TW201922655A - Optical glass and optical element having small variation in optical characteristics due to temperature change in addition to small specific gravity - Google Patents

Abstract

This invention provides an optical glass and an optical element, wherein the optical glass is a fluorophosphate glass having anomalous partial dispersion, and has a small specific gravity, in addition, it has little variation in optical characteristics due to temperature change, and is excellent in washing resistance, has higher refractive index and low dispersion, and is heat-resistant. An optical glass, which is a fluorophosphate glass having a specific gravity of 3.3 or less, provided in the present invention satisfies one or more of (a) to (d). (a) The temperature coefficient dn/dT of the relative refractive index at the wavelength (633 nm) of the He-Ne laser is in the range of 0±5.0*10<SP>6</SP> DEG C<SP>-1</SP> in the range of 20 to 40 DEG C. (b) The weight loss amount DSTPP per 1 cm2 of the glass surface when immersed in a 0.01 mol/L sodium tripolyphosphate Na5P3O10 aqueous solution for 1 hour is 0.4 mg/cm2·h or less. (c) The refractive index nd and the Abbe number [nu]d satisfy the following relational expression (1). (d) Glass transition temperature Tg is 360 DEG C or more.

Description

Optical glass and optical components

The present invention relates to an optical glass formed of a fluorophosphate glass having a high degree of dispersibility and an optical element formed of the optical glass.

In recent years, weight reduction of optical elements such as lenses has been demanded. In particular, in aerial photography using a small remote operation machine such as a drone, an optical element that is not only lightweight but also has optical characteristics such as a refractive index that does not change according to temperature changes is required.

Further, in the production of glass, the surface of the glass is corroded by the cleaning liquid in the cleaning step, and thus an optical glass excellent in washing resistance is required.

Further, in the correction of the chromatic aberration, an optical element made of an optical glass having a higher refractive index and a lower dispersion property is useful.

Further, in the production of optical glass, when the melting temperature of the glass is too high, the manufacturing cost becomes high, and the moldability of the glass also deteriorates. On the other hand, an antireflection film, a total reflection film, or the like can be coated on the optical functional surface of the optical element according to the purpose of use, but in the coating step, the coating agent is heated to approximately 350 ° C to be applied to the optical element. Therefore, heat resistance is required for the optical glass.

Patent Document 1 discloses a fluorophosphate glass having a small temperature change in refractive index. Specifically, an optical glass formed of a fluorophosphate glass having a relative refractive index (dn/dT) of from -4.3 to -4.4 at 20 to 40 ° C is disclosed. The relative refractive index referred to herein means the refractive index of the glass with respect to air.
However, the optical glass disclosed in Patent Document 1 has a large specific gravity and does not satisfy the level of weight reduction required in recent years.

Patent Document 2 discloses an optical glass formed of a fluorophosphate glass whose specific gravity is lowered.
It is understood that the optical glass disclosed in Patent Document 2 is inferior in cleaning resistance. Further, in the optical glass disclosed in Patent Document 2, when the refractive index satisfies the condition, the dispersion is extremely large, and an optical glass having high refractive index and low dispersion which is more suitable for correction of chromatic aberration is required. Further, the optical glass disclosed in Patent Document 2 has a low glass transition temperature Tg, and in the coating step, the optical functional surface is deformed or deteriorated by heat.
[Previous Technical Literature]
[Patent Literature]

Patent Document 1: Japanese Patent Application No. 2014-156394, Patent Document 2: International Publication No. 2003/037813

[Problems to be solved by the invention]

The present invention has been made in view of such circumstances, and an object thereof is to provide an optical glass and an optical element which are fluorophosphate glasses having an abnormal partial dispersibility and which have a characteristic of having a small specific gravity, and have other characteristics. Various characteristics such as small variation in optical characteristics due to temperature change, excellent washing durability, higher refraction and low dispersion, and excellent heat resistance.
[means to solve the problem]

The main contents of the present invention are as follows

[1] An optical glass having a specific gravity of 3.3 or less and satisfying one or more of (a) to (d).
(a) The temperature coefficient dn/dT of the relative refractive index of the He-Ne laser wavelength (633 nm) is in the range of 20 to 40 ° C and is within 0 ± 5.0 × 10 ^-6 ° C ^-1 .
(b) The weight loss amount D _STPP per 1 cm ² of the glass surface when immersed in a 0.01 mol/L sodium tripolyphosphate Na ₅ P ₃ O ₁₀ aqueous solution for 1 hour was 0.4 mg/cm ² ‧ h or less.
(c) The refractive index nd and the Abbe number νd satisfy the following relational expression (1).
Nd+0.00250×νd-1.69000≧0‧‧‧(1)
(d) The glass transition temperature Tg is 360 ° C or higher.

[2] The optical glass according to [1], wherein the Ba ²⁺ content is 10 cationic % or less.

[3] The optical glass according to [1] or [2] wherein, in the cation % representation, the total content of Mg ²⁺ and Ca ²⁺ is relative to Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba The cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] of the total content of ²⁺ and Zn ²⁺ is 0.40 or more.

[4] An optical glass comprising one or more ions selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn One or more ions, P ⁵⁺ and Al ³⁺ in the group consisting of ²⁺ are used as a cationic component,
The content of Ba ²⁺ is 10 cationic % or less,
In the cation % representation, the cation ratio [R' of the total content R' of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ with respect to the total content R of Li ⁺ , Na ⁺ and K ⁺ /R] is 0.6 or more,
The cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] of the total content of Mg ²⁺ and Ca ²⁺ to the total content R' is 0.40 or more,
The ratio of the total content of Li ⁺ and Na ⁺ to the cation ratio [(Li ⁺ +Na ⁺ ) / R] of the total content R is 0.8 or more.
As an anionic component, it contains O ^2- ,
The content of F ^- is 10 to 40 anionic %.

[5] The optical glass according to [4], wherein
The content of P ⁵⁺ is 30 to 50 cationic %,
The content of Al ³⁺ is 5 to 15 cationic %,
The content of Na ⁺ is 10 to 30 cationic %.

[6] The optical glass according to any one of [1] to [5] wherein a transmittance of a wavelength of 500 to 700 nm is 90% or more.

[7] An optical element formed of the optical glass according to any one of the above [1] to [6].
[Effects of invention]

According to the present invention, it is possible to provide an optical glass and an optical element which have a characteristic of having a small specific gravity, and having a small specific gravity, and having a small variation in optical characteristics due to a temperature change. It has various characteristics such as excellent washing durability, higher refraction and low dispersion, and excellent heat resistance.

Hereinafter, embodiments of the present invention will be described. In the present embodiment, the optical glass of the present invention will be described based on the content ratio of each component represented by the cation %. Therefore, in the following, each content is represented by a cation % unless otherwise specified.

In the present specification, the refractive index means the refractive index nd of the d-line (wavelength: 587.56 nm) of yttrium unless otherwise specified.

The Abbe number νd is used as a value indicating the property of the dispersion, and is represented by the following formula. Here, nF is a refractive index of an F-line (wavelength: 486.13 nm) of blue hydrogen, and nC is a refractive index of a C-line (wavelength of 656.27 nm) of red hydrogen.
Νd=(nd-1)/(nF-nC)

The cation % refers to the percentage of mole when the total content of all the cationic components is 100%. In addition, the total content means the total amount of the content of various cationic components (including the case where the content is 0%). Further, the cation ratio means a ratio (ratio) of the content of cationic components (including the total content of a plurality of cation components).

In addition, the anion % refers to the percentage of mole when the total content of all the anion components is 100%.

The valence of the cationic component (for example, the valence of B ³⁺ is +3, the valence of Si ⁴⁺ is +4, and the valence of La ³⁺ is +3) is a value determined by convention and expressed on the basis of oxides. B, Si, and La which are glass components are expressed as B ₂ O ₃ , SiO ₂ , and La ₂ O ₃ . Therefore, when analyzing the glass composition, the valence of the cationic component may not be analyzed. Further, the valence of the anion component (for example, the valence of O ^2- is -2) is also a value determined by a conventional formula, and as described above, the glass component based on the oxide is expressed as, for example, B ₂ O ₃ , SiO ₂ , La _{2 .} O _{3 is the} same. Therefore, when analyzing the glass composition, the valence of the anion component may not be analyzed.

The content of the glass component can be quantified by a known method such as inductively coupled plasma atomic emission spectrometry (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS). Further, in the present specification and the present invention, the content of the constituent component of 0% means that the constituent component is not substantially contained, and the component is allowed to be contained to the extent of unavoidable impurities.

In the first embodiment, the optical glass of the present invention will be described based on the physical property value. The optical glass of the present invention will be described based on the glass composition as the second embodiment.

[First Embodiment]
The optical glass of the first embodiment is characterized in that it is a fluorophosphate glass having a specific gravity of 3.3 or less, and satisfies one or more of (a) to (d).
(a) The temperature coefficient dn/dT of the relative refractive index of the He-Ne laser wavelength (633 nm) is in the range of 20 to 40 ° C within 0 ± 5.0 × 10 ^-6 ° C ^-1 .
(b) The weight loss amount D _STPP per 1 cm ² of the glass surface when immersed in a 0.01 mol/L sodium tripolyphosphate Na ₅ P ₃ O ₁₀ aqueous solution for 1 hour was 0.4 mg/cm ² ‧ h or less.
(c) The refractive index nd and the Abbe number νd satisfy the following relational expression (1).
Nd+0.00250×νd-1.69000≧0‧‧‧(1)
(d) The glass transition temperature Tg is 360 ° C or higher.

Hereinafter, the optical glass of the first embodiment will be described in detail.

In the optical glass of the first embodiment, the specific gravity is 3.3 or less. The specific gravity is preferably 3.2 or less, and more preferably 3.1 or less and 3.0 or less in order. By reducing the specific gravity of the glass, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the camera lens on which the lens is mounted can be reduced. The specific gravity can be adjusted by, for example, increasing or decreasing the content of Ba ²⁺ or P ⁵⁺ .

Further, the optical glass of the first embodiment satisfies the following (a) temperature coefficient dn/dT of relative refractive index, (b) weight loss amount D _STPP , (c) refractive index nd and Abbe number νd, and (d) One or more of the glass transition temperatures Tg are preferred numerical ranges described in the respective items.

(a) Temperature coefficient of relative refractive index dn/dT
In the optical glass of the first embodiment, the temperature coefficient dn/dT of the relative refractive index of the He-Ne laser wavelength (633 nm) is preferably 0 ± 5.0 × in the range of 20 to 40 ° C. Within 10 ^-6 ° C ^-1 , more preferably 0 ± 4.0 × 10 ^-6 or less, further preferably 0 ± 3.0 × 10 ^-6 ° C ^-1 or less. By setting dn/dT to the above range, the fluctuation of the refractive index can be made small even in an environment in which the temperature of the optical element greatly changes. Therefore, desired optical characteristics can be exhibited with high precision in a wider temperature range. .

The temperature coefficient dn/dT of the relative refractive index can be measured based on the interference method of JOGIS18.
Further, in the present specification, the temperature coefficient dn/dT is expressed in units of [°C ^-1 ], but in the case where [K ^-1 ] is used as a unit, the values of the temperature coefficients dn/dT are also the same.

(b) Weight loss D _STPP
When the optical glass of the first embodiment is immersed in a 0.01 mol/L sodium tripolyphosphate Na ₅ P ₃ O ₁₀ aqueous solution at 50 ° C for 1 hour, the weight loss amount D _STPP per 1 cm ² of the glass surface is preferably 0.4 mg/cm ² ‧ h or less, and more preferably 0.3 mg/cm ² ‧ h or less and 0.2 mg/cm ² ‧ h or less By setting D _STPP to the above range, there is little erosion of the glass surface at the time of cleaning, that is, glass having high washing durability.
Further, the weight loss amount D _STPP is a reduction amount (mg) per unit area (cm ² ) and unit time (h), and the unit thereof can also be expressed by [mg/(cm ² ‧h)].

(c) refractive index nd and Abbe number νd
In the optical glass of the first embodiment, the refractive index nd and the Abbe number νd preferably satisfy the following formula (1).
Nd+0.00250×νd-1.69000≧0‧‧‧(1)
Further, the refractive index nd and the Abbe number νd more preferably satisfy the following formula (2), and further preferably satisfy the following formula (3).
Nd+0.00250×νd-1.69200≧0‧‧‧式(2)
Nd+0.00250×νd-1.69500≧0‧‧‧式(3)
By satisfying the above formula (1), formula (2) or formula (3) by the refractive index nd and the Abbe number νd, an optical glass suitable for correction of chromatic aberration can be obtained.

(d) Glass transition temperature Tg
In the optical glass of the first embodiment, the glass transition temperature Tg is preferably 360° C. or higher, and more preferably 380° C. or higher and 400° C. or higher. By setting the glass transition temperature Tg to the above range, the heat resistance required in the coating step can be ensured.

The optical glass of the first embodiment has a specific gravity of 3.3 or less, and one or more of the above (a) to (d), preferably two or more, more preferably three or more, and still more preferably four. All of the preferred numerical ranges described in the various items are met.

(e) refractive index nd
In the optical glass of the first embodiment, the refractive index nd is preferably 1.50 or more, and may be 1.51 or more and 1.52 or more.

(f) Abbe number νd
In the optical glass of the first embodiment, the Abbe number νd is preferably 58 or more, and may be 65 or more, 68 or more, or 70 or more.

(g) Light transmittance The light transmittance of the optical glass of the first embodiment can be evaluated by the light transmittance of a wavelength of 500 nm to 700 nm.
For the glass sample having a thickness of 10.0 mm ± 0.1 mm, the external transmittance at a wavelength of 500 nm to 700 nm was measured with a spectrophotometer. The larger the value of the light transmittance of the wavelength of 500 nm to 700 nm, the more excellent the transmittance, and the less the color of the glass.

The external transmittance of the optical glass of the present embodiment at a wavelength of 500 nm to 700 nm is preferably 90% or more, more preferably 90.5% or more, still more preferably 91% or more. The external transmittance at a wavelength of 500 nm to 700 nm can be achieved by using V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm in the glass. The coloring component such as Ce is set to 10 ppm or less in total amount to satisfy the above values.

Further, in the optical glass of the first embodiment, the content of Ba ²⁺ is preferably 10% or less. The upper limit of the content of Ba ²⁺ is more preferably 9%, and more preferably 8% or 7% in turn. The lower limit of the content of Ba ²⁺ is preferably 0%. It should be noted that the content of Ba ²⁺ may also be 0%.

By setting the content of Ba ²⁺ to the above range, it is possible to obtain a glass excellent in washing durability while maintaining a low specific gravity, and it is possible to suppress phase separation, devitrification, and crystallization during vitrification. Further, a glass having a small temperature change in refractive index can be obtained.

The optical glass of the first embodiment preferably contains one or more ions selected from the group consisting of Li ⁺ , Na ⁺ and K ^{+ , and} is selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , and Ba ^{2+ .} One or more ions, P ⁵⁺ and Al ³⁺ in the group consisting of Zn ²⁺ are used as the cation component.

By including one or more kinds of ions selected from the group consisting of Li ⁺ , Na ^{+ ,} and K ⁺ as the cation component, the thermal stability of the glass can be improved. Further, by including one or more kinds of ions selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ^{2+ ,} and Zn ²⁺ as a cation component, the washing durability of the glass can be improved. . Further, by including P ⁵⁺ and Al ³⁺ , the temperature change of the refractive index of the glass can be reduced, and the washing durability of the glass can be improved.

In the optical glass of the first embodiment, the total content of Mg ²⁺ and Ca ²⁺ in the cation % indicates the total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ^{2+ ,} and Zn ²⁺ . The cation ratio of R' [(Mg ²⁺ + Ca ²⁺ ) / R'] is preferably 0.40 or more. The lower limit of the cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] is more preferably 0.45, and more preferably 0.50, 0.53, 0.60, 0.65, 0.7, 0.70, 0.75, 0.80.

By setting the cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] to the above range, an optical glass having a reduced specific gravity and a small temperature change in refractive index can be obtained.

In the optical glass of the first embodiment, in the cation %, the total content R' of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ^{2+ ,} and Zn ²⁺ is relative to Li ⁺ , Na ^{+ ,} and K ^{+ .} The cation ratio [R'/R] of the total content R is preferably 0.6 or more. The lower limit of the cation ratio [R'/R] is more preferably 0.8, further preferably 1.0.

By setting the cation ratio [R'/R] to the above range, it is possible to obtain an optical glass which is excellent in washing durability and has a small temperature change in refractive index.

Further, in the optical glass of the first embodiment, in the cation %, the total content of Li ⁺ and Na ⁺ is relative to the cation ratio of the total content R of Li ⁺ , Na ⁺ and K ⁺ [(Li ⁺ +Na ⁺ ) / R ] is preferably 0.8 or more. The lower limit of the cation ratio [(Li ⁺ +Na ⁺ )/R] is more preferably 0.85, still more preferably 0.90.

By setting the cation ratio [(Li ⁺ +Na ⁺ ) / R] to the above range, it is possible to obtain an optical glass which is excellent in washing durability and is less likely to cause streaks.

The optical glass of the first embodiment is a fluorophosphate glass. That is, F ^{- is} contained as an anion component. The content of F ^- is preferably from 10 to 40 anionic %, more preferably from 10 to 30 anionic %, still more preferably from 10 to 25 anionic %. By using fluorophosphate glass, an optical glass having a high degree of dispersibility of an abnormal portion can be obtained.

Further, the optical glass of the first embodiment can contain O ^{2 -} as an anion component. The content of O ^2- is preferably from 60 to 90 anionic %, more preferably from 70 to 90 anionic %.

(glass composition)
The glass components other than the above-described optical glass of the first embodiment will be described in detail below.

In the optical glass of the first embodiment, the lower limit of the content of P ⁵⁺ is preferably 30%, and more preferably 33% or 35%. Further, the upper limit of the content of P ⁵⁺ is preferably 50%, and more preferably 47%, 45%, or 42%.

P ⁵⁺ is a network forming component of glass, and is a component that reduces the temperature change of the refractive index and contributes to a decrease in specific gravity. On the other hand, when P ⁵⁺ is excessively contained, the washing resistance is deteriorated. Therefore, the content of P ⁵⁺ is preferably in the above range.

In the optical glass of the first embodiment, the lower limit of the content of Al ³⁺ is preferably 5%, and more preferably 6%, 7%, or 8% in this order. Further, the upper limit of the content of Al ³⁺ is preferably 15%, and more preferably 14%, 13%, or 12% in this order.

Al ³⁺ is a glass component having a function of reducing the temperature change of the refractive index of the glass, improving the washing resistance, and further reducing the optical characteristics. On the other hand, when the content of Al ³⁺ is increased, the devitrification resistance of the glass is lowered. Therefore, the content of Al ³⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Li ⁺ is preferably 25%, and more preferably 20%, 15%, or 10%. Further, the lower limit of the content of Li ⁺ is preferably 0%, and more preferably 1%, 2%, or 3% in this order. It should be noted that the content of Li ⁺ may also be 0%.

In the optical glass of the first embodiment, the lower limit of the Na ⁺ content is preferably 10%, and more preferably 12% or 15%. Further, the upper limit of the content of Na ⁺ is preferably 30%, and more preferably 28% or 25% in order.

Li ⁺ and Na ⁺ are components which contribute to the low specific gravity of the glass, and have an effect of improving the meltability of the glass and reducing the temperature change of the refractive index. On the other hand, when the content of Li ⁺ and Na ⁺ is increased, the devitrification resistance, the washing resistance, and the like are lowered. Therefore, the content of Li ⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the K ⁺ content is preferably 5%, and more preferably 3%, 2%, or 1% in this order. Further, the lower limit of the content of K ⁺ is preferably 0%. It should be noted that the content of K ⁺ may also be 0%.

K ⁺ is a component which contributes to the low specific gravity of glass and has an effect of improving the thermal stability of the glass. On the other hand, when the content thereof is increased, the thermal stability is lowered, and streaks are easily generated upon vitrification. Therefore, the content of K ⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Rb ⁺ is preferably 5%, and more preferably 4%, 3%, 2%, 1%, 0.5%, or 0.1%. Further, the lower limit of the content of Rb ⁺ is preferably 0%. It should be noted that the content of Rb ⁺ may also be 0%.

In the optical glass of the first embodiment, the upper limit of the content of Cs ⁺ is preferably 5%, and more preferably 4%, 3%, 2%, 1%, 0.5%, or 0.1%. Further, the lower limit of the content of Cs ⁺ is preferably 0%. It should be noted that the content of Cs ⁺ may also be 0%.

Both Rb ⁺ and Cs ⁺ have an effect of improving the meltability of the glass. When their content is increased, the refractive index nd is lowered, and the volatilization of the glass component is increased in the melting to obtain the desired glass. Therefore, the content of each of Rb ⁺ and Cs ^{+ is} preferably in the above range.

In the optical glass of the first embodiment, the lower limit of the content of Mg ²⁺ is preferably 5%, and more preferably 6%, 7%, or 8% in this order. Further, the upper limit of the content of Mg ²⁺ is preferably 25%, and more preferably 22%, 20%, or 18%.

In the optical glass of the first embodiment, the lower limit of the content of Ca ²⁺ is preferably 5%, and more preferably 6%, 7%, or 8% in this order. Further, the upper limit of the content of Ca ²⁺ is preferably 20%, and more preferably 18%, 16%, or 15% in this order.

In the optical glass of the first embodiment, the upper limit of the content of Sr ²⁺ is preferably 10%, and more preferably 8% or 5% in order. Further, the lower limit of the content of Sr ²⁺ is preferably 0%. It should be noted that the content of Sr ²⁺ may also be 0%.

By setting the content of each of Mg ²⁺ , Ca ^{2+ ,} and Sr ²⁺ to the above range, an optical glass excellent in washing resistance, thermal stability, meltability, and devitrification resistance can be obtained.

In the optical glass of the first embodiment, the upper limit of the content of Zn ²⁺ is preferably 10%, and more preferably 8% or 5% in order. Further, the lower limit of the content of Zn ²⁺ is preferably 0%. It should be noted that the content of Zn ²⁺ may also be 0%.

Zn ²⁺ is a glass component having an effect of improving the thermal stability of glass. On the other hand, when the content of Zn ²⁺ is too large, the meltability is deteriorated, and the Abbe number νd is decreased. Therefore, the content of Zn ²⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Y ³⁺ is preferably 5%, and more preferably 4% or 3% in order. Further, the lower limit of the content of Y ³⁺ is preferably 0%. It should be noted that the content of Y ³⁺ may also be 0%.

Y ³⁺ is a component having an effect of improving the washing resistance. On the other hand, when the content of Y ³⁺ becomes excessive, the thermal stability and devitrification resistance of the glass are lowered. Therefore, the content of Y ³⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of La ³⁺ is preferably 5%, and more preferably 4% or 3% in order. Further, the lower limit of the content of La ³⁺ is preferably 0%. It should be noted that the content of La ³⁺ may also be 0%.

La ³⁺ is a component having an effect of improving the washing resistance. On the other hand, when the content of La ³⁺ is increased, the thermal stability and devitrification resistance of the glass are lowered, and the glass is easily devitrified during production. Therefore, from the viewpoint of suppressing the decrease in thermal stability and resistance to devitrification, the content of La ³⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Gd ³⁺ is preferably 5%, and more preferably 4% or 3%. Further, the lower limit of the content of Gd ³⁺ is preferably 0%. It should be noted that the content of Gd ³⁺ may also be 0%.

Gd ³⁺ is a component having an effect of improving the washing resistance. On the other hand, when the content of Gd ³⁺ becomes too large, the thermal stability and devitrification resistance of the glass are lowered, and the glass is easily devitrified during production, and the specific gravity is increased. Therefore, the content of Gd ³⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Yb ³⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Yb ³⁺ is preferably 0%. It should be noted that the content of Yb ³⁺ may also be 0%.

Yb ³⁺ is a component having an effect of improving the washing resistance. On the other hand, when the content of Yb ³⁺ becomes too large, the thermal stability and devitrification resistance of the glass are lowered, and the glass is easily devitrified during production, and the specific gravity is increased. Therefore, the content of Yb ³⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Lu ³⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Lu ³⁺ is preferably 0%. It should be noted that the content of Lu ³⁺ may also be 0%.

Lu ³⁺ is a component having an effect of improving the washing resistance. On the other hand, when the content of Lu ³⁺ becomes excessive, the thermal stability and devitrification resistance of the glass are lowered. Also, the specific gravity will increase. Therefore, the content of Lu ³⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Ti ⁴⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Ti ⁴⁺ is preferably 0%. It should be noted that the content of Ti ⁴⁺ may also be 0%.

Ti ⁴⁺ is a component having an effect of improving the washing resistance. On the other hand, when the content of Ti ⁴⁺ becomes excessive, the Abbe number is drastically lowered. Further, Ti ^{4+ is} relatively easy to increase the color of the glass, and the meltability is also deteriorated. Therefore, the content of Ti ⁴⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Zr ⁴⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Zr ⁴⁺ is preferably 0%. It should be noted that the content of Zr ⁴⁺ may also be 0%.

Zr ⁴⁺ is a glass component having an effect of improving the washing resistance of the glass. On the other hand, when the content of Zr ⁴⁺ is increased, thermal stability and devitrification resistance are lowered. Therefore, the content of Zr ⁴⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Nb ⁵⁺ is preferably 4%, and more preferably 3%, 2%, or 1% in this order. Further, the lower limit of the content of Nb ⁵⁺ is preferably 0%. It should be noted that the content of Nb ⁵⁺ may also be 0%.

Nb ⁵⁺ is a glass component having an effect of improving the washing resistance of the glass. In addition, it is also a glass component that improves the thermal stability of the glass. On the other hand, when the content of Nb ⁵⁺ becomes too large, the Abbe number is drastically lowered. In addition, there is a tendency for the color of the glass to be strong. Therefore, the content of Nb ⁵⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of Ta ⁵⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Ta ⁵⁺ is preferably 0%. It should be noted that the content of Ta ⁵⁺ may also be 0%.

a ⁵⁺ is a glass component having an effect of improving the washing resistance of the glass. On the other hand, when the content of Ta ⁵⁺ is increased, the thermal stability of the glass is lowered. Therefore, the content of Ta ⁵⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of W ⁶⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of W ⁶⁺ is preferably 0%. It should be noted that the content of W ⁶⁺ may also be 0%.

By reducing the Tg by including W ^{6+ in} an appropriate amount, it has an effect of improving the thermal stability of the glass. On the other hand, when the content of W ⁶⁺ is increased, the color of the glass increases. Therefore, the content of W ⁶⁺ is preferably in the above range.

In the optical glass of the first embodiment, the upper limit of the content of B ³⁺ is preferably 5%, and more preferably 3%, 2%, and 1% in this order. Further, the lower limit of the content of B ³⁺ is preferably 0%. It should be noted that the content of B ³⁺ may also be 0%.

In the optical glass of the first embodiment, the upper limit of the content of Si ⁴⁺ is preferably 5%, and more preferably 3%, 2%, or 1% in this order. Further, the lower limit of the content of Si ⁴⁺ is preferably 0%. It should be noted that the content of Si ⁴⁺ may also be 0%.

In the optical glass of the first embodiment, the upper limit of the content of Bi ³⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Bi ³⁺ is preferably 0%. It should be noted that the content of Bi ³⁺ may also be 0%.

In the optical glass of the first embodiment, the upper limit of the content of Ga ³⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Ga ³⁺ is preferably 0%. It should be noted that the content of Ga ³⁺ may also be 0%.

In the optical glass of the first embodiment, the upper limit of the content of In ³⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of In ³⁺ is preferably 0%. It should be noted that the content of In ³⁺ may also be 0%.

In the optical glass of the first embodiment, the upper limit of the content of Sc ³⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Sc ³⁺ is preferably 0%. It should be noted that the content of Sc ³⁺ may also be 0%.

In the optical glass of the first embodiment, the upper limit of the content of Hf ⁴⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Hf ⁴⁺ is preferably 0%. It should be noted that the content of Hf ⁴⁺ may also be 0%.

In the optical glass of the first embodiment, the upper limit of the content of Ge ⁴⁺ is preferably 3%, and more preferably 2% or 1% in this order. Further, the lower limit of the content of Ge ⁴⁺ is preferably 0%. It should be noted that the content of Ge ⁴⁺ may also be 0%.

The cation component of the optical glass of the first embodiment is preferably mainly composed of the above components, that is, P ⁵⁺ , Al ³⁺ , Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Zn ²⁺ , Y ³⁺ , La ³⁺ , Gd ³⁺ , Yb ³⁺ , Lu ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , Nb ⁵⁺ , Ta ⁵⁺ , W ^{6 +} , B ³⁺ , Si ⁴⁺ , Bi ³⁺ , Ga ³⁺ , In ³⁺ , Sc ³⁺ , Hf ⁴⁺ and Ge ⁴⁺ , the total content of the above components is preferably more than 95%, more preferably More than 98%, further preferably more than 99%, still more preferably more than 99.5%.

The optical glass of the first embodiment can also contain a component other than F ^- and O ^{2 -} as an anion component. Examples of the anion component other than F ^- and O ^2- include Cl ^- , Br ^- and I ^- . However, Cl ^- , Br ^- , and I ^- are all easily volatilized in the melting of the glass. When the volatilization of these components occurs, there is a problem that the characteristics of the glass fluctuate, the homogeneity of the glass is lowered, and the consumption of the melting equipment becomes remarkable. Therefore, the content of Cl ^- is preferably less than 5 anionic %, more preferably less than 3 anionic %, further preferably less than 1 anionic %, still more preferably less than 0.5 anionic %, still more preferably less than 0.25 anionic %. Further, the total content of Br ^- and I ^- is preferably less than 5 anionic %, more preferably less than 3 anionic %, further preferably less than 1 anionic %, still more preferably less than 0.5 anionic %, still more preferably less than 0.1 anionic %, Still more preferably, it is 0 anion%.

The optical glass of the first embodiment is preferably composed of the above-described components. However, other components may be contained in a range that does not impair the effects of the present invention. Further, in the present invention, the inclusion of unavoidable impurities is not excluded.

<Other ingredients>
Pb, As, Cd, Tl, Be, Se are all toxic. Therefore, the optical glass of the first embodiment preferably does not contain these elements as a glass component.

U, Th, and Ra are all radioactive elements. Therefore, the optical glass of the first embodiment preferably does not contain these elements as a glass component.

V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Ce can increase the color of the glass and become a source of fluorescence. Therefore, the optical glass of the first embodiment preferably does not contain these elements as a glass component.

Sb (Sb ₂ O ₃ ), Sn (SnO ₂ ), and Ce (CeO ₂ ) are elements which function as a clarifying agent and can be arbitrarily added. Among them, Sb(Sb ₂ O ₃ ) is a clarifying agent having a large clarifying effect. However, Sb(Sb ₂ O ₃ ) is highly oxidizing, and if Sb(Sb ₂ O ₃ ) is added in a large amount, Sb(Sb ₂ O ₃ ) contained in the glass during oxidative press molding oxidizes the press-molding mold. Forming surface. Therefore, in the repeated precision press molding, the molding surface is remarkably deteriorated, and it is impossible to perform precision press molding. Moreover, the surface quality of the molded optical element is degraded. Further, Sn (SnO ₂ ) and Ce (CeO ₂ ) have a smaller clarifying effect than Sb (Sb ₂ O ₃ ). Further, when Ce (CeO ₂ ) is added in a large amount, the color of the glass is strong. Therefore, in the case where a clarifying agent is added, it is preferred to add Sb(Sb ₂ O ₃ ) while paying attention to the amount of addition.

The content of the following clarifying agent is shown as an oxide-converted value.
The content of Sb ₂ O ₃ is represented by an external addition amount. In other words, the content of Sb ₂ O ₃ when the total content of all the glass components other than Sb ₂ O ₃ , SnO ₂ and CeO ₂ is 100% by mass is preferably less than 1% by mass, more preferably less than 0.5% by mass. Further, it is preferably in the range of less than 0.1% by mass. The content of Sb ₂ O ₃ may be 0% by mass.

The content of SnO ₂ is also expressed by the amount of addition. In other words, the content of SnO ₂ when the total content of all the glass components other than SnO ₂ , Sb ₂ O ₃ and CeO ₂ is 100% by mass is preferably less than 2% by mass, more preferably less than 1% by mass, further. It is preferably in the range of less than 0.5% by mass, and still more preferably in the range of less than 0.1% by mass. The content of SnO ₂ may also be 0% by mass. By setting the content of SnO ₂ to the above range, the clarity of the glass can be improved.

The content of CeO ₂ is also expressed by the amount of addition. In other words, the content of CeO ₂ when the total content of all the glass components other than CeO ₂ , Sb ₂ O ₃ , and SnO ₂ is 100% by mass is preferably less than 2% by mass, more preferably less than 1% by mass, further. It is preferably in the range of less than 0.5% by mass, and still more preferably in the range of less than 0.1% by mass. The content of CeO ₂ may also be 0% by mass. By setting the content of CeO ₂ to the above range, the clarity of the glass can be improved.

(Manufacture of optical glass)
The optical glass of the first embodiment can be produced by blending a glass raw material by a method of forming the above-described predetermined composition, and mixing the glass raw material according to a known glass production method. For example, a plurality of compounds are blended, mixed well to prepare a batch raw material, and the batch raw materials are placed in a quartz crucible or a platinum crucible to carry out a rough melting. The melt obtained by the crude melting was rapidly cooled and pulverized to prepare cullet. Further, the cullet was placed in a platinum crucible, heated, and remelted to obtain a molten glass, which was further clarified and homogenized, and then the molten glass was molded and rapidly cooled to obtain an optical glass. A known method can be applied to the molding of the molten glass and the cooling.

In addition, as long as the desired glass component can be introduced into the glass so as to have a desired content, the compound to be used in the mixing of the bulk raw material is not particularly limited, and examples of such a compound include oxides, carbonates, and phosphates. , nitrates, sulfates, hydroxides, fluorides, chlorides, etc.

(Manufacture of optical components, etc.)
When an optical element is produced using the optical glass of the first embodiment, a known method can be applied. For example, the glass raw material is melted to obtain molten glass, and the molten glass is poured into a mold to form a plate shape, thereby producing a glass material formed of the optical glass of the present invention. The obtained glass material was appropriately cut, polished, and polished to prepare a slice having a size and shape suitable for press molding.

The slice is heated, softened, and subjected to press molding (reheat pressing) by a known method to produce an optical element blank approximate to the shape of the optical element. The optical element blank can be annealed and polished and polished in a known manner to produce an optical element.

It is also possible to rough the surface of the slice (roller polishing) to equalize the weight while making the surface easy to adhere to the release agent, and press-reforming the reheated and softened glass into a shape similar to the shape of the desired optical element, and finally Grinding, polishing, and making optical components.

Alternatively, it is also possible to separate a predetermined weight of molten glass on a molding die, directly perform press molding, and finally perform polishing and polishing to produce an optical element.

It is also possible to apply an antireflection film, a total reflection film, or the like to the optical functional surface of the optical element to be produced depending on the purpose of use.

As the optical element, various lenses such as a spherical lens, a prism, a diffraction grating, and the like can be exemplified.

[Second Embodiment]
The optical glass according to the second embodiment of the present invention includes one or more ions selected from the group consisting of Li ⁺ , Na ^{+ ,} and K ^{+ , and} is selected from the group consisting of Mg ²⁺ , Ca ²⁺ , and Sr ^{2 .} One or more ions, P ⁵⁺ and Al ³⁺ in the group consisting of ⁺ , Ba ²⁺ and Zn ²⁺ are used as the cation component,
The content of Ba ²⁺ is 10 cationic % or less,
In the cation % representation, the cation ratio [R' of the total content R' of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ with respect to the total content R of Li ⁺ , Na ⁺ and K ⁺ /R] is 0.6 or more,
The cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] of the total content of Mg ²⁺ and Ca ²⁺ to the total content R' is 0.40 or more,
The ratio of the total content of Li ⁺ and Na ⁺ to the cation ratio [(Li ⁺ +Na ⁺ ) / R] of the total content R is 0.8 or more.
As an anionic component, it contains O ^2- ,
The content of F ^- is 10 to 40 anionic %.

Hereinafter, the optical glass of the second embodiment will be described in detail.

The optical glass of the second embodiment contains one or more kinds of ions selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ as a cationic component. By including these components, the thermal stability and weather resistance of the glass can be improved.

The optical glass of the second embodiment contains one or more kinds of ions selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ^{2+ ,} and Zn ²⁺ as a cation component. By including these components, the washing durability and weather resistance of the glass can be improved.

Further, the optical glass of the second embodiment contains P ⁵⁺ and Al ³⁺ as cationic components. By including these components, the thermal stability, washing durability, and weather resistance of the glass can be improved.

In the optical glass of the second embodiment, the content of Ba ²⁺ is 10% or less. The upper limit of the content of Ba ²⁺ is preferably 9%, and more preferably 8% or 7% in order. The lower limit of the content of Ba ²⁺ is preferably 0%. It should be noted that the content of Ba ²⁺ may also be 0%.

By setting the content of Ba ²⁺ to the above range, it is possible to obtain a glass excellent in washing durability while maintaining a low specific gravity, and it is possible to suppress phase separation, devitrification, and crystallization during vitrification.

In the optical glass of the second embodiment, in the cation %, the total content R' of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ^{2+ ,} and Zn ²⁺ is relative to Li ⁺ , Na ^{+ ,} and K ^{+ .} The cation ratio [R'/R] of the total content R is 0.6 or more. The lower limit of the cation ratio [R'/R] is preferably 0.8, and more preferably 1.0.

By setting the cation ratio [R'/R] to the above range, an optical glass excellent in washing durability and small in temperature change in refractive index can be obtained.

In the optical glass of the second embodiment, the total content of Mg ²⁺ and Ca ²⁺ in the cation % indicates the total content of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ^{2+ ,} and Zn ²⁺ . The cation ratio of R' is [(Mg ²⁺ + Ca ²⁺ ) / R'] is 0.40 or more. The lower limit of the cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] is preferably 0.45, and more preferably 0.50, 0.53, 0.60, 0.65, 0.7, 0.70, 0.75, 0.80.

By setting the cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] to the above range, an optical glass having a reduced specific gravity and a small temperature change in refractive index can be obtained.

Further, in the optical glass of the second embodiment, in the cation %, the total content of Li ⁺ and Na ⁺ is relative to the cation ratio of the total content R of Li ⁺ , Na ⁺ and K ⁺ [(Li ⁺ +Na ⁺ ) / R ] is 0.8 or more. The lower limit of the cation ratio [(Li ⁺ +Na ⁺ )/R] is preferably 0.85, more preferably 0.90.

By setting the cation ratio [(Li ⁺ +Na ⁺ ) / R] to the above range, an optical glass excellent in washing durability and less likely to cause streaks can be obtained.

The optical glass of the second embodiment contains O ^{2 -} as an anion component. The content of O ^2- is preferably from 60 to 90 anionic %, more preferably from 70 to 90 anionic %.

Further, in the optical glass of the second embodiment, the content of F ^- is 10 to 40 anionic %, preferably 10 to 30 anionic %, more preferably 10 to 25 anionic %. By setting the content of F ^- in the above range, it is possible to obtain an optical glass which is excellent in weather resistance and washing resistance and which has a low specific gravity and a high dispersibility of an abnormal portion.

In the optical glass of the second embodiment, the glass component and other component compositions other than the above can be made the same as in the first embodiment.

In the optical glass of the second embodiment, the specific gravity is preferably 3.3 or less, and more preferably 3.2 or less, 3.1 or less, or 3.0 or less. By reducing the specific gravity of the glass, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the camera lens on which the lens is mounted can be reduced. The specific gravity can be adjusted by, for example, increasing or decreasing the content of Ba ²⁺ or P ⁵⁺ .

The optical glass of the second embodiment satisfies the temperature coefficient dn/dT, (b) weight loss amount D _STPP , (c) refractive index nd, and Abbe number of (a) relative refractive index described in the first embodiment. A preferred numerical range of one or more of νd and (d) the glass transition temperature Tg.

In the optical glass of the second embodiment, the characteristics (e) to (g) of the glass other than the above (a) to (d) can be the same as those of the first embodiment.

The manufacture of the optical glass of the second embodiment and the manufacture of optical elements and the like can be made in the same manner as in the first embodiment.
[Examples]

Hereinafter, the present invention will be described in detail by way of examples, but the invention is not limited to these examples.

(Example 1)
A glass sample having the glass compositions shown in Tables 1 to 5 was produced by the following procedure, and various evaluations were carried out.

In Tables 1 to 5, the cation component is represented by a cation % to indicate a glass composition, and the anion component is represented by an anion % to indicate a glass composition.

[Manufacture of optical glass]
Fluoride, oxide, hydroxide, carbonate, and nitrate corresponding to the constituent components of the glass are prepared as a raw material, and the glass composition of the obtained optical glass is set to the respective compositions shown in Tables 1 to 5, The raw materials are weighed and blended, and the raw materials are thoroughly mixed. The obtained blending raw material (batch raw material) is put into platinum crucible, and heated at 900 to 1200 ° C for 1 to 2 hours to obtain molten glass, which is stirred to homogenize and clarify, and then the molten glass is cast to preheat. Heat to the mold at the appropriate temperature. The cast glass was heat-treated in the vicinity of the glass transition temperature Tg, and allowed to cool to room temperature in the furnace to obtain a glass sample.

[Confirmation of composition of glass components]
The content of each glass component was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES), and it was confirmed that it was the same as the composition shown in Tables 1-5.

[Determination of Temperature Coefficient dn/dT of Relative Refractive Index]
The obtained glass sample was measured based on the interference method of JOGIS18. The light source was continuously measured using a He-Ne laser having a wavelength of 633 nm at a temperature of -70 to 150 °C. The dn/dT values in the range of 20 ° C to 40 ° C in the measurement results are shown in Tables 1 to 5.

[Measurement of weight loss D _STPP ]
The obtained glass sample was processed into a diameter of 43.7 mm (both sides 30 cm ² ) and a thickness of about 5 mm, and the opposite surface polishing was carried out, and it was measured at 50 ° C, 0.01 mol/L of an aqueous solution of sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ). The weight loss amount D _STPP per 1 cm ² of the glass surface when immersed for 1 hour. The results are shown in Tables 1 to 5.

[Measurement of optical properties]
The obtained glass sample was further annealed in the vicinity of the glass transition temperature Tg for about 30 minutes to about 2 hours, and then cooled to room temperature in a furnace at a temperature drop rate of -30 ° C / hour to obtain annealed sample. The obtained annealing sample was measured for refractive index nd, Abbe number νd, specific gravity, glass transition temperature Tg, and transmittance. The results are shown in Tables 1 to 5.

(i) refractive index nd and Abbe number νd
The refractive index nd, ng, nF, and nC were measured by the refractive index measurement method of JIS Standard JIS B 7071-1, and the Abbe's number νd was calculated based on the following formula. The results are shown in Tables 1 to 5. Νd=(nd-1)/(nF-nC)

(ii) Specific gravity The specific gravity is determined by the Archimedes method. The results are shown in Tables 1 to 5.

(iii) Glass transition temperature Tg
The glass transition temperature Tg was measured at a temperature increase rate of 10 ° C /min using a differential scanning calorimeter (DSC3300SA) manufactured by NETZSCH JAPAN. The results are shown in Tables 1 to 5.

(iv) Transmittance The glass sample was processed to have a thickness of 10 mm and a plane parallel to each other and optically polished. The external transmittance at a wavelength of 500 to 700 nm was measured, and as a result, all the samples were 90% or more. It should be noted that the external transmittance also includes the reflection loss of the light on the surface of the sample.

[Table 1]

[Table 2]

[table 3]

[Table 4]

[table 5]

(Example 2)
Using the glass sample obtained in Example 1, a preform for precision press molding was produced by a known method. The obtained preform was heated and softened in a nitrogen gas atmosphere, and subjected to precision press molding using a press molding die to shape the optical glass into the shape of an aspherical lens. Thereafter, the molded optical glass is taken out from the press molding die, annealed, and centered, whereby an aspherical lens can be obtained.

(Example 3)
The glass sample obtained in Example 1 was cut and polished to prepare a slice. The slice was press-molded by reheat pressing to prepare an optical element blank. The optical element blank is precisely annealed, the refractive index is precisely adjusted to a desired refractive index, and then ground and polished by a known method, thereby obtaining a lenticular lens, a biconcave lens, a plano-convex lens, a plano-concave lens, and a concave mirror meniscus lens. Various lenses such as convex mirror meniscus lenses.

The embodiments disclosed herein are to be considered in all respects as illustrative and not limiting. The scope of the present invention is defined by the scope of the appended claims, and is not intended to

For example, in the glass composition exemplified above, the optical glass of one embodiment of the present invention can be produced by adjusting the composition described in the specification.
Further, of course, two or more items described as examples or preferred ranges in the specification can be arbitrarily combined.

Finally, a preferred embodiment of the invention is summarized.
As described above, the optical glass of the first embodiment of the present invention is a fluorophosphate glass having a specific gravity of 3.3 or less, and satisfies one or more of (a) to (d).
(a) The temperature coefficient dn/dT of the relative refractive index of the He-Ne laser wavelength (633 nm) is in the range of 20 to 40 ° C within 0 ± 5.0 × 10 ^-6 ° C ^-1 .
(b) The weight loss amount D _STPP per 1 cm ² of the glass surface when immersed in a 0.01 mol/L sodium tripolyphosphate Na ₅ P ₃ O ₁₀ aqueous solution for 1 hour was 0.4 mg/cm ² ‧ h or less.
(c) The refractive index nd and the Abbe number νd satisfy the following relational expression (1).
Nd+0.00250×νd-1.69000≧0‧‧‧(1)
(d) The glass transition temperature Tg is 360 ° C or higher.

In addition, as another preferred embodiment of the present invention (the third embodiment), an optical glass which is fluorophosphate glass and satisfies one or more of the above (a) to (d) is exemplified. In the optical glass of the third embodiment, the characteristics (e) to (g) of the glasses other than the above (a) to (d) and (a) to (d) can be the same as those of the first embodiment. Further, the production of the glass component and other component components, the production of the optical glass, and the production of the optical element can be made the same as in the first embodiment.

In the first embodiment and the third embodiment, as the combination of (a) to (d), the following 15 combinations are possible. That is, as a combination, (a), (a) and (b), (a) and (c), (a) and (d), (a) and (b) and (c), (a) And (b) and (d), (a) and (c) and (d), (a) and (b) and (c) and (d), (b), (b) and (c), b) and (d), (b) and (c) and (d), (c), (c) and (d), (d).

Furthermore, as described above, the optical glass of the second embodiment of the present invention contains one or more ions selected from the group consisting of Li ⁺ , Na ⁺ and K ^{+ , and} is selected from the group consisting of Mg ²⁺ and Ca ²⁺ . One or more ions, P ⁵⁺ and Al ³⁺ in the group consisting of Sr ²⁺ , Ba ²⁺ and Zn ²⁺ are used as a cation component.
The content of Ba ²⁺ is 10 cationic % or less,
In the cation % representation, the cation ratio [R' of the total content R' of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ with respect to the total content R of Li ⁺ , Na ⁺ and K ⁺ /R] is 0.6 or more,
The cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] of the total content of Mg ²⁺ and Ca ²⁺ to the total content R' is 0.40 or more,
The ratio of the total content of Li ⁺ and Na ⁺ to the cation ratio [(Li ⁺ +Na ⁺ ) / R] of the total content R is 0.8 or more.
As an anionic component, it contains O ^2- ,
The content of F ^- is 10 to 40 anionic %.

According to still another preferred embodiment of the present invention, the optical glass of the second embodiment has the optical glass of the first embodiment and the optical glass of the second embodiment. An optical glass having the characteristics described in the third embodiment. In such a case, the matters described as a preferred range in the first embodiment, the second embodiment, and the third embodiment can be appropriately combined and applied.

An optical element according to an embodiment of the present invention is an optical element formed of the optical glass according to any of the embodiments described above.

no.

no.

Claims (7)

An optical glass having a specific gravity of 3.3 or less, satisfying one or more of (a) to (d), (a) a temperature coefficient dn/dT of a relative refractive index of a He-Ne laser having a wavelength of 633 nm. In the range of 20 to 40 ° C, 0 ± 5.0 × 10 ^-6 ° C ^-1 , (b) per 1 cm ² when immersed in 0.01 mol / L sodium tripolyphosphate Na ₅ P ₃ O ₁₀ aqueous solution for 1 hour The weight reduction of the glass surface D _STPP is 0.4 mg/cm ² ‧ h or less, (c) The refractive index (nd) and the Abbe number (νd) satisfy the following relationship (1): nd + 0.00250 × νd - 1.69000≧0‧‧‧式(1), (d) The glass transition temperature Tg is 360 °C or higher. The optical glass according to claim 1, wherein the content of Ba ²⁺ is 10 cationic % or less. The optical glass according to claim 1 or 2, wherein, in the cation % representation, the total content of Mg ²⁺ and Ca ²⁺ is relative to Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ^{2+ .} The cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] of the total content R' of Zn ²⁺ is 0.40 or more. An optical glass comprising one or more ions selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ selected from the group consisting of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ In the group of the composition, one or more ions, P ⁵⁺ and Al ^{3+ are} used as the cationic component, and the content of Ba ²⁺ is 10 cation % or less. In the cation %, Mg ²⁺ , Ca ²⁺ , Sr ^{2 +} , the total content of Ba ²⁺ and Zn ²⁺ R' relative to the total content of Li ⁺ , Na ⁺ and K ⁺ cation ratio [R' / R] is 0.6 or more, and the total of Mg ²⁺ and Ca ²⁺ The cation ratio [(Mg ²⁺ + Ca ²⁺ ) / R'] of the content with respect to the total content R' is 0.40 or more, and the total content of Li ⁺ and Na ⁺ is relative to the cation ratio of the total content R [( Li ⁺ +Na ⁺ )/R] is 0.8 or more, and as an anion component, O ² and F ^- are contained in an amount of 10 to 40 anionic %. The optical glass according to claim 4, wherein the content of P ⁵⁺ is 30 to 50 cationic %, the content of Al ³⁺ is 5 to 15 cationic %, and the content of Na ⁺ is 10 to 30 cationic %. The optical glass according to any one of claims 1 to 5, wherein the optical transmittance at a wavelength of 500 to 700 nm is 90% or more. An optical element formed of the optical glass described in any one of claims 1 to 6.