Optical glass, optical elements, optical systems, cemented lenses, interchangeable lenses for cameras, objective lenses for microscopes and optical devices

Abstract

This optical glass has, in terms of mass%, a SiO2 content of 20-30%, a Li2O content of 2-8%, a Na2O content of 0-8% (exclusive of 0), a BaO content of 0-8% (exclusive of 0), a ZrO2 content of 2-10%, and a Nb2O5 content of 40-60%.

Description

[Technical Field]

[0001] The present invention relates to optical glass, optical elements, optical systems, cemented lenses, interchangeable lenses for cameras, lenses for microscopes, and optical devices. [Background technology]

[0002] For example, Patent Document 1 discloses an optical glass made of borosilicate glass. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-46591 Summary of the Invention [Means for solving the problem]

[0004] In a first aspect of the present invention, the SiO2 content is 20% or more and 30% or less, the Li2O content is 2% or more and 6% or less, the Na2O content is more than 0% and 8% or less, the BaO content is more than 0% and 8% or less, the ZrO2 content is 2% or more and 10% or less, the Nb2O5 content is 40% or more and 60% or less, TiO 2 Content rate: more than 0% and less than 5.89%,The ratio of the TiO2 content to the Nb2O5 content (TiO2 / Nb2O5): more than 0% and not more than 0.15, the total content of Li2O, Na2O, and K2O (ΣA2O; where A = Li, Na, K): 10% or more and not more than 18%, the ratio of the total content of SiO2, BaO, and TiO2 to the total content of ΣA2O (A = Li, Na, K), ZrO2, and Nb2O5 ((SiO2 + BaO + TiO2) / The optical glass has a SiO2 content of 20% to 30%, a Li2O content of 2% to 6%, a Na2O content of 0% to 8%, a BaO content of 0% to 8%, a ZrO2 content of 2% to 10%, a Nb2O5 content of 40% to 60%, and a TiO2 content of 5.89%. Ta 2 O 5 Content rate: 0% or more and 6% or less, The optical glass has a total content of Li2O, Na2O, and K2O (ΣAO; where A = Li, Na, K): 10% to 18%, a ratio of the total content of SiO2, BaO, and TiO2 to the total content of ΣAO (A = Li, Na, K), ZrO2, and Nb2O5 ((SiO2 + BaO + TiO2) / (ΣAO + ZrO2 + Nb2O5)): 0.42 to 0.70, and a ratio of the SiO2 content to the total content of TiO2 and Nb2O5 (SiO2 / (TiO2 + Nb2O5)): 0.40 to 0.56. In addition, the optical glass has the following mass %: SiO2 content: 20% to 30%, Li2O content: 2% or more and 6% or less, Na2O content: more than 0% and less than 8%, BaO content: more than 0% and less than 8%, ZrO2 content: 2% to 10%, Nb2O5 content: 45.96% to 60%, TiO 2 Content rate: more than 0% and less than 5.89%, Total content of Li2O, Na2O and K2O (ΣA2O; where A = Li, Na, K): 10% or more and 18% or less, The ratio of the total content of SiO2, BaO, and TiO2 to the total content of ΣA2O (A = Li, Na, K), ZrO2, and Nb2O5 ((SiO2 + BaO + TiO2) / (ΣA2O + ZrO2 + Nb2O5)): 0.42 or more and 0.70 or less, This optical glass has a total content of TiO2, ZrO2, Nb2O5, and Ta2O5 (TiO2+ZrO2+Nb2O5+Ta2O5): 50% or more and 62% or less.

[0005] A second aspect of the present invention is a cemented lens having a first lens element and a second lens element, at least one of which is made of the optical glass described above.

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

[0007] A fourth aspect of the present invention is an objective lens for a microscope, which includes an optical system including the cemented lens described above.

[0008] A fifth aspect of the present invention is an interchangeable lens for a camera, including an optical system including the cemented lens described above.

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

[0010] A seventh aspect of the present invention is an optical element using the above-mentioned optical glass.

[0011] A third aspect of the present invention is an optical system including the optical element described above.

[0012] A fourth aspect of the present invention is an interchangeable lens for a camera, which includes an optical system including the optical element described above.

[0013] A fifth aspect of the present invention is an optical device including an optical system including the optical element described above. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of an imaging device equipped with an optical element using the optical glass according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram of another example of an imaging device equipped with an optical element using the optical glass according to this embodiment, and is a front view of the imaging device. [Figure 3] FIG. 3 is a schematic diagram of another example of an imaging device equipped with an optical element using the optical glass according to this embodiment, and is a rear view of the imaging device. [Figure 4] FIG. 4 is a block diagram showing an example of the configuration of a multiphoton microscope equipped with an optical element using the optical glass according to this embodiment. [Figure 5] FIG. 5 is a schematic diagram showing an example of a cemented lens according to this embodiment. [Figure 6] FIG. 6 is a graph plotting Pg, F and νd for each example and each comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] The optical glass according to this embodiment has, in mass %, an SiO2 content of 20 to 30%, an Li2O content of 2 to 8%, an Na2O content of more than 0 to 8%, an BaO content of more than 0 to 8%, a ZrO2 content of 2 to 10%, and an Nb2O5 content of 40 to 60%.

[0017] Unless otherwise specified, the content of each component in this specification is expressed as mass% of the total weight of the glass in terms of oxides. The oxide-equivalent composition here refers to 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 components are all decomposed and converted to oxides during melting, with the total mass of the oxides being 100%.

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

[0019] The expression "does not contain Q component" means that the Q component is substantially not contained, and indicates that the content of this component is at or below the impurity level. At or below the impurity level, for example, means less than 0.01%.

[0020] The expression "devitrification resistance" 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 its glass transition temperature or when the temperature is lowered from a molten state to or below its liquidus temperature.

[0021] In optical systems such as optical devices, chromatic aberration correction (achromatization) is achieved by combining glass materials with different refractive indices and dispersions. From the perspective of achieving this achromatization, glass materials that have high dispersion (low Abbe number) and a small partial dispersion ratio are desired.

[0022] However, as a general characteristic of optical glass, the Abbe number (ν d ) to the partial variance ratio (P g,F ) tends to be high. Therefore, in high-dispersion optical glass, the relationship between the Abbe number and the partial dispersion ratio deviates significantly in the positive direction from the linear relationship (baseline), and the anomalous dispersion (ΔP g,F ) became too large.

[0023] Furthermore, to achieve optical glass with high dispersion and low anomalous dispersion, it is necessary to use a composition containing a large amount of transition metal oxides, which poses a productivity issue in that the glass's devitrification resistance is likely to decrease. Glass with low devitrification resistance is likely to contain devitrification particles during manufacturing, reducing yield. Devitrification particles are also likely to form when the glass is reheated for press molding, etc. Therefore, there is a demand for optical glass that has high dispersion and low anomalous dispersion, as well as excellent devitrification resistance.

[0024] The optical glass according to this embodiment has high dispersion and low anomalous dispersion, and also has high stability against devitrification. d ≦1.88, 23≦ν d In the high refractive index, high dispersion region, the anomalous dispersion value is ΔP g,F ≦0.0090 and the glass transition temperature (T g ) and crystallization initiation temperature (T x ) difference (ΔT=T x -T g ) is 230°C or higher, and the liquidus temperature (T l ) can be realized as an optical glass having a temperature of 1220°C or less.

[0025] Such optical glass has a low risk of devitrification during manufacturing or press molding, and has a low Abbe number (ν d ) is low, and the partial variance ratio (P g,F ) is low. In other words, the deviation of the partial dispersion ratio from the reference line in the positive direction is small, and the positive anomalous dispersion (ΔP g,F ) is an optical glass having low refractive index. The optical glass according to this embodiment has such properties and can therefore fully meet the above-mentioned requirements.

[0026] The component composition of the optical glass according to this embodiment will be described below.

[0027] SiO2 is an oxide that forms glass, and can lower the refractive index and improve stability against devitrification. If the content is too high, the melting property of the glass decreases, and ΔP g,F This reduces the SiO2 content and increases the Abbe number. From this perspective, the SiO2 content is 20% or more and 30% or less. The lower limit of this content is preferably 22%, more preferably 24%. The upper limit of this content is preferably 28%, more preferably 26%.

[0028] Li2O has a ΔP g,F Li2O is a component that reduces the temperature and improves the meltability of the glass. If the content is too high, the devitrification resistance decreases and the Abbe number increases. From this perspective, the Li2O content is 2% or more and 8% or less. The lower limit of this content is preferably 3%, more preferably 4%. The upper limit of this content is preferably 7%, more preferably 6%.

[0029] Na2O has a ΔP g,F It is a component that reduces the temperature and improves the meltability of the glass. If this content is too high, the devitrification resistance decreases and the Abbe number increases. From this perspective, the Na2O content is more than 0% and not more than 8%. The lower limit of this content is preferably 3%, more preferably 4%. The upper limit of this content is preferably 7%, more preferably 6%.

[0030] BaO has a ΔP g,F It is a component that improves the devitrification resistance of the glass without significantly increasing ΔP. If BaO is not contained, the devitrification resistance of the glass will decrease. If this content is too high, g,F The resistance decreases and the Abbe number increases. From this viewpoint, the BaO content is more than 0% and not more than 8%. The lower limit of this content is preferably 1%, more preferably 2%. The upper limit of this content is preferably 5%, more preferably 3%.

[0031] ZrO2 is ΔP g,FIf the content is too high, the meltability and devitrification resistance stability of the glass will decrease. From this viewpoint, the ZrO2 content is 2% or more and 10% or less. The lower limit of this content is preferably 3.5%, more preferably 5%. The upper limit of this content is preferably 9%, more preferably 7%.

[0032] Nb2O5 has a ΔP g,F It is a component that decreases the refractive index, increases the refractive index, and decreases the Abbe number. If this content is too high, the meltability and devitrification resistance stability of the glass will be significantly impaired. From this perspective, the Nb2O5 content is 40% or more and 60% or less. The lower limit of this content is preferably 44%, more preferably 48%. The upper limit of this content is preferably 56%, more preferably 52%.

[0033] The optical glass according to this embodiment may further contain, as an optional component, one or more components selected from the group consisting of K2O, MgO, TiO2, Ta2O5, Sb2O3, Y2O3, La2O3, and Gd2O3.

[0034] K2O is ΔP g,F It is a component that reduces the glass's meltability and improves its meltability, but compared with Li2O and Na2O, it has a greater effect of reducing the glass's devitrification resistance and increasing its Abbe number. From this perspective, the K2O content is 0% or more and 5% or less. The lower limit of this content is preferably 1%, more preferably 2%. The upper limit of this content is preferably 4.5%, more preferably 4%.

[0035] MgO is a component that increases the Abbe number, but compared to BaO, ΔP g,F From this viewpoint, the content of MgO is 0% or more and 4% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 3%, more preferably 2%.

[0036] TiO2 is a component that improves the devitrification resistance of glass, increases the refractive index, and decreases the Abbe number. If the content is too high, ΔP g,F The transmittance also deteriorates. From this viewpoint, the TiO2 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 7%, more preferably 4%.

[0037] Ta2O5 has a ΔP g,F It is a component that decreases the refractive index, increases the refractive index, and decreases the Abbe number. If the content is too high, the melting property of the glass decreases and the specific gravity increases. Furthermore, Ta2O5 is an expensive raw material. The optical glass according to this embodiment has high dispersion and low ΔP without increasing the content of Ta2O5. g,F From this perspective, the Ta2O5 content is 0% or more and 6% or less. The lower limit of this content may be more than 0%. The upper limit of this content may be 5%. Furthermore, when it is desired to further reduce the cost of the optical glass according to this embodiment, it is preferable that Ta2O5 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 unavoidably contained as an impurity. For example, a content of about 100 ppm is considered to be substantially not contained.

[0038] Sb2O3 is an optional component that is effective for clarifying and homogenizing glass. If the content is too high, the transmittance of the glass decreases. From this perspective, the Sb2O3 content is 0% or more and 1% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 0.5%, more preferably 0.2%.

[0039] From the viewpoint of meltability, the Y2O3 content is 0% or more and 3% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 2%, more preferably 1%.

[0040] From the viewpoint of meltability, the La2O3 content is 0% or more and 3% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 2%, more preferably 1%.

[0041] From the viewpoint of meltability, the content of Gd2O3 is 0% or more and 3% or less. The lower limit of this content may be more than 0%. The upper limit of this content is preferably 2%, more preferably 1%.

[0042] Li2O, Na2O, and K2O are components that improve the meltability of glass and enhance devitrification resistance stability. From this perspective, the total content of Li2O, Na2O, and K2O (ΣA2O; where A = Li, Na, K) is 8% or more and 18% or less. The lower limit of this content is preferably 10%, more preferably 11%. The upper limit of this content is preferably 16%, more preferably 15%.

[0043] From the viewpoint of enhancing the devitrification resistance stability of the glass, the total content of MgO and BaO (MgO + BaO) 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 9%, more preferably 8%.

[0044] From the viewpoint of improving the devitrification resistance stability and decreasing the Abbe number, the total content of TiO2, ZrO2, Nb2O5, and Ta2O5 (TiO2 + ZrO2 + Nb2O5 + Ta2O5) is 50% or more and 65% or less. The lower limit of this content is preferably 53%, more preferably 56%. The upper limit of this content is preferably 62%, more preferably 59%.

[0045] ΔP g,F From the viewpoint of reducing the content of TiO2 and improving the stability against devitrification, the ratio of the content of TiO2 to the content of Nb2O5 (TiO2 / Nb2O5) is 0 to 0.20. The lower limit of this ratio may be more than 0. The upper limit of this ratio is preferably 0.15, and more preferably 0.10.

[0046] ΔP g,F From the viewpoint of reducing the content of SiO2, BaO, and TiO2 and enhancing the stability against devitrification, the ratio of the total content of SiO2, BaO, and TiO2 to the total content of ΣA2O (A = Li, Na, K), ZrO2, and Nb2O5 ((SiO2 + BaO + TiO2) / (ΣA2O + ZrO2 + Nb2O5)) is 0.30 to 0.70. The lower limit of this ratio is preferably 0.35, and more preferably 0.40. The upper limit of this ratio is preferably 0.60, and more preferably 0.50.

[0047] From the viewpoint of improving the stability against devitrification, the ratio of the SiO2 content to the total content of TiO2 and Nb2O5 (SiO2 / (TiO2+Nb2O5)) is 0.40 to 0.60. The lower limit of this ratio is preferably 0.44, more preferably 0.48. The upper limit of this ratio is preferably 0.56, more preferably 0.52.

[0048] From the viewpoint of improving the meltability of the glass and enhancing the devitrification resistance stability, the ratio of the total content of SiO2, ΣA2O (A = Li, Na, K), and BaO to the total content of ZrO2 and Nb2O5 ((SiO2 + ΣA2O + BaO) / (ZrO2 + Nb2O5)) is 0.60 to 0.90. The lower limit of this ratio is preferably 0.65, and more preferably 0.70. The upper limit of this ratio is preferably 0.85, and more preferably 0.80.

[0049] In addition to the above-mentioned components, other optional components may be added within the range that does not interfere with achieving the optical glass aimed at in this embodiment.

[0050] The optical glass according to this embodiment having the above-mentioned component composition has high dispersion and low ΔP g,F At the same time, excellent stability against devitrification can be maintained.

[0051] The preferred properties of the optical glass of this embodiment will be described below.

[0052] First, from the viewpoint that the optical glass according to this embodiment is suitable for use in a high refractive index, high dispersion region, the refractive index for the d line (n d The refractive index (n d The lower limit of the refractive index (n d The upper limit of the Abbe number (ν d ) is preferably in the range of 23 to 29. d The lower limit of the Abbe number (ν d ) is more preferably 27, and even more preferably 26.

[0053] From the viewpoint of correcting aberrations in the lens, the optical glass according to this embodiment has a partial dispersion ratio (P g , F In view of this situation, it is desirable that the partial dispersion ratio (P g , F ) is preferably 0.611 or less. g , F The upper limit of the partial dispersion ratio (P g , F The lower limit of ) is not particularly limited, but may be, for example, 0.600.

[0054] Furthermore, the value indicating the anomalous dispersion of the optical glass according to this embodiment (ΔP g,F ) is preferably greater than 0 and not greater than 0.0090. g,F The upper limit of ) is more preferably 0.0085, and even more preferably 0.0080.

[0055] From the viewpoint of stability against devitrification, the liquidus temperature (T l The liquidus temperature (Tl The upper limit of the glass transition temperature (T g ) and crystallization initiation temperature (T x ) temperature difference (ΔT=T x -T g ) is 230°C or more. This temperature difference (ΔT = T x -T g The lower limit of the temperature is preferably 240°C, more preferably 250°C.

[0056] Optical glasses that combine these properties are able to maintain excellent stability against devitrification while exhibiting high dispersion and low anomalous dispersion. These optical glasses have a low risk of generating devitrification particles during manufacturing, and when used in optical lenses, they can effectively correct chromatic aberration.

[0057] The optical glass according to this embodiment, which has the properties described above, can be suitably used, for example, as an optical element used in optical devices. Examples of such optical elements include mirrors, lenses, prisms, and filters. Examples of optical systems in which the optical elements are used include objective lenses, condenser lenses, imaging lenses, and interchangeable camera lenses. Furthermore, these optical systems can be suitably used in optical devices for imaging devices such as interchangeable-lens cameras and non-interchangeable-lens cameras, and microscopes such as multiphoton microscopes and fluorescence 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, monoculars, laser rangefinders, projectors, and the like. Examples of these optical devices are described below.

[0058] <Imaging device> FIG. 1 is a perspective view of an example in which the optical device is an imaging device.

[0059] The imaging device 1 is a so-called digital single-lens reflex camera (interchangeable lens camera), and its taking lens 103 (optical system) is equipped with an optical element whose base material is the optical glass according to this embodiment. A lens barrel 102 is detachably attached to a lens mount (not shown) of a camera body 101. Light passing through the taking lens 103 of the lens barrel 102 forms an image on a sensor chip (solid-state image sensor) 104 of a multi-chip module 106 disposed on the rear side of the camera body 101. This sensor chip 104 is a bare chip such as a so-called CMOS image sensor, and the multi-chip module 106 is, for example, a COG (chip-on-glass) type module in which the sensor chip 104 is bare-chip mounted on a glass substrate 105.

[0060] 2 and 3 are schematic diagrams of another example in which the optical device is an imaging device, where Fig. 2 shows a front view of the imaging device CAM and Fig. 3 shows a rear view of the imaging device CAM.

[0061] The imaging device CAM is a so-called digital still camera (a camera with non-interchangeable lenses), and the taking lens WL (optical system) is equipped with an optical element whose base material is the optical glass according to this embodiment.

[0062] When the power button (not shown) of the imaging device CAM is pressed, the shutter (not shown) of the taking lens WL is opened, light from the subject (object) is collected by the taking lens WL, and an image is formed on the imaging element located on the image plane. The subject image formed on the imaging element is displayed on the LCD monitor M located 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).

[0063] 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 to set various conditions for the image pickup device CAM, and the like.

[0064] <Microscope> FIG. 4 is a block diagram showing an example of the configuration of the multiphoton microscope 2. As shown in FIG.

[0065] 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 whose base material is the optical glass according to this embodiment. The following description will focus on the optical system of the multiphoton microscope 2.

[0066] The pulsed laser device 201 emits ultrashort pulsed light, for example, with a near-infrared wavelength (approximately 1000 nm) and a pulse width in femtosecond units (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.

[0067] The pulse splitting device 202 splits the ultrashort pulsed light, increases the repetition frequency of the ultrashort pulsed light, and emits it.

[0068] The beam adjusting unit 203 has functions such as adjusting the beam diameter of the ultrashort pulsed light incident from the pulse splitter 202 to match the pupil diameter of the objective lens 206, adjusting the focusing and divergence angles of the ultrashort pulsed light to correct on-axis 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) that imparts inverse group velocity dispersion to the ultrashort pulsed light to correct the pulse width of the ultrashort pulsed light that widens due to group velocity dispersion while passing through the optical system.

[0069] 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 by the dichroic mirror 204 in the direction of the dichroic mirror 205, passes through the dichroic mirror 205, and is collected by the objective lens 206 to be irradiated onto the sample S. At this time, the ultrashort pulsed light may be scanned over the observation surface of the sample S by using a scanning means (not shown).

[0070] 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") with a wavelength shorter than that of the ultrashort pulsed light, which is an infrared wavelength.

[0071] 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.

[0072] The observation light reflected by the dichroic mirror 205 enters the fluorescence detection unit 207. The fluorescence detection unit 207 is configured with, 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.

[0073] 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 an imaging lens 210, and entered the fluorescence detection unit 211.

[0074] The fluorescence detection unit 211 is configured with, for example, a barrier filter, a PMT, etc., receives the observation light imaged on the light receiving surface of the fluorescence detection unit 211 by the imaging lens 210, and outputs an electrical signal according to the amount of light. Furthermore, the fluorescence detection unit 211 detects the observation light across the observation surface of the sample S as the ultrashort pulsed light scans the observation surface of the sample S.

[0075] Furthermore, observation light emitted from the sample S in the direction opposite to the objective lens 206 is reflected by the dichroic mirror 212 and enters the fluorescence detection unit 213. The fluorescence detection unit 213 is configured, for example, with a barrier filter, a PMT, etc., and receives the observation light reflected by the dichroic mirror 212 and outputs an electrical signal according to the amount of light. Furthermore, the fluorescence detection unit 213 detects the observation light across the observation surface of the sample S as the ultrashort pulsed light scans the observation surface of the sample S.

[0076] The electrical signals output from the fluorescence detection units 207, 211, and 213 are input, for example, to a computer (not shown), which can generate an observation image based on the input electrical signals, display the generated observation image, and store the data of the observation image.

[0077] <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 term "lens element" refers to each of the lenses that make up a single lens or a cemented lens.

[0078] The cemented lens according to this embodiment is useful from the viewpoint of correcting chromatic aberration, and can be suitably used in the optical elements, optical systems, optical devices, etc. described above. Furthermore, optical systems including cemented lenses can be particularly suitably used in interchangeable lenses for cameras, optical devices, etc. While the cemented lens using two lens elements has been described in the above embodiment, this is not limiting, and a cemented lens using three or more lens elements may also be used. When a cemented lens using three or more lens elements is used, it is sufficient that at least one of the three or more lens elements is formed using the optical glass according to this embodiment. [Example]

[0079] Next, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples.

[0080] <Production of optical glass> The optical glasses according to the examples and comparative examples were produced by the following procedure. First, glass raw materials such as oxides, hydroxides, carbonates, and nitrates were weighed out to a total weight of 100 g so as to obtain the chemical compositions (mass %) shown in Tables 1 to 7. Next, the weighed raw materials were mixed and placed in a platinum crucible, melted at a temperature of 1300 to 1400°C for about 1 hour, and stirred to homogenize. After that, the mixture was cooled to an appropriate temperature and poured into a mold or the like, and slowly cooled to obtain each sample.

[0081] <Optical glass measurement> Refractive index (n d ) and Abbe number (ν d ) The refractive index (n d ) and Abbe number (ν d The Abbe number (ν) was measured and calculated using a refractive index measuring instrument (Shimadzu Device Manufacturing Co., Ltd.: KPR-2000). d ) was calculated based on the following formula (1). The refractive index value used in the calculation was rounded to six decimal places. ν d =(n d -1) / (n F -n C )····(1) n d : Refractive index of glass for light with a wavelength of 587.562 nm n F : Refractive index of glass for light with a wavelength of 486.133 nm n C : Refractive index of glass for light with a wavelength of 656.273 nm

[0082] The partial variance ratio (P g,F ) was calculated based on the following formula (2). The partial dispersion ratio value was rounded to four decimal places. Pg,F =(n g -n F ) / (n F -n C )····(2) n F : Refractive index of glass for light with a wavelength of 486.133 nm n C : Refractive index of glass for light with a wavelength of 656.273 nm n g : Refractive index of glass for light with a wavelength of 435.835 nm

[0083] Anomalous dispersion value (ΔP g,F ) The value indicating the anomalous dispersion of each sample (ΔP g,F ) was determined in accordance with the method shown below.

[0084] (1) Creating a reference line First, as normal partial dispersion glass, the Abbe number (ν d ) and partial variance ratio (P g,F Two glasses, "F2" and "K7", having the same refractive index, were selected as the reference materials. For each glass, the horizontal axis represents the Abbe number, and the vertical axis represents the partial dispersion ratio (P g,F ) and the line connecting the two points corresponding to the two reference materials was used as the reference line. Characteristics of optical glass F2: ν d =36.33, P g,F =0.5834 Characteristics of optical glass K7: ν d =60.47, P g,F =0.5429

[0085] (2)ΔP g,F Calculation of Next, as shown in Figure 6, the horizontal axis represents the Abbe number (ν d ), and the vertical axis is the partial variance ratio (P g,F ), the values ​​corresponding to the optical glass of each example were plotted on a graph, and the Abbe number (ν d ) and the point on the reference line (solid line) corresponding to the vertical axis value (P g,F ) is the value indicating anomalous dispersion (ΔP g,F) was calculated. The partial variance ratio (P g,F ) is above the reference line, ΔP g,F has a positive value, and the partial variance ratio (P g,F ) is below the reference line, ΔP g,F has a negative value.

[0086] Glass transition temperature (T g ), crystallization initiation temperature (T x ) The glass transition temperature (T g The crystallization temperature (T) of each sample was determined as the intersection of the extension of the baseline in the glassy state and the tangent to the inflection point on the DTA curve measured at a heating rate of 10°C per minute using a differential thermal and thermogravimetric simultaneous analyzer (Rigaku Thermo Plus EVO2 TG8121). x ) was determined from the intersection of the tangent to the inflection point on the low-temperature side of the crystallization peak in the DTA curve and an extension of the baseline. The sample weight was 100 mg, and measurements were made using a cylindrical, lidless platinum cell with an opening diameter of 5 mm and a height of 5 mm. To prevent distortion of the DTA curve due to softening and deformation of the glass during measurement, the sample was inserted into the platinum cell, heated at 1350°C for 5 minutes, and then quenched before use. Before measurement, it was visually confirmed that the glass had not overflowed from the platinum cell and that the glass inside the platinum cell had not devitrified.

[0087] Supercooling temperature range of glass (ΔT) The supercooling temperature range (ΔT) of each sample was determined by the crystallization onset temperature (T x ) and glass transition temperature (T g ) is calculated from the difference between the glass transition temperature and the crystallization onset temperature. In the temperature range between the glass transition temperature and the crystallization onset temperature, the glass becomes a supercooled liquid, allowing atoms to move easily and resulting in viscous flow. In the supercooled temperature range, the viscosity drops rapidly as the temperature rises, making reheat press molding possible, but it also makes it easier for atoms to rearrange, making crystal precipitation more likely to occur. Therefore, the larger the supercooled temperature range (ΔT), the more likely a glass is to not undergo crystal precipitation until a higher temperature, and so it can be considered to have higher resistance to devitrification.

[0088] ·Liquidus temperature (T l ) The liquidus temperature (T l ) was determined by holding the glass in a devitrification test furnace with a temperature gradient of 1050 to 1250°C for 18 minutes, then observing the presence or absence of crystals using a microscope with a magnification of 100x, and determining the lowest temperature at which devitrification did not occur when viewed from the high-temperature side.

[0089] Tables 1 to 7 show the component compositions (by mass) and refractive indices (n d ), Abbe number (ν d ), partial dispersion ratio (P g,F ), anomalous variance value (ΔP g,F ), glass transition temperature (T g ), crystallization initiation temperature (T x ), supercooling temperature range (ΔT), liquidus temperature (T l ) is shown.

[0090] FIG. 6 shows the P g,F and ν d The graph plotting the above is shown below.

[0091] [Table 1]

[0092] [Table 2]

[0093] [Table 3]

[0094] [Table 4]

[0095] [Table 5]

[0096] [Table 6]

[0097] [Table 7]

[0098] From the above, the optical glasses of the examples have high resistance to devitrification, high dispersion, and low anomalous dispersion (ΔP g,F ) was confirmed to be low.

[0099] On the other hand, in each comparative example, the supercooling temperature range (ΔT) was small, the sample was devitrified and could not be used as optical glass, or the partial dispersion ratio was large and the positive anomalous dispersion was high. [Explanation of symbols]

[0100] 1...imaging device, 101...camera body, 102...lens barrel, 103...photographing lens, 104...sensor chip, 105...glass substrate, 106...multi-chip module, 2...multiphoton microscope, 201...pulse laser device, 202...pulse splitter, 203...beam adjustment unit, 204, 205, 212...dichroic mirror, 206...objective lens, 207, 211, 213...fluorescence detection unit, 208...condenser lens, 209...pinhole, 210...imaging lens, CAM...imaging device, WL...photographing lens, EF...fill-in light emitter, M...liquid crystal monitor, B1...release button, B2...function button, S...sample

Claims

1. In mass%, SiO ２ Content rate: 20% to 30% Li ２ O content: 2% to 6% Na ２ O content: 0% to below 8% BaO content: more than 0% and less than 8%, ZrO ２ Content rate: 2% to 10% Nb ２ O ５ Content rate: 40% to 60% TiO 2 content: more than 0% and less than 5.89%, Nb ２ O ５ TiO content ２ The ratio of the content (TiO ２ / Nb ２ O ５ ): more than 0% and less than 0.15, Li ２ O and Na ２ O and K ２ Total content of O (ΣA ２ O; where A = Li, Na, K): 10% or more and 18% or less, ΣA ２ O (A=Li, Na, K) and ZrO ２ and Nb ２ O ５ SiO relative to the total content ２ and BaO and TiO ２ The ratio of the total content of (SiO ２ +BaO +TiO ２ ) / (ΣA ２ O+ZrO ２ +Nb ２ O ５ )): 0.42 or more and 0.70 or less, TiO ２ and Nb ２ O ５ SiO relative to the total content ２ Content ratio (SiO ２ / (TiO ２ +Nb ２ O ５ )): 0.40 or more and 0.56 or less, TiO ２ and ZrO ２ and Nb ２ O ５ and Ta ２ O ５ The total content of (TiO ２ + ZrO ２ +Nb ２ O ５ +Ta ２ O ５ ): an optical glass having a porosity of 50% or more and 62% or less.

2. In mass%, SiO ２ Content rate: 20% to 30% Li ２ O content: 2% to 6% Na ２ O content: 0% to below 8% BaO content: more than 0% and less than 8%, ZrO ２ Content rate: 2% to 10% Nb ２ O ５ Content rate: 40% to 60% TiO ２ Content rate: 0% above 5.89% Ta 2 O 5 content: 0% or more and 6% or less, Li ２ O and Na ２ O and K ２ Total content of O (ΣA ２ O; where A = Li, Na, K): 10% or more and 18% or less, ΣA ２ O (A=Li, Na, K) and ZrO ２ and Nb ２ O ５ SiO relative to the total content ２ and BaO and TiO ２ The ratio of the total content of (SiO ２ +BaO +TiO ２ ) / (ΣA ２ O+ZrO ２ +Nb ２ O ５ )): 0.42 or more and 0.70 or less, TiO ２ and Nb ２ O ５ SiO relative to the total content ２ Content ratio (SiO ２ / (TiO ２ +Nb ２ O ５ )): an optical glass having a refractive index of 0.40 or more and 0.56 or less.

3. In mass%, TiO ２ and ZrO ２ and Nb ２ O ５ and Ta ２ O ５ The total content of (TiO ２ + ZrO ２ +Nb ２ O ５ +Ta ２ O ５ 3. The optical glass according to claim 2, wherein the content of SiO 2 is 50% or more and 65% or less.

4. In mass%, K ２ O content: 0% to 5% MgO content: 0% or more and 4% or less, Ta ２ O ５ Content rate: 0% to 6% The optical glass according to any one of claims 1 to 3, wherein

5. In mass%, SiO ２ Content rate: 20% to 30% Li ２ O content: 2% to 6% Na ２ O content: 0% to below 8% BaO content: more than 0% and less than 8%, ZrO ２ Content rate: 2% to 10% Nb ２ O ５ Content rate: 45.96% or higher, less than 60% TiO 2 content: more than 0% and less than 5.89%, Li ２ O and Na ２ O and K ２ Total content of O (ΣA ２ O; where A = Li, Na, K): 10% or more and 18% or less, ΣA ２ O (A=Li, Na, K) and ZrO ２ and Nb ２ O ５ SiO relative to the total content ２ and BaO and TiO ２ The ratio of the total content of (SiO ２ +BaO +TiO ２ ) / (ΣA ２ O+ZrO ２ +Nb ２ O ５ )): 0.42 or more and 0.70 or less, TiO ２ and ZrO ２ and Nb ２ O ５ and Ta ２ O ５ The total content of (TiO ２ + ZrO ２ +Nb ２ O ５ +Ta ２ O ５ ): an optical glass having a porosity of 50% or more and 62% or less.

6. TiO ２ and Nb ２ O ５ SiO relative to the total content ２ Content ratio (SiO ２ / (TiO ２ +Nb ２ O ５ 6. The optical glass according to claim 5, wherein σ is 0.40 or more and 0.60 or less.

7. In mass%, K ２ O content: 0% to 5% MgO content: 0% or more and 4% or less, TiO ２ Content rate: 0% to 10% Ta ２ O ５ Content rate: 0% to 6% 7. The optical glass according to claim 5, wherein

8. Nb ２ O ５ TiO relative to the content ２ The ratio of the content of (TiO ２ / Nb ２ O ５ ): 0 or more and 0.20 or less, The optical glass according to any one of claims 5 to 7.

9. In mass%, Sb ２ O ３ Content rate: 0% to 1% Y ２ O ３ Content rate: 0% to 3% La ２ O ３ Content rate: 0% to 3% Gd ２ O ３ Content: 0% or more and 3% or less, The optical glass according to any one of claims 1 to 8.

10. 1. The total content of MgO and BaO (MgO + BaO): 0% or more and 10% or less.

10. The optical glass according to any one of claims 1 to 9.

11. ZrO ２ and Nb ２ O ５ SiO relative to the total content ２ and ΣA ２ The ratio of the total content of O (A = Li, Na, K) and BaO ((SiO ２ +ΣA ２ O+BaO) / (ZrO ２ +Nb ２ O ５ 11. The optical glass according to claim 1, wherein the refractive index is 0.60 or more and 0.90 or less.

12. Refractive index (n ｄ ) is in the range of 1.78 or more and 1.88 or less, The optical glass according to any one of claims 1 to 11.

13. Abbe number (ν ｄ ) is in the range of 23 to 29, The optical glass according to any one of claims 1 to 12.

14. Partial dispersion ratio (P ｇ，Ｆ ) is 0.611 or less; The optical glass according to any one of claims 1 to 13.

15. Anomalous variance value (ΔP ｇ，Ｆ ) is 0.0090 or less; The optical glass according to any one of claims 1 to 14.

16. Glass transition temperature (T ｇ ) and crystallization initiation temperature (T ｘ ) difference (ΔT = T ｘ -T ｇ ) is 230°C or higher; The optical glass according to any one of claims 1 to 15.

17. Liquidus temperature (T ｌ ) is 1220°C or less, The optical glass according to any one of claims 1 to 16.

18. 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 made of the optical glass according to any one of claims 1 to 17.

19. An optical system comprising the cemented lens of claim 18.

20. 20. A microscope objective comprising the optical system of claim 19.

21. An interchangeable lens for a camera, comprising the optical system of claim 19.

22. 20. An optical device comprising the optical system of claim 19.

23. An optical element using the optical glass according to any one of claims 1 to 17.

24. An optical system comprising the optical element of claim 23.

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

26. An interchangeable lens for a camera, comprising the optical system of claim 24.

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

Images