO2 and Nb2O5 (TiO2+Nb2O5) within the above range, the decrease in transmittance can be suppressed, and high transmittance can be obtained.

[0052] The total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is 32% or more and 65% or less. The lower limit of this total content is preferably 37%, more preferably 40%, and even more preferably 43%. The upper limit of this total content is preferably 59%, more preferably 55%, and even more preferably 52%. By ensuring that the total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is within the above range, the devitrification resistance during melting can be improved, while also achieving both high refractive index and high transmittance.

[0053] The total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is 15% or more and 55% or less. The lower limit of this total content is preferably 20%, more preferably 25%, and even more preferably 30%. The upper limit of this total content is preferably 50%, more preferably 45%, and even more preferably 40%. By ensuring that the total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is within the above range, the refractive index and transmittance can be improved.

[0054] The total content of SiO2 and Al2O3 (SiO2 + Al2O3) is 42% or more and 75% or less. The lower limit of this total content is preferably 44%, more preferably 47%, and even more preferably 50%. The upper limit of this total content is preferably 70%, more preferably 65%, and even more preferably 60%. By keeping the total content of SiO2 and Al2O3 (SiO2 + Al2O3) within the above range, it is possible to suppress the decrease in refractive index while maintaining a low specific gravity.

[0055] In addition, known clarifying agents, coloring agents, defoaming agents, fluorine compounds, and other components can be added to the glass composition in appropriate amounts as needed for purposes such as clarification, coloring, decolorization, and fine-tuning of optical constant values. Furthermore, other components may be added within the range that achieves the effects of the optical glass of this embodiment, and are not limited to the aforementioned components.

[0056] The preferred raw materials are high-purity products with low impurity content. High-purity products are defined as those containing 99.85% or more by mass. By using high-purity products, impurities are reduced, resulting in a tendency to improve the internal transmittance of optical glass.

[0057] Next, the physical properties of the optical glass of the first embodiment will be explained.

[0058] The optical glass of the first embodiment preferably has high internal transmittance. Based on this, the wavelength (λ5) at which the internal transmittance per 10 mm of the optical glass in this embodiment reaches 5% is 352 nm or less. The lower limit of this wavelength (λ5) is, for example, 259 nm. The upper limit of this wavelength (λ5) is preferably 310 nm, more preferably 300 nm, and even more preferably 285 nm.

[0059] From the viewpoint of making the lens thinner, the optical glass in this embodiment preferably has a high refractive index (refractive index (n)). d (Large). However, there is usually a refractive index (n) d The higher the refractive index (n) of the d-line, the lower the transmittance tends to be. Based on this actual situation, the optical glass of this embodiment has a refractive index (n) for the d-line... dThe refractive index (n) is above 1.75 and below 1.97. d The lower limit for the refractive index (n) is preferably 1.78, more preferably 1.80, and even more preferably 1.82. d The upper limit of ) is preferably 1.87, more preferably 1.85, and even more preferably 1.84.

[0060] The Abbe number (ν) of the optical glass in the first embodiment d The Abbe number is 28 or higher and 47 or lower. d The lower limit for the Abbe number is preferably 30, more preferably 31, and even more preferably 32. d The upper limit of ) is preferably 37, more preferably 36, and even more preferably 35.

[0061] Regarding the optical glass of the first embodiment, the refractive index (n) d ) and Abbe number (ν d The preferred combination is: for the refractive index (n) of the d-line d The range is 1.80 or higher and 1.87 or lower, and the Abbe number (ν) is... d The value is in the range of 33 or higher and 37 or lower. Optical glass of this embodiment, possessing this property, can be combined with other optical glasses to design optical systems that effectively correct chromatic aberration and other aberrations.

[0062] From the viewpoint of lens aberration correction, the optical glass in this embodiment preferably has a small partial dispersion ratio (P0). g,F Based on this actual situation, the partial dispersion ratio (P) of the optical glass in this embodiment is... g,F It is preferable to satisfy the following formula (1).

[0063] P g,F <-0.00204×ν d +0.657…(1)

[0064] Furthermore, it is more preferable to satisfy the following equation (2).

[0065] -0.00204×ν d +0.640 <P g,F <-0.00204×ν d +0.657…(2)

[0066] From the viewpoint of the transmittance of ultraviolet or visible light in an optical system, the wavelength (λ5) at which the internal transmittance of the optical glass per 10 mm is 5% preferably satisfies the following formula (3).

[0067] λ5<-5.625×ν d +542…(3)

[0068] Furthermore, it is more preferable to satisfy the following equation (4).

[0069] -5.625×ν d +535<λ5<-5.625×ν d +542…(4)

[0070] ΔT can be used as an indicator of devitrification resistance. Generally, a high ΔT indicates high devitrification resistance of the glass. Furthermore, in this embodiment, the glass transition temperature (Tg) is used as an indicator of devitrification resistance. g ) and crystallization initiation temperature (T) x All of these can be determined using differential thermal analysis. Based on this, the glass transition temperature (T0) of the optical glass in this embodiment is... g ) and crystallization initiation temperature (T) x The temperature difference (ΔT=T) x -T g The temperature difference is 73°C or higher and 259°C or lower. The lower limit of this difference is preferably 150°C, more preferably 180°C, and even more preferably 200°C. The upper limit of this difference is preferably 250°C, more preferably 230°C, and even more preferably 220°C.

[0071] The diameter (D) of the optical glass in the first embodiment is 10 mm or more. The lower limit of the diameter (D) is preferably 11.0 mm, more preferably 12.5 mm, and even more preferably 13.5 mm. The upper limit of the diameter (D) is, for example, 14.3 mm. Here, "diameter" refers to the maximum value in the diametrical direction of the glass droplet; in the case of an approximately spherical droplet, it refers to its diameter value.

[0072] The thickness (T) of the optical glass in the first embodiment is 5.03 mm or more. The lower limit of the thickness (T) is preferably 5.20 mm, more preferably 5.40 mm, and even more preferably 5.50 mm. The upper limit of the thickness (T) is, for example, 5.94 mm. Here, "thickness" refers to the height in the vertical direction relative to the maximum value of the diameter (diameter (D)) of the glass droplet, and in the case of an approximately spherical shape, it refers to its diameter value.

[0073] The optical glass in the first embodiment weighs 1700 mg or more. The lower limit of the weight is preferably 1900 mg, more preferably 2000 mg, and even more preferably 2200 mg. The upper limit of the weight is, for example, 3600 mg.

[0074] The specific gravity (S) of the optical glass in the first embodiment g The specific gravity (S) is between 4.2 and 5.8. g The lower limit of ) is preferably 4.3, more preferably 4.6, and even more preferably 4.7. Specific gravity (S) gThe upper limit of ) is preferably 5.6, more preferably 5.4, and even more preferably 5.3.

[0075] <Optical Glass of the Second Embodiment>

[0076] The optical glass of the second embodiment is an optical glass in which, in mole percent, the SiO2 content is 7% or more and 35% or less, the Al2O3 content is 5% or more and 45% or less, the total content of La2O3, Y2O3, ZrO2 and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is 30% or more and 65% or less, and the total content of Al2O3, TiO2, ZrO2, Nb2O5 and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is 45% or more and 78% or less.

[0077] The optical glass of the second embodiment is a novel optical glass containing La2O3, Ta2O5, etc. as high refractive index components and Al2O3, etc., as low specific gravity stabilizing components. Furthermore, the optical glass of this embodiment can achieve high refractive index, medium dispersion, high ultraviolet transmittance, low specific gravity, and high thermal stability (T). x -T g Large glass droplets are stably produced in the suspension melting method.

[0078] First, the components of the optical glass in the second embodiment will be explained.

[0079] SiO2 is a component that maintains a low specific gravity and improves devitrification resistance, as well as a component that lowers the refractive index. Furthermore, it forms a mesh-like oxide and improves melt permeability. If the SiO2 content is too low, the viscosity decreases; conversely, if it is too high, the refractive index decreases. From this perspective, the SiO2 content, expressed as a mole percent, is 7% or more and 35% or less. Moreover, the lower limit of this content is preferably 11%, more preferably 13%, and even more preferably 15%. Furthermore, the upper limit of this content is preferably 32%, more preferably 28%, and even more preferably 24%.

[0080] Al2O3 is a component that maintains a low specific gravity and improves resistance to devitrification, but it also reduces the refractive index, partial dispersion ratio, and solubility. If the Al2O3 content is too low, the solubility stability decreases; conversely, if it is too high, the refractive index decreases. From this perspective, the Al2O3 content, expressed as 5% to 45% (mol%), is preferred. Furthermore, the lower limit of this content is preferably 10%, more preferably 15%, and even more preferably 20%. The upper limit of this content is preferably 40%, more preferably 35%, and even more preferably 30%.

[0081] MgO is a component that maintains a low specific gravity and improves devitrification resistance. When the MgO content is low, devitrification resistance decreases, and there is a tendency to make it difficult to achieve a low specific gravity. Furthermore, when the MgO content is too high, the refractive index tends to decrease. From this perspective, the MgO content, expressed as a mole percent, is 0% or more and 9% or less. Moreover, the lower limit of this content is preferably 2%, more preferably 3%, and even more preferably 4%. Furthermore, the upper limit of this content is preferably 8%, more preferably 7%, and even more preferably 6%.

[0082] La2O3 is a component that increases refractive index and transmittance without compromising devitrification resistance, but it also increases specific gravity. A low La2O3 content tends to decrease transmittance, while an excessively high content results in a high specific gravity. From this perspective, the La2O3 content, expressed as a mole percent, is 10% or more and 30% or less. Furthermore, the lower limit of this content is preferably 13%, more preferably 15%, and even more preferably 17%. The upper limit of this content is preferably 25%, more preferably 23%, and even more preferably 21%.

[0083] Y₂O₃ is a component that improves refractive index and transmittance. However, when the content of Y₂O₃ is low, the refractive index tends to decrease; conversely, when the content is too high, solubility decreases. From this perspective, the content of Y₂O₃, expressed as mole percent, is 0% or more and 8% or less. The lower limit of this content is preferably 2%, more preferably 3%, and even more preferably 4%. The upper limit of this content is preferably 7%, more preferably 6%, and even more preferably 5%.

[0084] TiO2 can either increase the refractive index and maintain a low specific gravity, or it can decrease the transmittance. A low TiO2 content tends to result in a higher specific gravity, while an excessively high content leads to decreased transmittance. From this perspective, the TiO2 content, expressed as mole percent, is 0% or more and 8% or less. Furthermore, the lower limit of this content is preferably 1%, more preferably 2%, and even more preferably 3%. The upper limit of this content is preferably 7%, more preferably 6%, and even more preferably 5%.

[0085] ZrO2 is a component that improves refractive index, transmittance, and devitrification resistance. However, if the ZrO2 content is low, there is a tendency for reduced solubility; conversely, if it is too high, devitrification resistance decreases. From this perspective, the ZrO2 content, expressed as 0% in moles, is 0% or more and 27% or less. Moreover, the lower limit of this content is preferably 5%, more preferably 9%, and even more preferably 13%. Furthermore, the upper limit of this content is preferably 25%, more preferably 23%, and even more preferably 21%.

[0086] Nb₂O₅ is a component that increases the refractive index, but it also reduces transmittance and dispersion. A low Nb₂O₅ content tends to decrease the refractive index, while a high content decreases transmittance. From this perspective, the Nb₂O₅ content, expressed as 0% to 22%, is preferred. Furthermore, the lower limit of this content is preferably 1%, more preferably 2%, and even more preferably 3%. The upper limit of this content is preferably 20%, more preferably 16%, and even more preferably 12%.

[0087] Ta₂O₅ is a component that improves refractive index and transmittance, but it also increases specific gravity. A low Ta₂O₅ content tends to decrease the refractive index, while a high content results in a high specific gravity. From this perspective, the Ta₂O₅ content, expressed as 0% to 28%, is preferred. Furthermore, the lower limit of this content is preferably 4%, more preferably 8%, and even more preferably 12%. The upper limit of this content is preferably 26%, more preferably 24%, and even more preferably 22%.

[0088] The total content of SiO2 and Al2O3 (SiO2 + Al2O3) is 28% or more and 60% or less. The lower limit of this total content is preferably 30%, more preferably 32%, and even more preferably 34%. The upper limit of this total content is preferably 55%, more preferably 50%, and even more preferably 45%. By keeping the total content of SiO2 and Al2O3 (SiO2 + Al2O3) within the above range, it is possible to suppress the decrease in refractive index while maintaining a low specific gravity.

[0089] The total content of Nb2O5 and TiO2 (Nb2O5+TiO2) is 0% or more and 24% or less. The lower limit of this total content is preferably 1%, more preferably 3%, and even more preferably 5%. The upper limit of this total content is preferably 20%, more preferably 18%, and even more preferably 15%. By setting the total content of Nb2O5 and TiO2 (Nb2O5+TiO2) within the above range, the decrease in transmittance can be suppressed, and high transmittance can be obtained.

[0090] The total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is 30% or more and 65% or less. The lower limit of this total content is preferably 33%, more preferably 38%, and even more preferably 43%. The upper limit of this total content is preferably 64%, more preferably 61%, and even more preferably 58%. By ensuring that the total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is within the above range, the refractive index and transmittance can be improved.

[0091] The total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is 45% or more and 78% or less. The lower limit of this total content is preferably 50%, more preferably 55%, and even more preferably 60%. The upper limit of this total content is preferably 75%, more preferably 72%, and even more preferably 69%. By ensuring that the total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is within the above range, the devitrification resistance during melting can be improved, while also achieving both high refractive index and high transmittance.

[0092] The total content of La2O3 and Ta2O5 (La2O3+Ta2O5) is 20% or more and 50% or less. The lower limit of this total content is preferably 25%, more preferably 29%, and even more preferably 33%. The upper limit of this total content is preferably 48%, more preferably 46%, and even more preferably 44%. By ensuring the total content of La2O3 and Ta2O5 (La2O3+Ta2O5) is within the above range, the refractive index and transmittance can be improved. Furthermore, at least one component selected from MgO, Y2O3, ZrO2, TiO2, and Nb2O5 may be included.

[0093] In addition, known clarifying agents, coloring agents, defoaming agents, fluorine compounds, and other components can be added to the glass composition in appropriate amounts as needed for purposes such as clarification, coloring, decolorization, and fine-tuning of optical constant values. Furthermore, other components may be added within the range that achieves the effects of the optical glass of this embodiment, and are not limited to the aforementioned components.

[0094] The preferred raw materials are high-purity products with low impurity content. High-purity products are defined as those containing 99.85% or more by mass. By using high-purity products, impurities are reduced, resulting in a tendency to improve the internal transmittance of optical glass.

[0095] Next, the physical properties of the optical glass in the second embodiment will be explained.

[0096] From the viewpoint of making the lens thinner, the optical glass in this embodiment preferably has a high refractive index (refractive index (n)). d (Large). However, there is usually a refractive index (n) d The higher the refractive index (n) of the d-line, the lower the transmittance tends to be. Based on this actual situation, the optical glass of this embodiment has a refractive index (n) for the d-line... d The refractive index (n) is above 1.85 and below 2.05. d The lower limit for the refractive index (n) is preferably 1.87, more preferably 1.89, and even more preferably 1.91.d The upper limit of ) is preferably 2.03, more preferably 2.02, and even more preferably 2.01.

[0097] The Abbe number (ν) of the optical glass in the second embodiment d The Abbe number is 25 or higher and 40 or lower. d The lower limit for the Abbe number is preferably 28, more preferably 29, and even more preferably 30. d The upper limit of ) is preferably 38, more preferably 36, and even more preferably 35.

[0098] Regarding the optical glass of this embodiment, the refractive index (n) d ) and Abbe number (ν d Optimal combination of ) for the refractive index (n) of the d-line: d The range is 1.95 or higher and 2.01 or lower, and the Abbe number (ν) is... d The value is in the range of 31 or higher and 34 or lower. Optical glass of this embodiment, possessing this property, can be combined with other optical glasses to design optical systems that effectively correct chromatic aberration and other aberrations.

[0099] From the viewpoint of lens aberration correction, the optical glass in this embodiment preferably has a small partial dispersion ratio (P0). g,F Based on this actual situation, the partial dispersion ratio (P) of the optical glass in this embodiment is... g,F It is preferable to satisfy the following formula (1).

[0100] -0.0028×ν d +0.5606 <P g,F <-0.0028×ν d +0.6775…(1)

[0101] From the viewpoint of lens aberration correction, the optical glass in this embodiment preferably has a large anomalous dispersion (ΔP). g，F Based on this actual situation, the value (ΔP) represents the aberrant dispersion property of the optical glass in this embodiment. g，F The value is preferably -0.013 or higher. Furthermore, the value representing anomalous dispersion (ΔP) g，F The lower limit for ) is more preferably -0.0011, and even more preferably -0.009. Additionally, the value representing anomalous dispersion (ΔP) g，F There is no specific upper limit for ), for example, it can be -0.002.

[0102] The specific gravity (S) of the optical glass in this embodiment g The specific gravity (S) is between 4.5 and 6.5. gThe lower limit of ) is preferably 4.7, more preferably 4.8, and even more preferably 4.9. Specific gravity (S) g The upper limit of ) is preferably 6.4, more preferably 6.3, and even more preferably 6.2.

[0103] ΔT can be used as an indicator of devitrification resistance. Generally, a high ΔT indicates high devitrification resistance of the glass. Furthermore, in this embodiment, the glass transition temperature (Tg) is used as an indicator of devitrification resistance. g ) and crystallization initiation temperature (T) x All of these can be determined using differential thermal analysis. Based on this, the glass transition temperature (T0) of the optical glass in this embodiment is... g ) and crystallization initiation temperature (T) x The temperature difference (ΔT=T) x -T g The temperature difference is 75°C or higher and 220°C or lower. The lower limit of this difference is preferably 95°C, more preferably 115°C, and even more preferably 135°C. The upper limit of this difference is preferably 210°C, more preferably 200°C, and even more preferably 190°C.

[0104] The diameter (D) of the optical glass in the second embodiment is 8 mm or more. The lower limit of the diameter (D) is preferably 9.2 mm, more preferably 9.4 mm, and even more preferably 9.6 mm. The upper limit of the diameter (D) is, for example, 11.8 mm. Here, "diameter" refers to the maximum value in the diametrical direction of the glass droplet; in the case of an approximately spherical droplet, it refers to its diameter value.

[0105] The thickness (T) of the optical glass in the second embodiment is 4.5 mm or more. The lower limit of the thickness (T) is preferably 4.7 mm, more preferably 4.8 mm, and even more preferably 4.9 mm. The upper limit of the thickness (T) is, for example, 5.8 mm. Here, "thickness" refers to the height in the vertical direction relative to the maximum value of the diameter (diameter (D)) of the glass droplet, and in the case of an approximately spherical shape, it refers to its diameter value.

[0106] The optical glass in this embodiment weighs 1450 mg or more. The lower limit of the weight is preferably 1500 mg, more preferably 1600 mg, and even more preferably 1700 mg. The upper limit of the weight is, for example, 1950 mg.

[0107] <Optical Glass of the Third Embodiment>

[0108] The optical glass of the third embodiment is an optical glass in which, in mole percent, the SiO2 content is 7% or more and 55% or less, the Al2O3 content is 5% or more and 45% or less, the total content of La2O3, Y2O3, ZrO2 and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is 15% or more and 65% or less, and the total content of Al2O3, TiO2, ZrO2, Nb2O5 and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is 32% or more and 78% or less.

[0109] The optical glass of the third embodiment is a novel optical glass that arbitrarily contains high-refractive-index components such as La2O3, Y2O3, ZrO2, and Ta2O5, and low-density stabilizing components such as SiO2 and Al2O3. Furthermore, the optical glass of this embodiment has high refractive index and medium dispersion, and as an example, it can be suitable for use as a lens material in various optical devices. In addition, for example, large glass droplets can be stably manufactured using a suspension melting method.

[0110] First, the components of the optical glass in the third embodiment will be explained.

[0111] SiO2 is a component that maintains a low specific gravity and improves devitrification resistance, as well as a component that lowers the refractive index. Furthermore, it forms a mesh-like oxide and improves melt permeability. If the SiO2 content is too low, the viscosity decreases; conversely, if it is too high, the refractive index decreases. From this perspective, the SiO2 content, expressed as a mole percent, is 7% or more and 55% or less. The lower limit of this content is preferably 11%, more preferably 13%, and even more preferably 15%. The upper limit of this content is preferably 50%, more preferably 42%, and even more preferably 35%.

[0112] Al2O3 is a component that maintains a low specific gravity and improves resistance to devitrification, but it also reduces the refractive index, partial dispersion ratio, and solubility. If the Al2O3 content is too low, the solubility stability decreases; conversely, if it is too high, the refractive index decreases. From this perspective, the Al2O3 content, expressed as 5% to 45% (mol%), is preferred. Furthermore, the lower limit of this content is preferably 10%, more preferably 15%, and even more preferably 20%. The upper limit of this content is preferably 40%, more preferably 35%, and even more preferably 30%.

[0113] MgO is a component that maintains a low specific gravity and improves devitrification resistance. When the MgO content is low, devitrification resistance decreases, and there is a tendency to make it difficult to achieve a low specific gravity. Furthermore, when the MgO content is too high, the refractive index tends to decrease. From this perspective, the MgO content, expressed as a mole percent, is 0% or more and 9% or less. Moreover, the lower limit of this content is preferably 2%, more preferably 3%, and even more preferably 4%. Furthermore, the upper limit of this content is preferably 8%, more preferably 7%, and even more preferably 6%.

[0114] BaO is a component that reduces dispersion while maintaining the devitrification resistance of optical glass. However, if the BaO content is too low, the devitrification resistance decreases; conversely, if it is too high, the solubility decreases. From this perspective, the BaO content, expressed as mole percent, is 0% or more and 25% or less. Furthermore, the lower limit of this content is preferably 1%, more preferably 5%, and even more preferably 12%. The upper limit of this content is preferably 23%, more preferably 19%, and even more preferably 15%.

[0115] La2O3 is a component that increases refractive index and transmittance without compromising devitrification resistance, but it also increases specific gravity. A low La2O3 content tends to decrease transmittance, while an excessively high content results in a high specific gravity. From this perspective, the La2O3 content, expressed as 0% to 33%, is preferred. Furthermore, the lower limit of this content is preferably 5%, more preferably 9%, and even more preferably 13%. The upper limit of this content is preferably 30%, more preferably 26%, and even more preferably 22%.

[0116] Y₂O₃ is a component that improves refractive index and transmittance. When the Y₂O₃ content is low, the refractive index tends to decrease; conversely, when the content is too high, solubility decreases. From this perspective, the Y₂O₃ content, expressed as a mole percent, is 0% or more and 10% or less. The lower limit of this content is preferably 2%, more preferably 3%, and even more preferably 4%. The upper limit of this content is preferably 7%, more preferably 6%, and even more preferably 5%.

[0117] TiO2 can either increase the refractive index and maintain a low specific gravity, or it can decrease the transmittance. A low TiO2 content tends to result in a higher specific gravity, while an excessively high content leads to decreased transmittance. From this perspective, the TiO2 content, expressed as mole percent, is 0% or more and 8% or less. Furthermore, the lower limit of this content is preferably 1%, more preferably 2%, and even more preferably 3%. The upper limit of this content is preferably 7%, more preferably 6%, and even more preferably 5%.

[0118] ZrO2 is a component that improves refractive index, transmittance, and devitrification resistance. When the ZrO2 content is low, its solubility tends to decrease; conversely, when it is too high, devitrification resistance decreases. From this perspective, the ZrO2 content, expressed as 0% to 27%, is preferred. Furthermore, the lower limit of this content is preferably 5%, more preferably 9%, and even more preferably 13%. The upper limit of this content is preferably 25%, more preferably 23%, and even more preferably 21%.

[0119] Nb₂O₅ is a component that increases the refractive index, but it also reduces transmittance and dispersion. A low Nb₂O₅ content tends to decrease the refractive index, while a high content decreases transmittance. From this perspective, the Nb₂O₅ content, expressed as 0% to 22%, is preferred. Furthermore, the lower limit of this content is preferably 1%, more preferably 2%, and even more preferably 3%. The upper limit of this content is preferably 20%, more preferably 16%, and even more preferably 12%.

[0120] Ta₂O₅ is a component that improves refractive index and transmittance, but it also increases specific gravity. A low Ta₂O₅ content tends to decrease the refractive index, while a high content results in a high specific gravity. From this perspective, the Ta₂O₅ content, expressed as 0% to 28%, is preferred. Furthermore, the lower limit of this content is preferably greater than 0%, more preferably 4%, and even more preferably 8%. The upper limit of this content is preferably 26%, more preferably 24%, and even more preferably 22%.

[0121] B2O3 is a component used to form the oxide that contributes to the mesh structure. However, B2O3 is highly volatile, so excessive addition can alter the glass composition during manufacturing, sometimes making the corrugations more pronounced. From this perspective, the B2O3 content, expressed as a molar percentage, is 0% to 5%. The upper limit of this content is preferably 3%, more preferably 2%, and even more preferably 1%. Most preferably, it does not contain B2O3.

[0122] The total content of SiO2 and Al2O3 (SiO2 + Al2O3) is 28% or more and 75% or less. The lower limit of this total content is preferably 30%, more preferably 32%, and even more preferably 34%. The upper limit of this total content is preferably 70%, more preferably 65%, and even more preferably 60%. By keeping the total content of SiO2 and Al2O3 (SiO2 + Al2O3) within the above range, it is possible to suppress the decrease in refractive index while maintaining a low specific gravity.

[0123] The total content of Nb₂O₅ and TiO₂ (Nb₂O₅ + TiO₂) is 0% or more and 24% or less. The lower limit of this total content is preferably 1%, more preferably 3%, and even more preferably 5%. The upper limit of this total content is preferably 20%, more preferably 18%, and even more preferably 15%. By ensuring the total content of Nb₂O₅ and TiO₂ (Nb₂O₅ + TiO₂) is within the above range, the decrease in transmittance can be suppressed, resulting in high transmittance. It should be noted that "total content of Nb₂O₅ and TiO₂ (Nb₂O₅ + TiO₂)" and "total content of TiO₂ and Nb₂O₅ (TiO₂ + Nb₂O₅)" have the same meaning.

[0124] The total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is 15% or more and 65% or less. The lower limit of this total content is preferably 20%, more preferably 25%, and even more preferably 30%. The upper limit of this total content is preferably 64%, more preferably 61%, and even more preferably 58%. By ensuring that the total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5) is within the above range, the refractive index and transmittance can be improved.

[0125] The total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is 32% or more and 78% or less. The lower limit of this total content is preferably 37%, more preferably 40%, and even more preferably 43%. The upper limit of this total content is preferably 75%, more preferably 72%, and even more preferably 69%. By ensuring that the total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5) is within the above range, it is possible to improve the devitrification resistance during melting while maintaining both high refractive index and high transmittance.

[0126] The total content of La2O3 and Ta2O5 (La2O3+Ta2O5) is 13% or more and 50% or less. The lower limit of this total content is preferably 17%, more preferably 21%, and even more preferably 25%. The upper limit of this total content is preferably 48%, more preferably 46%, and even more preferably 44%. By ensuring the total content of La2O3 and Ta2O5 (La2O3+Ta2O5) is within the above range, the refractive index and transmittance can be improved. Furthermore, at least one component selected from MgO, BaO, Y2O3, ZrO2, TiO2, and Nb2O5 may be included.

[0127] In addition, known clarifying agents, coloring agents, defoaming agents, fluorine compounds, and other components can be added to the glass composition in appropriate amounts as needed for purposes such as clarification, coloring, decolorization, and fine-tuning of optical constant values. Furthermore, other components may be added within the range that achieves the effects of the optical glass of this embodiment, and are not limited to the aforementioned components.

[0128] The preferred raw materials are high-purity products with low impurity content. High-purity products are defined as those containing 99.85% or more by mass. By using high-purity products, impurities are reduced, resulting in a tendency to improve the internal transmittance of optical glass.

[0129] Next, the physical properties of the optical glass in the third embodiment will be explained.

[0130] From the viewpoint of making the lens thinner, the optical glass in this embodiment preferably has a high refractive index (refractive index (n)). d (Large). Therefore, the refractive index (n) of the optical glass of this embodiment for the d-line is... d The refractive index (n) is greater than 1.75 and less than 2.05. d The lower limit for the refractive index (n) is preferably 1.78, more preferably 1.80, and even more preferably 1.82. d The upper limit of ) is preferably 2.03, more preferably 2.02, and even more preferably 2.01.

[0131] The Abbe number (ν) of the optical glass in the third embodiment d The Abbe number is between 25 and 47. d The lower limit for the Abbe number is preferably 28, more preferably 29, and even more preferably 30. d The upper limit of ) is preferably 44, more preferably 41, and even more preferably 38.

[0132] The specific gravity (S) of the optical glass in the third embodiment g The specific gravity (S) is between 4.2 and 6.5. g The lower limit of ) is preferably 4.3, more preferably 4.6, and even more preferably 4.7. Specific gravity (S) g The upper limit of ) is preferably 6.4, more preferably 6.3, and even more preferably 6.2.

[0133] ΔT can be used as an indicator of devitrification resistance. Generally, a high ΔT indicates high devitrification resistance of the glass. Furthermore, in this embodiment, the glass transition temperature (Tg) is used as an indicator of devitrification resistance. g ) and crystallization initiation temperature (T) x All of these can be determined using differential thermal analysis. Based on this, the glass transition temperature (T0) of the optical glass in this embodiment is... g) and crystallization initiation temperature (T) x The temperature difference (ΔT=T) x -T g The temperature difference is 73°C or higher and 259°C or lower. The lower limit of this difference is preferably 95°C, more preferably 115°C, and even more preferably 135°C. The upper limit of this difference is preferably 250°C, more preferably 230°C, and even more preferably 220°C.

[0134] The diameter (D) of the optical glass in the third embodiment is 8 mm or more. The diameter (D) is preferably 9.2 mm, more preferably 9.4 mm, and even more preferably 9.6 mm. There is no particular upper limit to the diameter (D), and it can be, for example, 11.8 mm. Here, "diameter" refers to the maximum value in the diametrical direction of the glass droplet; in the case of an approximately spherical droplet, it refers to its diameter value.

[0135] The thickness (T) of the optical glass in the third embodiment is 4.5 mm or more. The lower limit of the thickness (T) is preferably 4.7 mm, more preferably 4.8 mm, and even more preferably 4.9 mm. The upper limit of the thickness (T) is not particularly limited, and can be, for example, 5.8 mm. Here, "thickness" refers to the height in the vertical direction relative to the maximum value of the diameter (diameter (D)) of the glass droplet, and in the case of an approximately spherical shape, it refers to its diameter value.

[0136] The optical glass in the third embodiment weighs 1450 mg or more. The lower limit of the weight is preferably 1500 mg, more preferably 1600 mg, and even more preferably 1700 mg. The upper limit of the weight is not particularly limited, and for example, it can be 1950 mg.

[0137] Next, the uses of the optical glass in the first to third embodiments described above will be explained.

[0138] From the above perspective, the optical glass of the first to third embodiments can be suitable for use as optical elements in optical devices. Such optical elements include mirrors, lenses, prisms, filters, etc. Optical elements can be formed solely from the optical glass of the above embodiments, or the optical glass of the above embodiments can be bonded to other optical materials (glass, resin, crystal, etc.), and a desired film can be formed on the optical glass of the above embodiments. Furthermore, as optical systems using the above-mentioned optical elements, examples include objective lenses, converging lenses, imaging lenses, and interchangeable lenses for cameras. Moreover, these optical systems can be applied to various optical devices of imaging devices such as interchangeable-lens cameras and non-interchangeable-lens cameras, and microscope devices such as fluorescence microscopes and multiphoton microscopes. These optical devices are not limited to the aforementioned imaging devices and microscopes, but also include, but are not limited to, telescopes, binoculars, laser rangefinders, projectors, defect inspection devices, etc. An example of one of them will be described below.

[0139] <Camera Device>

[0140] Figure 1 This is a perspective view showing an example of using the optical device of this embodiment as a camera device. The camera device 1 is a so-called digital single-lens reflex camera (interchangeable lens camera), and the camera lens 103 (optical system) has optical elements using the optical glass of this embodiment as the base material. The lens barrel 102 is detachably mounted to the lens mounting section (not shown) of the camera body 101. Furthermore, the light passing through the lens 103 of the lens barrel 102 is imaged on the sensor chip (solid-state imaging element) 104 of the multi-chip module 106 disposed on the back side of the camera body 101. The sensor chip 104 is a bare chip such as a so-called CMOS image sensor, and the multi-chip module 106 is a COG (Chip On Glass) type module formed by mounting, for example, the sensor chip 104 as a bare chip on a glass substrate 105.

[0141] Figure 2 and Figure 3 This is a schematic diagram showing another example of using the optical device of this embodiment as a camera device. Figure 2 Showing the front view of the camera device CAM, Figure 3 The rear view of the camera device CAM is shown. The camera device CAM is a so-called digital still camera (non-interchangeable lens camera), and the camera lens WL (optical system) has optical elements with the optical glass of this embodiment as the base material.

[0142] In the camera device CAM, pressing the power button (not shown) opens the shutter (not shown) of the camera lens WL, allowing light from the subject (object) to be focused by the camera lens WL and imaged on the imaging element located on the image plane. The image of the subject on the imaging element is displayed on the LCD screen M located on the back of the camera device CAM. The photographer observes the LCD screen M while deciding on the composition of the subject image, then presses the release button B1 to capture the image using the imaging element and record it in the memory (not shown).

[0143] The camera device CAM is equipped with an auxiliary light emitting part EF that emits auxiliary light when the subject is dark, and function buttons B2 for setting various conditions of the camera device CAM.

[0144] For optical systems used in digital cameras and similar devices, higher resolution, lower chromatic aberration, and miniaturization are required. To achieve these, using glass with different dispersion characteristics in the optical system is effective. In particular, glass with medium or high dispersion and a lower partial dispersion ratio (P0) is preferred. g,F The demand for high-quality glass is high. From this perspective, the optical glass of this embodiment is suitable as a component of the optical device. It should be noted that the optical device applicable to this embodiment is not limited to the imaging device described above; for example, a projector can also be used. Regarding optical elements, it is not limited to lenses; for example, a prism can also be used.

[0145] <microscope>

[0146] Figure 4 This is a block diagram illustrating an example of the configuration of the multiphoton microscope 2 according to this embodiment. The multiphoton microscope 2 includes an objective lens 206, a converging lens 208, and an imaging lens 210. At least one of the objective lens 206, the converging lens 208, and the imaging lens 210 has an optical element using the optical glass of the above embodiment as the base material. The following description focuses on the optical system of the multiphoton microscope 2.

[0147] The pulsed laser device 201 emits, for example, ultrashort pulses of light with a near-infrared wavelength (approximately 1000 nm) and a pulse width in femtosecond units (e.g., 100 femtoseconds). The ultrashort pulses immediately after being emitted from the pulsed laser device 201 typically form linearly polarized light with polarization along a specified direction.

[0148] The pulse segmentation device 202 segments the ultrashort pulse light and emits it after increasing the repetition frequency of the ultrashort pulse light.

[0149] The beam adjustment unit 203 has the following functions: adjusting the beam diameter of the ultrashort pulse light incident from the pulse splitting device 202 in accordance with the pupil diameter of the objective lens 206; adjusting the convergence and divergence angles of the ultrashort pulse light in order to correct the chromatic aberration (focal difference) between the wavelength of the light emitted from the sample S and the wavelength of the ultrashort pulse light on the axis; and pre-chirping the ultrashort pulse light to correct the widening of the pulse width of the ultrashort pulse light due to group velocity dispersion during its passage through the optical system (group velocity dispersion compensation function), etc.

[0150] The ultrashort pulse light emitted from the pulsed laser device 201 has its repetition rate increased under the action of the pulse splitting device 202, and the beam adjustment unit 203 performs the aforementioned adjustment. Furthermore, the ultrashort pulse light emitted from the beam adjustment unit 203 is reflected by the dichroic mirror 204 towards the dichroic mirror 205, passes through the dichroic mirror 205, and is focused by the objective lens 206 to illuminate the sample S. At this time, the ultrashort pulse light can be scanned on the observation surface of the sample S using a scanning device (not shown).

[0151] For example, in the case of fluorescence observation of sample S, in the area of ​​sample S irradiated by ultrashort pulse light and its vicinity, the fluorescent dye that stains sample S is excited by multiphotons and emits fluorescence with a wavelength shorter than that of ultrashort pulse light (hereinafter referred to as "observation light").

[0152] The observation light emitted from the sample S toward the objective lens 206 is collimated by the objective lens 206 and, depending on its wavelength, is either reflected by or transmitted through the dichroic mirror 205.

[0153] The observation light reflected by the dichroic mirror 205 is incident on the fluorescence detection unit 207. The fluorescence detection unit 207 is composed of, for example, a blocking filter or a PMT (photomultiplier tube), and receives the observation light reflected by the dichroic mirror 205, outputting an electrical signal corresponding to the amount of light. In addition, the fluorescence detection unit 207 detects the observation light on the observation surface of the sample S by scanning the observation surface with an ultrashort pulse light.

[0154] It should be noted that, alternatively, by removing the dichroic mirror 205 from the optical path, the fluorescence detection unit 211 can detect all the observation light emitted from the sample S towards the objective lens 206. In this case, the observation light is descanned by the scanning unit (not shown), passes through the dichroic mirror 204, is converged by the converging lens 208, passes through the pinhole 209 located approximately conjugate to the focal point of the objective lens 206, passes through the imaging lens 210, and enters the fluorescence detection unit 211.

[0155] The fluorescence detection unit 211 is composed of, for example, a blocking filter or a PMT, and 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 corresponding to the amount of light. In addition, the fluorescence detection unit 211 detects the observation light on the observation surface of the sample S by scanning the ultrashort pulse light on the observation surface of the sample S.

[0156] It should be noted that all the observation light emitted from the sample S toward the objective lens 206 can also be detected by the fluorescence detection unit 211 by removing the dichroic mirror 205 from the optical path.

[0157] Furthermore, the observation light emitted from the sample S in the opposite direction to the objective lens 206 is reflected by the dichroic mirror 212 and incident on the fluorescence detection unit 213. The fluorescence detection unit 213, for example, is composed of a blocking filter, a PMT, etc., receives the observation light reflected by the dichroic mirror 212, and outputs an electrical signal corresponding to the amount of light. In addition, the fluorescence detection unit 213 detects the observation light on the observation surface of the sample S in conjunction with the scanning of the observation surface of the sample S with ultrashort pulse light.

[0158] The electrical signals output by the fluorescence detection units 207, 211, and 213 are input into, for example, a computer (not shown). The computer can generate an observation image based on the input electrical signals and display or store the data of the observation image.

[0159] <Joint Lens>

[0160] Figure 5 This is a schematic diagram illustrating an example of applying the optical glass of the first to third embodiments described above to a bonding lens. The bonding lens 3 is a composite 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 of the above embodiments. The first lens element and the second lens element are bonded by a bonding member 303. Known adhesives or the like can be used as the bonding member 303. It should be noted that the term "lens element" refers to each lens constituting a single lens or a bonding lens.

[0161] The bonded lens of this embodiment is useful for chromatic aberration correction and is suitable for use in the aforementioned optical elements, optical systems, optical devices, etc. Furthermore, optical systems including the bonded lens are particularly suitable for interchangeable lenses for cameras, optical devices, etc. It should be noted that the above description refers to a bonded lens using two lens elements, but it is not limited to this; a bonded lens using three or more lens elements may also be used. When manufacturing a bonded lens using three or more lens elements, at least one of the three or more lens elements can be formed using the optical glass of the above embodiment.

[0162] <Endoscopic device>

[0163] Figure 6 This diagram illustrates an example of the configuration of the endoscope device according to this embodiment. The endoscope device 4 of this embodiment includes an objective lens 401 and an eyepiece 402. Furthermore, it may include a relay unit 403, which may include a relay lens (not shown). At least one of the objective lens 401, eyepiece 402, and relay lens includes an optical element based on the optical glass of the above embodiment. In other words, at least one of the optical elements included in the endoscope device is based on the optical glass of the above embodiment.

[0164] A light source (not shown) illuminates the affected area P with any type of light. The objective lens 401 captures the reflected light or fluorescence from the affected area P, i.e., the observation light. The observer observes the image of the affected area P (observation section E) through the eyepiece 402, or takes a picture using a desired imaging device. If a relay section 403 is included, the image captured by the objective lens 401 can be relayed to the vicinity of the eyepiece 402 via the relay section 403. The relay section 403 can be composed of multiple relay lenses or can be an optical fiber.

[0165] The endoscopic device of this embodiment can be, for example, a gastroscope, a hysteroscope, a colonoscope, or an ENT camera. In particular, the optical glass of this embodiment has a high refractive index, which allows for miniaturization of the optical system and makes it suitable for use as a lens in an endoscopic device.

[0166] Next, the manufacturing methods of the optical glass according to the first to third embodiments described above will be explained.

[0167] The optical glass described in the above embodiments can be manufactured, for example, using a suspension furnace. Suspension furnaces include electrostatic, electromagnetic, acoustic, magnetic, and gas-jet types, and are not particularly limited; however, a gas-jet type suspension furnace is preferred for the suspension melting of oxides. The manufacturing method using a gas-jet type suspension furnace will be described below as an example.

[0168] Figure 7 A schematic diagram showing the overall structure of a gas-jet suspension furnace is provided. Figure 8 This is an enlarged schematic diagram of the base on the workbench of a gas-jet suspended furnace.

[0169] In the gas-jet suspended furnace 5, raw material U is placed on base 502 on worktable 501. A laser L emitted from laser source 503 is irradiated onto raw material U via reflectors 504 and 505. The temperature of raw material U heated by laser L is monitored using radiation thermometer 506. Based on the temperature information of raw material U monitored by radiation thermometer 506, the output of laser source 503 is controlled by computer 507. Furthermore, the state of raw material U is captured by CCD camera 508 and output to monitor 509 (see reference). Figure 7 It should be noted that, as a laser source, various types of lasers can be used, such as carbon dioxide lasers, semiconductor lasers, fiber lasers, and YAG lasers.

[0170] In the gas-jet suspension furnace 5, the raw material U is suspended in a state by the gas fed into the base (see reference). Figure 8 The flow rate of the gas fed into the base is controlled by the gas flow regulator 510. For example, gas can be injected from a nozzle with a conical orifice, and non-contact heating can be performed using the laser L while the raw material U is suspended. When the raw material U melts, it forms a spherical or ellipsoidal shape due to its own surface tension and is suspended in this state.

[0171] Subsequently, when laser L is interrupted, the molten material U is cooled, resulting in transparent glass. It should be noted that the type of gas is not particularly limited; any known gas can be used, such as oxygen, nitrogen, carbon dioxide, argon, or air. Furthermore, the shape of the nozzle and the heating method are not particularly limited; any known method can be used.

[0172] It should be noted that external pressure can also be applied to the molten raw material U to shape it into the desired thickness and size. The optical glass obtained in this way can be processed into the desired shape as needed, and by performing grinding and other processes, the desired optical element can be manufactured.

[0173] In the past, when manufacturing optical glass using containers such as crucibles, a significant amount of mesh-forming oxides such as SiO2, B2O3, P2O5, and GeO2 was required to improve glass-forming ability. Therefore, when the glass composition contains a large amount of materials that are not mesh-forming oxides, and the content of the aforementioned mesh-forming oxides is low, crystallization (heterogeneous nucleation) often occurs at the container-molten interface, preventing vitrification. Furthermore, glass droplets are sometimes used as materials for optical lenses in various optical devices; there is a desire to stably manufacture large glass droplets.

[0174] Regarding this, in this embodiment, for example, when manufacturing optical glass using the aforementioned levitation furnace method, since the container does not contact the molten metal, heterogeneous nucleation can be suppressed to the maximum extent. As a result, glass formation of the molten metal is greatly promoted, and even compositions that cannot be manufactured by crucible melting, or those with low or no content of mesh-forming oxides, can vitrify. By employing this manufacturing method, optical glass with the composition system of this embodiment, which was previously unable to vitrify, can be manufactured. Furthermore, the aforementioned large glass droplets can also be produced. In addition, the optical glass of this embodiment has a high refractive index and high ultraviolet transmittance. The optical glass of this embodiment has many such advantages, and therefore can be used as a high-refractive-index glass material or a broadband transmission material.

[0175] Example

[0176] Next, embodiments of the present invention will be described. It should be noted that the present invention is not limited to these embodiments.

[0177] <Fabrication of Optical Glass>

[0178] The optical glass used in each embodiment Figure 7 and Figure 8 The gas-jet suspension furnace 5 shown is manufactured according to the following steps. First, glass raw materials selected from oxides are weighed in accordance with the composition (molar percentage) listed in each table. Alternatively, glass raw materials from hydroxides, carbonates, nitrates, and sulfates can be selected. Next, the weighed raw materials are mixed in an alumina mortar. The raw materials are uniaxially pressurized at 20 MPa to form cylindrical particles. The obtained particles are sintered in an electric furnace at 1000–1300°C in atmospheric air for 6–12 hours to produce a sintered body. The obtained sintered body is coarsely pulverized, and 50–3500 mg is placed on a nozzle in the base. Then, carbon dioxide laser is irradiated from above while air gas is injected, thereby melting the raw materials. The molten raw materials become spherical or ellipsoidal in shape due to their own surface tension and are suspended due to the pressure of the gas. By blocking the laser output while the raw materials are completely melted, the raw materials are cooled to obtain droplets (glass spheres). For the glass of each embodiment, no identifiable volatilization during melting was confirmed, nor were bubbles or devitrification confirmed.

[0179] The optical glass of Comparative Example 1 was prepared using a crucible and following the same steps as conventional optical glass. First, glass raw materials selected from oxides, hydroxides, and carbonates were weighed to achieve the chemical composition (molar percentage) listed in Table 15. Next, the weighed raw materials were mixed and placed into a platinum crucible, melted at approximately 1400°C for about 1 hour, and stirred to homogenize. Then, the mixture was lowered to a suitable temperature and cast into a mold, etc., and slowly cooled to obtain the sample.

[0180] <Physical Property Evaluation>

[0181] Figure 9 , 11 This is a graph obtained by plotting the optical constant values ​​of each embodiment. Figure 10 The graph is obtained by plotting the optical constant values ​​of the embodiment.

[0182] Crystallization initiation temperature (T) x ), glass transition temperature (T) g Measurement of its temperature difference (ΔT)

[0183] Crystallization initiation temperature (T) x ) and glass transition temperature (T g All measurements were performed using differential thermal analysis (heating temperature 10℃ / minute) during the heating process. x -T g As the temperature difference (ΔT).

[0184] Diameter (D), Thickness (T)

[0185] The diameter (D) and thickness (T) of each sample were measured using electronic calipers.

[0186] Specific gravity (S) g )

[0187] Specific gravity (S) of each sample g The specific gravity was measured using a dry hydrometer (Shimadzu Corporation; "Accupyc II1340"). The specific gravity value was set to three decimal places.

[0188] Refractive index (n) d ) and Abbe number (ν d )

[0189] The sample was processed with a 90-degree prism, and the refractive index was measured using a refractive index meter (Kalnew Optical Industries, Ltd.; "KPR-3000") via the V-block method. The Abbe number, partial dispersion ratio, and anomalous dispersion were then calculated.

[0190] In the prism coupling method, the glass sample is ground to ensure a tight fit between the ground surface and a single-crystal rutile prism. The total internal reflection angle when light of the measured wavelength is incident is measured, and the refractive index is calculated. Measurements are taken five times each at three wavelengths: 473 nm, 594.1 nm, and 656 nm, and the average value is taken as the measured value. Then, for the obtained measured values, the Drude-Voigt dispersion equation is used to perform a least-squares fitting to calculate the refractive index and Abbe number (ν) at d-rays (587.562 nm), F-rays (486.133 nm), and C-rays (656.273 nm). d )

[0191] [Number 1]

[0192] (n: refractive index, m: electron mass, c: speed of light, e: elementary charge, N: number of molecules per unit volume, f: oscillator strength, λ0: intrinsic resonance wavelength, λ: wavelength)

[0193] n d The Abbe number (ν) represents the refractive index of the glass for light at 587.562 nm. d The value of n is obtained through the following equation (5). C n F These represent the refractive indices of the glass for light with wavelengths of 656.273 nm and 486.133 nm, respectively.

[0194] ν d =(n d -1) / (n F -n C (5)

[0195] The value of the refractive index is set to the sixth decimal place.

[0196] Partial dispersion ratio (P) g,F )

[0197] Partial dispersion ratio (P) of each sample g,F ) represents partial dispersion (n g -n F ) relative to the principal dispersion (n F -n C The ratio of n to n can be obtained using the following equation (6). g This represents the refractive index of the glass for light with a wavelength of 435.835 nm. Partial dispersion ratio (P) g,F The value of ) is set to the sixth decimal place.

[0198] P g,F =(n g -n F ) / (n F -n C )…(6)

[0199] Anomalous dispersion (ΔP) g,F )

[0200] Anomalous dispersion (ΔP) of each sample g,F This indicates the deviation from the partial dispersion ratio standard line relative to two types of glass with normal dispersion, F2 and K7. In other words, it represents the deviation from the partial dispersion ratio (P...) standard line relative to the standard line. g,F () is used as the vertical axis, and the Abbe value ν is used as the plot. dOn the horizontal axis, the difference between the line connecting the two types of glass and the value of the glass used for comparison on the vertical axis represents the deviation of the partial dispersion ratio, i.e., anomalous dispersion (ΔP). g,F In the coordinate system described above, when the value of the partial dispersion ratio is located above the straight line connecting the standard glass types, the glass exhibits positive anomalous dispersion (+ΔP). g,F When the partial dispersion ratio is located at a lower position, the glass exhibits negative anomalous dispersion (-ΔP). g,F It should be noted that the Abbe numbers ν of F2 and K7... d The partial dispersion ratios (Pg, F) ​​are as follows.

[0201] F2: Abbe number ν d =36.33, partial dispersion ratio (P g,F )=0.5834

[0202] K7: Abbe number ν d =60.47, partial dispersion ratio (P g,F )=0.5429

[0203] ΔP g,F =P g,F -(-0.0016777×ν d +0.6443513)…(7)

[0204] Internal transmittance

[0205] The internal transmittance of each sample was measured using a spectrophotometer (Hitachi High-Tech Science Corporation; "UH4150 UV-Vis-IR spectrophotometer") at wavelengths of 200–700 nm for parallel millings 4–9 mm thick. Further correction was performed using refractive index measurements to remove the contribution of reflectance at each wavelength, resulting in transmittance values ​​equivalent to a 10 mm thickness. Based on the refractive index data from the V-block method using the 10 bright lines of the h, g, F', F, e, d, C', C, r, and t lines, a least-squares-based fitting was performed using the following dispersion curve equation.

[0206] [Number 2]

[0207] The refractive index n at each wavelength λ is calculated using the dispersion curve equation. λ The surface reflectivity R for each wavelength and the transmittance T when there is no light absorption inside are calculated using the following formula, assuming multiple reflections of the incident light from the surface and back. th External transmittance measurement value T when using thickness t mm. expand T th Calculate the internal transmittance T (tmm) .

[0208] [Number 3]

[0209] Using the internal transmittance T calculated from the above thickness t mm, the internal transmittance is... (tmm) The transmittance value T for a 10mm thickness can be calculated using the following formula. (10mm) .

[0210] [Number 4]

[0211] Using the transmittance value T calculated above for a 10mm thickness (10mm) The wavelength (λ5) at which the internal transmittance of the optical glass per 10 mm is 53% is calculated.

[0212] The tables show the composition and physical properties of each embodiment. It should be noted that, unless otherwise specified, the content of each component is based on mole percent.

[0213] [Table 1]

[0214] [Table 2]

[0215] [Table 3]

[0216] [Table 4]

[0217] [Table 5]

[0218] [Table 6]

[0219] [Table 7]

[0220] As can be seen from the above, the optical glasses of Examples 1-32 have high transmittance in the medium dispersion, high refractive index region. Furthermore, it can be seen that large glass droplets can be stably manufactured.

[0221] [Table 8]

[0222] [Table 9]

[0223] [Table 10]

[0224] [Table 11]

[0225] [Table 12]

[0226] [Table 13]

[0227] [Table 14]

[0228] [Table 15]

[0229] As can be seen from the above, the optical glasses of Examples 33-67 achieve high refractive index and medium dispersion, while also achieving low specific gravity and high thermal stability, enabling the stable fabrication of large glass droplets. Such optical glasses can be suitable for use as lens materials in various optical devices, and by using such optical glasses as lens materials, miniaturization of various optical devices can be achieved. Furthermore, Comparative Example 1 yielded a glass with a refractive index lower than that of the glass in this embodiment.

[0230] Furthermore, the optical glasses of Examples 1 to 67 all possess high refractive index and medium dispersion, making them suitable for various optical components in various optical devices. Moreover, they are also excellent from the viewpoints of low specific gravity and thermal stability.

[0231] Explanation of reference numerals in the attached figures

[0232] 1…Camera device; 101…Camera body; 102…Lens barrel; 103…Lens; 104…Sensor chip; 105…Glass substrate; 106…Multi-chip module; CAM…Camera device (non-interchangeable lens camera); WL…Photographic lens; M…Liquid crystal display; EF…Auxiliary light emission unit; B1…Release button; B2…Function button; 2…Multiphoton microscope; 201…Pulsed laser device; 202…Pulse splitting device; 203…Beam adjustment unit; 204, 205, 212…Divination mirror; 206…Objective lens; 207, 211, 213…Fluorescence detection unit; 208…Converging lens; 2 09…pinhole; 210…imaging lens; S…sample; 3…joining lens; 301…first lens element; 302…second lens element; 303…jointing component; 4…endoscope device; 401…objective lens; 402…eyepiece; 403…relay unit; P…affected area; E…observation unit; 5…gas suspension furnace; 501…workbench; 502…base; 503…laser source; 504, 505…reflectors; 506…radiation thermometer; 507…computer; 508…CCD camera; 509…monitor; 510…gas flow regulator; L…laser; U…raw material

Claims

1. An optical glass, wherein, In mole percent, SiO2 content: 7% or more and 55% or less; Al2O3 content: 5% or more and 45% or less; total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5): 15% or more and 65% or less; total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5): 32% or more and 78% or less.

2. The optical glass according to claim 1, wherein, The total content of SiO2 and Al2O3 (SiO2+Al2O3) in mole percent is above 28% and below 75%.

3. The optical glass according to claim 1 or 2, wherein, The B2O3 content is between 0% and 5% in molar percentage.

4. The optical glass according to any one of claims 1 to 3, wherein, The total content of La2O3 and Ta2O5 (La2O3+Ta2O5) is between 13% and 50% in mole percent.

5. The optical glass according to any one of claims 1 to 4, wherein, The total content of Nb2O5 and TiO2 (Nb2O5+TiO2) is above 0% and below 24% in mole percent.

6. The optical glass according to any one of claims 1 to 5, wherein, In mole percent, the content of La2O3 is 0% or more and less than 33%, the content of Y2O3 is 0% or more and less than 10%, the content of ZrO2 is 0% or more and less than 27%, and the content of Ta2O5 is 0% or more and less than 28%.

7. The optical glass according to any one of claims 1 to 6, wherein, In molar percentage, MgO content is 0% or more and 9% or less, and BaO content is 0% or more and 25% or less.

8. The optical glass according to any one of claims 1 to 7, wherein, In molar percentage, TiO2 content is 0% or more and 8% or less, and Nb2O5 content is 0% or more and 22% or less.

9. The optical glass according to any one of claims 1 to 8, wherein, The content of La2O3 is between 10% and 30% in molar percentage.

10. The optical glass according to any one of claims 1 to 9, wherein, Ta2O5 content (in mole percent): greater than 0% and less than 28%.

11. The optical glass according to any one of claims 1 to 10, wherein, For the refractive index (n) of the d-line d The value is above 1.75 and below 2.

05.

12. The optical glass according to any one of claims 1 to 11, wherein, Abbe number (ν) d The value is 25 or higher and 47 or lower.

13. The optical glass according to any one of claims 1 to 12, wherein, The specific gravity (S) of the optical glass g The value is between 4.2 and 6.

5.

14. The optical glass according to any one of claims 1 to 13, wherein, The diameter (D) of the optical glass is 8 mm or more.

15. An optical glass, wherein, Expressed in mole percent, SiO2 content: ≥15% and ≤55%; Al2O3 content: ≥7% and ≤42%; Total content of TiO2 and Nb2O5 (TiO2+Nb2O5): ≥0% and ≤21%; Total content of La2O3, Y2O3, ZrO2 and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5): ≥15% and ≤55%; Total content of Al2O3, TiO2, ZrO2, Nb2O5 and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5): ≥32% and ≤65%.

16. The optical glass according to claim 15, wherein, Expressed in mole percent, the content of La2O3 is 0% or more and less than 33%, the content of Y2O3 is 0% or more and less than 10%, the content of ZrO2 is 0% or more and less than 23%, and the content of Ta2O5 is 0% or more and less than 25%.

17. The optical glass according to claim 15 or 16, wherein, The content of BaO is expressed as 0.0% to 25%, with a mole percentage of 0.0%.

18. The optical glass according to any one of claims 15 to 17, wherein, The B2O3 content is expressed as a percentage in moles: 0% or more and 5% or less.

19. The optical glass according to any one of claims 15 to 18, wherein, Expressed in mole percent, Nb2O5 content: ≥0% and ≤21%, TiO2 content: ≥0% and ≤5%.

20. The optical glass according to any one of claims 15 to 19, wherein, The total content of SiO2 and Al2O3 (SiO2+Al2O3) is expressed as mole% and is between 42% and 75%.

21. The optical glass according to any one of claims 15 to 20, wherein, The optical glass has an internal transmittance of 5% per 10 mm and a wavelength (λ5) of less than 352 nm.

22. The optical glass according to any one of claims 15 to 21, wherein, For the refractive index (n) of the d-line d The value is above 1.75 and below 1.

97.

23. The optical glass according to any one of claims 15 to 22, wherein, Abbe number (ν) d The value is 28 or higher and 47 or lower.

24. The optical glass according to any one of claims 15 to 23, wherein, The partial dispersion ratio (P) of the optical glass g,F ) satisfies equation (1), P g,F <-0.00204×ν d +0.657…(1)。 25. The optical glass according to any one of claims 15 to 24, wherein, The internal transmittance of the optical glass per 10 mm is 5% of the wavelength (λ5), satisfying equation (3). λ5<-5.625×ν d +542…(3).

26. The optical glass according to any one of claims 15 to 25, wherein, The specific gravity (S) of the optical glass g The value is between 4.2 and 5.

8.

27. The optical glass according to any one of claims 15 to 26, wherein, The glass transition temperature (T) of the optical glass g ) and crystallization initiation temperature (T) x The temperature difference (ΔT=T) x -T g The temperature is above 73℃ and below 259℃.

28. The optical glass according to any one of claims 15 to 27, wherein, The diameter (D) of the optical glass is 10 mm or more.

29. An optical glass, wherein, In mole percent, SiO2 content: 7% or more and 35% or less; Al2O3 content: 5% or more and 45% or less; total content of La2O3, Y2O3, ZrO2, and Ta2O5 (La2O3+Y2O3+ZrO2+Ta2O5): 30% or more and 65% or less; total content of Al2O3, TiO2, ZrO2, Nb2O5, and Ta2O5 (Al2O3+TiO2+ZrO2+Nb2O5+Ta2O5): 45% or more and 78% or less.

30. The optical glass according to claim 29, wherein, The total content of La2O3 and Ta2O5 (La2O3+Ta2O5) is above 20% and below 50% in mole percentage.

31. The optical glass as claimed in claim 29 or 30, wherein, The total content of Nb2O5 and TiO2 (Nb2O5+TiO2) is above 0% and below 24% in mole percent.

32. The optical glass according to any one of claims 29 to 31, wherein, In molar percentage, the content of La2O3 is above 10% and below 30%, and the content of Ta2O5 is above 0% and below 28%.

33. The optical glass according to any one of claims 29 to 32, wherein, In molar percentage, MgO content: ≥0% and ≤9%, Y2O3 content: ≥0% and ≤8%, ZrO2 content: ≥0% and ≤27%.

34. The optical glass according to any one of claims 29 to 33, wherein, In molar percentage, TiO2 content is 0% or more and 8% or less, and Nb2O5 content is 0% or more and 22% or less.

35. The optical glass according to any one of claims 29 to 34, wherein, For the refractive index (n) of the d-line d The value is above 1.85 and below 2.

05.

36. The optical glass according to any one of claims 29 to 35, wherein, Abbe number (ν) d () is 25 or above and 40 or below.

37. The optical glass according to any one of claims 29 to 36, wherein, The partial dispersion ratio (P) of the optical glass g,F ) satisfies the following equation (1), -0.0028×ν d +0.5606 <P g,F <-0.0028×ν d +0.6775…(1)。 38. The optical glass according to any one of claims 29 to 37, wherein, The specific gravity (S) of the optical glass g The value is between 4.5 and 6.

5.

39. The optical glass according to any one of claims 29 to 38, wherein, The glass transition temperature (T) of the optical glass g ) and crystallization initiation temperature (T) x The temperature difference (ΔT=T) x -T g The temperature is above 75℃ and below 220℃.

40. The optical glass according to any one of claims 29 to 39, wherein, The diameter (D) of the optical glass is 8 mm or more.

41. An optical element that uses the optical glass according to any one of claims 1 to 40.

42. An optical system comprising the optical element of claim 41.

43. A microscope objective lens comprising the optical system of claim 42.

44. A camera lens that includes the optical system of claim 42.

45. An endoscope device comprising the optical system of claim 42.

46. ​​An optical device comprising the optical system of claim 42.

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