JP2008019103A - Glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide glass having a refractive index (nd) of 1.60-1.67 and an Abbe number (νd) of 50-65, which prevents double refraction from occurring and hardly suffers from influence of imaging characteristics even used under exposure to high intensity light. <P>SOLUTION: The glass, in which the value of α×β×(1-τ) is ≤2.0×10<SP>-12</SP>[K<SP>-1</SP>×nm×cm<SP>-1</SP>×Pa<SP>-1</SP>], is obtained by containing SiO<SB>2</SB>, B<SB>2</SB>O<SB>3</SB>and BaO as essential components and adjusting the ratio between the structural components, when an average linear expansion coefficient for -30 to +70°C is α, an opto-elastic constant at 546.1 nm wavelength is β and an internal transmittance (10 mm thickness) at 420 nm is τ, is realized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a glass having a refractive index (nd) of 1.60 to 1.67 and an Abbe number (νd) of 50 to 65, which hardly causes birefringence, and a lens obtained using the glass, With regard to optical elements such as prisms, they are particularly suitable for projection lenses and prisms of optical devices such as cameras and projectors that are used in environments exposed to high-intensity light and require high-precision imaging characteristics. The present invention relates to a glass material, an optical element and an optical device made from them.

  2. Description of the Related Art In recent years, digital devices and high-definition optical devices have been advanced, and high performance is required for optical elements used in image reproduction (projection) devices such as projectors and projection televisions as well as photographing devices such as digital cameras and video cameras. . The performance includes not only the characteristics required for glass materials, such as refractive index, Abbe number, and coloring degree, but also the small fluctuation in characteristics in the actual usage environment and the environmental impact during glass manufacturing and optical element processing. Small things are being included.

The reason why the imaging characteristics change in the actual use environment is that optical elements such as lenses and prisms are fixed with jigs in optical equipment, and the temperature change in the use environment (temperature change inside the housing, use at high temperatures) The thermal expansion of the optical element and the expansion coefficient differ from the fixture, resulting in stress on the optical element, resulting in birefringence in the optical element and changes in imaging characteristics. It is estimated that

In particular, when used in an environment exposed to high-intensity light, the optical element itself generates heat due to light absorption in addition to the temperature change of the usage environment, which increases the risk of further increasing birefringence due to thermal stress. .

As described above, if the imaging characteristics designed with optical constants such as refractive index and Abbe number acquired at a constant temperature (mainly about room temperature) are not realized in the actual usage environment, the usage environment is assumed at the time of optical design. However, there is a disadvantage that it must be designed by predicting complicated characteristic fluctuations.

Although the optical glass for projector-mounted prism and the optical glass for projector-mounted lens are disclosed in Patent Publications 1 and 2, the refractive index (nd) of the described examples is as low as less than 1.52, especially the lens. When the lens is used, the refractive power of light cannot be sufficiently obtained from the lens material. Therefore, the thickness of the lens must be increased, and the entire apparatus becomes large and heavy.

  When manufacturing prisms, glass is rarely used alone, and various optical thin films are applied. Especially for prisms having a polarization separation film, the refractive index (nd) of glass is greater than 1.60. Is an important parameter from the viewpoint of optical thin film design.

  Glass having a refractive index (nd) of 1.60 to 1.67 and an Abbe number (νd) of 50 to 65 is intended to increase the design flexibility of the optical thin film and the design freedom of the entire optical system. Since it is a useful region, many glass materials have been commercially available for a long time. However, it does not take into account fluctuations in imaging characteristics in an actual use environment, and cannot be said to sufficiently satisfy market requirements.

Special measures are taken to prevent the diffusion of pollutants into the atmosphere, soil and water quality when components containing high environmental loads such as lead (Pb) compounds and arsenic (As) compounds are used during optical glass manufacturing and optical element processing. There will be disadvantages such as necessity. In addition, using a large amount of rare mineral resources such as yttrium (Y), gadolinium (Gd), and ytterbium (Yb) not only increases the production cost, but also requires cost and labor for resource recovery. End up.

Various glass compositions having a refractive index (nd) of 1.60 to 1.67 and an Abbe number (νd) of 50 to 65, which do not contain a component having a high environmental load, are disclosed in Patent Documents 3 to 5. However, no consideration is given to fluctuations in imaging characteristics in an actual use environment. For example, a desired refractive index can be obtained by introducing a large amount of TiO ₂ component or Nb ₂ O ₅ component into glass. In the case where the Abbe number is realized, there is a disadvantage that the above-described undesirable light absorption occurs.

JP 2003-292339 A JP 2005-37651 A JP-A-10-212133 JP-A-11-157868 JP-A-56-73646

Under such circumstances, the present invention has a refractive index (nd) of 1.60 to 1.67, which is hardly affected by imaging characteristics even when used in an environment exposed to high intensity light, and An object of the present invention is to provide a glass having an Abbe number (νd) of 50 to 65 that hardly causes birefringence without using a large amount of a component having a high environmental load and a rare mineral resource.

As a result of intensive studies and studies to achieve the above-mentioned goal, the inventors have included SiO ₂ , B ₂ O ₃ , BaO as essential components and adjusted the ratio of the constituent components to obtain −30 When the average linear expansion coefficient at ˜ + 70 ° C. is represented by α, the photoelastic constant at a wavelength of 546.1 nm is represented by β, and the internal transmittance (420 mm thickness) at 420 nm is represented by τ, the formula α × β × (1-τ) A glass that realizes a value of 2.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less is produced without using a large amount of components and rare mineral resources that have a high environmental load, The inventors have found that the object can be achieved, and have made the present invention. The configuration is shown below.

(Configuration 1)
On an oxide basis, of SiO ₂ containing 25.0 to 45.0 _wt%, the B 2 _{O 3} containing 3.0 to 25.0 wt%, a BaO containing 30.0 to 60.0 wt% When the average linear expansion coefficient at −30 to + 70 ° C. is expressed as α, the photoelastic constant at a wavelength of 546.1 nm is expressed as β, and the internal transmittance (thickness of 10 mm) at 420 nm is expressed as τ, the calculation formula α × β × (1− A glass having a value of τ) of 2.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less.
(Configuration 2)
2. The glass according to Configuration 1, which has an optical constant having a refractive index (nd) of 1.60 to 1.67 and an Abbe number (νd) of 50 to 65.
(Configuration 3)
The glass according to Configuration 1 or 2, wherein the glass is expressed in mass% based on an oxide.
Li ₂ O 0~5.0%, and / or _Na 2 O _0~5.0%, and / or _K 2 O _0~5.0%, and / or _Cs 2 O _0~5.0%, and / or MgO 0 to 5.0%, and / or CaO 0 to 15.0%, and / or SrO 0 to 15.0%, and / or ZnO 0 to 10.0%, and / or _Al 2 _{O 3} 0 to 10.0%, and / or La ₂ O ₃ 0 to 12.0% and / or _Y 2 _O 3 from 0 to 15.0% and / or _Gd 2 _O 3 _0~25.0%, and / Or Lu ₂ O ₃ 0-5.0% and / or Yb ₂ O ₃ 0.0-5.0% and / or Sb ₂ O ₃ 0-2.0% and / or TiO ₂ 0 3.0%, and / or _ZrO 2 0 to 10.0%, and / or _SnO 2 0 to 3.0% and / or _TeO 2 0 to 3.0% and / or P O ₅ 0 to 5.0%, and / or _Ta 2 _O 5 _0~5.0%, and / or _Nb 2 _O 5 _0~5.0%, and / or _WO 3 0.0 to 5.0% And / or the total amount of F, expressed as a mass percentage of the mass of F atoms actually contained with respect to the mass of the oxide, is 0 to 3.0%. .
(Configuration 4)
It is glass as described in any one of the structures 1-3, Comprising: By the mass% display of an oxide basis,
TiO ₂ less than 0.0 to 1.0%, and / or _SnO 2 than 0.0 to 1.0%, and / or _Nb less than 2 _O 5 0.0 to 1.0%, and / or _Yb 2 O ₃ 0.0 to less than 1.0% and / or Bi ₂ O ₃ 0.0 to 1.0%,
A glass characterized by substantially not containing a lead compound such as PbO and an arsenic compound such as As ₂ O ₃ .
(Configuration 5)
Configuration A glass according to any one of 1 to 4, weight% ratio _{BaO / (SiO 2 + B 2} O 3 + Al 2 O 3) is less than 0.80 to 2.0, -30 When the average linear expansion coefficient at + 70 ° C. is α, the photoelastic constant at a wavelength of 546.1 nm is β, and the internal transmittance (420 mm thickness) at 420 nm is τ, the value of the formula α × β × (1−τ) Is 1.5 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less.
(Configuration 6)
A glass according to any one of configurations 1 to 5, mass% ratio _SiO 2 _/ B 2 _{O 3} in the oxide basis, less than 1.50 to 7.0, and fluorine (F ) Substantially free of glass.
(Configuration 7)
A glass according to any one of configurations 1 to 6, the glass, wherein the weight percent of the multiplication in the oxide basis _{(ZrO 2 × TiO 2 × ZnO} ) is zero.
(Configuration 8)
It is glass as described in any one of the structures 1-7, Comprising: In mass% notation of an oxide basis,
SiO ₂ 28.0-40.0%
B ₂ O ₃ 4.0-22.0%
BaO 40.0-55.0%
Al ₂ O ₃ exceeding 3.0% to 7.0%
Li ₂ O 0~2.0%, and / or _Na 2 O _0~2.0%, and / or _K 2 O _0~2.0%, and / or _Cs 2 O _0~2.0%, and MgO 0-2.0% and / or CaO 0-2.0% and / or SrO 0-2.0% and / or ZnO 0-2.0% and / or ZrO ₂ 0 less than 2.0%, and / or _Sb 2 _O 3 0 to 1.0%
However, the total amount of the alkali metal oxide (ΣR ₂ O) is 0.0 to 2.0%.
Glass containing respective components, wt% sum _{(SiO 2 + B 2 O 3} + BaO + Al 2 O 3) is, which is a 98.0 to 100.0% of.
(Configuration 9)
In mass% notation based on oxide,
SiO ₂ 30.0~38.0%
B ₂ O ₃ 5.0~20.0%
BaO 43.0-50.0%
Al ₂ O ₃ exceeding 3.0% to 7.0%
Na ₂ O 0-2.0% and / or K ₂ O 0-2.0% and / or CaO 0-2.0% and / or SrO 0-2.0% and / or ZnO 0 less than 2.0%, and / or _TiO 2 less than 0 to 1.0%, and / or _Sb 2 _O 3 0 to 1.0%
However, the total amount of Na ₂ O and K ₂ O is 0.0 to 2.0%.
MgO, Li ₂ O, ZrO ₂ , Nb ₂ O ₅ , WO ₃ , Gd ₂ O ₃ , La ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Ta ₂ O ₅ , Bi ₂ O ₃ , SnO ₂ , lead compounds such as PbO, arsenic compounds such as As ₂ O ₃ , and fluorine (F) are substantially not contained, and the mass% sum (SiO ₂ + B ₂ O ₃ + BaO + Al ₂ O3) is 90.0 to 100.0%, and the mass% ratio SiO ₂ / B ₂ O ₃ is 1.50 or more and less than 4.0, and the mass% ratio BaO / (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is 0.80 or more and less than 2.0, the average linear expansion coefficient of −30 to + 70 ° C. is α, the photoelastic constant is β at a wavelength of 546.1 nm, and the internal transmittance (thickness is 10 mm) at 420 nm is τ. When expressed by the formula α × β × (1-τ) There wherein the at ^{1.0 × 10 -12 [K -1 ×} nm × cm -1 × Pa -1] or less, the refractive index (nd) from 1.60 to 1.63, Abbe's number ([nu] d) Glass that is 56-62.
(Configuration 10)
Optical elements, such as lenses and prisms, using the glass of constitutions 1 to 9 as a base material.
(Configuration 11)
Optical elements, such as lenses and prisms, produced by reheat pressing the glass having structures 1 to 10.
(Configuration 12)
An optical device such as a camera / projector using an optical element and an optical substrate material made of the glass having configurations 1 to 11.

By adopting each of the above-mentioned configurations, glass that has a predetermined optical constant and is unlikely to cause birefringence is hardly affected by the imaging characteristics even when used in an environment exposed to high-intensity light. Can be provided without using a large amount of high components and rare mineral resources.

The glass of the present invention that hardly causes birefringence will be described.
The optical glass having the above-mentioned constitution 1 is expressed by a formula when an average linear expansion coefficient at −30 to + 70 ° C. is represented by α, a photoelastic constant at a wavelength of 546.1 nm is represented by β, and an internal transmittance (at a thickness of 10 mm) at 420 nm is represented by τ. The value of α × β × (1-τ) is 2.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less, and this α × β × (1− The index [tau] indicates the amount of change in imaging characteristics in a use environment exposed to high intensity light. More specifically, it means that the larger the average thermal expansion coefficient α, the larger the expansion coefficient (volume change) of the optical element with respect to the temperature change of the use environment. It means that a large thermal stress is generated in the element. In addition, the larger the photoelastic constant β, the greater the birefringence generated by the generated thermal stress. In addition, the larger (1-τ), the greater the light absorption when exposed to high-intensity light, and part of the absorbed light energy is converted into heat, so that the glass itself generates heat, and the jig A large thermal stress is generated in the optical element fixed by the. That is, it is suggested that the smaller the α × β × (1−τ) is, the smaller the change in imaging characteristics in the usage environment exposed to high intensity light. For optical applications such as lenses and prisms, the calculated value is preferably 2.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less, and 1.5 × 10 ^−12. It is more preferably [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less, and 1.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less. More preferred.

In order to realize the value of the glass calculation formula α × β × (1-τ) of 2.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less, the structure 1 is oxidized. in object reference, that the SiO ₂ containing 25.0 to 45.0 _wt%, the B 2 _{O 3} containing 3.0 to 25.0 wt%, containing BaO 30.0 to 60.0 wt% It is characterized by.
Explaining the individual components, the SiO ₂ component promotes stable glass formation, and has the effect of suppressing devitrification (generation of crystals) and striae (nonuniformity inside the glass), which are undesirable as optical glass. If it is contained excessively, the refractive index (nd) is decreased, the photoelastic constant β is remarkably increased, and it becomes difficult to obtain desired characteristics. Therefore, the upper limit is preferably 45.0% by mass, more preferably 40%. It is 0.0 mass% or less, Most preferably, it is 38.0 mass% or less, Preferably it is 25.0 mass% or more, More preferably, it is 28.0 mass% or more, Most preferably, it contains 30.0 mass% or more. The SiO ₂ component can be contained in any raw material form, but is preferably introduced in the form of an oxide (SiO ₂ ), K ₂ SiF ₆ , or Na ₂ SiF ₆ .
The B ₂ O ₃ component is an indispensable component for promoting stable glass formation like the SiO ₂ component and realizing a small average linear thermal expansion coefficient. However, if the amount is too small, it is difficult to obtain a stable glass. If the amount is too large, the refractive index (nd) decreases, the photoelastic constant β increases remarkably, and it becomes difficult to obtain desired characteristics. The upper limit is preferably 25.0% by mass, more preferably 22.0% by mass, most preferably 20.0% by mass, preferably 3.0% by mass, more preferably 4.0% by mass, and most preferably 5%. The lower limit is 0.0 mass%. The B ₂ O ₃ component can be contained in a raw material form such as H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ · 10H ₂ O, BPO _4, etc., but the form of H ₃ BO ₃ It is preferable to introduce by.
The BaO component is a glass-modifying component that has a particularly high effect of reducing the photoelastic constant β, and is indispensable for increasing the refractive index and realizing an appropriate Abbe number and achieving a high internal transmittance. Is an essential ingredient. However, if it is contained excessively, the content of SiO ₂ and B ₂ O ₃ is relatively reduced, and not only is it easily devitrified, but chemical durability is liable to deteriorate. Therefore, the upper limit is preferably 60.0% by mass, more preferably 55.0% by mass, and most preferably 50.0% by mass, preferably 30.0% by mass, more preferably 40.0% by mass. % By mass, most preferably 43.0% by mass is the lower limit. The BaO component can be introduced in various forms, but is preferably introduced in the form of carbonate (BaCO ₃ ) and / or nitrate (Ba (NO ₃ ) ₂ ).

  The glass of constitution 2 is characterized by having an optical constant having a refractive index (nd) of 1.60 to 1.67 and an Abbe number (νd) of 50 to 65. Useful for design.

By including the components in the range described in the glass of the configuration 3, the characteristics described in the configurations 1 and 2 can be stably realized. The reasons for limiting the individual components will be described.
Alkali metal oxide components (Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O) can be added arbitrarily because they have the effect of improving the meltability of the glass. If contained, the average thermal expansion coefficient α increases, the refractive index decreases, the glass becomes unstable, and undesirable phenomena such as devitrification are likely to occur. A range of 5.0% is preferable. A more preferred upper limit is 2.0% by mass for each component. The most preferable upper limit is that each component of Na ₂ O and K ₂ O is 1.0% by mass or less, and the Li ₂ O component and the Cs ₂ O component are not contained at all. Alkali metal oxide components include carbonate (Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Cs ₂ CO ₃ ), nitrate (LiNO ₃ , NaNO ₃ , KNO ₃ , CsNO ₃ ), fluoride (LiF , NaF, KF, KHF ₂ ), complex salts (Na ₂ SiF ₆ , K ₂ SiF ₆ ) and the like can be introduced in various forms, but it is preferable to introduce them in carbonates and / or nitrates.
Alkaline earth metal oxide components (MgO, CaO, SrO) excluding BaO can be added arbitrarily because the effect of adjusting the refractive index and the photoelastic constant of the glass can be obtained. Then, it becomes difficult to realize a desired optical constant (especially refractive index). In particular, since the MgO component significantly increases the photoelastic constant, 0.0 to 5.0% by mass, and the CaO and SrO components are in the range of 0. It is preferable to set it as the range of 0-15.0 mass%. A more preferable upper limit value is 5.0% by mass for each component. The most preferable upper limit value contains no MgO component, and the CaO and SrO components are 2.0% by mass. These alkaline earth metal oxide components are introduced in various forms such as carbonate (MgCO ₃ , CaCO ₃ ), nitrate (Sr (NO ₃ ) ₂ ), and fluoride (MgF ₂ , CaF ₂ , SrF ₂ ). Preferably, it is introduced in the form of carbonates and / or nitrates and / or fluorides.
While the ZnO component can improve the meltability of the glass while obtaining the effect of reducing the average thermal expansion coefficient α, it can be arbitrarily contained in the range of 0 to 10.0% by mass. When it is contained, it has the property of deteriorating the transmittance on the short wavelength side in the visible region and remarkably increasing the photoelastic constant β, making it difficult to achieve desired characteristics. The upper limit is more preferably 5.0% by mass, and most preferably less than 2.0% by mass. The ZnO component can be introduced in an arbitrary raw material form, but is preferably introduced in the form of oxide (ZnO) and / or fluoride (ZnF ₂ ).
The Al ₂ O ₃ component can be arbitrarily added because it has the effect of improving the chemical durability of the optical glass and the optical element, or improving the devitrification resistance of the molten glass. When contained, the refractive index is remarkably lowered and the photoelastic constant is increased. Therefore, the upper limit is preferably 10.0% by mass, more preferably 9.0% by mass, and most preferably 7.0% by mass. On the other hand, from the viewpoint of chemical durability, the lower limit is more preferably 1.0% by mass, and most preferably the content exceeds 3.0% by mass. The Al ₂ O ₃ component can be introduced in any raw material form, but is introduced in the form of an oxide (Al ₂ O ₃ ), a hydroxide (Al (OH) ₃ ), or a fluoride (AlF ₃ ). It is preferable.
The La ₂ O ₃ component is a glass-modifying component that has a high effect of reducing the photoelastic constant β, has the effect of increasing the refractive index, realizing an appropriate Abbe number, and realizing high internal transmittance. An optional ingredient that can be made. In order to realize the value of the desired calculation formula, it can be added arbitrarily. However, if it is contained excessively, the glass becomes unstable and devitrification is likely to occur. Unnecessary energy is required for melting. In addition, compared with the BaO component, which is a component that reduces the photoelastic constant β, the raw material price is high, so in order to realize a desired glass at a lower cost, preferably 12.0% by mass, More preferably, the upper limit is 6.0% by mass, and most preferably none is contained. The La ₂ O ₃ component can be contained in an arbitrary raw material form, but is preferably an oxide (La ₂ O ₃ ), nitrate and nitrate hydrate (La (NO ₃ ) ₃ .XH ₂ O (X is It is preferably introduced in the form of an arbitrary integer)).
The Y ₂ O ₃ component is an optional component having an effect of adjusting the refractive index and dispersion. However, when it is contained in a large amount, not only the devitrification property is deteriorated but also a rare mineral resource. Manufacturing cost will be high. The upper limit is preferably 15% by mass, more preferably 6.0% by mass, and most preferably none. The Y ₂ O ₃ component can be introduced in an arbitrary raw material form, but is preferably introduced in the form of oxide (Y ₂ O ₃ ) or fluoride (YF ₃ ).
Similar to the Y ₂ O ₃ component, the Gd ₂ O ₃ component is an optional component that has the effect of increasing the refractive index and reducing the dispersion and maintaining the photoelastic constant small. However, if it is contained excessively, not only devitrification is likely to occur, but since it is a rare mineral resource, if it is contained in a large amount, the production cost becomes high. Therefore, the upper limit is preferably 25.0% by mass, more preferably 10.0% by mass, and most preferably none at all. The Gd ₂ O ₃ component can be introduced in an arbitrary raw material form, but is preferably introduced in the form of an oxide (Gd ₂ O ₃ ) or a fluoride (GdF ₃ ).
The Lu ₂ O ₃ component has an effect of realizing a high refractive index and low dispersion in the same manner as the La ₂ O ₃ , Gd ₂ O ₃ , and Y ₂ O ₃ components. However, since it is a rare mineral resource, it is not preferable to contain it excessively. A more preferable upper limit value is 3.0% by mass, and most preferably, no upper limit value is contained. The Lu ₂ O ₃ component can be introduced in an arbitrary raw material form, but is preferably introduced as an oxide (Lu ₂ O ₃ ).
The Yb ₂ O ₃ component can be arbitrarily added in the range of 0.0 to 5.0% by mass for adjusting the refractive index, but has the property of increasing the photoelastic constant β, so the upper limit is 5.0 mass% is preferable. However, since this component is also a rare mineral resource, if it is contained in a large amount, the production cost becomes high. Therefore, a more preferable upper limit value is less than 1.0% by mass, and most preferably it is not contained at all. This component can be introduced in any raw material form, but is preferably introduced in the form of an oxide (Yb ₂ O ₃ ).
Since the effect as a defoaming material for glass is obtained, the Sb ₂ O ₃ component can be arbitrarily contained in the range of 0 to 2.0% by mass. Not only the internal transmittance of visible wavelength and short wavelength is remarkably deteriorated, it becomes difficult to realize desired characteristics (calculation formula = 2.0 or less), but excessive foaming occurs during glass melting, melting equipment (especially Pt, etc.) There is a risk of alloying with noble metals. Therefore, it is preferably 2.0% by mass or less, and more preferably 1.0% or less. The Sb ₂ O ₃ component can be introduced in any raw material form, but is introduced in the form of an oxide (Sb ₂ O ₃ , Sb ₂ O ₅ ) or Na ₂ H ₂ Sb ₂ O ₇ · 5H ₂ O. It is preferable.
TiO ₂ component is an optional component that improves chemical durability, suppresses solarization, and can be optionally added to adjust the refractive index and Abbe number. In particular, and the internal transmittance of visible short wavelengths (500 nm or less) tends to deteriorate. Therefore, a preferable upper limit is 3.0% by mass, a more preferable upper limit is 2.0% by mass, and a most preferable upper limit is less than 1.0% by mass. The TiO ₂ component can be introduced in any raw material form, but is preferably introduced in the form of an oxide (TiO ₂ ).
The ZrO ₂ component is an optional component that has the effect of increasing the refractive index (nd) and improving the devitrification resistance. However, since this component is a hardly fusible component, if it is contained excessively, it is hot during glass production. Therefore, energy loss becomes a problem. On the other hand, the effect of suppressing devitrification may be obtained by adding a predetermined amount. As a result of these considerations, the upper limit is preferably 10.0% by mass, more preferably 5.0% by mass, and most preferably less than 2.0% by mass. The ZrO ₂ component can be introduced in an arbitrary raw material form, but is preferably introduced in the form of an oxide (ZrO ₂ ) and a fluoride (ZrF ₄ ).
The SnO ₂ component is an optional component that can be arbitrarily contained because the effect of preventing the oxidation of the molten glass, the clarification effect, and the deterioration of the transmittance with respect to light irradiation can be obtained, but if contained excessively, There is a risk of coloring the glass by reduction, and there is a risk of alloying with melting equipment (especially noble metals such as Pt). Therefore, the upper limit is preferably 3.0% by mass, more preferably 2.0% by mass, and most preferably less than 1.0% by mass. The SnO ₂ component can be introduced in an arbitrary raw material form, but is preferably introduced in the form of an oxide (SnO, SnO ₂ ) or a fluoride (SnF ₂ , SnF ₄ ).
TeO ₂ component is an optional component that can be arbitrarily contained in the range of 0 to 3.0% by mass because an effect of promoting the clarification action at the time of glass melting is obtained. Coloring on the glass becomes remarkable, and the internal transmittance deteriorates. A more preferable upper limit value is 1.5% by mass, and most preferably no inclusion. The TeO ₂ component can be introduced in any raw material form, but is preferably introduced as an oxide (TeO ₂ ).
The P ₂ O ₅ component can be arbitrarily contained since the effect of improving the meltability of the glass is obtained. However, if it is excessively contained, the devitrification resistance of the glass is remarkably deteriorated, and devitrification is caused. This is not preferable because it is difficult to obtain an optical glass free of glass. Accordingly, the upper limit is preferably 5.0% by mass, more preferably 1.0% by mass, and most preferably none. The P ₂ O ₅ component can be introduced in any raw material form, but is in the form of Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ . It is preferable to introduce.
The Ta ₂ O ₅ component can be arbitrarily added because it has the effect of increasing the refractive index and stabilizing the glass. However, the Ta ₂ O ₅ component is a rare mineral resource, has a high raw material price, is a difficult-to-melt component, and is forced to melt at high temperature during glass production, which not only increases the production cost but also increases the photoelastic constant β. The upper limit of the content is preferably 5.0% by mass because it has the property of significantly increasing. A more preferable upper limit value is 3.0% by mass, and most preferably, it is not contained at all. The Ta ₂ O ₅ component can be introduced in an arbitrary raw material form, but is preferably introduced in the form of an oxide (Ta ₂ O ₅ ).
The Nb ₂ O ₅ and WO ₃ components have the effect of increasing the refractive index and increasing the dispersion, and the effect of improving the chemical durability is obtained. Therefore, the Nb ₂ O ₅ and WO ₃ components are optionally contained in the range of 0 to 5.0% by mass. Is possible. However, both components have a tendency to deteriorate the internal transmittance particularly in the visible short wavelength (500 nm or less) and have a property of remarkably increasing the photoelastic constant β. Therefore, the upper limit of the content is 5.0% by mass, respectively. Is preferred. A more preferable upper limit value is less than 1.0% by mass, and most preferably no inclusion. Nb ₂ O ₅ and the WO ₃ component can be introduced in any raw material form, but are preferably introduced in the form of an oxide (Nb ₂ O ₅ , WO ₃ component).
The F component has an effect of increasing the Abbe number, an effect of reducing the photoelastic constant β, and an effect of improving the internal transmittance of the visible region short wavelength, and thus is arbitrarily contained in the range of 0 to 3.0% by mass. However, when the content exceeds the upper limit, not only the refractive index is lowered and the average linear thermal expansion coefficient α may be increased, but also a substrate defect such as striae tends to occur. A more preferable upper limit value is 1.0% by mass, and most preferably, it is not contained at all. In the introduction of the various oxides described above, the F component is introduced into the glass when the raw material form is introduced with fluoride.
It should be noted that the content of each component used in the present specification is expressed by the fact that oxides, composite salts, metal fluorides, etc. used as raw materials for the glass constituents of the present invention are all decomposed during melting into oxides. In the case of fluoride, the mass percentage of the F oxide actually contained with respect to the mass of the generated oxide is expressed as a mass percentage. It is what was expressed in.

Each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, excluding Ti, is colored even when contained in a small amount by combining them individually or in combination. In order to cause absorption at the wavelength of the optical glass, it is preferable that the optical glass using the wavelength in the visible region does not substantially contain. Furthermore, each component of Pb, Th, Cd, Tl, As, Os, Be, and Se has tended to be refrained from being used as a harmful chemical material in recent years. Therefore, it is preferable not to include it substantially when the environmental impact is important.

In the glass of the constitution 4, each component of TiO ₂ , SnO ₂ , Nb ₂ O ₅ , and Bi ₂ O ₃ is 0.0 to 1 from the concern of coloring of the glass and deterioration of internal transmittance in the visible region short wavelength, respectively. A range of less than 0.0% by mass is particularly preferable. Further _Yb 2 _{O 3} component, from the viewpoint of avoiding mass consumption of scarce mineral resources, in the range of less than 0.0 to 1.0 wt%.
A lead compound such as PbO and an arsenic compound such as As ₂ O ₃ are components that have a high environmental load, and thus are not substantially contained. In the present specification, “substantially does not contain” means that it is not contained except for unavoidable contamination such as contamination by impurities.

In the optical glass having the above-described constitution 5, in order to use it for an optical element for higher-precision and high-definition applications, the value of the glass calculation formula α × β × (1-τ) is 1.5 × 10 ⁻¹² [ it is preferred ^{K -1 × nm × cm -1 ×} Pa -1] or less.
In order to realize the numerical value of the above calculation formula, the mass% ratio BaO / (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is preferably 0.80 or more and less than 2.0.
Here, BaO of the molecule is the total of components that can reduce the photoelastic constant and increase the short wavelength internal transmittance in the visible region among the glass constituent components. One denominator (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is a component that has the effect of promoting stable glass formation and reducing the average thermal expansion coefficient among the glass components, but has a significant photoelastic constant. This is the sum of ingredients to be increased. Therefore, if this mass% ratio is too large, the glass becomes unstable, and undesirable phenomena such as defects such as devitrification and deterioration of chemical durability occur. On the other hand, if this mass% ratio is too small, The elastic constant is remarkably increased, and it becomes difficult to realize a desired calculation formula value. That is, by adjusting these ratios within a certain range, a glass having a value of a desired calculation formula can be stably obtained. A more preferred range is 0.805 to 1.80, most preferably 0.810 to 1.50.

The optical glass of Structure 6 is characterized in that the mass% ratio SiO ₂ / B ₂ O _{3 on} an oxide basis is 1.50 or more and less than 7.0 and substantially does not contain fluorine (F). To do. By setting the mass% ratio SiO ₂ / B ₂ O ₃ to 1.50 or more, an important index for obtaining the effect of increasing the meltability of the raw material and the stability of the glass while appropriately maintaining the chemical durability. However, if this value becomes too large, unmelted (mainly, hardly fusible crystals containing SiO ₂ ) are generated at the time of melting the glass, the productivity is deteriorated, and the internal quality may be adversely affected. Accordingly, the lower limit is preferably 1.50, more preferably 1.55, and most preferably 1.60, preferably less than 7.0, more preferably 5.50 or less, and most preferably less than 4.00. contains.
Further, fluorine (F) is not only disadvantageous but also an expensive raw material, so it is preferable not to contain it substantially.

In the optical glass of Configuration 7, the value of the calculation formula α × β × (1-τ) stably realizes 1.5 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less. Therefore, the multiplication by mass% (ZrO ₂ × TiO ₂ × ZnO) is 0. The coexistence of ZrO ₂ , TiO ₂ , and ZnO (that is, multiplication by mass% (ZrO ₂ × TiO ₂ × ZnO) is not 0) particularly tends to deteriorate the internal transmittance of the visible region short wavelength. By containing ZrO ₂ , glass melting at high temperature is unavoidable, and it is considered that the internal transmittance deteriorates due to elution of platinum group ions due to the reaction of the melting equipment formed of ZnO and the platinum group. As described above, in the TiO ₂ component, Ti ions themselves have absorption at a short wavelength in the visible region. Therefore, it is not preferable that ZrO ₂ , TiO ₂ , and ZnO coexist.

The glass having the characteristics described in Structures 1 to 7 can be stably realized by incorporating the components in the ranges described in the glass of Structure 8. The reasons for limiting the individual components are as described above.
The essential components are SiO ₂ , B ₂ O ₃ , BaO, Al ₂ O ₃ , and the mass% sum (SiO ₂ + B ₂ O ₃ + BaO + Al ₂ O ₃ ) of the essential components is 98.0 to 100.0%. Preferably there is. These essential components can be introduced using relatively inexpensive raw materials, and by limiting the constituent components of the glass, it is possible to reduce the weighing work at the time of production and to reduce the production cost.
The total amount of the alkali metal oxide (ΣR ₂ O) is preferably 0.0 to 2.0%. When this total amount exceeds 2.0% by mass, not only the chemical durability is deteriorated, but also the average thermal expansion coefficient is increased, so that the calculation formula = 1.5 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less is difficult to achieve, which is not preferable.

Configuration 9 is the glass that hardly causes birefringence described in the above configurations 1 to 7, α is an average linear expansion coefficient of −30 to + 70 ° C., β is a photoelastic constant at a wavelength of 546.1 nm, and internal transmission is 420 nm. When the rate (10 mm thickness) is represented by τ, the value of the calculation formula α × β × (1-τ) is 1.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less. This is the most suitable configuration for inexpensively and stably producing glass having a refractive index (nd) of 1.60 to 1.63 and an Abbe number (νd) of 56 to 62.
In the present configuration, the value of the equation in order to achieve a ^{1.0 × 10 -12 [K -1 ×} nm × cm -1 × Pa -1] or less, an effect to increase the photoelastic constant The upper limit of SiO ₂ is 38.0% by mass, and the lower limit of the BaO component that achieves high internal transmittance while reducing the photoelastic constant while realizing appropriate optical constants (refractive index and Abbe number). In order to achieve an appropriate average thermal expansion coefficient, the Li ₂ O component is not substantially contained, and the upper limit of the Na ₂ O and K ₂ O components is 2.0 masses respectively. %, The upper limit of the total amount of Na ₂ O and K ₂ O components is 2.0% by mass, the upper limit of ZnO is less than 2.0%, and TiO ₂ in order to realize high internal transmittance. the upper limit of the content of less than 1.0 wt%, _La 2 O is hardly molten component And it contains substantially no ZrO ₂ component, and expensive raw materials (for example, fluorides and rare earth _{oxide, Y 2 O 3, Yb 2} O 3, etc. _Ta 2 _{O 5)} not used.
Further, the mass% ratio SiO ₂ / B ₂ O ₃ was limited to a range of 1.50 to less than 4.00.

As described in Structures 10-12, the optical glass described in Structures 1-9 is useful as a base material for producing optical elements such as lenses and prisms, and the optical elements are used in cameras and projectors. As a result, high-definition and high-precision imaging and projection characteristics can be realized.

As a representative example of a method for producing a lens or a prism using the glass of the present invention as a base material, reheat press processing has been given as the configuration 11, but the present invention is not limited to this method. For example, techniques such as mold press processing It is possible to produce an optical element using

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.

  Tables 1 to 5 show that the refractive index (nd) is 1.60 to 1.67, and the Abbe number (νd) is not easily affected by the imaging characteristics even when used in an environment exposed to high-intensity light. ) Is a glass composition of preferred examples (Nos. 1 to 23), an average linear thermal expansion coefficient α of −30 to + 70 ° C., and a wavelength of 546.1 nm. Photoelastic constant β, internal transmittance at 420 nm (10 mm thickness) τ, calculation formula α × β × (1-τ), refractive index (nd), Abbe number (νd), ratio and content of various component contents Indicates the rate sum.

Table 6 shows the glass compositions and various physical property values of comparative examples (No. A and B) of known optical glasses. Here, Comparative Example A is Example 5 of JP-A-10-212133, and Comparative Example B is Example 13 of JP-A-11-157868. The refractive index (nd) and Abbe number (νd) in the table are the values described in the respective publications.

About the obtained optical glass, an average linear thermal expansion coefficient (α) of −30 to + 70 ° C., a photoelastic constant (β) at a wavelength of 546.1 nm, an internal transmittance (10 mm thickness) (τ) at 420 nm, a refractive index ( nd) and Abbe number (νd) were measured as follows.

(1) Average linear thermal expansion coefficient (α) of −30 to + 70 ° C. [10 ⁻⁷ K ⁻¹ ]
According to the method described in Japan Optical Glass Industry Association standard JOGIS08- ²⁰⁰³ (method of measuring the thermal expansion of optical glass), it was measured. Here, the evaluation temperature range was −30 to + 70 ° C., and a sample having a length of 50 mm and a diameter of 4 mm was used as a test piece.
(2) Photoelastic constant (β) [10 ⁻⁵ nm · cm ⁻¹ · Pa ⁻¹ ] at a wavelength of 546.1 nm
The photoelastic constant (β) is a disk shape having a diameter of 25 mm and a thickness of 8 mm, the sample shape being face-polished, a compressive load is applied in a predetermined direction, and the optical path difference generated at the center of the glass is measured. Δ = β × d It calculated | required with the relational expression of * F. An ultra-high pressure mercury lamp was used as the 546.1 nm measurement light source. In the above formula, the optical path difference is expressed as δ (nm), the glass thickness as d (cm), and the stress as F (Pa).
(3) Internal transmittance at 420 nm (10 mm thickness) (τ)
According to the method described in Japan Optical Glass Industry Society Standard JOGIS17- ¹⁹⁸² (method of measuring the internal transmittance of the optical glass) were measured.
(4) Refractive index (nd) and Abbe number (νd)
It measured about the optical glass obtained by making slow cooling temperature-fall rate -25 degreeC / hour.

The glasses of the examples of the present invention described in Tables 1 to 5 are all oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphate compounds and the like corresponding to the raw materials of the respective components. After weighing and mixing at a predetermined ratio using ordinary optical glass raw materials, it is put into a platinum crucible and melted in a temperature range of 1100 to 1350 ° C. for 3 to 4 hours in an electric furnace according to the melting difficulty of the glass composition. After stirring and homogenizing, the temperature was lowered to an appropriate temperature, and then cast into a mold and gradually cooled.

As shown in Tables 1 to 5, it has been found that all of the preferred embodiments of the present invention can realize the desired optical constant, the calculation formula α × β × (1−τ). On the other hand, in the comparative example shown in Table X, since Comparative Example A contains a large amount of ZnO, it has a large photoelastic constant, and additionally contains 1.0% by mass or more of TiO _2. Since the multiplication by mass% (ZrO ₂ × TiO ₂ × ZnO) is not 0, the internal transmittance τ is low. As a result, the value of the calculation formula is 3.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ^{− 1} × Pa ⁻¹ ] or more, which is very large. In Comparative Example B, the ZnO content is relatively small, but the multiplication by mass% (ZrO ₂ × TiO ₂ × ZnO) is not 0, the internal transmittance τ is low, and the value of the calculation formula is 2.0. × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less could not be realized.

  Moreover, when the glass of the Example described in Tables 1-5 was cold-worked or reheat press-processed, problems, such as devitrification, did not arise, but it was able to be stably processed into various lenses and prism shapes. Moreover, when the precision mold press molding process was implemented about the glass of the Example whose glass softening temperature is comparatively low, it was possible to acquire a favorable lens.

  The lenses and prisms manufactured as described above were mounted on cameras and projectors, and the imaging characteristics were confirmed. The imaging characteristics expected for optical design using optical constants acquired at room temperature were high-intensity light. It was confirmed that it can be reproduced even in an environment exposed to the environment and at high temperature (about 50 to 70 ° C.) operation.

Although the present invention has been described in detail for the purpose of illustration, this embodiment is only for the purpose of illustration, and many modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention. Will be understood.

According to the present invention, the refractive index (nd) is 1.60 to 1.67 and the Abbe number (νd) is hardly affected by the imaging characteristics even when used in an environment exposed to high-intensity light. A glass with a birefringence of 50 to 65 can be provided. By using this optical glass, lenses and prisms of imaging devices such as high-precision cameras and image projection (reproduction) devices such as projectors can be stably created. it can.

Claims (12)

On an oxide basis, of SiO ₂ containing 25.0 to 45.0 _wt%, the B 2 _{O 3} containing 3.0 to 25.0 wt%, a BaO containing 30.0 to 60.0 wt% When the average linear expansion coefficient at −30 to + 70 ° C. is expressed as α, the photoelastic constant at a wavelength of 546.1 nm is expressed as β, and the internal transmittance (thickness of 10 mm) at 420 nm is expressed as τ, the calculation formula α × β × (1− A glass having a value of τ) of 2.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less. The glass according to claim 1, wherein the glass has an optical constant having a refractive index (nd) of 1.60 to 1.67 and an Abbe number (νd) of 50 to 65. The glass according to claim 1 or 2, wherein the glass is expressed in mass% based on oxide.
Li ₂ O 0~5.0%, and / or _Na 2 O _0~5.0%, and / or _K 2 O _0~5.0%, and / or _Cs 2 O _0~5.0%, and / or MgO 0 to 5.0%, and / or CaO 0 to 15.0%, and / or SrO 0 to 15.0%, and / or ZnO 0 to 10.0%, and / or _Al 2 _{O 3} 0 to 10.0%, and / or La ₂ O ₃ 0 to 12.0% and / or _Y 2 _O 3 from 0 to 15.0% and / or _Gd 2 _O 3 _0~25.0%, and / Or Lu ₂ O ₃ 0-5.0% and / or Yb ₂ O ₃ 0.0-5.0% and / or Sb ₂ O ₃ 0-2.0% and / or TiO ₂ 0 3.0%, and / or _ZrO 2 0 to 10.0%, and / or _SnO 2 0 to 3.0% and / or _TeO 2 0 to 3.0% and / or P O ₅ 0 to 5.0%, and / or _Ta 2 _O 5 _0~5.0%, and / or _Nb 2 _O 5 _0~5.0%, and / or _WO 3 0.0 to 5.0% And / or the total amount of F, expressed as a mass percentage of the mass of F atoms actually contained with respect to the mass of the oxide, is 0 to 3.0%. . It is glass as described in any one of Claims 1-3, Comprising: By the mass% display of an oxide basis,
TiO ₂ less than 0.0 to 1.0%, and / or _SnO 2 than 0.0 to 1.0%, and / or _Nb less than 2 _O 5 0.0 to 1.0%, and / or _Yb 2 O ₃ 0.0 to less than 1.0% and / or Bi ₂ O ₃ 0.0 to 1.0%,
A glass characterized by substantially not containing a lead compound such as PbO and an arsenic compound such as As ₂ O ₃ . A glass according to any one of claims 1 to 4, weight% ratio _{BaO / (SiO 2 + B 2} O 3 + Al 2 O 3) is less than 0.80 to 2.0, -30 When the average linear expansion coefficient at ˜ + 70 ° C. is represented by α, the photoelastic constant at a wavelength of 546.1 nm is represented by β, and the internal transmittance (420 mm thickness) at 420 nm is represented by τ, the formula α × β × (1-τ) A glass having a value of 1.5 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less. A glass according to any one of claims 1 to 5, mass% ratio _SiO 2 _/ B 2 _{O 3} in the oxide basis, less than 1.50 to 7.0, and fluorine ( Glass substantially free of F). A glass according to any one of claims 1 to 6, the glass, wherein the weight percent of the multiplication in the oxide basis _{(ZrO 2 × TiO 2 × ZnO} ) is zero. It is the glass according to any one of claims 1 to 7, and is expressed in mass% based on an oxide.
SiO ₂ 28.0-40.0%
B ₂ O ₃ 4.0-22.0%
BaO 40.0-55.0%
Al ₂ O ₃ exceeding 3.0% to 7.0%
Li ₂ O 0~2.0%, and / or _Na 2 O _0~2.0%, and / or _K 2 O _0~2.0%, and / or _Cs 2 O _0~2.0%, and MgO 0-2.0% and / or CaO 0-2.0% and / or SrO 0-2.0% and / or ZnO 0-2.0% and / or ZrO ₂ 0 less than 2.0%, and / or _Sb 2 _O 3 0 to 1.0%
However, the total amount of the alkali metal oxide (ΣR ₂ O) is 0.0 to 2.0%.
Glass containing respective components, wt% sum _{(SiO 2 + B 2 O 3} + BaO + Al 2 O 3) is, which is a 98.0 to 100.0% of. In mass% notation based on oxide,
SiO ₂ 30.0~38.0%
B ₂ O ₃ 5.0~20.0%
BaO 43.0-50.0%
Al ₂ O ₃ exceeding 3.0% to 7.0%
Na ₂ O 0-2.0% and / or K ₂ O 0-2.0% and / or CaO 0-2.0% and / or SrO 0-2.0% and / or ZnO 0 less than 2.0%, and / or _TiO 2 less than 0 to 1.0%, and / or _Sb 2 _O 3 0 to 1.0%
However, the total amount of Na ₂ O and K ₂ O is 0.0 to 2.0%.
MgO, Li ₂ O, ZrO ₂ , Nb ₂ O ₅ , WO ₃ , Gd ₂ O ₃ , La ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Ta ₂ O ₅ , Bi ₂ O ₃ , SnO ₂ , lead compounds such as PbO, arsenic compounds such as As ₂ O ₃ , and fluorine (F) are substantially not contained, and the mass% sum (SiO ₂ + B ₂ O ₃ + BaO + Al ₂ O ₃ ) Is 98.0 to 100.0%, the mass% ratio SiO ₂ / B ₂ O ₃ is 1.50 or more and less than 4.0, and the mass% ratio BaO / (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is 0.80 or more and less than 2.0, an average linear expansion coefficient of −30 to + 70 ° C. is α, a photoelastic constant is β at a wavelength of 546.1 nm, and an internal transmittance (thickness is 10 mm) at 420 nm. When expressed by τ, the formula α × β × (1-τ) Refractive index (nd) 1.60 to 1.63, Abbe number (νd), characterized in that the value is 1.0 × 10 ⁻¹² [K ⁻¹ × nm × cm ⁻¹ × Pa ⁻¹ ] or less. ) 56-62 glass. An optical element such as a lens or a prism using the glass according to claim 1 as a base material. An optical element such as a lens / prism produced by reheat pressing the glass of claim 1. An optical device such as a camera / projector using the optical element and the optical substrate material made of the glass according to claim 1.