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

Abstract

To provide optical glass having a high refractive index and a low partial dispersion ratio.SOLUTION: Optical glass has, in terms of mass%, SiO2 percentage content: 15% or more and 30% or less, Na2O percentage content: more than 0% and 10% or less, K2O percentage content: more than 0% and 15% or less, Nb2O5 percentage content: 35% or more and 65% or less, total percentage content of MgO, CaO, SrO and BaO (ΣRO:R=Mg, Ca, Sr, Ba are shown): more than 0% and 20% or less, and B2O3 is substantially not contained.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] For various applications, optical glasses having a high refractive index and a low partial dispersion ratio are required. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-121833 A Summary of the Invention

[0004] One embodiment of the present invention is an optical glass having, in mass%, a SiO2 content of 15% or more and 30% or less, a Na2O content of more than 0% and less than 10%, a K2O content of more than 0% and less than 15%, a Nb2O5 content of more than 35% and less than 65%, a total content of MgO, CaO, SrO, and BaO (ΣRO: where R = Mg, Ca, Sr, Ba): more than 0% and less than 20%, and substantially no B2O3.

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

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

[0007] Another aspect of the present invention is an objective lens for a microscope, including the optical system described above.

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

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

[0010] Another 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] Another aspect of the present invention is an optical system including the above-mentioned cemented lens.

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

[0013] Another aspect of the present invention is an interchangeable lens for a camera, including an optical system that includes the above-mentioned cemented lens.

[0014] Another aspect of the present invention is an optical device including an optical system including the above-mentioned cemented lens. [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 nd and νd for each example of the optical glass according to the present embodiment. [Figure 7] 1 is a graph plotting Pg, F and νd for each example of the optical glass according to the present embodiment. 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] 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 not more than N%.

[0018] 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%.

[0019] 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.

[0020] The composition, physical properties, and applications of the optical glass according to this embodiment will be described below.

[0021] <Composition of optical glass> The optical glass according to this embodiment has, in mass%, a SiO2 content of 15% or more and 30% or less, a Na2O content of more than 0% and 10% or less, a K2O content of more than 0% and 15% or less, a Nb2O5 content of 35% or more and 65% or less, a total content of MgO, CaO, SrO, and BaO (ΣRO: where R = Mg, Ca, Sr, Ba): more than 0% and 20% or less, and is optical glass that substantially does not contain B2O3.

[0022] SiO2 is a component that forms the glass skeleton and improves chemical durability, but if its content is too high, it becomes difficult to make the glass have a high refractive index. From this perspective, the SiO2 content is 15% or more and 30% or less. The lower limit of this content is preferably 17%, more preferably 19%, and even more preferably 20%. The upper limit of this content is preferably 29.5%, more preferably 29.0%, and even more preferably 28.5%.

[0023] Na2O improves the melting property of the raw material and g,F If the content is too high, it becomes difficult to achieve a high refractive index, and the stability against devitrification also decreases. From this viewpoint, the content of Na2O is greater than 0% and equal to or less than 10%. The lower limit of the content is preferably 0.5%, more preferably 1.0%, and even more preferably 1.5%. The upper limit of the content is preferably 9%, more preferably 8%, and even more preferably 7%.

[0024] K2O is a component that increases the refractive index of glass and improves the melting properties of glass raw materials. However, if its content is too high, g,F From this viewpoint, the content of K2O is more than 0% and not more than 15%. The lower limit of this content is preferably 1%, more preferably 2%, and even more preferably 3%. The upper limit of this content is preferably 14%, preferably 13%, and even more preferably 12%.

[0025] Nb2O5 is a component that increases the refractive index and makes the glass highly dispersible. If the content is too low, it becomes difficult to achieve a high refractive index and high dispersion. If the content is too high, the stability against devitrification decreases. From this viewpoint, the content of Nb2O5 is 35% or more and 65% or less. The lower limit of this content is preferably 37%, more preferably 39%, and even more preferably 40%. The upper limit of this content is preferably 64%, more preferably 63%, and even more preferably 62%.

[0026] B2O3 is a component that forms the glass network, but it volatilizes when melted at high temperatures, so it is preferable that the glass does not substantially contain B2O3.

[0027] The optical glass according to this embodiment preferably further contains, as an optional component, one or more selected from the group consisting of MgO, CaO, SrO, BaO, Li2O, Al2O3, TiO2, ZnO, ZrO2, WO3, and Sb2O3.

[0028] MgO is P g,F It is a component that enhances the devitrification resistance stability of the glass without increasing the refractive index. If MgO is not contained, the devitrification resistance stability of the glass decreases, making it difficult to achieve a high refractive index. If the content is too high, it becomes difficult to achieve high dispersion of the glass. From this viewpoint, the content of MgO is 0% or more and 10% or less. The lower limit of this content is preferably 0.5%, more preferably 1.0%, and even more preferably 1.5%. The upper limit of this content is preferably 9%, more preferably 8%, and even more preferably 7%.

[0029] CaO is an effective component for adjusting the constants of glass. From this viewpoint, the CaO content is 0% or more and 10% or less. The lower limit of this content is preferably 0.5%, more preferably 1.0%, and even more preferably 1.5%. The upper limit of this content is preferably 9%, more preferably 8%, and even more preferably 7%.

[0030] SrO is an effective component for adjusting the constants of glass. From this viewpoint, the content of SrO is 0% or more and 5% or less. The lower limit of this content is preferably 0.5%, more preferably 1.0%, and even more preferably 1.5%. The upper limit of this content is preferably 4.5%, more preferably 4.0%, and even more preferably 3.5%.

[0031] BaO is a component that increases the refractive index of glass. However, if its content is too high, g,F From this viewpoint, the BaO content is 0% or more and 15% or less. The lower limit of this content is preferably 1%, more preferably 2%, and even more preferably 3%. The upper limit of this content is preferably 14%, more preferably 13%, and even more preferably 12%.

[0032] From the viewpoint of resistance to devitrification, the total content of MgO, CaO, SrO and BaO (ΣRO: where R=Mg, Ca, Sr, Ba) is greater than 0% and less than or equal to 20%. The lower limit of this content is preferably 1%, more preferably 2%, and even more preferably 3%. The upper limit of this content is preferably 19%, more preferably 18%, and even more preferably 17%.

[0033] Li2O is a component that increases the refractive index of glass and improves the melting property of glass raw materials, but if its content is too high, the devitrification resistance stability decreases. From this viewpoint, the Li2O content is 0% or more and 10% or less. The lower limit of this content is preferably 0.5%, more preferably 1.0%, and even more preferably 1.5%. The upper limit of this content is preferably 9%, more preferably 8%, and even more preferably 7%.

[0034] Al2O3 is a component that disperses glass and improves chemical durability. However, if its content is too high, g,FFrom this viewpoint, the content of Al2O3 is 0% or more and 5% or less. The lower limit of this content is preferably 0.2%, more preferably 0.4%, and even more preferably 0.6%. The upper limit of this content is preferably 4%, more preferably 3%, and even more preferably 2%.

[0035] TiO2 is a component that increases the refractive index of glass and makes it highly dispersive. However, if its content is too high, g,F This significantly increases the transmittance and also deteriorates the transmittance. From this viewpoint, the TiO2 content is 0% or more and 5% or less. The lower limit of this content is preferably 0.2%, more preferably 0.4%, and even more preferably 0.6%. The upper limit of this content is preferably 4%, more preferably 3%, and even more preferably 2%.

[0036] ZnO is a component that increases the refractive index of glass and further improves the stability against devitrification. From this viewpoint, the ZnO content is 0% or more and 10% or less. The lower limit of this content is preferably 0.5%, more preferably 1.0%, and even more preferably 1.5%. The upper limit of this content is preferably 9%, more preferably 8%, and even more preferably 7%.

[0037] ZrO2 is a component that increases the refractive index of glass and provides high dispersion. g,F If the content is too high, the melting property and devitrification resistance stability of the glass raw material are deteriorated. From this viewpoint, the content of ZrO2 is 0% or more and 5% or less. The lower limit of this content is preferably 0.2%, more preferably 0.4%, and further preferably 0.6%. The upper limit of this content is preferably 4%, more preferably 3%, and further preferably 2%.

[0038] WO3 is a component that increases the refractive index of the glass, provides high dispersion, and further improves the stability against devitrification. From this viewpoint, the content of WO3 is 0% or more and 5% or less. The lower limit of this content is preferably 0.2%, more preferably 0.4%, and even more preferably 0.6%. The upper limit of this content is preferably 4%, more preferably 3%, and even more preferably 2%.

[0039] Sb2O3 is a component that functions as a defoaming agent for clarifying glass, but if its content is too high, it reduces the transmittance. From this viewpoint, the content of Sb2O3 is 0% or more and 1% or less. The lower limit of this content is preferably 0.01%, more preferably 0.02%, and even more preferably 0.03%. The upper limit of this content is preferably 0.80%, more preferably 0.60%, and even more preferably 0.40%.

[0040] From the viewpoint of adjusting the meltability of the glass, the total content of Li2O, Na2O and K2O (ΣA2O: where A = Li, Na, K) is 5% or more and 15% or less. The lower limit of this content is preferably 6%, more preferably 7%, and even more preferably 8%. The upper limit of this content is preferably 14%, more preferably 13%, and even more preferably 12%.

[0041] From the viewpoint of adjusting the melting property and the stability against devitrification, the ratio (SiO2+Nb2O5) / ΣA2O of the total content (SiO2+Nb2O5) of SiO2 and Nb2O5 to the total content (ΣA2O: where A=Li, Na, K) of Li2O, Na2O, and K2O is 5.8 or more and 9.4 or less. The upper limit of this ratio is preferably 9.3, more preferably 9.2, and even more preferably 9.1. The lower limit of this ratio is preferably 5.9, more preferably 6.0, and even more preferably 6.1.

[0042] From the viewpoint of devitrification resistance stability, the ratio (TiO2+ZnO+ZrO2+Nb2O5+WO3) / SiO2 of the total content (TiO2+ZnO+ZrO2+Nb2O5+WO3) of TiO2, ZnO, ZrO2, Nb2O5, and WO3 to the content of SiO2 is 1.5 or more and 2.9 or less. The upper limit of this ratio is preferably 2.8, more preferably 2.7, and even more preferably 2.6. The lower limit of this ratio is preferably 1.6, more preferably 1.7, and even more preferably 1.8.

[0043] From the viewpoint of adjusting the melting property and the stability against devitrification, the ratio ΣRO / ΣA2O of the total content of MgO, CaO, SrO and BaO (ΣRO: where R=Mg, Ca, Sr, Ba) to the total content of Li2O, Na2O and K2O (ΣA2O: where A=Li, Na, K) is 0.30 or more and 1.76 or less. The upper limit of this ratio is preferably 1.75, more preferably 1.74, and even more preferably 1.73. The lower limit of this ratio is preferably 0.31, more preferably 0.32, and even more preferably 0.33.

[0044] In addition, other than the above-mentioned components, known clarifiers, colorants, defoamers, fluorine compounds, phosphoric acid, and other components may be added to the glass composition in appropriate amounts as necessary for the purpose of clarifying, coloring, decoloring, adjusting optical constants, etc. Furthermore, other components may be added in a range in which the effects of this embodiment can be obtained, without being limited to the above-mentioned components.

[0045] It is preferable to use high-purity products with low impurity content as raw materials for each of the above-mentioned components. For example, it is preferable to use high-purity products for one or more of the SiO2 raw material and Nb2O5 raw material. A high-purity product is one that contains 99.85 mass% or more of the component. By using high-purity products, the amount of impurities is reduced, and as a result, for example, the internal transmittance of light with a wavelength of 400 nm or less tends to be increased.

[0046] <Physical properties of optical glass> 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 From this viewpoint, the refractive index (n d ) is 1.75 or more and 1.95 or less. And the refractive index (n d The lower limit of the refractive index (n d ) is preferably 1.93, more preferably 1.91, and even more preferably 1.90.

[0047] From the viewpoint of correcting aberrations in optical lenses and the like, the optical glass according to this embodiment has a small Abbe number (ν d From this viewpoint, it is desirable for the Abbe number (ν d ) is between 15 and 35. And the Abbe number (ν d The lower limit of the Abbe number (ν d ) is preferably 33, more preferably 31, and even more preferably 29.7.

[0048] From the viewpoint of lens aberration correction, the optical glass according to this embodiment has a small partial dispersion ratio (P g , F ), it is preferable that the partial dispersion ratio is 0.63 or less. From this viewpoint, the partial dispersion ratio (P g , F ) is 0.58 to 0.63. And the partial dispersion ratio (P g , F The lower limit of the partial dispersion ratio (P g , FThe upper limit of is preferably 0.628, more preferably 0.626, and even more preferably 0.624.

[0049] The optical glass according to this embodiment has a refractive index (n d ) is 1.75 or more and 1.95 or less, and the Abbe number (ν d ) is between 15 and 35, and the partial variance ratio (P g , F ) is 0.58 or more and 0.63 or less.

[0050] As described above, the optical glass according to this embodiment has a high refractive index (refractive index (n d )), high dispersion (Abbe number (ν d ) is small, while the partial variance ratio (P g , F The use of such optical glass makes it possible to reduce the thickness of optical elements such as optical lenses, and to design optical systems in which chromatic aberration and other aberrations are well corrected.

[0051] The optical glass according to this embodiment has a glass transition temperature (T g ) is 555 to 655°C. And the glass transition temperature (T g The lower limit of the glass transition temperature (T g ) is preferably 650° C., more preferably 645° C., and even more preferably 640° C. The heat softening step refers to a step of heating the optical glass when the optical glass is heated and shaped (so-called reheat press).

[0052] It is desirable for the optical glass according to this embodiment to have a small weight loss rate during the heat melting process. The weight loss rate (ΔM) is expressed by the following formula (2): △M=(M Tl+100 -M Tl ) / M A ×100···(2) In the formula, M A is the weight of the optical glass, M Tl+100 is the weight loss of optical glass at the liquidus temperature +100℃, M Tl represents the weight loss of optical glass at the liquidus temperature. For example, the weight of the sample (M A ) is 30 mg, if the sample weight at the liquidus temperature +100°C is 25 mg, the weight loss M Tl+100 is 5 mg, and if the sample weight at the liquidus temperature is 27 mg, the weight loss M Tl is 3 mg, the weight loss rate ΔM is (5 mg-3 mg) / 30 mg x 100 = 6.67%. The upper limit of the weight loss rate ΔM is preferably 0.1%, more preferably 0.09%, and even more preferably 0.08%. The heat melting process refers to a process in which raw materials are mixed, melted once to produce granular glass called glass frit, and then the glass frit is melted again to obtain plate- or gob-shaped glass. The molten glass frit melted in the heat melting process is cooled in a plate- or gob-shaped state to become optical glass.

[0053] The optical glass according to this embodiment has a small weight loss rate during the heating and melting process, which makes it possible to improve the stability of optical performance despite fluctuations in manufacturing conditions and reduce damage to equipment during the manufacturing process.

[0054] The manufacturing method of the optical glass according to this embodiment is not particularly limited, and a known method can be adopted. In addition, the manufacturing conditions can be appropriately selected. For example, the oxides, hydroxides, phosphoric acid compounds (phosphates, orthophosphoric acid, etc.), carbonates, sulfates, nitrates, and fluorides corresponding to the above-mentioned raw materials are mixed to obtain a target composition, melted at preferably 1100 to 1500°C, more preferably 1340 to 1400°C, homogenized by stirring, and then poured into a mold for molding. The optical glass thus obtained can be processed into a desired shape by reheat pressing, etc. as necessary, and polished to obtain a desired optical element.

[0055] <Applications of optical glass> 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.

[0056] 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.

[0057] 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.

[0058] 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).

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] The pulse splitting device 202 splits the ultrashort pulse light, increases the repetition frequency of the ultrashort pulse light, and emits it.

[0064] 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.

[0065] 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).

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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

[0075] Examples and comparative examples of the optical glass according to this embodiment will be described below, although the present invention is not limited to these.

[0076] Each sample of the optical glass according to each example and each comparative example was produced by the following procedure. First, glass raw materials such as oxides, carbonates, and nitrates were weighed out so that the chemical compositions (weight %) shown in Tables 1 to 6 were obtained, with a total weight of 100 g. Next, the weighed raw materials were mixed and charged into a crucible, melted at a temperature of 1200 to 1400°C, and stirred and homogenized. After fining, the mixture was poured into a mold or the like, slowly cooled, and molded to obtain each sample.

[0077] FIG. 6 shows n of each example of the optical glass according to this embodiment. d and ν d 7 is a graph plotting P g,F and ν d Graph showing the plot of

[0078] Refractive index (n d ) and Abbe number (ν d ) The refractive index (n d ) and Abbe number (ν d ) was measured and calculated using a refractive index measuring instrument (Shimadzu Device Manufacturing Co., Ltd.: KPR-3000). The refractive index was measured using a V-block. d indicates the refractive index of glass for light of 587.562 nm. d was calculated using the following formula (3). C , n F and indicate the refractive index of the glass for light with wavelengths of 656.273 nm and 486.133 nm, respectively. The refractive index values ​​are rounded to five decimal places. ν d =(n d -1) / (n F -n C ) · · · (3)

[0079] Partial dispersion ratio (P g, F ) The partial dispersion 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 (4). g indicates the refractive index of glass for light with a wavelength of 435.835 nm. g , F ) values ​​were rounded to four decimal places. P g , F =(n g -n F ) / (n F -n C ) · · · (4)

[0080] Glass transition temperature (T g ) The glass transition temperature (T g ) is a cylindrical sample with a diameter of 5 mm and a length of 40 mm, processed in accordance with JOGIS-08:2019. While applying a force of 20 gf, the sample is heated at a rate of 4°C / min in an electric furnace for measuring thermal expansion of glass, and the change in the sample dimensions is measured. The glass transition temperature (T g ) was sought.

[0081] Liquidus temperature (Tl) The liquidus temperature (Tl) of each sample was measured by placing about 0.1g of glass on a platinum plate with holes, holding it in a test furnace with a temperature gradient of 10℃ for 18 minutes, then removing it from the furnace and rapidly cooling it, and observing the presence or absence of devitrification under a microscope with a magnification of 100. The liquidus temperature was the lowest temperature at which devitrification did not occur when viewed from the high temperature side.

[0082] Weight loss rate For each of the samples of Examples 15 to 17 and Comparative Examples 1 to 3, the weight loss rate was calculated by the following procedure.

[0083] Glass raw materials equivalent to 100 g in oxide equivalent were mixed, melted at 1340°C for 120 minutes, cast into a mold, and cooled slowly to prepare glass. Samples for thermogravimetry (TG) and liquidus temperature measurements were taken from the same glass pieces. The samples for thermogravimetry (TG) were prepared by crushing the glass in a mortar, and the sample weight was 30 mg (=M A The samples for measuring the liquidus temperature were crushed into granules in a mortar or other container so that each granule weighed approximately 0.1 g.

[0084] Thermogravimetry (TG) of each sample of the optical glass according to this embodiment was performed using a differential thermal and thermogravimetry simultaneous measurement device (TG-DTA2000SA manufactured by Bruker AXS Co., Ltd.). The temperature range to be measured was a temperature range sufficiently exceeding liquid phase + 100 ° C., and the heating rate was set to 20 ° C. per minute. The liquid phase temperature of the sample was measured by the above-mentioned method. The thermogravimetry (TG) measurement temperature range of Examples 15 to 17 and Comparative Examples 1 to 3 was 20 ° C. to 1350 ° C. In addition, a platinum cell was used on the reference side of the measurement device. The weight of each sample of the optical glass was continuously recorded while heating at a rate of 20 ° C. / min. The weight loss was determined by the difference between the weight of the sample before heating and the weight of the sample extracted from the data at the corresponding temperature.

[0085] The weight loss of each optical glass at its liquidus temperature is M Tl The weight loss of each optical glass at the liquidus temperature +100°C is M Tl+100 , the weight of the optical glass is M A The weight loss rate (%) was determined as ΔM and was calculated by substituting it into the following formula (2). △M=(M Tl+100 -M Tl ) / M A ×100···(2) M A : Weight of optical glass M Tl+100 : Weight loss of optical glass at liquidus temperature +100℃ M Tl : Weight loss of optical glass at liquidus temperature

[0086] Tables 1 to 6 show the compositions of the optical glasses of the Examples and Comparative Examples in terms of mass % based on the oxide content of each component, and the evaluation results of each physical property.

[0087] Unless otherwise specified, the content of each component is based on mass%. In the formula, "ΣA2O" indicates the total content of Li2O, Na2O, and K2O; (A = Li, Na, K). Also, in the formula, "ΣRO" indicates the total content of MgO, CaO, SrO, and BaO; (R = Mg, Ca, Sr, Ba).

[0088] [Table 1]

[0089] [Table 2]

[0090] [Table 3]

[0091] [Table 4]

[0092] [Table 5]

[0093] [Table 6]

[0094] As can be seen from Tables 1 to 6, the optical glass according to this embodiment has a high refractive index (n d ), small Abbe number (ν d ), small P g,F It was also confirmed that in Examples 15 to 17, the weight loss rate was small. [Explanation of symbols]

[0095] 1····imaging device, 101···camera body, 102···lens barrel, 103···lens, 104···sensor chip, 105···glass substrate, 106···multi-chip module, CAM···imaging device (non-interchangeable lens camera), WL···taking lens, M···liquid crystal monitor, EF···auxiliary light emitter, B1···release button, B2···function button, 2···multiphoton microscope, 201· Pulsed laser device, 202, pulse splitting device, 203, beam adjustment section, 204, 205, 212, dichroic mirror, 206, objective lens, 207, 211, 213, fluorescence detection section, 208, focusing 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%, SiO ２ Content rate: 15% to 30% Na ２ O content: greater than 0% and less than 10% K ２ O content: greater than 0% and less than 15% Nb ２ O ５ Content rate: 35% to 65% The total content of MgO, CaO, SrO, and BaO (ΣRO: R = Mg, Ca, Sr, Ba): greater than 0% and less than 20%; B ２ O ３ An optical glass that is substantially free of:

2. In mass%, MgO content: 0% or more and 10% or less, CaO content: 0% or more and 10 or less, SrO content: 0% or more and 5% or less, 2. The optical glass according to claim 1, wherein the BaO content is 0% or more and 15% or less.

3. In mass%, Li ２ 2. The optical glass according to claim 1, wherein the O content is from 0% to 10%.

4. In mass%, Al ２ O ３ Content rate: 0% to 5% TiO ２ Content rate: 0% to 5% ZnO content: 0% or more and 10% or less, ZrO ２ Content rate: 0% to 5% WO ３ 2. The optical glass according to claim 1, wherein the content is 0% or more and 5% or less.

5. In mass%, Li ２ O, Na ２ O and K ２ Total content of O (ΣA ２ 2. The optical glass according to claim 1, wherein O: A=Li, Na, or K): 5% or more and 15% or less.

6. In mass%, Li ２ O, Na ２ O and K ２ Total content of O (ΣA ２ O: A = Li, Na, K) ２ +Nb ２ O ５ The ratio of the total content of (SiO ２ +Nb ２ O ５ ) / ΣA ２ 2. The optical glass according to claim 1, wherein A=Li, Na, or K: O is 5.8 or more and 9.4 or less.

7. In mass%, SiO ２ TiO relative to the content ２ , ZnO, ZrO ２ , Nb ２ O ５ and W.O. ３ to the total content (TiO ２ +ZnO + ZrO ２ +Nb ２ O ５ +WO ３ ) / SiO ２ 2. The optical glass according to claim 1, wherein the refractive index is 1.5 or more and 2.9 or less.

8. In mass%, Li ２ O, Na ２ O and K ２ Total content of O (ΣA ２ Ratio of the total content of MgO, CaO, SrO, and BaO to the total content of MgO, CaO, SrO, and BaO (where R=Mg, Ca, Sr, Ba) / ΣA ２ 2. The optical glass according to claim 1, wherein A=Li, Na, or K. O is 0.30 or more and 1.76 or less.

9. Refractive index for d line (n ｄ 2. The optical glass according to claim 1, wherein σ is 1.75 or more and 1.95 or less.

10. Abbe number (ν ｄ 2. The optical glass according to claim 1, wherein σ is 15 or more and 35 or less.

11. Partial dispersion ratio (P ｇ，Ｆ 2. The optical glass according to claim 1, wherein σ is 0.58 or more and 0.63 or less.

12. The following formula (1): (M Ｔｌ＋１００ -M Ｔｌ ) / M Ａ ×100≦0.1・・・(1) (In the formula, M Ａ is the weight of the optical glass, M Ｔｌ＋１００ is the weight loss of the optical glass at the liquidus temperature + 100°C, M Ｔｌ is the weight loss of the optical glass at its liquidus temperature.

13. An optical element using the optical glass according to any one of claims 1 to 12.

14. An optical system comprising the optical element of claim 13.

15. 15. A microscope objective comprising the optical system of claim 14.

16. An interchangeable lens for a camera, comprising the optical system according to claim 14.

17. An optical device comprising the optical system of claim 14.

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 the optical glass according to claim 1 .

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.

Images