JP2017036187A - Optical glass, optical element prepared with optical glass, and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass having high refractive index and low dispersion, and excellent devitrification stability, and an optical element and an optical device.SOLUTION: An optical glass comprises each component (mass%) of SiO: 9%-22%, BO: 3%-10%, BaO: 15%-45%, NaO: 0.5%-6%, KO: 1%-4%, ZrO: 1%-10%, TiO: 5%-less than 22%, and NbO: 5%-20% and also comprises each component (mass%) of AlO: 0%-1%, CaO: 0%-5%, ZnO: 0%-5%, and LaO: 0%-5%.SELECTED DRAWING: None

Description

  The present invention relates to an optical glass, an optical element, and an optical device that can be used for an optical element used in an optical apparatus such as a camera.

  High resolution is required by optical systems used in digital cameras. In order to realize a high resolution, it is effective to increase the radius of curvature of the lens by using high refractive index glass for the optical system. In particular, there is a high development demand for high refractive index and low dispersion glass.

  For example, Patent Document 1 discloses a glass having a high refractive index.

JP 2006-225220 A

  However, in the conventional optical glass as described above, the devitrification stability may be lowered by adjusting the components for increasing the refractive index.

  Therefore, an object of the present invention is to provide an optical glass, an optical element, and an optical device that have high refractive index, low dispersion, and excellent devitrification stability.

The first aspect of the present invention for solving the above problems is, in mass%,
SiO ₂ : 9% or more and 22% or less,
B ₂ O ₃ : 3% or more and 10% or less,
BaO: 15% to 45%,
Na ₂ O: 0.5% or more and 6% or less,
K ₂ O: 1% or more and 4% or less,
ZrO ₂ : 1% or more and 10% or less,
TiO ₂ : 5% or more and less than 22%,
Nb ₂ O ₅ : 5% or more and 20% or less,
It is an optical glass characterized by containing these components.

  The second aspect of the present invention is an optical element using the optical glass of the first aspect.

  A third aspect of the present invention is an optical device including the optical element of the second aspect.

It is a perspective view of an imaging device provided with an optical element using optical glass concerning one embodiment of the present invention.

  Hereinafter, an embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents.

  In the present specification, unless otherwise specified, the content of each component is assumed to be% by mass with respect to the total weight of the glass in terms of oxide composition. The oxide-converted composition here means that the oxide, composite salt, etc. used as the raw material of the glass component of the present invention are all decomposed and converted into oxides when melted, and the total of the oxides. It is the composition which described each component contained in glass by making mass into 100 mass%.

The optical glass according to the present embodiment is an optical glass excellent in devitrification stability while having a high refractive index and low dispersion. The optical glass in the present embodiment contains SiO ₂ , B ₂ O ₃ , BaO, Na ₂ O, K ₂ O, ZrO ₂ , TiO ₂ , and Nb ₂ O ₅ as essential components. Specific examples of the composition range of each component include, in mass%, SiO ₂ : 9% to 22%, B ₂ O ₃ : 3% to 10%, BaO: 15% to 45%, Na ₂ O: 0.5% to 6%, K ₂ O: 1% to 4%, ZrO ₂ : 1% to 10%, TiO ₂ : 5% to less than 22%, Nb ₂ O ₅ : 5% or more What contains 20% or less is mentioned. The reason why the content of each component is limited as described above will be described below.

The content of SiO ₂ is preferably 9% or more and 22% or less, more preferably 12% or more and 19% or less. By setting it as this range, it is possible to increase the refractive index of the optical glass, and it is possible to improve the devitrification stability and improve the moldability. If the SiO ₂ content is too low, devitrification of the optical glass tends to occur. Moreover, there exists a possibility that the viscosity at the time of the melting of glass may fall and shaping | molding may become difficult. If the SiO ₂ content is too high, the refractive index tends to decrease, and coloring may easily occur.

The content of B ₂ O ₃ is preferably 3% or more and 10% or less, more preferably 5% or more and 8% or less. By setting it as this range, it is possible to increase the refractive index of the optical glass, and it is possible to improve the devitrification stability and improve the moldability. If the content of B ₂ O ₃ is too low, the meltability is deteriorated and the glass is easily devitrified. If the content of B ₂ O ₃ is too high, it is difficult to increase the refractive index. In addition, the viscosity at the time of melting tends to be low and molding tends to be difficult.

  The content of BaO is preferably 15% to 45%, more preferably 20% to 40%. By setting it as this range, devitrification stability can be improved and a refractive index can be raised. In addition, if the content rate of BaO is too low, the said effect is not fully exhibited. If the BaO content is too high, the chemical durability of the optical glass may be affected. Further, the devitrification stability tends to be lowered.

The content of Na ₂ O is preferably 0.5% or more and 6% or less, more preferably 1% or more and 5% or less. By setting it as this range, while improving glass meltability, effects, such as reducing press molding temperature and suppressing press mold deterioration, can be acquired. Incidentally, if Na 2 _O content is too low, the effect is not sufficiently exhibited. If the content of Na ₂ O is too high, the chemical durability decreases, the volatilization amount increases during pressing and melting, the moldability decreases due to the decrease in viscosity during melting, and the devitrification stability decreases. There is a risk of inviting.

The content of K ₂ O is preferably 1% or more and 4% or less, more preferably 1% or more and 3% or less. By setting it as this range, while improving glass meltability, effects, such as reducing press molding temperature and suppressing deterioration of a press type | mold, can be acquired. Incidentally, K 2 _O content is too low, the effect is not sufficiently exhibited. If the content of K ₂ O is too high, the chemical durability decreases, the volatilization amount increases during pressing or melting, the moldability decreases due to the decrease in viscosity during melting, and the devitrification stability decreases. There is a risk of inviting.

The content of ZrO ₂ is preferably 1% or more and 10% or less, more preferably 3% or more and 8% or less. By setting it as this range, a refractive index and dispersion | distribution can be improved. If the content of ZrO ₂ is too low, the effect of increasing the refractive index and dispersion cannot be obtained sufficiently. If the content of ZrO ₂ is too high, the meltability deteriorates and the devitrification stability may be lowered.

The content of TiO ₂ is preferably 5% or more and less than 22%, more preferably 8% or more and 20% or less. By setting it as this range, the refractive index and dispersion | distribution of glass can be improved, and devitrification stability can be made favorable. If the content of TiO ₂ is too low, the effect of increasing the refractive index and dispersion cannot be sufficiently obtained, and the devitrification stability may be lowered. If the content of TiO ₂ is too high, the glass may be easily colored.

The content of Nb ₂ O ₅ is preferably 5% or more and 20% or less, more preferably 8% or more and 18% or less. By setting it as this range, the refractive index and dispersion | distribution of glass can be improved, and devitrification stability can be improved. If the content of Nb ₂ O ₅ is too low, the effect of increasing the refractive index and dispersion cannot be obtained sufficiently. If the content of Nb ₂ O ₅ is too high, the devitrification stability tends to decrease.

In addition to the essential components, the optical glass in the present embodiment includes, as an optional component, mass%, Al ₂ O ₃ : 0% to 1%, CaO: 0% to 5%, ZnO: 0% or more _5%, La _{2 O} 3: 0% 5% or more of the following may contain one or more.

Al ₂ O ₃ is an effective component for improving devitrification resistance and chemical durability of glass. The content is preferably 0% or more and 1% or less, more preferably 0% or more and 0.5% or less. By setting it as this range, the devitrification resistance of the optical glass can be improved. If the content of Al ₂ O ₃ is too high, the devitrification resistance of the optical glass may be affected.

  CaO is a component that reduces the specific gravity of glass and is effective in improving chemical durability and devitrification stability. The content is preferably 0% or more and 5% or less, more preferably 0% or more and 3% or less. By setting it as this range, the devitrification stability of the optical glass can be improved. If the CaO content is too high, the meltability and devitrification stability may be reduced.

  ZnO is an effective component for improving the meltability of glass. The content is preferably 0% or more and 5% or less, more preferably 0% or more and 3% or less. By setting it as this range, the meltability of glass can be improved, the press molding temperature can be lowered, and the deterioration of the press mold can be suppressed. If the ZnO content is too high, the devitrification stability may be reduced.

La ₂ O ₃ is an effective component for increasing the refractive index. The content is preferably 0% or more and 5% or less, more preferably 0% or more and 3% or less. By setting it as this range, while improving a refractive index, devitrification stability can be improved. If the content of La ₂ O ₃ is too high, the meltability is deteriorated and devitrification may occur easily.

  In addition, components such as known fining agents, coloring agents, defoaming agents, fluorine compounds, diphosphorus pentoxide are added to the glass for the purpose of clarifying, coloring, decoloring and fine adjustment of optical constants as necessary. An appropriate amount can be added to the composition. Moreover, not only the said component but another component can also be added in the range with which the effect of the optical glass of this embodiment is acquired.

For example, the optical glass of the present embodiment includes Li ₂ O, Ta ₂ O ₅ , MgO, SrO, Y ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ , As ₂ O ₃ , and Sb ₂ O as optional components. 1 or 2 or more of ₃ may be included.

Li ₂ O is useful for improving the meltability, and also provides effects such as lowering the press molding temperature and preventing the press mold from deteriorating.

Ta ₂ O ₅ has an effect of increasing the refractive index of glass and improving chemical durability. However, since Ta ₂ O ₅ is an expensive material, it is preferably not contained substantially from the viewpoint of manufacturing cost.

  MgO and SrO are useful for adjusting the optical constants of the glass.

Y ₂ O ₃ , Gd ₂ O ₃ and Yb ₂ O ₃ all have the effects of improving the chemical durability of the glass and increasing the refractive index.

As ₂ O ₃ and Sb ₂ O ₃ can be added as defoamers. Each of these contents is, for example, preferably 0% or more and 1% or less, more preferably 0% or more and 0.5% or less, with respect to the total amount of the optical glass.

  The optical glass of the present embodiment can be configured to contain substantially no rare earth element or to contain rare earth elements in an amount of 5% by mass or less in terms of oxide.

The rare earth elements are Sc, Y, and L (lanthanoids; La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). The oxide containing an element is La ₂ O ₃ , Y ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ or the like.

  Here, “substantially not contained” means that it is not substantially contained as a substantial component that affects the properties of the glass composition beyond the concentration unavoidably contained as an impurity. For example, the contamination of about several ppm to several tens of ppm in the production process is not substantially contained.

  According to the glass composition of the present embodiment, an optical glass excellent in transmittance and devitrification resistance with high refractive index and high dispersion even when it contains substantially no rare earth element or only a small amount. Thus, problems such as an increase in raw material cost and instability of raw material acquisition due to the use of rare earth elements can be avoided.

The raw material is preferably a high-purity product with a low impurity content. For example, it is preferable to use a high-purity product for one or more of SiO ₂ raw material, B ₂ O ₃ raw material, and TiO ₂ raw material. A high-purity product includes 99.85% by mass or more of the component. As a result of the use of a high-purity product, the amount of impurities is reduced, so that the internal transmittance of light having a wavelength of 410 nm or less can be increased.

  Next, physical property values of the optical glass of the present embodiment will be described.

  The optical glass according to this embodiment desirably has a high refractive index (nd). However, generally, the higher the refractive index (nd), the lower the Abbe number (νd). Therefore, the refractive index (nd) of the optical glass according to the present embodiment may be in the range of 1.73 to 1.91 with 1.73 as the lower limit and 1.91 as the upper limit.

  The optical glass according to the present embodiment desirably has low dispersibility (large Abbe number (νd)). However, generally, the refractive index tends to decrease as the Abbe number increases. Therefore, the Abbe number (νd) of the optical glass according to the present embodiment may be in the range of 24 to 41 with 24 as the lower limit and 41 as the upper limit.

  In addition, the optical glass in this embodiment can be manufactured by a normal method. For example, raw materials such as oxides, carbonates, nitrates and sulfates are prepared so as to have a target composition, melted at about 1100 to 1400 ° C., stirred and homogenized, blown out of bubbles, and then poured into a mold. The manufacturing method to shape | mold is employable.

  Such optical glass in this embodiment is suitable as an optical element such as a lens provided in an optical apparatus such as a camera or a microscope.

  In addition, the optical glass of this embodiment can be used as an optical element with which an optical apparatus is provided, for example. FIG. 1 shows an image pickup apparatus 1 (optical apparatus) including a lens 4 (optical element) using the optical glass according to the present embodiment as a base material.

  The imaging device 1 is a so-called digital single-lens reflex camera, and a lens barrel 3 is detachably attached to a lens mount (not shown) of a camera body 2. The light passing through the lens 4 of the lens barrel 3 is imaged on the sensor chip (solid-state imaging device) 5 of the multichip module 7 disposed on the back side of the camera body 2. The sensor chip 5 is a bare chip such as a so-called CMOS image sensor, and the multichip module 7 is a COG (Chip On Glass) type module in which the sensor chip 5 is mounted on the glass substrate 6 in a bare chip, for example.

  Note that the optical apparatus is not limited to such an imaging apparatus, and examples thereof include a projector. The optical element is not limited to a lens, and examples thereof include a prism.

  Next, examples and comparative examples of the present invention will be described. Tables 1 to 4 show the chemical composition of each component of the optical glass according to the embodiment of the present invention based on the mass% of the oxide standard, and Table 5 shows the oxidation of each component of the optical glass according to the comparative example of the present invention. The composition by mass% on an object basis is shown together with the evaluation of refractive index (nd), Abbe number (νd), and devitrification resistance. The present invention is not limited to these examples.

<Production of optical glass>
The optical glass according to Examples and Comparative Examples of the present invention was produced by the following procedure. First, glass raw materials such as oxides, hydroxides, phosphoric acid compounds (phosphate, normal phosphoric acid, etc.), carbonates, and nitrates so as to have chemical compositions (mass%) shown in Tables 1 to 5 are used. Weighed. Next, the weighed raw materials were mixed, put into a platinum crucible, melted at a temperature of 1200 to 1400 ° C., and homogenized with stirring. After the foam was blown out, each sample was obtained by lowering the temperature to an appropriate temperature, casting it into a mold or the like, gradually cooling it, and molding it.

(1) Refractive index (nd) and Abbe number (νd)
The refractive index (nd) and Abbe number (νd) of each sample described in Tables 1 to 4 were measured and calculated using a normal refractive index measuring device. In addition, the value of the refractive index is set to the sixth decimal place.

(2) Evaluation of devitrification resistance The devitrification resistance of each sample described in Tables 1 to 5 was obtained by polishing the produced glass and visually confirming the presence or absence of devitrification. In Tables 1 to 3, devitrification means a state in which a devitrification portion is confirmed in a sample.

  From Tables 1 to 4, it was found that each of Examples 1 to 26 of the present invention had a refractive index (nd) of 1.73 to 1.91 and an Abbe number (νd) of 24 to 41. . Furthermore, as a result of evaluation of devitrification resistance, devitrification was not observed in any composition.

  From Table 5, devitrification was recognized in the produced samples in any of the comparative examples having compositions different from the composition range of the present invention. For this reason, it was difficult to measure various physical property values.

As described above, the optical glass of this example has a refractive index (nd) of 1.73 to 1.91 and an Abbe number (νd).
Was in the range of 24-41, excellent in devitrification resistance, and coloring was also suppressed.

  As described above, it was possible to achieve a high refractive index and a high dispersion while suppressing the amount of rare earth elements to a small amount. Since the amount of expensive rare earth elements used can be suppressed, the manufacturing cost can be reduced.

  1: imaging device, 2: camera body, 3: lens barrel, 4: lens, 5: sensor chip, 6: glass substrate, 7: multichip module

Claims (7)

% By mass
SiO ₂ : 9% or more and 22% or less,
B ₂ O ₃ : 3% or more and 10% or less,
BaO: 15% to 45%,
Na ₂ O: 0.5% or more and 6% or less,
K ₂ O: 1% or more and 4% or less,
ZrO ₂ : 1% or more and 10% or less,
TiO ₂ : 5% or more and less than 22%,
Nb ₂ O ₅ : 5% or more and 20% or less,
An optical glass comprising the following components. % By mass
Al ₂ O ₃ : 0% or more and 1% or less,
CaO: 0% or more and 5% or less,
ZnO: 0% or more and 5% or less,
La ₂ O ₃ : containing 0% or more and 5% or less of each component,
The optical glass according to claim 1. The total content of rare earth elements in terms of oxide is 5% by mass or less,
The optical glass according to claim 1 or 2. It is characterized by substantially not containing rare earth elements,
The optical glass according to any one of claims 1 to 3.   The optical glass according to any one of claims 1 to 4, wherein the refractive index (nd) is in the range of 1.73 to 1.91 and the Abbe number (νd) is in the range of 24 to 41.   The optical element using the optical glass as described in any one of Claim 1 to 5.   An optical device comprising the optical element according to claim 6.

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