Optical glass, optical element, interchangeable lens for camera, objective lens for microscope, optical system, optical device, reflective element, and position measuring device

Abstract

Provided is an optical glass in which, in terms of mass%: the SiO2 content is greater than 0% and equal to or less than 15%; the B2O3 content is greater than 0% and equal to or less than 13%; the La2O3 content is 18% to 55%; the TiO2 content is 8% to 30%; the Nb2O5 content is 3% to 22%; the ZnO content is greater than 0% and equal to or less than 20%; and the ZrO2 content is greater than 0% and equal to or less than 13%.

Description

Optical glass, optical element, interchangeable lens for camera, objective lens for microscope, optical system, optical device, reflection element, position measuring device

[0001] The present invention relates to optical glass, optical elements, interchangeable lenses for cameras, objective lenses for microscopes, optical systems, optical devices, reflection elements, and position measuring devices. The present invention claims the priority of Japanese Patent Application No. 2024-205571 filed on November 26, 2024. For designated countries where incorporation by reference is permitted, the content described in that application is incorporated herein by reference.

[0002] Glass with a high refractive index tends to have high dispersion, which has been a constraint in design. Glass with a high refractive index and low dispersion is in demand.

[0003] Japanese Patent Application Laid-Open No. 2006-219365

[0004] One aspect of the present invention is, in mass%, SiO ２ content: greater than 0% and 15% or less, B ２ O ３ content: greater than 0% and 13% or less, La ２ O ３ content: 18% or more and 55% or less, TiO ２ content: 8% or more and 30% or less, Nb ２ O ５ content: 3% or more and 22% or less, ZnO content: greater than 0% and 20% or less, ZrO ２ content: greater than 0% and 13% or less, which is optical glass.

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

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

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

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

[0009] Another aspect of the present invention is an optical device that includes an optical system containing the above-described optical elements.

[0010] Another embodiment of this model is a reflective element that includes the optical glass described above.

[0011] Another embodiment of this embodiment is a position measuring device that includes the above-described reflective element, an illumination unit that irradiates the above-described reflective element with measurement light, and a light receiving unit that receives the measurement light reflected by the above-described reflective element.

[0012] This is a perspective view showing an example where the optical device according to this embodiment is used as an imaging device. This is a schematic diagram showing another example where the optical device according to this embodiment is used as an imaging device, and is a front view of the imaging device. This is a schematic diagram showing another example where the optical device according to this embodiment is used as an imaging device, and is a rear view of the imaging device. This is a block diagram showing an example of the configuration of a multiphoton microscope according to this embodiment. This is a schematic diagram showing an example of a cemented lens according to this embodiment. Figures 6A and 6B are schematic diagrams showing an example of a position measuring device using a reflective element according to this embodiment.

[0013] The following describes embodiments of the present invention (hereinafter referred to as "these embodiments"). These embodiments are illustrative examples for explaining the present invention and are not intended to limit the present invention to the following content. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[0014] The optical glass according to this embodiment is composed of SiO2 by mass. ２ Content: Greater than 0% and 15% or less, B ２ O ３ Content: Greater than 0% and less than or equal to 13%, La ２ O ３ Content rate: 18% or more and 55% or less, TiO ２ Content: 8% or more and 30% or less, Nb ２ O ５ Content: 3% to 22%, ZnO content: greater than 0% and 20% or less, ZrO ２ Optical glass with a content greater than 0% but less than or equal to 13%.

[0015] In this specification, unless otherwise specified, the content of each component shall be expressed as mass % (mass percentage) relative to the total weight of the glass in terms of oxide composition. The oxide-equivalent composition referred to herein is the composition in which each component contained in the glass is expressed, assuming that the oxides, complex salts, etc., used as raw materials for the glass components of this embodiment all decompose into oxides during melting, and the total mass of said oxides is set to 100% by mass.

[0016] Furthermore, the expression "Q component-free" means that this Q component is substantially absent, and that the content of this component is below the level of an impurity. Below the level of an impurity means, for example, less than 0.01%.

[0017] Furthermore, the term "devitrification resistance" refers to the glass's resistance to devitrification. Here, "devitrification" refers to the phenomenon in which the transparency of glass is lost due to crystallization or phase separation that occurs when the glass is heated above its glass transition temperature or when it is cooled from a molten state to below its liquidus temperature.

[0018] The optical glass according to this embodiment can achieve a glass with a high refractive index and low dispersion.

[0019] The component composition of the optical glass according to this embodiment will be described below.

[0020] SiO ２ SiO is a component that forms the glass skeleton and lowers the refractive index. If the content is too low, the glass will not resist devitrification. Conversely, if the content is too high, it will be difficult to make the glass have a high refractive index, and the viscosity of the glass itself will increase, making molding difficult. From this perspective, SiO ２ The content is greater than 0% 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 11%.

[0021] B ２ O ３ This is a component that makes up the network-forming oxide. ２ O３ Because it is a highly volatile component, if introduced in excess, it can cause changes in the composition of the glass during manufacturing, making striations apparent. From this perspective, B ２ O ３ The content is greater than 0% and 13% 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 12%, more preferably 11%, and even more preferably 10%.

[0022] The MgO content is between 0% and 7% from the viewpoint of low dispersion. The lower limit of this content is preferably 0.5%, more preferably 1%, and even more preferably 1.5%. The upper limit of this content is preferably 6%, more preferably 5%, and even more preferably 4%.

[0023] The CaO content is 0% to 10% from the viewpoint of low dispersion. 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 9%, more preferably 8%, and even more preferably 7%.

[0024] The SrO content is 0% to 10% from the viewpoint of low dispersion. 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 9%, more preferably 8%, and even more preferably 7%.

[0025] BaO is a component that improves the devitrification resistance of glass without significantly increasing dispersion. From this viewpoint, the BaO content is 0% to 15%. The lower limit of this content is preferably 1%, more preferably 2%, and even more preferably 4%. The upper limit of this content is preferably 12%, more preferably 10%, and even more preferably 8%.

[0026] ZnO is a component that improves devitrification resistance. If the ZnO content is too low, devitrification resistance tends to decrease. If the ZnO content is too high, dispersion tends to increase. From this viewpoint, the ZnO content is greater than 0% and 20% or less. The lower limit of this content is preferably 2%, more preferably 3%, and even more preferably 4%. The upper limit of this content is preferably 18%, more preferably 16%, and even more preferably 15%.

[0027] La ２ O ３ It has the effect of increasing the refractive index without impairing low dispersion and can maintain the devitrification resistance of glass. However, as the content of this substance increases, it tends to increase the specific gravity. From this viewpoint, La ２ O ３ The content is between 18% and 55%. The lower limit of this content is preferably 20%, more preferably 22%, and even more preferably 24%. The upper limit of this content is preferably 53%, more preferably 50%, and even more preferably 48%.

[0028] TiO ２ This allows for an increased refractive index while simultaneously maintaining a low specific gravity. From the perspective of these effects and the content of rare earth and transition metal components, TiO ２ The content is between 8% and 30%. The lower limit of this content is preferably 10%, more preferably 12%, and even more preferably 14%. The upper limit of this content is preferably 28%, more preferably 26%, and even more preferably 24%.

[0029] ZrO ２ This has the effect of improving devitrification resistance and refractive index while maintaining low dispersion. From this viewpoint, ZrO ２ The content is greater than 0% and 13% 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 11%, more preferably 10%, and even more preferably 9%.

[0030] Nb ２ O ５ This can further improve the low dispersion properties of the glass. On the other hand, if the content is too high, the meltability of the glass may decrease. From this perspective, Nb ２ O ５ The content is between 3% and 22%. The lower limit of this content is preferably 5%, more preferably 7%, and even more preferably 10%. The upper limit of this content is preferably 20%, more preferably 18%, and even more preferably 16%.

[0031] WO ３ The content of is 0% or more and 5% or less from the viewpoint of transmittance. The lower limit of this content is preferably 0.3%, more preferably 0.5%, and even more preferably 0.8%. The upper limit of this content is preferably 4%, more preferably 3%, and even more preferably 2%.

[0032] Al ２ O ３ Al is a component that adjusts the refractive index and dispersion of glass. ２ O ３ The content is between 0% and 5%. The lower limit of this content is preferably 0%, more preferably 0.2%, and even more preferably 0.5%. The upper limit of this content is preferably 4.5%, more preferably 4%, and even more preferably 3%.

[0033] Sb ２ O ３ Sb is a component that functions as a defoaming agent to clarify glass, but if its content is too high, it reduces transmittance. From this perspective, ２ O ３ The content is 0% or more and 0.2% 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 0.15%, more preferably 0.12%, and even more preferably 0.10%.

[0034] Furthermore, the optical glass according to this embodiment may satisfy the following conditions for the components described above.

[0035] From the perspective of obtaining a high refractive index, B ２ O ３ Ratio of ZnO content to total content (ZnO / B ２ O ３ The ratio is between 0.4 and 10.0. The lower limit of this ratio is preferably 1.0, more preferably 1.5, even more preferably 2.0, and even more preferably 2.5. The upper limit of this ratio is preferably 5.0, more preferably 4.5, even more preferably 4.0, and even more preferably 3.5.

[0036] From the perspective of improving resistance to devitrification, SiO ２ and B ２ O ３ Total content (SiO ２ +B ２ O ３ The content of the total is 4% to 20%. The lower limit of this total content is preferably 6%, more preferably 7%, and even more preferably 8%. The upper limit of this total content is preferably 18%, more preferably 16%, and even more preferably 15%.

[0037] From the perspective of obtaining a viscosity that is easy to process, B ２ O ３ SiO content ２ Ratio of content (SiO ２ / B ２ O ３ The ratio is greater than 0 and less than or equal to 8. The lower limit of this ratio is preferably 0.25, more preferably 0.30, even more preferably 0.35, and even more preferably 0.40. The upper limit of this ratio is preferably 3.3, more preferably 3.0, even more preferably 2.8, and even more preferably 2.6.

[0038] From the perspective of obtaining a high refractive index, TiO ２ and Nb ２ O ５ Total content (TiO ２ +Nb ２ O５ is 20% or more and 43% or less. The lower limit of this total content rate is preferably 22%, more preferably 24%, and still more preferably 25%. The upper limit of this total content rate is preferably 41%, more preferably 39%, and still more preferably 37%.

[0039] From the viewpoint of obtaining a higher transmittance, Nb ２ O ５ The ratio of the TiO ２ content rate to the Nb ２ / Nb ２ O ５ is 0.8 or more and 3.3 or less. The lower limit of this ratio is preferably 0.9, more preferably 1.0, and still more preferably 1.1. The upper limit of this ratio is preferably 3.1, more preferably 2.9, and still more preferably 2.7.

[0040] From the viewpoint of obtaining low dispersion, the ratio of the total content rate of La ２ O ３ to the total content rate of TiO ２ and Nb ２ O ５ ((TiO ２ + Nb ２ O ５ ) / La ２ O ３ is 0.4 or more and 1.6 or less. The lower limit of this ratio is preferably 0.45, more preferably 0.50, and still more preferably 0.55. The upper limit of this ratio is preferably 1.5, more preferably 1.4, and still more preferably 1.3.

[0041] From the viewpoint of obtaining a high refractive index, the total content rate of La ２ O ３ , ZrO ２ , TiO ２ and Nb ２ O ５ is 62% or more and 85% or less. The lower limit of this total content rate is preferably 64%, more preferably 66%, and still more preferably 68%. The upper limit of this total content rate is preferably 83%, more preferably 80%, and still more preferably 77%.

[0042] From the viewpoints of fusibility, refractive index, and chemical durability, the total content of MgO, CaO, BaO, and SrO (MgO + CaO + BaO + SrO) is 0% or more and 15% or less. And the lower limit of this total content is preferably 1%, more preferably 2%, and still more preferably 3%. Also, the upper limit of this total content is preferably 13%, more preferably 11%, and still more preferably 9%. By setting such a total content, fusibility can be maintained, and the refractive index and chemical durability can be enhanced.

[0043] The optical glass according to this embodiment has a more preferable combination of components, in mass%, SiO ２ content: greater than 0% and 15% or less, B ２ O ３ content: greater than 0% and 13% or less, La ２ O ３ content: 18% or more and 55% or less, TiO ２ content: 8% or more and 30% or less, Nb ２ O ５ content: 3% or more and 22% or less, ZnO content: greater than 0% and 20% or less, ZrO ２ content: greater than 0% and 13% or less, B ２ O ３ The ratio of the ZnO content to the B ２ O ３ content (ZnO / B ２ O ３ ): 1.0 or more and 10.0 or less can be mentioned. By setting such a combination, a glass with a higher refractive index can be obtained. As another preferable combination, instead of setting the ratio of the ZnO content to the B ２ O ３ content (ZnO / B ２ O ３ ): 1.0 or more and 5.0 or less, the La ２ O ２ content: 40% or more and 55% or less, or the total content of SiO ３ and B ２ (SiO ２ + B ３ ): 4% or more and 13% or less can also obtain a glass with a higher refractive index.

[0044] The method for manufacturing optical glass according to this embodiment is not particularly limited, and known methods can be employed. Furthermore, the manufacturing conditions can be appropriately selected. For example, a manufacturing method can be employed in which raw materials such as oxides, carbonates, nitrates, and sulfates are blended to a target composition, preferably melted at 1100 to 1500°C, homogenized by stirring, de-bubbled, and then poured into a mold for molding. The lower limit of the melting temperature mentioned above is more preferably 1200°C, the upper limit is more preferably 1350°C, and even more preferably 1300°C. The optical glass thus obtained can be processed into a desired shape by reheat pressing or the like as needed, and then polished to become a desired optical element.

[0045] It is preferable to use high-purity raw materials with a low impurity content. High-purity materials are those containing 99.85% by mass or more of the relevant component. Using high-purity materials tends to result in a lower amount of impurities, which in turn tends to increase the internal transmittance of the optical glass.

[0046] Furthermore, as needed, appropriate amounts of known clarifying agents, colorants, defoaming agents, fluorine compounds, and other components can be added to the glass composition for purposes such as clarification, coloring, decolorization, and fine-tuning of optical constants. In addition, other components can be added, not limited to those mentioned above, as long as the effects of the optical glass according to this embodiment can be obtained.

[0047] Next, the physical properties of the optical glass in this embodiment will be described.

[0048] The refractive index (n) of the d-line in the optical glass according to this embodiment. ｄ The refractive index (n) is between 1.98 and 2.1. ｄ The lower limit of the refractive index (n) is preferably 1.99, more preferably 2.00, and even more preferably 2.01. ｄ The upper limit of ) is preferably 2.08, more preferably 2.06, and even more preferably 2.04.

[0049] From the viewpoint of use in the near-infrared region, the refractive index (n) of the optical glass according to this embodiment for light with a wavelength of 1552.1 nm is１５５２．１ The refractive index (n) at 1552.1 nm is between 1.96 and 2.04. １５５２．１ The lower limit of the refractive index (n) at 1552.1 nm is preferably 1.97, more preferably 1.98, and even more preferably 1.99. １５５２．１ The upper limit of ) is preferably 2.02, more preferably 2.01, and even more preferably 2.00.

[0050] The Abbe number (ν) of the optical glass according to this embodiment ｄ The Abbe number (ν) is between 18 and 30. ｄ The lower limit of the Abbe number (ν) is preferably 20, more preferably 22, and even more preferably 24. ｄ The upper limit of ) is preferably 28, more preferably 27, and even more preferably 26.

[0051] From the viewpoint of correcting lens aberrations, the optical glass according to this embodiment has a small partial dispersion ratio (P ｇ , Ｆ It is desirable that the optical glass according to this embodiment has a partial dispersion ratio (P ｇ，Ｆ The partial variance ratio (P) is between 0.590 and 0.630. ｇ，Ｆ The lower limit of the partial variance ratio (P) is preferably 0.600, more preferably 0.605, and even more preferably 0.609. ｇ，Ｆ The upper limit of ) is preferably 0.625, more preferably 0.620, and even more preferably 0.615.

[0052] From the viewpoint of correcting lens aberrations, the optical glass according to this embodiment has a small anomalous dispersion (ΔP ｇ , Ｆ It is desirable that the optical glass according to this embodiment has a value (ΔP) that indicates the anomalous dispersion. ｇ , Ｆ The value (ΔP) indicating anomalous dispersion is between 0.001 and 0.030. ｇ , ＦThe lower limit of (ΔP) is preferably 0.003, more preferably 0.005, and even more preferably 0.007. ｇ , Ｆ The upper limit of ) is preferably 0.025, more preferably 0.020, and even more preferably 0.015.

[0053] From the above-mentioned perspective, the optical glass according to this embodiment can be suitably used, for example, as an optical element in an optical instrument. For example, an optical element can be obtained by processing the shape of the optical glass according to this embodiment, depositing any film such as an anti-reflective film or a reflective film, or bonding it with other glass. Such optical elements include mirrors, lenses, prisms, filters, reflectors, and reflective elements. Examples of optical systems in which the above optical elements are used include objective lenses, focusing lenses, imaging lenses, interchangeable lenses for cameras, and position measuring devices. These optical systems can be suitably used in imaging devices such as interchangeable-lens cameras and non-interchangeable-lens cameras, various optical devices for microscopes such as fluorescence microscopes and multiphoton microscopes, and position measuring devices such as laser trackers. Such optical devices are not limited to the imaging devices and microscopes mentioned above, but also include, but are not limited to, telescopes, binoculars, laser rangefinders, and projectors. An example of these will be described below.

[0054] <Imaging Device> Figure 1 is a perspective view showing an example in which the optical device according to this embodiment is used as an imaging device. The imaging device 1 is a so-called digital single-lens reflex camera (interchangeable lens camera), and the photographic lens 103 (optical system) is equipped with an optical element made of optical glass according to this embodiment. The lens barrel 102 is detachably attached to the lens mount (not shown) of the camera body 101. The light passing through the lens 103 of the lens barrel 102 is then imaged onto the sensor chip (solid-state image sensor) 104 of the multi-chip module 106 located on the back 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 a COG (Chip On Glass) type module in which the sensor chip 104 is bare-chip mounted on a glass substrate 105.

[0055] 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 a non-interchangeable lens), and the photographic lens WL (optical system) is equipped with optical elements made of optical glass according to this embodiment.

[0056] When the power button (not shown) of the imaging device CAM is pressed, the shutter (not shown) of the photographic lens WL is opened, and light from the subject (object) is collected by the photographic lens WL and formed on the image sensor located on the image plane. The image of the subject formed on the image sensor is displayed on the LCD monitor M located behind the imaging device CAM. After the photographer determines the composition of the subject image while looking at the LCD monitor M, they press down the release button B1 to capture the subject image with the image sensor and record and save it in memory (not shown).

[0057] The imaging device CAM is equipped with an auxiliary light emitter EF that emits auxiliary light when the subject is dark, and function buttons B2 used for setting various conditions of the imaging device CAM, etc.

[0058] Optical systems used in digital cameras and the like require higher resolution, lower chromatic aberration, and miniaturization. To achieve these, it is effective to use glasses with different dispersion characteristics or glasses with high refractive indices in the optical system. From this viewpoint, the optical glass according to this embodiment is suitable as a component for such optical devices. In addition to the imaging device described above, the optical devices to which this embodiment can be applied are not limited to the optical imaging device described above, but also include, for example, projectors. The optical elements are not limited to lenses, but also include, for example, prisms.

[0059] <Microscope> Figure 4 is a block diagram showing an example of the configuration of the multiphoton microscope 2 according to this embodiment. The multiphoton microscope 2 comprises an objective lens 206, a focusing lens 208, and an imaging lens 210. At least one of the objective lens 206, focusing lens 208, and imaging lens 210 is equipped with an optical element made of optical glass according to this embodiment. The optical system of the multiphoton microscope 2 will be described below.

[0060] The pulsed laser device 201 emits ultrashort pulsed light, for example, with a near-infrared wavelength (approximately 1000 nm) and a pulse width in the femtosecond range (for example, 100 femtoseconds). The ultrashort pulsed light immediately after being emitted from the pulsed laser device 201 is generally linearly polarized and polarized in a predetermined direction.

[0061] The pulse splitting device 202 splits the ultrashort pulse light and emits it with a higher repetition frequency.

[0062] The beam adjustment unit 203 has functions such as adjusting the beam diameter of the ultrashort pulse light incident from the pulse splitting device 202 to match the pupil diameter of the objective lens 206, adjusting the focusing and divergence angles of the ultrashort pulse light to correct axial chromatic aberration (focus difference) between the wavelength of light emitted from the sample S and the wavelength of the ultrashort pulse light, and a pre-chirp function (group velocity dispersion compensation function) that applies the opposite group velocity dispersion to the ultrashort pulse light to correct the widening of the pulse width of the ultrashort pulse light due to group velocity dispersion as it passes through the optical system.

[0063] The ultrashort pulse light emitted from the pulse laser device 201 has its repetition frequency increased by the pulse splitting device 202, and the beam adjustment unit 203 performs the adjustments described above. The ultrashort pulse light emitted from the beam adjustment unit 203 is reflected in the direction of the dichroic mirror 204 by the dichroic mirror 204, passes through the dichroic mirror 205, is focused by the objective lens 206, and irradiates the sample S. At this time, a scanning means (not shown) may be used to scan the ultrashort pulse light on the observation surface of the sample S.

[0064] For example, when observing a sample S using fluorescence, the fluorescent dye staining the sample S is multiphoton-excited in the area of ​​the sample S irradiated with ultrashort pulse light and its vicinity, and fluorescence with a wavelength shorter than the ultrashort pulse light, which is in the infrared range (hereinafter referred to as "observation light") is emitted.

[0065] Observation light emitted from the sample S in the direction of the objective lens 206 is collimated by the objective lens 206 and, depending on its wavelength, is either reflected by the dichroic mirror 205 or transmitted through the dichroic mirror 205.

[0066] 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), and receives the observation light reflected by the dichroic mirror 205 and outputs an electrical signal corresponding to the amount of light. The fluorescence detection unit 207 also detects the observation light across the observation surface of the sample S as the ultrashort pulse light is scanned across the observation surface of the sample S.

[0067] Alternatively, by removing the dichroic mirror 205 from the optical path, all observation light emitted from the sample S toward the objective lens 206 may be detected by the fluorescence detection unit 211. In this case, the observation light is descanned by a scanning means (not shown), passes through the dichroic mirror 204, is focused by the focusing lens 208, passes through a pinhole 209 located at a position approximately conjugate to the focal point of the objective lens 206, passes through the imaging lens 210, and enters the fluorescence detection unit 211.

[0068] The fluorescence detection unit 211 is composed of, for example, a barrier filter, a PMT, etc., and receives the observation light imaged on the light-receiving surface of the fluorescence detection unit 211 by the imaging lens 210, and outputs an electrical signal corresponding to the amount of light. The fluorescence detection unit 211 also detects the observation light across the observation surface of the sample S as the ultrashort pulse light is scanned across the observation surface of the sample S.

[0069] Furthermore, observation light emitted from the sample S in the opposite direction to the objective lens 206 is reflected by the dichroic mirror 212 and incident on the fluorescence detection unit 213. The fluorescence detection unit 113 is composed of, for example, a barrier filter, a PMT, etc., and receives the observation light reflected by the dichroic mirror 212 and outputs an electrical signal corresponding to the amount of light. The fluorescence detection unit 213 also detects the observation light across the observation surface of the sample S as the ultrashort pulse light is scanned across the observation surface of the sample S.

[0070] The electrical signals output from the fluorescence detection units 207, 211, and 213 are input to, for example, a computer (not shown), which can generate an observation image based on the input electrical signals, display the generated observation image, or store the data of the observation image.

[0071] <Bonded Lens> Figure 5 is a schematic diagram showing an example of a bonded lens according to this embodiment. The bonded lens 3 is a composite lens having a first lens element 301 and a second lens element 302. At least one of the first lens element and the second lens element is made of optical glass according to this embodiment. The first lens element and the second lens element are joined together via a bonding member 303. A known adhesive or the like can be used as the bonding member 303. Note that "lens element" refers to each lens that constitutes a single lens or a bonded lens.

[0072] The cemented lens according to this embodiment is useful in terms of chromatic aberration correction and can be suitably used in the optical elements, optical systems, and optical devices described above. Furthermore, the optical system including the cemented lens can be particularly suitably used in interchangeable lenses for cameras and optical devices. In the above embodiment, a cemented lens using two lens elements has been described, but the invention is not limited to this, and a cemented lens using three or more lens elements may also be used. In the case of a cemented lens using three or more lens elements, it is sufficient that at least one of the three or more lens elements is formed using the optical glass according to this embodiment.

[0073] <Position Measuring Device> As shown in Figure 6A, the optical glass according to this embodiment can also be used as a reflective element (retroreflector) 402 of a position measuring device 401 such as a laser tracker. The position measuring device 401 is an integrated unit comprising an irradiation unit 403 that projects light onto the reflective element 402 and a light receiving unit 404 that receives the light reflected by the reflector. The reflective element 402 can be attached to a part of a workpiece (object to be measured) 405 such as a robot arm, machine tool, or aircraft housing. Any number of reflective elements can be attached to the workpiece. The shape of the reflective element 402 may be a hemispherical optical glass according to this embodiment bonded with a hemispherical glass of a different embodiment, and preferably, cat's eye glass (spherical glass) is used. A reflective film may be formed on the reflective surface of the reflective element 402.

[0074] Next, the operation of the position measuring device 401 will be explained using Figures 6A and 6B. First, as shown in Figure 6A, the position measuring device 401 directs the irradiation unit 403 toward the reflective element 402 provided on the workpiece 405 and irradiates it with measurement light. Next, as shown in Figure 6B, the light reflected by the reflective element 402 is received by the light receiving unit 404. The position measuring device 401 measures the distance to the reflective element 402 based on the time from when light was irradiated onto the reflective element until the reflected light was received, and determines the three-dimensional position of the reflective element 402 from the measured distance and the direction (elevation angle and azimuth angle) from which the measurement light was irradiated. As a method of measuring the distance, a reference light and the measurement light reflected back from the reflective element 402 may be interfered with, and the distance may be determined from the phase difference between the two lights.

[0075] Next, examples and comparative examples of the present invention will be described. However, the present invention is not limited to these examples.

[0076] <Preparation of Optical Glass> The optical glass for each example and comparative example was prepared by the following procedure. First, glass raw materials selected from oxides, hydroxides, phosphate compounds (phosphates, orthophosphoric acid, etc.), carbonates, and nitrates were weighed to achieve the composition (mass%) shown in each table. Next, the weighed raw materials were mixed and placed in a platinum crucible, where they were melted at a temperature of 1200 to 1450°C and stirred until homogenized. After de-bubbling, the temperature was lowered to an appropriate level, and then the mixture was cast into a mold, slowly cooled, and molded to obtain each sample.

[0077] <Evaluation of physical properties> Refractive index (n ｄ ), (n １５５２．１ ) and Abbe number (ν ｄ ) Refractive index (n) of each sample ｄ ), (n １５５２．１ ) and Abbe number (ν ｄ The refractive index was measured and calculated using a refractive index measuring instrument (Shimadzu Device Mfg. Co., Ltd.: KPR-2000). ｄ This indicates the refractive index of the glass for light at 587.562 nm. ｄ n was calculated using the following equation (1). Ｃ , n Ｆ , and indicate the refractive index of the glass for light with wavelengths of 656.273 nm and 486.133 nm, respectively. Refractive index (n ｄ ), (n １５５２．１ The value of ν was rounded to six decimal places. ｄ = (n ｄ -1) / (n Ｆ -n Ｃ ) ... (1)

[0078] Partial dispersion ratio (P ｇ , Ｆ ) Partial variance ratio (P) of each sample ｇ , Ｆ ) is the principal variance (n Ｆ -n Ｃ Partial variance (n) for ) ｇ -n Ｆ The ratio of ) was shown and obtained from the following equation (2). n ｇThis indicates the refractive index of the glass for light with a wavelength of 435.835 nm. Partial dispersion ratio (P) ｇ , Ｆ The value of ) was rounded to four decimal places. ｇ , Ｆ = (n ｇ -n Ｆ ) / (n Ｆ -n Ｃ ) ... (2)

[0079] Anomalous dispersion (ΔP ｇ，Ｆ ) Abnormal dispersion of each sample (ΔP ｇ，Ｆ ) shows the deviation from the standard line of partial dispersion ratio, based on two glass types, F2 and K7, which are considered to have normal dispersion properties. That is, the vertical axis is the partial dispersion ratio (P ｇ，Ｆ ), the horizontal axis is the Abbe number ν ｄ On this coordinate system, the difference in the vertical coordinate between the line connecting the two glass types and the value of the glass being compared represents the bias in the partial dispersion ratio, i.e., the anomalous dispersion (ΔP). ｇ，Ｆ ) In the above coordinate system, if the value of the partial dispersion ratio is located above the line connecting the reference glass types, the glass has positive anomalous dispersion (+ΔP). ｇ，Ｆ ) exhibits negative anomalous dispersion (-ΔP) when located on the lower side. ｇ，Ｆ This shows the Abbe numbers ν for F2 and K7. ｄ The partial variance ratio (Pg, F) ​​is as follows: F²: Abbe number ν ｄ =36.33, partial dispersion ratio (P ｇ , Ｆ ) = 0.5834 K7: Abbe number ν ｄ =60.47, partial dispersion ratio (P ｇ , Ｆ )=0.5429ΔP ｇ , Ｆ = P ｇ , Ｆ - (-0.0016777 × ν) ｄ +0.6443513) ... (3)

[0080] Each table shows the composition and physical properties of each example and comparative example. Unless otherwise specified, the content of each component is given in mass percent.

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099] From the above, it was confirmed that the optical glass of this embodiment has a high refractive index and low dispersibility. Furthermore, it was confirmed that the optical glass of Comparative Example 1 has a lower refractive index in the near-infrared region compared to the embodiment. In Comparative Example 2, a large amount of unmelted material was generated when the mixed raw materials were melted, and it was not possible to obtain optical glass.

[0100] 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...Photography lens, M...LCD monitor, EF...Auxiliary light emission unit, B1...Release button, B2...Function button, 2...Multiphoton microscope, 201...Pulse laser device, 202...Pulse splitting device, 20 3... Beam adjustment unit, 204, 205, 212... Dichroic mirror, 206... Objective lens, 207, 211, 213... Fluorescence detection unit, 208... Focusing lens, 209... Pinhole, 210... Imaging lens, S... Sample, 3... Bonded lens, 301... First lens element, 302... Second lens element, 303... Bonding member, 401... Position measuring device, 402... Reflecting element, 403... Irradiation unit, 404... Light receiving unit, 405... Workpiece

Claims

1. By mass%, SiO ２ Content: greater than 0% and 15% or less, B ２ O ３ Content: greater than 0% and 13% or less, La ２ O ３ Content: 18% or more and 55% or less, TiO ２ Content: 8% or more and 30% or less, Nb ２ O ５ Content: 3% or more and 22% or less, ZnO content: greater than 0% and 20% or less, ZrO ２ Content: greater than 0% and 13% or less, is an optical glass.

2. In mass%, B ２ O ３ Ratio of ZnO content to total content (ZnO / B ２ O ３ The optical glass according to claim 1, wherein the coefficient is 0.4 or more and 10.0 or less.

3. The optical glass according to claim 1 or 2, wherein, by mass%, the MgO content is 0% or more and 7%, the SrO content is 0% or more and 10%, and the BaO content is 0% or more and 15%.

4. In mass%, WO ３ The optical glass according to any one of claims 1 to 3, wherein the content is 0% or more and 5% or less.

5. The optical glass according to any one of claims 1 to 4, wherein the total content of MgO, CaO, BaO, and SrO (MgO + CaO + BaO + SrO) in mass percent is 0% or more and 15% or less.

6. By mass%, SiO ２ and B ２ O ３ Total content (SiO ２ +B ２ O ３ ): The optical glass according to any one of claims 1 to 5, wherein the content is 4% or more and 20% or less.

7. In mass%, B ２ O ３ SiO content ２ Ratio of content (SiO ２ / B ２ O ３ The optical glass according to any one of claims 1 to 6, wherein the value is greater than 0 and less than or equal to 8.

8. TiO ２ and Nb ２ O ５ Total content (TiO ２ +Nb ２ O ５ ): The optical glass according to any one of claims 1 to 7, wherein the content is 20% or more and 43% or less.

9. Nb by mass% ２ O ５ TiO content ２ Ratio of content (TiO ２ / Nb ２ O ５ The optical glass according to any one of claims 1 to 8, wherein the value is 0.8 or more and 3.3 or less.

10. In mass%, La ２ O ３ TiO content ２ and Nb ２ O ５ Ratio of total content ((TiO ２ +Nb ２ O ５ ) / La ２ O ３ The optical glass according to any one of claims 1 to 9, wherein the coefficient is 0.4 or more and 1.6 or less.

11. In mass%, La ２ O ３ , ZrO ２ , TiO ２ and Nb ２ O ５ The optical glass according to any one of claims 1 to 10, wherein the total content of is 62% or more and 85% or less.

12. Al (by mass%) ２ O ３ The optical glass according to any one of claims 1 to 11, wherein the content is 0% or more and 5% or less.

13. In mass%, B ２ O ３ Ratio of ZnO content to total content (ZnO / B ２ O ３ The optical glass according to any one of claims 1 to 12, wherein the value is 1.0 or more and 10.0 or less.

14. In mass%, La ２ O ３ The optical glass according to any one of claims 1 to 13, wherein the content is 40% or more and 55% or less.

15. SiO₂ (by mass%) ２ and B ２ O ３ Total content (SiO ２ +B ２ O ３ ): The optical glass according to any one of claims 1 to 14, wherein the content is 4% or more and 13% or less.

16. Refractive index (n) for light with a wavelength of 1552.1 nm １５５２．１ The optical glass according to any one of claims 1 to 15, wherein the coefficient of the optical glass is 1.96 or more and 2.04 or less.

17. Abbe number (ν ｄ The optical glass according to any one of claims 1 to 16, wherein the ratio is 18 or more and 30 or less.

18. Partial dispersion ratio (P ｇ，Ｆ The optical glass according to any one of claims 1 to 17, wherein the ratio is 0.590 or more and 0.630 or less.

19. An optical element using optical glass as described in any one of claims 1 to 18.

20. An optical system including the optical element described in claim 19.

21. A replacement lens for a microscope, comprising the optical system described in claim 20.

22. A camera interchangeable lens comprising the optical system described in claim 20.

23. An optical apparatus including the optical system described in claim 20.

24. A reflective element comprising the optical glass described in any one of claims 1 to 18.

25. A position measuring device comprising: a reflective element according to claim 24; an illumination unit for irradiating the reflective element with measuring light; and a light receiving unit for receiving the measuring light reflected by the reflective element.

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