Patent ID: 12234183

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment according to the present invention (hereinafter, referred to as “the present embodiment”) will be described in details. The following present embodiments are examples for describing the present invention, and are not intended to limit the present invention to the following description. The present invention may be appropriately modified within the scope of the gist thereof.

Herein, unless specified otherwise, it is assumed that all the content of each component refers to a mass % (mass percentage) with respect to a total weight of the glass in terms of oxide-equivalent composition. Note that the oxide-equivalent composition herein refers to a composition obtained by expressing each component contained in the glass by setting a total mass of the oxides to 100 mass %, assuming that all of oxides, composite salts, or the like used as raw materials of the glass constituents according to the present embodiment are decomposed at the time of melting and are changed into oxides.

The optical glass according to the present embodiment contains a P2O5component of 30 to 60 mass % (exclusive of 30), an Al2O3component of 2 to 10 mass % (exclusive of 2), a TiO2component of 10 to 36 mass % (exclusive of 36), an Nb2O5component of 0 to 5 mass %, a Ta2O5component of 0 to 15 mass %, a Bi2O3component of 0 to 5 mass % (exclusive of 5), and an Sb2O3component of 0 to 1 mass %.

In the related art, in order to achieve higher dispersibility, a technique of increasing the content of the component such as TiO2or Nb2O5has been tested. However, if the content of such a component increases, transmittance tends to decrease, and specific gravity tends to increase. In this regard, the optical glass according to the present embodiment can reduce the specific gravity while achieving higher dispersibility (smaller Abbe number). Therefore, it is possible to implement a lightweight lens advantageous in aberration correction.

P2O5is a component that forms a glass structure, improves devitrification resistance, and decreases the refractive index and the chemical durability. If the content of P2O5is too small, devitrification tends to easily occur. If the content of P2O5is too large, the refractive index and the chemical durability tend to decrease. From such a viewpoint, the content of P2O5is set to 30 to 60% (exclusive of 30), preferably 35 to 50%, and more preferably 40 to 50%. By setting the content of P2O5within such a range, it is possible to increase the devitrification resistance and obtain the higher refractive index while improving the chemical durability.

Al2O3is a component that improves the chemical durability and decreases the partial dispersion ratio. If the content of Al2O3is too small, the chemical durability tends to decrease. If the content of Al2O3is too large, the partial dispersion ratio tends to decrease. From such a viewpoint, the content of Al2O3is set to 2 to 10% (exclusive of 2), preferably 2 to 9% (exclusive of 2), and more preferably 2 to 8%. By setting the content of Al2O3within such a range, it is possible to increase the chemical durability and prevent the partial dispersion ratio from decreasing.

TiO2is a component that increases the refractive index and the partial dispersion ratio and decreases the transmittance. If the content of TiO2is too small, the refractive index and the partial dispersion ratio tend to decrease. If the content of TiO2is too large, the transmittance tends to degrade. In addition, in the related art, a technique of increasing the content of TiO2or the like has been used to obtain higher dispersibility. However, it is not necessary to increase the content of TiO2in the optical glass according to the present embodiment. From such a viewpoint, the content of TiO2is set to 10 to 36% (exclusive of 36), preferably 15 to 30%, and more preferably 17 to 25%. By setting the content of TiO2within such a range, it is possible to implement high transmittance without decreasing the refractive index and the partial dispersion ratio.

Nb2O5is a component that increases the refractive index and dispersion and decreases the transmittance. If the content of Nb2O5is small, the refractive index tends to decrease. In addition, if the content of Nb2O5is large, the transmittance tends to degrade. In the related art, a technique of increasing the content of Nb2O5has been used to implement higher dispersibility. However, it is not necessary to increase the content of Nb2O5in the optical glass according to the present embodiment. From such a viewpoint, the content of Nb2O5is set to 0 to 5%, preferably 0 to 3%, more preferably 0 to 2%. Further preferably, Nb2O5is not substantially contained.

Herein, “being not substantially contained” means that the corresponding component is not contained as a component affecting the property of the glass composition over a concentration inevitably contained as an impurity. For example, if the content is approximately 100 ppm, it is considered that the content is not substantially contained.

Ta2O5is a component that increases the refractive index and dispersion and decreases the devitrification stability. If the content of Ta2O5is large, the devitrification stability tends to degrade. From such a viewpoint, the content of Ta2O5is set to 0 to 15%, preferably 0 to 10%, more preferably 0 to 5%. Further preferably, Ta is not substantially contained. Using the optical glass according to the present embodiment, it is possible to reduce the content of Ta2O5, which is expensive raw material. In addition, since Ta2O5may not be contained, it is excellent in terms of cost of the raw material.

Bi2O3is a component that increases the refractive index and dispersion and decreases the transmittance. If the content of Bi2O3is large, the transmittance tends to degrade. From such a viewpoint, the content of Bi2O3is set to 0 to 5% (exclusive of 5), preferably 0 to 3%, and more preferably 0 to 2%.

From the viewpoint of defoamability at the time of glass melting, the content of Sb2O3is set to 0 to 1%, preferably 0 to 0.5%, and more preferably 0 to 0.2%.

As an optional component, the optical glass according to the present embodiment may further contain at least one selected from a group consisting of Li2O, Na2O, K2O, BaO, ZnO, MgO, CaO, SrO, SiO2, B2O3, WO3, ZrO2, Y2O3, La2O3, or Gd2O3.

From the viewpoint of meltability, the content of Li2O is preferably 0 to 20%, more preferably 0 to 15%, and further preferably 0 to 10%.

Na2O is a component that improves the meltability and decreases the refractive index. If the content of Na2O is too small, the meltability tends to decrease. If the content of Na2O is too large, the refractive index and the chemical durability tend to decrease. From such a viewpoint, the content of Na2O is preferably set to 0 to 30%, more preferably 10 to 25%, and further preferably 10 to 20%. By setting the content of Na2O within such a range, it is possible to improve the meltability and prevent the refractive index and the chemical durability from decreasing.

K2O is a component that improves the meltability and decreases the refractive index. If the content of K2O is too small, the meltability tends to decrease. If the content of K2O is too large, the refractive index and the chemical durability tend to decrease. From such a viewpoint, the content of K2O is preferably set to 0 to 30%, more preferably 3 to 25%, and further preferably 3 to 15%. By setting the content of K2O within such a range, it is possible to improve the meltability and prevent the refractive index and the chemical durability from decreasing.

The total amount of Li2O, Na2O, and K2O (ΣR2O; where R═Li, Na, or K) is preferably set to 10 to 35%, more preferably 15 to 33%, further preferably 20 to 30% from the viewpoint of the meltability, the refractive index, and the chemical durability.

BaO is a component that improves the partial dispersion ratio and decreases the devitrification stability. If the content of BaO is too small, the partial dispersion ratio tends to decrease. If the content of BaO is too large, the devitrification stability tends to decrease. From such a viewpoint, the content of BaO is preferably set to 0 to 20%, more preferably 0 to 15%, and further preferably 1 to 8%. By setting the content of BaO within such a range, it is possible to increase the partial dispersion ratio and prevent the devitrification stability from decreasing.

ZnO is a component that improves the devitrification stability and decreases the partial dispersion ratio. If the content of ZnO is too small, the devitrification stability tends to decrease. If the content of ZnO is too large, the partial dispersion ratio tends to decrease. From such a viewpoint, the content of ZnO is preferably set to 0 to 20%, more preferably 0 to 15%, and further preferably 1 to 8%. By setting the content of ZnO within such a range, it is possible to improve the devitrification stability and prevent the partial dispersion ratio from decreasing.

From the viewpoint of higher dispersibility, the content of MgO is preferably set to 0 to 20%, more preferably 0 to 15%, and further preferably 0 to 10%.

From the viewpoint of higher dispersibility, the content of CaO is preferably set to 0 to 20%, more preferably 0 to 15%, and further preferably 0 to 10%.

From the viewpoint of higher dispersibility, the content of SrO is preferably set to 0 to 20%, more preferably 0 to 15%, and further preferably 0 to 10%.

From the viewpoint of meltability, the content of SiO2is preferably set to 0 to 10%, more preferably 0 to 7%, and further preferably 0 to 5%.

From the viewpoint of higher dispersibility, the content of B2O3is preferably set to 0 to 20%, more preferably 0 to 15%, and further preferably 0 to 10%.

From the viewpoint of transmittance, the content of WO3is preferably set to 0 to 15%, more preferably 0 to 10%, and further preferably 0 to 7%.

From the viewpoint of meltability, the content of ZrO2is preferably set to 0 to 10%, more preferably 0 to 7%, and further preferably 0 to 3%.

From the viewpoint of meltability, the content of Y2O3is preferably set to 0 to 15%, more preferably 0 to 10%, and further preferably 0 to 7%.

From the viewpoint of meltability, the content of La2O3is preferably set to 0 to 10%, more preferably 0 to 7%, and further preferably 0 to 5%. From the viewpoint of cost, it is still more preferable that La2O3is not substantially contained.

Since Gd2O3is expensive raw material, its content is preferably set to 0 to 20%, more preferably 0 to 15%, and further preferably 0 to 7%.

A desirable combination of these contents includes an Li2O component of 0 to 20%, an Na2O component of 0 to 30%, and a K2O component of 0 to 30%. By setting such a combination, it is possible to improve meltability and prevent chemical durability from decreasing.

Another desirable combination includes a BaO component of 0 to 20%, a ZnO component of 0 to 20%, an MgO component of 0 to 20%, a CaO component of 0 to 20%, and an SrO component of 0 to 20%. Using such a combination, it is possible to increase the partial dispersion ratio and prevent dispersibility from decreasing.

Still another desirable combination includes an SiO2component of 0 to 10% and a B2O3component of 0 to 20%. Using such a combination, it is possible to improve meltability and prevent dispersibility from decreasing.

Furthermore, the optical glass according to the present embodiment preferably satisfies the following relationship.

The content ratio of TiO2with respect to P2O5(TiO2/P2O5) is preferably set to 0.3 to 0.8, more preferably 0.3 to 0.7, and further preferably 0.3 to 0.6. By setting the ratio TiO2/P2O5within such a range, it is possible to increase the partial dispersion ratio.

The content ratio of TiO2with respect to Al2O5(TiO2/Al2O5) is preferably set to 2 to 16, more preferably 2 to 10, and further preferably 2 to 8. By setting the ratio TiO2/Al2O5within such a range, it is possible to increase the partial dispersion ratio.

In addition, if necessary, for the purpose of clarification, coloring, decoloring, fine adjustment of optical constants, or the like, a suitable amount of components such as a clarifier, a coloring agent, a defoaming agent, and a fluorine compound known in the art may be added to the glass composition. Furthermore, in addition to the components described above, other components may also be added as long as the effect of the optical glass according to the present embodiment can be obtained.

A method of manufacturing the optical glass according to the present embodiment is not particularly limited, and any method known in the art may be employed. In addition, a suitable manufacturing condition may be appropriately selected. For example, a manufacturing method may be employed, in which raw materials such as oxide, carbonate, nitrate, and sulfate are prepared at a target composition and are melted preferably at a temperature of 1100 to 1400° C., and more preferably 1200 to 1300° C., homogenization is performed by stirring, bubbles are removed, and molding is then performed by flowing them to a mold. A desired optical element may be obtained by fabricating the optical glass obtained in this manner into a desired shape through a reheat press or the like, as necessary, and performing polishing or the like.

As the raw material, it is preferable to use a high-purity product having a low impurity content. The high-purity product contains the corresponding component of 99.85 mass % or more. The use of the high-purity product reduces the amount of the impurity. As a result, the internal transmittance of the optical glass tends to increase.

Next, physical properties of the optical glass according to the present embodiment will be described.

From the viewpoint of reducing the thickness of the lens, it is desirable that the optical glass according to the present embodiment has a high refractive index (a refractive index (nd) is large). However, in general, the specific gravity tends to increase as the refractive index (nd) increases. On the basis of such a fact, the refractive index (nd) of the optical glass according to the present embodiment with respect to the d-line is preferably within a range of 1.60 to 1.75, and more preferably 1.64 to 1.73.

The Abbe number (νd) of the optical glass according to the present embodiment is preferably within a range of 20 to 35 and more preferably 22 to 30. As a desirable combination of the refractive index (nd) and the Abbe number (νd) in the optical glass according to the present embodiment, the refractive index (nd) with respect to the d-line is 1.60 to 1.75, and the Abbe number (νd) is 20 to 35. For example, by combining the optical glass according to the present embodiment having such properties with other optical glasses, it is possible to design an optical system capable of successfully correcting chromatic aberration or other aberrations.

From the viewpoint of reducing the weight of the lens, the optical glass according to the present embodiment desirably has a low specific gravity. However, in general, the refractive index tends to decrease as the specific gravity increases. On the basis of such a fact, a desirable specific gravity (Sg) of the optical glass according to the present embodiment is within a range of 2.9 to 3.6, in which “2.9” is the lower limit, and “3.6” is the upper limit.

From the viewpoint of aberration correction of the lens, the optical glass according to the present embodiment desirably has a large partial dispersion ratio (Pg,F). On the basis of such as fact, the lower limit of the partial dispersion ratio (Pg,F) of the optical glass according to the present embodiment is preferably 0.60 or greater, more preferably 0.61 or greater, and further preferably 0.62. In addition, the upper limit of the partial dispersion ratio (Pg,F) may be, for example, 0.66, but not limited thereto.

From the viewpoint of the fact described above, the optical glass according to the present embodiment may be suitably used, for example, as an optical element included in an optical device. Such an optical element includes a mirror, a lens, a prism, a filter, or the like, and can be widely used as an optical system. As a suitable example of the optical element, for example, an optical lens, an interchangeable lens for cameras, or the like may be included. In addition, these may be suitably used in imaging devices such as a lens-interchangeable camera or a non-lens-interchangeable camera, and various optical devices such as a multi-photon microscopic device. Hereinafter, such examples will be described.

<Imaging Device>

FIG.1is a perspective view illustrating an exemplary optical device according to the present embodiment as an imaging device. The imaging device1is a so-called digital single-lens reflex camera (lens-interchangeable camera), and a photographing lens103(optical system) includes an optical element based on the optical glass according to the present embodiment. A lens barrel102is detachably installed in a lens mount (not shown) of a camera body101. In addition, the light passing through the lens103of the lens barrel102is focused on a sensor chip (solid-state imaging element)104of a multi-chip module106disposed on the back side of the camera body101. The sensor chip104is a bare chip such as a so-called CMOS image sensor, and the multi-chip module106is, for example, a COG (chip on glass) type module in which the sensor chip104is mounted on a glass substrate105as a bare chip.

FIGS.2A and2Bare schematic diagrams illustrating another example in which the optical device according to the present embodiment is used as an imaging device.FIG.2Ais a front view illustrating the imaging device CAM, andFIG.2Bis a rear view illustrating the imaging device CAM. The imaging device CAM is a so-called digital still camera (non-lens-interchangeable camera), and the photographing lens WL (optical system) includes an optical element based on the optical glass according to the present embodiment.

If a power button (not shown) of the imaging device CAM is pressed, a shutter (not shown) of the photographing lens WL is opened, and the light from a subject (object) is condensed by the photographing lens WL and focused on the imaging element arranged on the image plane. The subject image formed on the imaging element is displayed on a liquid crystal monitor M arranged behind the imaging device CAM. A photographer determines the arrangement of the subject image while looking at the liquid crystal monitor M, and then presses down a release button B1to capture the subject image with the imaging element and record and save the image in a memory (not shown).

The imaging device CAM has an auxiliary light-emitting unit EF that emits auxiliary light when the subject is dark, a function button B2or the like, used for setting various conditions of the imaging device CAM, or the like.

An optical system used in such a digital camera is required to have higher resolution, lighter weight, and smaller size. In order to satisfy such requirements, it is effective to use glasses having different dispersion characteristics in the optical system. In particular, there is a high demand for glasses having a lower specific gravity (Sg) while having high dispersibility. From such a viewpoint, the optical glass according to the present embodiment is suitable as a member of such optical instrument. Note that the optical instrument applicable to the present embodiment is not limited to the imaging device described above, but may include, for example, a projector or the like. The optical element is not limited to a lens, but may include, for example, a prism or the like.

<Multi-Photon Microscope>

FIG.3is a block diagram illustrating an example of a configuration of a multi-photon microscope2using the optical glass according to the present embodiment. The multi-photon microscope2includes an objective lens206, a condensing lens208, and an image forming lens210. At least one of the objective lens206, the condensing lens208, and the image forming lens210includes an optical element using the optical glass according to the present embodiment as a mother material. Hereinafter, description is mainly made on the optical system of the multi-photon microscope2.

A pulse laser device201emits ultrashort pulse light having, for example, a near infrared wavelength (approximately 1,000 nm) and a pulse width of a femtosecond unit (for example, 100 femtoseconds). In general, ultrashort pulse light immediately after being emitted from the pulse laser device201is linearly polarized light that is polarized in a predetermined direction.

A pulse division device202divides the ultrashort pulse light, increases a repetition frequency of the ultrashort pulse light, and emits the ultrashort pulse light.

A beam adjustment unit203has a function of adjusting a beam diameter of the ultrashort pulse light, which enters from the pulse division device202, to a pupil diameter of the objective lens206, a function of adjusting convergence and divergence angles of the ultrashort pulse light in order to correct chromatic aberration (a focus difference) on an axis of a wavelength of multi-photon excitation light emitted from a sample S and the wavelength of the ultrashort pulse light, a pre-chirp function (group velocity dispersion compensation function) providing inverse group velocity dispersion to the ultrashort pulse light in order to correct the pulse width of the ultrashort pulse light, which is increased due to group velocity dispersion at the time of passing through the optical system, and the like.

The ultrashort pulse light emitted from the pulse laser device201have a repetition frequency increased by the pulse division device202, and is subjected to the above-mentioned adjustments by the beam adjustment unit203. Furthermore, the ultrashort pulse light emitted from the beam adjustment unit203is reflected on a dichroic mirror204in a direction toward a dichroic mirror205, passes through the dichroic mirror205, is converged by the objective lens206, and is radiated to the sample S. At this time, an observation surface of the sample S may be scanned with the ultrashort pulse light through use of scanning means (not illustrated).

For example, when the sample S is subjected to fluorescence observation, a fluorescent pigment by which the sample S is dyed is subjected to multi-photon excitation in an irradiated region with the ultrashort pulse light and the vicinity thereof on the sample S, and fluorescence having a wavelength shorter than an infrared wavelength of the ultrashort pulse light (hereinafter, also referred to “observation light”) is emitted.

The observation light emitted from the sample S in a direction toward the objective lens206is collimated by the objective lens206, and is reflected on the dichroic mirror205or passes through the dichroic mirror205depending on the wavelength.

The observation light reflected on the dichroic mirror205enters a fluorescence detection unit207. For example, the fluorescence detection unit207is formed of a barrier filter, a photo multiplier tube (PMT), or the like, receives the observation light reflected on the dichroic mirror205, and outputs an electronic signal depending on an amount of the light. Further, the fluorescence detection unit207detects the observation light over the observation surface of the sample S, in conformity with the ultrashort pulse light scanning on the observation surface of the sample S.

Meanwhile, the observation light passing through the dichroic mirror205is de-scanned by scanning means (not illustrated), passes through the dichroic mirror204, is converged by the condensing lens208, passes through a pinhole209provided at a position substantially conjugate to a focal position of the objective lens206, passes through the image forming lens210, and enters a fluorescence detection unit211.

For example, the fluorescence detection unit211is formed of a barrier filter, a PMT, or the like, receives the observation light forming an image on a light formed by the image forming lens210on the reception surface of the fluorescence detection unit211, and outputs an electronic signal depending on an amount of the light. Further, the fluorescence detection unit211detects the observation light over the observation surface of the sample S, in conformity with the ultrashort pulse light scanning on the observation surface of the sample S.

Note that all the observation light emitted from the sample S in a direction toward the objective lens206may be detected by the fluorescence detection unit211by excluding the dichroic mirror205from the optical path.

Further, the observation light emitted from the sample S in a direction opposite to the objective lens206is reflected on a dichroic mirror212, and enters a fluorescence detection unit213. The fluorescence detection unit213is formed of, for example, a barrier filter, a PMT, or the like, receives the observation light reflected on the dichroic mirror212, and outputs an electronic signal depending on an amount of the light. Further, the fluorescence detection unit213detects the observation light over the observation surface of the sample S, in conformity with the ultrashort pulse light scanning on the observation surface of the sample S.

The electronic signals output from the fluorescence detection units207,211, and213are input to, for example, a computer (not illustrated). The computer is capable of generating an observation image, displaying the generated observation image, storing data on the observation image, based on the input electronic signals.

<Cemented Lens>

FIG.4is a schematic diagram illustrating an exemplary cemented lens according to the present embodiment. The cemented lens3is a combinational lens having a first lens element301and a second lens element302. At least one of the first lens element and the second lens element is formed using the optical glass according to the present embodiment. The first lens element and the second lens element are bonded by interposing a bonding member303. As the bonding member303, an adhesive or the like known in the art may be used. Note that, in some cases, the lens included in the cemented lens may be referred to as a “lens element” as described above from the viewpoint of clarifying that the lens is an element of the cemented lens.

The cemented lens according to the present embodiment is useful from the viewpoint of chromatic aberration correction, and can be suitably used in the optical element, the optical system, the optical device, or the like as described above. In addition, an optical system including the cemented lens can be particularly suitably used in an interchangeable lens for camera, an optical device, or the like. Note that, although a cemented lens using two lens elements has been described in the aforementioned embodiment, the present invention may include a cemented lens using three or more lens elements without limiting thereto. In the case of the cemented lens using three or more lens elements, at least one of the three or more lens elements may be formed using the optical glass according to the present embodiment.

Examples

Next, Examples and Comparative Examples of the present invention will be described. Note that the present invention is not limited to these examples.

<Production of Optical Glass>

The optical glasses according to each example and each comparative example were produced in the following procedure. First, a glass material selected from oxides, hydroxides, phosphate compounds (such as phosphate or orthophosphoric acid), carbonates, nitrates, or the like was weighed to obtain the compositions (mass %) shown in each table. Then, the weighed raw materials were mixed, put into a platinum crucible, melted at a temperature of 1100 to 1300° C., and homogenized by stirring. After removing bubbles, the temperature was lowered to an appropriate level. Then, the molten materials were cast into a mold, gradually cooled, and molded to obtain each sample.

<Physical Property Evaluation>

Refractive Index (nd) and Abbe Number (νd)

The refractive indices (nd) and the Abbe numbers (νd) of each sample were measured and calculated using a refractometer (KPR-2000, manufactured by Shimadzu Device Corporation). “nd” denotes a refractive index of the glass with respect to light having a wavelength of 587.562 nm. “νd” was obtained from the following Equation (1). “nc” and “nF” denote the refractive indices of the glass with respect to light having wavelengths of 656.273 nm and 486.133 nm, respectively.
νd−(nd−1)/(nF−nc)  (1)
Partial Dispersion Ratio (Pg,F)

The partial dispersion ratio (Pg,F) of each sample indicates a ratio of the partial dispersion (ng−nF) with respect to the main dispersion (nF−nc), and was obtained from the following Equation (2). “ng” denotes a refractive index of the glass with respect to light having a wavelength of 435.835 nm. The value of the partial dispersion ratio (Pg,F) was set to four decimal places.
(Pg,F)−(ng−nF)/(nF−nc)  (2)
Specific Gravity (Sg)

The specific gravity (Sg) of each sample was determined from the mass ratio with respect to the same volume of pure water at a temperature of 4° C.

Tables 1 to 11 show the compositions and the evaluation results of the physical properties for the optical glasses of each of the examples and comparative examples on the basis of the mass % of each component with respect to the oxide. “ΣR2O” in the equation denotes a total amount of Li2O, Na2O, and K2O (where R═Li, Na, or K). In Comparative Example 2, since the optical glass was not obtainable, the physical property was set to “unmeasurable”.

TABLE 1Example No.123456P2O537.6436.7836.7635.7544.1445.25SiO20.000.000.000.000.000.00B2O34.444.346.508.430.000.00Li2O0.000.000.000.000.000.00Na2O17.3216.9316.9216.4516.3717.42K2O7.817.637.637.427.397.57MgO0.000.000.000.000.000.00CaO0.000.000.000.000.000.00SrO0.000.000.000.000.000.00BaO5.785.655.655.497.004.02ZnO1.571.531.531.492.302.36Al2O34.906.904.784.652.582.65TiO220.4220.1220.1120.2020.1120.61ZrO20.000.000.000.000.000.00Nb2O50.000.000.000.000.000.00Sb2O30.120.120.120.120.120.12Ta2O50.000.000.000.000.000.00Y2O30.000.000.000.000.000.00La2O30.000.000.000.000.000.00Gd2O30.000.000.000.000.000.00WO30.000.000.000.000.000.00Bi2O30.000.000.000.000.000.00total100.00100.00100.00100.00100.00100.00Σ R2O25.1324.5624.5523.8723.7625.00TiO2/P2O50.540.550.550.570.460.46TiO2/Al2O34.172.914.204.347.797.79nd1.645971.642011.644121.645231.670821.66678vd30.8631.5031.0830.9626.7726.54Pg, F0.61510.61210.61500.61580.63470.6345Sg2.902.872.882.862.952.90

TABLE 2Example No.789101112P2O545.8345.6544.7843.5644.3445.22SiO20.000.000.000.000.000.00B2O30.000.000.000.000.000.00Li2O0.000.000.000.000.000.92Na2O16.3615.6717.2414.9315.2015.50K2O7.677.647.497.2910.277.57MgO0.000.000.000.000.000.00CaO0.000.000.000.000.000.00SrO0.000.000.000.000.000.00BaO4.074.063.988.433.944.02ZnO2.392.382.332.272.312.35Al2O32.683.703.663.563.623.69TiO220.8820.8020.4019.8420.2020.60ZrO20.000.000.000.000.000.00Nb2O50.000.000.000.000.000.00Sb2O30.120.120.120.120.120.12Ta2O50.000.000.000.000.000.00Y2O30.000.000.000.000.000.00La2O30.000.000.000.000.000.00Gd2O30.000.000.000.000.000.00WO30.000.000.000.000.000.00Bi2O30.000.000.000.000.000.00total100.00100.00100.00100.00100.00100.00Σ R2O24.0323.3024.7422.2225.4723.99TiO2/P2O50.460.460.460.460.460.46TiO2/Al2O37.795.635.585.585.585.58nd1.671071.669601.664871.673721.663701.67298vd26.2326.6326.9627.0326.8426.62Pg, F0.63600.63350.63260.63250.63430.6339Sg2.902.902.912.992.892.92

TABLE 3Example No.131415161718P2O542.6243.8845.3442.6743.8440.47SiO20.000.000.000.000.000.00B2O30.000.000.000.000.002.13Li2O0.000.001.540.000.000.00Na2O12.8013.1813.6213.4211.9312.20K2O7.1312.057.597.1410.1610.38MgO0.000.000.000.000.000.00CaO0.000.000.000.000.000.00SrO0.000.000.000.000.000.00BaO11.233.904.039.753.903.98ZnO2.222.282.362.226.346.48Al2O34.474.604.764.483.583.66TiO219.4219.9920.6520.2120.1320.58ZrO20.000.000.000.000.000.00Nb2O50.000.000.000.000.000.00Sb2O30.110.120.120.110.120.12Ta2O50.000.000.000.000.000.00Y2O30.000.000.000.000.000.00La2O30.000.000.000.000.000.00Gd2O30.000.000.000.000.000.00WO30.000.000.000.000.000.00Bi2O30.000.000.000.000.000.00total100.00100.00100.00100.00100.00100.00Σ R2O19.9425.2322.7520.5622.0922.58TiO2/P2O50.460.460.460.470.460.51TiO2/Al2O34.344.344.344.525.625.62nd1.674201.660241.675411.679051.675941.66859vd27.8127.3026.9327.1826.5428.35Pg, F0.63070.63290.63280.63050.63310.6267Sg3.022.892.913.022.962.95

TABLE 4Example No.192021222324P2O545.2845.6744.9745.3945.0142.96SiO20.000.000.000.000.000.00B2O30.000.000.000.000.000.00Li2O2.552.573.182.512.532.11Na2O17.3618.8417.8518.7315.9413.34K2O7.837.909.056.8610.787.43MgO0.000.000.000.000.000.00CaO0.000.000.000.000.000.00SrO0.000.000.000.000.000.00BaO4.164.195.928.774.1311.69ZnO2.442.461.620.002.422.31Al2O34.912.762.202.143.804.66TiO215.3615.4915.0815.4815.2715.38ZrO20.000.000.000.000.000.00Nb2O50.000.000.000.000.000.00Sb2O30.120.130.130.120.120.12Ta2O50.000.000.000.000.000.00Y2O30.000.000.000.000.000.00La2O30.000.000.000.000.000.00Gd2O30.000.000.000.000.000.00WO30.000.000.000.000.000.00Bi2O30.000.000.000.000.000.00total100.00100.00100.00100.00100.00100.00Σ R2O27.7329.3030.0828.0929.2522.88TiO2/P2O50.340.340.340.340.340.36TiO2/Al2O33.135.616.877.224.023.30nd1.625131.625851.620521.630201.624261.64479vd32.0331.0732.0430.9631.3831.59Pg, F0.61880.62130.61910.62230.62270.6211Sg2.852.842.842.892.833.00

TABLE 5Example No.252627282930P2O544.9343.6945.0444.7344.5047.75SiO20.000.000.000.000.000.00B2O30.000.000.000.000.000.00Li2O1.260.000.000.000.003.74Na2O20.8516.8216.7417.8617.1410.73K2O8.527.318.496.547.457.99MgO0.000.000.000.000.000.00CaO0.000.000.000.000.000.00SrO0.000.000.000.000.000.00BaO4.533.885.558.360.005.97ZnO2.652.271.520.004.421.57Al2O32.122.032.062.042.072.06TiO215.0323.8820.5220.3724.3220.07ZrO20.000.000.000.000.000.00Nb2O50.000.000.000.000.000.00Sb2O30.120.120.090.090.120.13Ta2O50.000.000.000.000.000.00Y2O30.000.000.000.000.000.00La2O30.000.000.000.000.000.00Gd2O30.000.000.000.000.000.00WO30.000.000.000.000.000.00Bi2O30.000.000.000.000.000.00total100.00100.00100.00100.00100.00100.00Σ R2O30.6324.1325.2224.4024.5822.45TiO2/P2O50.330.550.460.460.550.42TiO2/Al2O37.1011.779.969.9611.779.72nd1.614051.688851.668091.667161.687371.68416vd32.0125.1726.3226.7525.0226.19Pg, F0.61840.63850.63680.63270.63820.6352Sg2.842.922.912.942.892.91

TABLE 6Example No.313233343536P2O544.4847.0945.0947.6648.9341.81SiO20.000.000.000.000.000.00B2O30.000.000.000.000.000.00Li2O0.003.042.910.000.000.00Na2O22.0518.1317.3614.4014.7815.54K2O0.003.693.538.989.227.88MgO0.000.000.000.006.830.00CaO0.000.000.009.250.000.00SrO0.000.000.000.000.000.00BaO5.560.000.000.000.005.15ZnO1.460.000.000.000.001.41Al2O32.032.192.092.182.249.08TiO224.3125.7328.8817.4417.9119.05ZrO20.000.000.000.000.000.00Nb2O50.000.000.000.000.000.00Sb2O30.120.120.120.100.100.08Ta2O50.000.000.000.000.000.00Y2O30.000.000.000.000.000.00La2O30.000.000.000.000.000.00Gd2O30.000.000.000.000.000.00WO30.000.000.000.000.000.00Bi2O30.000.000.000.000.000.00total100.00100.00100.00100.00100.00100.00Σ R2O22.0524.8723.8123.3824.0023.42TiO2/P2O50.550.550.640.370.370.46TiO2/Al2O311.9711.7713.808.018.012.10nd1.689061.698251.715421.643971.641891.63307vd25.6924.6224.0030.0929.0632.89Pg, F0.63360.64000.64090.62500.62700.6069Sg2.962.832.872.832.792.88

TABLE 7Example No.373839404142P2O543.2044.6344.0244.6945.1541.84SiO20.000.000.000.000.000.00B2O30.000.000.000.000.006.17Li2O1.212.581.241.261.272.35Na2O20.040.0014.3812.6314.7414.82K2O8.1919.717.3710.457.5510.02MgO0.000.000.000.000.000.00CaO0.000.000.000.000.000.00SrO0.000.000.000.000.000.00BaO4.3511.760.000.000.003.84ZnO5.852.320.000.000.002.25Al2O32.042.612.042.072.103.53TiO215.0116.2730.8328.7729.0715.06ZrO20.000.000.000.000.000.00Nb2O50.000.000.000.000.000.00Sb2O30.120.120.120.120.120.11Ta2O50.000.000.000.000.000.00Y2O30.000.000.000.000.000.00La2O30.000.000.000.000.000.00Gd2O30.000.000.000.000.000.00WO30.000.000.000.000.000.00Bi2O30.000.000.000.000.000.00total100.00100.00100.00100.00100.00100.00Σ R2O29.4422.2922.9824.3523.5727.19TiO2/P2O50.350.360.700.640.640.36TiO2/Al2O37.376.2415.0913.8713.874.26nd1.616891.657921.735351.724221.723901.62082vd32.6228.5322.4322.5822.8233.72Pg, F0.61190.63180.64770.64810.64570.6103Sg2.882.952.892.862.872.82

TABLE 8Example No.434445464748P2O540.1338.2646.4845.5644.1840.95SiO20.000.000.000.000.000.00B2O35.925.640.000.000.000.00Li2O1.970.003.012.950.000.00Na2O12.4611.8811.027.0013.3512.37K2O6.9412.558.7614.368.337.72MgO0.000.000.000.000.000.00CaO0.000.000.000.000.000.00SrO0.000.000.000.0015.840.00BaO10.9210.415.735.620.0021.73ZnO2.162.061.571.540.000.00Al2O34.354.152.132.082.022.06TiO215.0415.0621.1720.7616.1715.06ZrO20.000.000.000.000.000.00Nb2O50.000.000.000.000.000.00Sb2O30.110.000.120.120.120.11Ta2O50.000.000.000.000.000.00Y2O30.000.000.000.000.000.00La2O30.000.000.000.000.000.00Gd2O30.000.000.000.000.000.00WO30.000.000.000.000.000.00Bi2O30.000.000.000.000.000.00total100.00100.00100.00100.00100.00100.00Σ R2O21.3724.4322.7924.3221.6720.09TiO2/P2O50.370.390.460.460.370.37TiO2/Al2O33.463.639.969.968.017.31nd1.637641.625211.692841.685461.646401.65593vd33.9733.5625.3825.5230.3830.27Pg, F0.61050.61230.63740.63970.62480.6240Sg2.972.922.932.913.003.16

TABLE 9Example No.495051525354P2O545.7341.8039.9039.0242.7232.87SiO20.000.000.000.002.420.00B2O30.001.030.910.002.106.48Li2O0.002.352.240.002.400.00Na2O13.8214.8114.1315.0315.1315.12K2O8.6210.019.556.5310.236.82MgO0.000.000.000.000.000.00CaO0.000.000.000.000.000.00SrO0.000.000.000.000.000.00BaO0.003.843.660.003.925.05ZnO12.882.252.150.002.301.37Al2O32.092.022.032.013.614.28TiO216.7415.1215.1125.1315.0513.20ZrO20.000.000.000.000.000.00Nb2O50.000.000.000.000.004.79Sb2O30.120.110.110.100.120.11Ta2O50.000.000.0012.190.000.00Y2O30.006.660.000.000.000.00La2O30.000.000.000.000.000.00Gd2O30.000.0010.210.000.000.00WO30.000.000.000.000.005.06Bi2O30.000.000.000.000.004.86total100.00100.00100.00100.00100.00100.00Σ R2O22.4427.1625.9321.5627.7621.95TiO2/P2O50.370.360.380.640.350.40TiO2/Al2O38.017.477.4512.514.173.09nd1.653731.633631.638821.722731.621341.65072vd28.3433.3933.5924.0632.6931.74Pg, F0.62870.60930.60960.62360.61410.6039Sg2.952.933.063.082.823.07

TABLE 10Example No.555657P2O539.8043.7344.661SiO20.000.000.00B2O30.001.071.10Li2O1.122.462.51Na2O13.0015.4915.82K2O6.6610.4710.69MgO0.000.000.00CaO0.000.000.00SrO0.000.000.00BaO0.004.024.10ZnO0.002.352.40Al2O32.042.122.16TiO226.3814.8315.15ZrO20.000.001.29Nb2O50.000.000.00Sb2O30.110.120.12Ta2O50.000.000.00Y2O30.000.000.00La2O30.003.350.00Gd2O30.000.000.00WO36.520.000.00Bi2O34.370.000.00total100.00100.00100.00Σ R2O20.7828.4129.02TiO2/P2O50.660.340.34TiO2/Al2O312.947.007.00nd1.744601.629641.62841vd22.6531.8431.40Pg, F0.64540.61850.6194Sg3.092.902.85

TABLE 11Comparative Example No.12P2O527.1737.20SiO20.000.00B2O35.350.00Li2O0.002.40Na2O12.5014.32K2O5.642.92MgO0.000.00CaO0.000.00SrO0.000.00BaO4.170.00ZnO1.130.00Al2O33.541.73TiO27.1041.33ZrO20.000.00Nb2O53.960.00Sb2O30.090.10Ta2O521.140.00Y2O30.000.00La2O30.000.00Gd2O30.000.00WO34.180.00Bi2O34.020.00total100.00100.00Σ R2O18.1519.64TiO2/P2O50.261.11TiO2/Al2O32.0123.94nd1.67449Unmeasurablevd32.00UnmeasurablePg, F0.5990UnmeasurableSg3.48Unmeasurable

From the aforementioned examples, it was recognized that the optical glass according to the present example has a low specific gravity while having a high dispersibility. In addition, it was recognized that coloring is suppressed, and excellent transmittance is obtained in the optical glass according to the present example.1imaging device,101camera body,102lens barrel,103lens,104sensor chip,105glass substrate,106multi-chip module,CAM imaging device (non-lens-interchangeable camera),WL photographing lens,M liquid crystal monitor,EF auxiliary light-emitting unit,B1release button,B2function button,2multi-photon microscope,201pulse laser device,202pulse division device,203beam adjustment unit,204,205,212dichroic mirror,206objective lens,207,211,213fluorescence detection unit,208condensing lens,209pin hole,210image forming lens,S sample,3cemented lens,301first lens element,302second lens element,303bonding member