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

Abstract

To provide a lightweight optical lens that is advantageous in aberration correction because a partial dispersion ratio can be increased despite low dispersion (large Abbe number).SOLUTION: An optical glass comprises, by mass%, P2O5 content: 20 to 55%, TiO2 content: 10 to 40%, Nb2O5 content: 0 to 30%, Al2O3 content: 0 to 2%, B2O3 content: 0 to 10%, the content of BaO: 0 to 30%, the content of Bi2O3: 0 to 30%, the content of Ta2O5: 0 to 20%, the content of WO3: 0 to 25%, where a ratio of the content of TiO2 to the total content of P2O5, B2O3 and Al2O3 (TiO2 / (P2O5+B2O3+Al2O3)) is 0.25 to 0.85, and a ratio of the content of TiO2 to the total content of TiO2, Nb2O5, WO3, Bi2O3 and Ta2O5 (TiO2 / (TiO2+Nb2O5+WO3+Bi2O3+Ta2O5)) is 0.25 to 1.00.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to optical glass, an optical element, an optical system, a cemented lens, an optical system, an interchangeable lens for a camera, an objective lens for a microscope, and an optical device. [Background technology]

[0002] In recent years, imaging devices equipped with image sensors with a high number of pixels have been developed, and optical glass having low dispersion and a high partial dispersion ratio is required for use in these devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-219365 A Summary of the Invention

[0004] In the first aspect of the present invention, the P2O5 content is 20 to 55%, the TiO2 content is 10 to 40%, the Nb2O5 content is 0 to 30%, the Al2O3 content is 0 to 2%, the B2O3 content is 0 to 10%, the BaO content is 0 to 30%, the Bi2O3 content is 0 to 30%, the Ta2O5 content is 0 to 20%, and the WO3 content is 0 to 25%, in mass %. It is an optical glass in which the ratio of the TiO2 content to the total content of TiO2 and Al2O3 (TiO2 / (P2O5+B2O3+Al2O3)) is 0.25 to 0.85, and the ratio of the TiO2 content to the total content of TiO2, Nb2O5, WO3, Bi2O3, and Ta2O5 (TiO2 / (TiO2+Nb2O5+WO3+Bi2O3+Ta2O5)) is 0.25 to 1.00. The optical glass has, in mass %, a P2O5 content of 20 to 55%, a TiO2 content of 10 to 40%, a Nb2O5 content of 0 to 30%, an Al2O3 content of 0 to 2%, a B2O3 content of 0 to 10%, a BaO content of 0 to 30%, a Bi2O3 content of 0 to 30%, a Ta2O5 content of 0 to 20%, and a WO3 content of 0 to 25%, and the ratio of the total content of BaO and TiO2 to the P2O5 content ((BaO+TiO2) / P2O5) is 0.40 to 1.50.

[0005] A second aspect of the present invention is an optical element using the above-mentioned optical glass.

[0006] A third aspect of the present invention is an optical system including the optical element described above.

[0007] A fourth aspect of the present invention is an interchangeable lens for a camera, including an optical system that includes the optical element described above.

[0008] A fifth aspect of the present invention is an objective lens for a microscope, comprising an optical system including the optical element described above.

[0009] A sixth aspect of the present invention is an optical device including an optical system including the optical element described above.

[0010] A seventh aspect of the present invention is a cemented lens having a first lens element and a second lens element, at least one of the first lens element and the second lens element being made of the optical glass described above.

[0011] An eighth aspect of the present invention is an optical system including the above-mentioned cemented lens.

[0012] A ninth aspect of the present invention is an objective lens for a microscope, including an optical system including the cemented lens described above.

[0013] A tenth aspect of the present invention is an interchangeable lens for a camera, comprising an optical system including the cemented lens described above.

[0014] An eleventh aspect of the present invention is an optical device including an optical system including the cemented lens described above. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view showing an example in which the optical device according to the present embodiment is used as an imaging device. [Diagram 2] FIG. 11 is a schematic diagram showing another example in which the optical device according to the present embodiment is used as an imaging device, and is a front view of the imaging device. [Diagram 3] FIG. 13 is a schematic diagram showing another example in which the optical device according to the present embodiment is used as an imaging device, and is a rear view of the imaging device. [Figure 4] FIG. 1 is a block diagram showing an example of the configuration of a multiphoton microscope according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic diagram illustrating an example of a cemented lens according to the present embodiment. [Figure 6] 1 is a graph plotting Pg, F and νd for each of the examples and comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described. The present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be practiced with appropriate modifications within the scope of its gist.

[0017] In this specification, unless otherwise specified, the content of each component is expressed as mass% (mass percentage) based on the total weight of the glass in terms of oxide composition. Note that the oxide composition referred to here is a composition in which each component contained in the glass is expressed, assuming that the oxides, composite salts, etc. used as raw materials for the glass constituent components of this embodiment are all decomposed and converted to oxides during melting, and the total mass of the oxides is set to 100 mass%,.

[0018] Furthermore, the expression that the Q content is "0 to N%" includes cases where the Q component is not included and cases where the Q component is more than 0% and equal to or less than N%.

[0019] The expression "not containing Q component" means that the Q component is substantially not contained, and indicates that the content of this component is equal to or less than the impurity level. For example, equal to or less than the impurity level means that the content is less than 0.01%.

[0020] The expression "devitrification resistance stability" refers to the resistance of glass to devitrification. Here, "devitrification" refers to a phenomenon in which glass loses transparency due to crystallization or phase separation that occurs when the temperature of glass is raised to or above the glass transition temperature or when the temperature is lowered from a molten state to or below the liquidus temperature.

[0021] The optical glass according to this embodiment has, in mass %, a P2O5 content of 20 to 55%, a TiO2 content of 10 to 40%, a Nb2O5 content of 0 to 30%, an Al2O3 content of 0 to 2%, a B2O3 content of 0 to 10%, a BaO content of 0 to 30%, a Bi2O3 content of 0 to 30%, a Ta2O5 content of 0 to 20%, and a WO3 content of 0 to 25%. It is an optical glass in which the ratio of the TiO2 content to the total content of O3 and Al2O3 (TiO2 / (P2O5+B2O3+Al2O3)) is 0.25 to 0.85, and the ratio of the TiO2 content to the total content of TiO2, Nb2O5, WO3, Bi2O3, and Ta2O5 (TiO2 / (TiO2+Nb2O5+WO3+Bi2O3+Ta2O5)) is 0.25 to 1.00. The optical glass has, in mass %, a P2O5 content of 20 to 55%, a TiO2 content of 10 to 40%, a Nb2O5 content of 0 to 30%, an Al2O3 content of 0 to 2%, a B2O3 content of 0 to 10%, a BaO content of 0 to 30%, a Bi2O3 content of 0 to 30%, a Ta2O5 content of 0 to 20%, and a WO3 content of 0 to 25%, and the ratio of the total content of BaO and TiO2 to the P2O5 content ((BaO+TiO2) / P2O5) is 0.40 to 1.50.

[0022] The optical glass according to this embodiment is capable of increasing the partial dispersion ratio while having low dispersion (large Abbe number), and is therefore advantageous for correcting aberrations and enabling the realization of lightweight lenses.

[0023] P2O5 is a component that forms a glass skeleton, improves the stability against devitrification, and reduces the refractive index and chemical durability. If the content of P2O5 is too low, devitrification tends to occur easily. If the content of P2O5 is too high, the refractive index and chemical durability tend to decrease. From this viewpoint, the content of P2O5 is 20% or more and 55% or less. The lower limit of this content is preferably 25%, more preferably 30%, and even more preferably 38%. The upper limit of this content is preferably 50%, more preferably 45%, and even more preferably 40%. By setting the content of P2O5 in this range, it is possible to improve the stability against devitrification and improve the chemical durability while achieving a high refractive index.

[0024] TiO2 is a component that increases the refractive index and partial dispersion ratio and decreases the transmittance. If the content of TiO2 is too low, the refractive index and partial dispersion ratio tend to decrease. If the content of TiO2 is too high, the transmittance tends to deteriorate. From this viewpoint, the content of TiO2 is 10% or more and 40% or less. The lower limit of this content is preferably 15%, more preferably 17%. The upper limit of this content is preferably 30%, more preferably 28%, and even more preferably 25%. By setting the content of TiO2 in this range, high transmittance can be achieved without decreasing the refractive index and partial dispersion ratio.

[0025] Nb2O5 is a component that increases the refractive index and dispersion and decreases the transmittance. If the content of Nb2O5 is low, the refractive index tends to be low. Also, if the content of Nb2O5 is high, the transmittance tends to deteriorate. From this viewpoint, the content of Nb2O5 is 0% or more and 30% or less. The lower limit of this content is preferably more than 0%, more preferably 5% or more. The upper limit of this content is preferably 25%, more preferably 18%, and even more preferably 10%.

[0026] Al2O3 is a component that improves chemical durability and reduces the partial dispersion ratio and meltability. If the content of Al2O3 is too low, the chemical durability tends to decrease. If the content of Al2O3 is too high, the partial dispersion ratio tends to decrease and the meltability tends to deteriorate. From this viewpoint, the content of Al2O3 is 0% or more and 2% or less. The lower limit of this content is preferably 1%. The upper limit of this content is preferably 1.6%. By setting the content of Al2O3 in this range, it is possible to improve chemical durability and prevent a decrease in the partial dispersion ratio.

[0027] The content of B2O3 is 0% or more and 10% or less from the viewpoint of high dispersion. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 6%, more preferably 4%.

[0028] BaO is a component that improves the partial dispersion ratio and reduces the devitrification resistance stability. If the BaO content is too low, the partial dispersion ratio tends to decrease. If the BaO content is too high, the devitrification resistance stability tends to decrease. From this viewpoint, the BaO content is 0% or more and 30% or less. The lower limit of this content is preferably 3%, more preferably 5%, and even more preferably 7%. The upper limit of this content is preferably 25%, more preferably 20%, and even more preferably 15%. By setting the BaO content in this range, it is possible to increase the partial dispersion ratio and prevent a decrease in the devitrification resistance stability.

[0029] Bi2O3 is a component that increases the refractive index and partial dispersion ratio. If the Bi2O3 content is too high, the transmittance tends to deteriorate and the dispersion tends to increase. If the Bi2O3 content is too low, the meltability tends to decrease. From this viewpoint, the Bi2O3 content is 0% or more and 30% or less. The lower limit of this content is preferably 2%, more preferably 5%, and even more preferably 10%. The upper limit of this content is preferably 25%, more preferably 20%. By setting the Bi2O3 content within this range, the meltability can be improved and the increase in dispersion can be prevented.

[0030] Ta2O5 is a component that increases the refractive index and dispersion and decreases the devitrification resistance stability. If the content of Ta2O5 is high, the devitrification resistance stability tends to deteriorate. From this viewpoint, the content of Ta2O5 is 0% or more and 20% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 16%, more preferably 10%. It is more preferable that Ta is not substantially contained. "Substantially not contained" means that the component is not contained as a constituent component that affects the properties of the glass composition beyond the concentration that is inevitably contained as an impurity. For example, a content of about 100 ppm is considered to be substantially not contained. The optical glass according to this embodiment can reduce the content of Ta2O5, which is an expensive raw material, and can even be free of it, so it is also excellent in terms of raw material costs.

[0031] From the viewpoint of transmittance, the content of WO3 is 0% or more and 25% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 20%, more preferably 15%, and even more preferably 10%.

[0032] The ratio of the TiO2 content to the total content of P2O5, B2O3, and Al2O3 (TiO2 / (P2O5+B2O3+Al2O3)) is preferably 0.25 to 0.85. The lower limit of this ratio is more preferably 0.30, and more preferably 0.40. The upper limit of this ratio is more preferably 0.70, and even more preferably 0.60. By setting TiO2 / (P2O5+B2O3+Al2O3) in this range, the partial dispersion ratio can be increased.

[0033] The ratio of the content of TiO2 to the total content of TiO2, Nb2O5, WO3, Bi2O3, and Ta2O5 (TiO2 / (TiO2+Nb2O5+WO3+Bi2O3+Ta2O5)) is preferably 0.25 to 1.00. The lower limit of this ratio is more preferably 0.30, and even more preferably 0.40. The upper limit of this ratio is more preferably 0.90, and even more preferably 0.80. By setting TiO2 / (TiO2+Nb2O5+WO3+Bi2O3+Ta2O5) in this range, the partial dispersion ratio can be increased.

[0034] The ratio of the total content of BaO and TiO2 to the content of P2O5 ((BaO+TiO2) / P2O5) is preferably 0.40 to 1.50. The lower limit of this ratio is more preferably 0.70. The upper limit of this ratio is more preferably 1.10, and even more preferably 0.90. By setting (BaO+TiO2) / P2O5 in this range, the refractive index can be increased.

[0035] The optical glass according to this embodiment may further contain, as an optional component, one or more components selected from the group consisting of Na2O, K2O, Li2O, ZnO, MgO, CaO, SrO, SiO2, ZrO2, Sb2O3, Y2O3, La2O3, and Gd2O3.

[0036] Na2O is a component that improves meltability and reduces the refractive index. If the Na2O content is too low, the meltability tends to decrease. If the Na2O content is too high, the refractive index and chemical durability tend to decrease. From this viewpoint, the Na2O content is 0% or more and 30% or less. The lower limit of this content is preferably more than 0%, and more preferably 5%. The upper limit of this content is preferably 20%, and more preferably 15%. By setting the Na2O content within this range, it is possible to improve the meltability and prevent a decrease in the refractive index and chemical durability.

[0037] K2O is a component that improves meltability and reduces the refractive index. If the content of K2O is too low, the meltability tends to decrease. If the content of K2O is too high, the refractive index and chemical durability tend to decrease. From this viewpoint, the content of K2O is 0% or more and 25% or less. The lower limit of this content is preferably more than 0%, more preferably 3%. The upper limit of this content is preferably 20%, more preferably 15%, and even more preferably 5%. By setting the content of K2O within this range, it is possible to improve the meltability and prevent a decrease in the refractive index and chemical durability.

[0038] From the viewpoint of meltability, the content of Li2O is 0% or more and 5% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 4%, and more preferably 2%.

[0039] ZnO is a component that improves the devitrification resistance stability and reduces the partial dispersion ratio. If the ZnO content is too low, the devitrification resistance stability tends to decrease. If the ZnO content is too high, the partial dispersion ratio tends to decrease. From this viewpoint, the ZnO content is 0% or more and 15% or less. The lower limit of this content is preferably more than 0%, more preferably 1%. The upper limit of this content is preferably 10%, more preferably 8%. By setting the ZnO content in this range, it is possible to improve the devitrification resistance stability and prevent a decrease in the partial dispersion ratio.

[0040] The content of MgO is 0% or more and 10% or less from the viewpoint of high dispersion. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 5%, more preferably 4%.

[0041] The CaO content is 0% or more and 10% or less from the viewpoint of high dispersion. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 8%, more preferably 6%.

[0042] From the viewpoint of high dispersion, the content of SrO is 0% or more and 15% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 12%, and more preferably 10%.

[0043] The SiO2 content is 0% or more and 5% or less from the viewpoint of meltability. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 3%, and more preferably 1%.

[0044] From the viewpoint of meltability, the content of ZrO2 is 0% or more and 5% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 3% or less, and more preferably 1.5%.

[0045] The content of Sb2O3 is 0% or more and 1% or less from the viewpoint of defoaming property during glass melting. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 0.5%, and more preferably 0.2%.

[0046] The content of Y2O3 is 0% or more and 8% or less from the viewpoint of meltability. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 6%, more preferably 5%, and further preferably 4.5%.

[0047] The content of La2O3 is 0% or more and 5% or less from the viewpoint of meltability. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 4%, more preferably 3.5%. Moreover, from the viewpoint of cost, it is even more preferable that La2O3 is not substantially contained. "Substantially not contained" means that the component is not contained as a constituent component that affects the properties of the glass composition at a concentration exceeding the concentration that is inevitably contained as an impurity. For example, a content of about 100 ppm is considered to be substantially not contained.

[0048] Since Gd2O3 is an expensive raw material, its content is 0% or more and 10% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 8%, and more preferably 7.5%.

[0049] Furthermore, the optical glass according to this embodiment preferably satisfies the following relationship.

[0050] The ratio of the TiO2 content to the P2O5 content (TiO2 / P2O5) is preferably 0.25 to 0.85. The lower limit of this ratio is more preferably 0.30, and even more preferably 0.40. The upper limit of this ratio is more preferably 0.75, and even more preferably 0.60. By setting TiO2 / P2O5 in this range, the partial dispersion ratio can be increased.

[0051] The ratio of the Al2O5 content to the TiO2 content (Al2O3 / TiO2) is 0 to 0.15. The lower limit of this ratio may be greater than 0. The upper limit of this ratio is preferably 0.12, and more preferably 0.09. By setting Al2O3 / TiO2 within this range, the partial dispersion ratio can be increased.

[0052] The ratio of the content of B2O3 to the content of P2O5 (B2O3 / P2O5) is preferably 0 to 0.30. The lower limit of this ratio may be more than 0. The upper limit of this ratio is more preferably 0.25, and further preferably 0.20. By setting B2O3 / P2O5 in this range, the partial dispersion ratio can be increased.

[0053] The ratio of the total content of BaO, TiO2, Nb2O5, WO3, Bi2O3, and Ta2O5 to the total content of P2O5, B2O3, SiO2, and Al2O3 ((BaO+TiO2+Nb2O5+WO3+Bi2O3+Ta2O5) / (P2O5+B2O3+SiO2+Al2O3)) is preferably 0.40 to 2.00. The lower limit of this ratio is more preferably 0.50, and even more preferably 0.60. The upper limit of this ratio is more preferably 1.60, and even more preferably 1.00. By setting (BaO+TiO2+Nb2O5+WO3+Bi2O3+Ta2O5) / (P2O5+B2O3+SiO2+Al2O3) in this range, the partial dispersion ratio can be increased and a decrease in the refractive index can be prevented.

[0054] The total content of Li2O, Na2O and K2O (ΣA2O; where A=Li, Na, K) is 5 to 35% from the viewpoints of meltability, refractive index and chemical durability. The lower limit of this total content is preferably 7%, more preferably 9%, and even more preferably 11%. The upper limit of this total content is preferably 25%, more preferably 20%, and even more preferably 18%.

[0055] A suitable combination of these contents is Li2O content: 0% to 5%, Na2O content: 0% to 30%, and K2O content: 0% to 25%. By using such a combination, it is possible to improve the melting property and prevent a decrease in chemical durability.

[0056] The total content of MgO, CaO, SrO, BaO and ZnO (ΣEO; where E=Mg, Ca, Sr, Ba, Zn) is 0 to 30% from the viewpoints of meltability, refractive index and chemical durability. The lower limit of this total content is preferably 5%, more preferably 8%, and further preferably 10%. The upper limit of this total content is preferably 25%, and more preferably 15%.

[0057] Another suitable combination is BaO content: 0% to 30%, ZnO content: 0% to 15%, MgO content: 0% to 10%, CaO content: 0% to 10%, and SrO content: 0% to 15%. By using such a combination, the partial dispersion ratio can be increased and low dispersion can be prevented.

[0058] The total content of SiO2 and B2O3 (SiO2+B2O3) is 0% or more and 10% or less. The lower limit of this total content is preferably more than 0%, more preferably 1%, and even more preferably 2%. The upper limit of this total content is preferably 7%, more preferably 6%, and even more preferably 4%.

[0059] Yet another preferable combination is a SiO2 content of 0% or more and 5% or less, and a B2O3 content of 0% or more and 10% or less. By using such a combination, the melting property can be improved and low dispersion can be prevented.

[0060] The ratio (ΣA2O / TiO2) of the total content of Li2O, Na2O, and K2O relative to TiO2 (ΣA2O; where A=Li, Na, K) is preferably 0.10 to 2.00. The lower limit of this ratio is more preferably 0.20, and even more preferably 0.30. The upper limit of this ratio is more preferably 1.60, and even more preferably 1.30. By setting ΣA2O / TiO2 in this range, the partial dispersion ratio can be increased and a decrease in melting property can be prevented.

[0061] The ratio (ΣEO / ΣA2O) of the total content of Li2O, Na2O, and K2O (ΣAO; where A=Li, Na, K) to the total content of MgO, CaO, SrO, BaO, and ZnO (ΣEO; where E=Mg, Ca, Sr, Ba, Zn) is preferably 0 to 3.00. The lower limit of this ratio is preferably more than 0, more preferably 0.20, and even more preferably 0.80. The upper limit of this ratio is more preferably 2.00, and even more preferably 1.50. By setting ΣEO / ΣA2O in this range, it is possible to improve the melting property and prevent a decrease in the refractive index.

[0062] In addition, appropriate amounts of known clarifiers, colorants, defoamers, fluorine compounds, and other components may be added to the glass composition as needed for the purpose of clarifying, coloring, decoloring, fine adjustment of optical constants, etc. Furthermore, other components may be added in addition to the above-mentioned components within the range in which the effects of the optical glass according to this embodiment can be obtained.

[0063] The method for producing the optical glass according to this embodiment is not particularly limited, and a known method can be adopted. In addition, the production conditions can be appropriately selected. For example, a production method can be adopted in which raw materials such as oxides, carbonates, nitrates, and sulfates are mixed to obtain a target composition, melted at preferably 1100 to 1400°C, homogenized by stirring, bubble-removing, and then poured into a mold for molding. The lower limit of the above-mentioned melting temperature is more preferably 1200°C, and the upper limit is more preferably 1350°C, and further preferably 1300°C. The optical glass thus obtained can be processed into a desired shape by reheat pressing or the like as necessary, and polished to form a desired optical element.

[0064] It is preferable to use high-purity raw materials with low impurity content. A high-purity product is one that contains 99.85% or more by mass of the relevant component. The use of high-purity products reduces the amount of impurities, which tends to increase the internal transmittance of the optical glass.

[0065] Next, the physical properties of the optical glass of this embodiment will be described.

[0066] From the viewpoint of making the lens thinner, the optical glass according to this embodiment has a high refractive index (refractive index (n d However, in general, the refractive index (n d In view of this situation, the refractive index (n d ) is preferably in the range of 1.60 to 1.85. dThe lower limit of the refractive index (n d ) is more preferably 1.80.

[0067] The Abbe number (ν d ) is preferably in the range of 20 to 35. d The lower limit of the Abbe number (ν d ) is more preferably 30.

[0068] From the viewpoint of lens aberration correction, the optical glass according to this embodiment has a large partial dispersion ratio (P g , F In view of this situation, it is desirable for the optical glass according to this embodiment to have a partial dispersion ratio (P g , F ) is preferably 0.61 or more. g , F The lower limit of the partial dispersion ratio (P g , F ) is not particularly limited, but may be set to, for example, 0.66.

[0069] From the viewpoint of lens aberration correction, the optical glass according to this embodiment has a large anomalous dispersion (ΔP g , F In view of this situation, it is desirable that the value (ΔP g , F ) is preferably 0.015 or more. And the value indicating the anomalous dispersion (ΔP g , F The lower limit of the value indicating the anomalous dispersion (ΔP g , F ) is not particularly limited, but may be set to, for example, 0.055.

[0070] From the above viewpoint, the optical glass according to the present embodiment can be suitably used as, for example, an optical element provided in an optical instrument. Such optical elements include mirrors, lenses, prisms, filters, and the like. Examples of optical systems in which the optical elements are used include objective lenses, condenser lenses, imaging lenses, and interchangeable lenses for cameras. These optical systems can be suitably used in various optical devices, such as imaging devices, such as interchangeable lens cameras and non-interchangeable lens cameras, and microscope devices, such as fluorescent microscopes and multiphoton microscopes. Such optical devices are not limited to the imaging devices and microscopes described above, but also include, but are not limited to, telescopes, binoculars, laser range finders, projectors, and the like. Examples of these devices are described below.

[0071] <Imaging device> FIG. 1 is a perspective view showing an example of an optical device according to the present embodiment as an imaging device. The imaging device 1 is a so-called digital single-lens reflex camera (lens-interchangeable camera), and a photographing lens 103 (optical system) is provided with an optical element made of the optical glass according to the present embodiment as a base material. 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 is imaged on a sensor chip (solid-state imaging element) 104 of a multi-chip module 106 arranged on the rear 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, for example, a COG (Chip On Glass) type module in which the sensor chip 104 is bare-chip mounted on a glass substrate 105.

[0072] Figures 2 and 3 are schematic diagrams showing another example in which the optical device according to this embodiment is used as an imaging device. Figure 2 shows a front view of the imaging device CAM, and Figure 3 shows a rear view of the imaging device CAM. The imaging device CAM is a so-called digital still camera (a camera with non-interchangeable lenses), and the photographing lens WL (optical system) is equipped with an optical element whose base material is the optical glass according to this embodiment.

[0073] When the power button (not shown) of the imaging device CAM is pressed, the shutter (not shown) of the taking lens WL is opened, and light from the subject (object) is collected by the taking lens WL and imaged on the imaging element arranged on the image plane. The subject image formed on the imaging element is displayed on the LCD monitor M arranged behind the imaging device CAM. After the photographer decides on the composition of the subject image while looking at the LCD monitor M, he or she presses the release button B1 to capture the subject image with the imaging element, which is then recorded and saved in memory (not shown).

[0074] The image pickup device CAM is provided with an auxiliary light emitting section EF that emits auxiliary light when the subject is dark, a function button B2 used for setting various conditions of the image pickup device CAM, and the like.

[0075] Optical systems used in digital cameras and other devices require higher resolution, lower chromatic aberration, and smaller size. To achieve these, it is effective to use glasses with different dispersion characteristics in the optical system. In particular, glasses that have low dispersion and a high partial dispersion ratio (P g , F ) is in high demand. From this viewpoint, the optical glass according to this embodiment is suitable as a component of such optical equipment. Note that optical equipment to which this embodiment can be applied is not limited to the above-mentioned imaging device, but also includes, for example, a projector. The optical element is also not limited to a lens, but also includes, for example, a prism.

[0076] <Microscope> 4 is a block diagram showing an example of the configuration of a multiphoton microscope 2 according to this embodiment. The multiphoton microscope 2 includes an objective lens 206, a condenser lens 208, and an imaging lens 210. At least one of the objective lens 206, the condenser lens 208, and the imaging lens 210 includes an optical element having optical glass according to this embodiment as a base material. The optical system of the multiphoton microscope 2 will be mainly described below.

[0077] The pulsed laser device 201 emits ultrashort pulsed light having, for example, a near-infrared wavelength (about 1000 nm) and a pulse width in femtosecond units (for example, 100 femtoseconds). The ultrashort pulsed light immediately after being emitted from the pulsed laser device 201 is generally linearly polarized in a predetermined direction.

[0078] The pulse splitting device 202 splits the ultrashort pulse light, increases the repetition frequency of the ultrashort pulse light, and emits it.

[0079] The beam adjusting unit 203 has a function of adjusting 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 of adjusting the focusing and divergence angles of the ultrashort pulsed light in order to correct the axial chromatic aberration (focus difference) between the wavelength of the light emitted from the sample S and the wavelength of the ultrashort pulsed light, and a pre-chirp function (group velocity dispersion compensation function) of imparting inverse group velocity dispersion to the ultrashort pulsed light in order to correct the pulse width of the ultrashort pulsed light being broadened due to group velocity dispersion while passing through the optical system.

[0080] 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. Then, the ultrashort pulsed light emitted from the beam adjusting unit 203 is reflected in the direction of the dichroic mirror by the dichroic mirror 204, 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).

[0081] 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.

[0082] 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.

[0083] 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 according 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.

[0084] 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. In this case, the observation light is descanned by a scanning means (not shown), transmitted through the dichroic mirror 204, collected by the collecting lens 208, passed through a pinhole 209 provided at a position approximately conjugate with the focal position of the objective lens 206, transmitted through the imaging lens 210, and entered the fluorescence detection unit 211.

[0085] The fluorescence detection unit 211 is composed of, 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.

[0086] Moreover, the 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., receives the observation light reflected by the dichroic mirror 212, and outputs an electrical signal according to the amount of light. Moreover, 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.

[0087] The electrical signals output from the fluorescence detection units 207, 211, and 213, respectively, are input, for example, to a computer (not shown), and the computer can generate an observation image based on the input electrical signals, display the generated observation image, and store data of the observation image.

[0088] <Cemented lens> FIG. 5 is a schematic diagram showing an example of a cemented lens according to this 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 this 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 "lens element" refers to each lens constituting a single lens or a cemented lens.

[0089] The cemented lens according to this embodiment is useful from the viewpoint of chromatic aberration correction, and can be suitably used in the above-mentioned optical elements, optical systems, optical devices, and the like. The optical system including the cemented lens can be particularly suitably used in interchangeable lenses for cameras, optical devices, and the like. In the above-mentioned embodiment, the cemented lens using two lens elements has been described, but the present invention is not limited to this, and a cemented lens using three or more lens elements may 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. EXAMPLES

[0090] Next, examples of the present invention and comparative examples will be described, but the present invention is not limited to these.

[0091] <Production of optical glass> The optical glasses according to each of the examples and comparative examples were produced by the following procedure. First, glass raw materials selected from oxides, hydroxides, phosphate compounds (phosphates, orthophosphates, etc.), carbonates, nitrates, etc. were weighed out so as to obtain the composition (mass%) shown in each table. Next, the weighed raw materials were mixed and charged into a platinum crucible, melted at a temperature of 1100 to 1350°C, and stirred and homogenized. After bubble removal, the temperature was lowered to an appropriate level, and the mixture was cast into a mold and slowly cooled, followed by molding, to obtain each sample.

[0092] <Physical property evaluation> FIG. 6 shows the P of each example and each comparative example. g,F and ν d Graph showing the plot of

[0093] Refractive index (n d ) and Abbe number (ν d ) The refractive index of each sample (n d ) and Abbe number (ν d ) was measured and calculated using a refractive index measuring instrument (Shimadzu Device Manufacturing Co., Ltd.: KPR-2000). d indicates the refractive index of glass for light of 587.562 nm. d was calculated using the following formula (1). C , n F and indicate the refractive index of glass for light with wavelengths of 656.273 nm and 486.133 nm, respectively. ν d =(n d -1) / (n F -n C ) · · · (1)

[0094] Partial dispersion ratio (P g , F ) The partial variance ratio (P g , F) is the principal variance (n F -n C ) for partial variance (n g -n F ) and was calculated using the following formula (2). g indicates the refractive index of glass for light with a wavelength of 435.835 nm. g , F ) values ​​were rounded to three decimal places. P g , F =(n g -n F ) / (n F -n C ) · · · (2)

[0095] Anomalous dispersion (ΔP g,F ) The anomalous dispersion (ΔP g,F ) indicates the deviation from the partial dispersion ratio standard line, which is based on the two glass types F2 and K7, which are considered to have normal dispersion. g,F ), the horizontal axis is the Abbe number ν d The difference between the ordinate of the line connecting the two glass types and the value of the glass being compared is the bias of the partial dispersion ratio, that is, the anomalous dispersion (ΔP g,F In the above coordinate system, if the partial dispersion ratio value is above the line connecting the standard glass types, the glass has positive anomalous dispersion (+ΔP g,F ), and when it is located on the lower side, the glass has negative anomalous dispersion (-ΔP g,F The Abbe number νd and partial dispersion ratio (Pg,F) of F2 and K7 are as follows: F2: Abbe number νd=36.33, partial dispersion ratio (Pg,F)=0.5834 K7: Abbe number νd=60.47, partial dispersion ratio (Pg,F)=0.5429 Anomalous dispersion (ΔP g , F ) values ​​were rounded to three decimal places. ΔP g , F =P g , F -(-0.0016777×ν d+0.6443513) · · · (3)

[0096] Tables 1 to 36 show the composition in terms of mass % of each component based on the oxide and the evaluation results of each physical property for the optical glasses of each Example and Comparative Example. "ΣA2O" in the formula indicates the total content of Li2O, Na2O, and K2O; A = Li, Na, K. "ΣEO" in the formula indicates the total content of MgO, CaO, SrO, BaO, and ZnO; E = Mg, Ca, Sr, Ba, Zn. For Comparative Examples 1 to 3, optical glass could not be obtained, so the physical properties were "measurable."

[0097] [Table 1]

[0098] [Table 2]

[0099] [Table 3]

[0100] [Table 4]

[0101] [Table 5]

[0102] [Table 6]

[0103] [Table 7]

[0104] [Table 8]

[0105]

Table 9

[0106]

Table 10

[0107]

Table 11

[0108]

Table 12

[0109]

Table 13

[0110]

Table 14

[0111]

Table 15

[0112]

Table 16

[0113]

Table 17

[0114]

Table 18

[0115]

Table 19

[0116]

Table 20

[0117]

Table 21

[0118]

Table 22

[0119]

Table 23

[0120]

Table 24

[0121]

Table 25

[0122]

Table 26

[0123]

Table 27

[0124]

Table 28

[0125] [Table 29]

[0126] [Table 30]

[0127] [Table 31]

[0128] [Table 32]

[0129] [Table 33]

[0130] [Table 34]

[0131] [Table 35]

[0132] [Table 36]

[0133] From the above, it was confirmed that the optical glass of this example has high dispersion and high partial dispersion. It was also confirmed that the optical glass of this example has suppressed coloring and excellent transmittance. [Explanation of symbols]

[0134] 1...imaging device, 101...camera body, 102...lens barrel, 103...lens, 104...sensor chip, 105...glass substrate, 106...multi-chip module, CAM...imaging device (lens non-interchangeable camera), WL...taking lens, M...liquid crystal monitor, EF...auxiliary light emitting unit, B1...release button, B2...function button, 2...multiphoton microscope, 201...pulse laser device, 202...pulse splitting device, 203...beam adjustment unit, 204, 205, 212...dichroic mirror, 206...objective lens, 207, 211, 213...fluorescence detection unit, 208...condensing lens, 209...pinhole, 210...imaging lens, S...sample, 3...cemented lens, 301...first lens element, 302...second lens element, 303...cemented member

Claims

1. In mass percent, P ２ O ５ Content rate: 20-55%, TIO ２ Content rate: 10-40%, Nb ２ O ５ Content rate: 0~30%, A ２ O ３ Content rate: 0-2%, B ２ O ３ Content rate: 0-10%, BaO content: 0 to 30%, Bi ２ O ３ Content: 0-30%, T ２ O ５ Content: 0-20%, WO ３ Content: 0-25%, and P ２ O ５ and B ２ O ３ and Al ２ O ３ TiO relative to the total content ２ The ratio of the content of TiO ２ / (P ２ O ５ +B ２ O ３ +Al ２ O ３ )): 0.25-0.85, TiO ２ and Nb ２ O ５ and W.O. ３ and Bi ２ O ３ and Ta ２ O ５ TiO relative to the total content ２ The ratio of the content of TiO ２ / (TiO ２ +Nb ２ O ５ +W.O. ３ +Bi ２ O ３ +Ta ２ O ５ )): 0.25 to 1.

00.

2. In mass percent, P ２ O ５ BaO and TiO ２ The ratio of the total content of BaO + TiO ２ ) / P ２ O ５ 2. The optical glass according to claim 1, wherein the refractive index is 0.40 to 1.

50.

3. In mass percent, P ２ O ５ Content rate: 20-55%, TIO ２ Content rate: 10-40%, Nb ２ O ５ Content rate: 0~30%, A ２ O ３ Content rate: 0-2%, B ２ O ３ Content rate: 0-10%, BaO content: 0-30%, Bi ２ O ３ Content rate: 0~30%, Ta ２ O ５ Content rate: 0~20%, WO ３ Content rate: 0~25%, and P ２ O ５ The content of BaO and TiO ２ The ratio of the total content of BaO + TiO ２ ) / P ２ O ５ ): 0.40 to 1.

50.

4. In mass percent, P ２ O ５ and B ２ O ３ and Al ２ O ３ TiO relative to the total content ２ The ratio of the content of TiO ２ / (P ２ O ５ +B ２ O ３ +Al ２ O ３ 4. The optical glass according to claim 3, wherein .gamma..times ...

5. In mass percent, TiO ２ and Nb ２ O ５ and W.O. ３ and Bi ２ O ３ and Ta ２ O ５ TiO relative to the total content ２ The ratio of the content of TiO ２ / (TiO ２ +Nb ２ O ５ +W.O. ３ +Bi ２ O ３ +Ta ２ O ５ 4. The optical glass according to claim 3, wherein .gamma..times ...

6. In mass percent, Na ２ O content: 0-30%, K ２ O content: 0-25%, Li ２ O content: 0-5%, 6. The optical glass according to claim 1, wherein

7. In mass percent, ZnO content: 0 to 15%, MgO content: 0-10%, CaO content: 0-10%, SrO content: 0 to 15%, The optical glass according to any one of claims 1 to 6, wherein

8. In mass percent, SiO ２ Content rate: 0-5%, ZrO ２ Content rate: 0-5%, SB ２ O ３ Content rate: 0-1%, The optical glass according to any one of claims 1 to 7, wherein

9. In mass percent, SiO ２ and B ２ O ３ Total content: 0-10%, The optical glass according to any one of claims 1 to 8, wherein

10. In mass percent, Y ２ O ３ Content rate: 0-8%, La ２ O ３ Content rate: 0-5%, Gd ２ O ３ Content rate: 0-10%, The optical glass according to any one of claims 1 to 9, wherein

11. Li ２ O and Na ２ O and K ２ Total content of O (ΣA ２ O; where A=Li, Na, K): 5 to 35%, The optical glass according to any one of claims 1 to 10,

12. The total content of MgO, CaO, SrO, BaO and ZnO (ΣEO; where E =Mg, Ca, Sr, Ba, Zn): 0 to 30%, The optical glass according to any one of claims 1 to 11,

13. In mass percent, P ２ O ５ TiO content ２ Content ratio (TiO ２ / P ２ O ５ 13. The optical glass according to claim 1, wherein the refractive index is 0.25 to 0.

85.

14. TiO ２ Al content ２ O ５ Content ratio (Al ２ O ３ / TiO ２ 14. The optical glass according to claim 1, wherein the refractive index is 0 to 0.

15.

15. P ２ O ５ B relative to content ２ O ３ Content ratio (B ２ O ３ / P ２ O ５ 15. The optical glass according to claim 1, wherein:

16. P ２ O ５ and B ２ O ３ and SiO ２ and Al ２ O ３ The total content of BaO and TiO ２ and Nb ２ O ５ and W.O. ３ and Bi ２ O ３ and Ta ２ O ５ The ratio of the total content of BaO + TiO ２ +Nb ２ O ５ +W.O. ３ +Bi ２ O ３ +Ta ２ O ５ ) / (P ２ O ５ +B ２ O ３ +SiO ２ +Al ２ O ３ 16. The optical glass according to claim 1, wherein the refractive index is 0.40 to 2.

00.

17. TiO ２ Li content ２ O and Na ２ O and K ２ Total content of O (ΣA ２ O; where A = Li, Na, K) ratio (ΣA ２ O / TiO ２ 17. The optical glass according to claim 1, wherein:

18. Li ２ O and Na ２ O and K ２ Total content of O (ΣA ２ The ratio (ΣEO / ΣA ２ 18. The optical glass according to claim 1, wherein:

19. Refractive index for d line (n ｄ 19. The optical glass according to claim 1, wherein the refractive index is in the range of 1.60 to 1.

85.

20. Abbe number (ν ｄ 20. The optical glass according to claim 1, wherein the refractive index is in the range of 20 to 35.

21. Partial dispersion ratio (P ｇ , Ｆ 21. The optical glass according to claim 1, wherein .lambda.=0.61 to 0.

66.

22. Anomalous dispersion (ΔP ｇ , Ｆ 22. The optical glass according to claim 1, wherein n is 0.015 to 0.

055.

23. An optical element comprising the optical glass according to any one of claims 1 to 22.

24. An optical system comprising the optical element according to claim 23.

25. An interchangeable lens for a camera, comprising the optical system according to claim 24.

26. 25. A microscope objective comprising the optical system of claim 24.

27. 25. An optical device comprising the optical system of claim 24.

28. A first lens element and a second lens element, A cemented lens, wherein at least one of the first lens element and the second lens element is the optical glass according to any one of claims 1 to 22.

29. 30. An optical system comprising the cemented lens of claim 28.

30. 30. A microscope objective comprising the optical system of claim 29.

31. 30. An interchangeable lens for a camera, comprising the optical system according to claim 29.

32. 30. An optical device comprising the optical system of claim 29.

Images