JP6840660B2 - Optical glass and optical elements - Google Patents

Description

The present invention relates to optical glasses and optical elements having a desired optical constant.

Patent Document 1 discloses an optical glass having a predetermined refractive index nd and Abbe number νd. The optical glass described in Patent Document 1 is characterized in that the inside of the glass does not devitrify in a reheating test. However, in recent years, higher stability has been required during reheating.

JP-A-2017-105703

In addition to the higher stability during reheating as described above, the optical elements mounted on the autofocus type optical system are required to be lighter in order to reduce the power consumption when driving the autofocus function. Has been done. If the specific gravity of glass can be reduced, the weight of an optical element such as a lens can be reduced. Further, it is required that the partial dispersion ratios Pg and F are small in order to correct the chromatic aberration.

Therefore, the present invention provides an optical glass having a desired optical constant, small specific gravity and partial dispersion ratios Pg and F, and excellent stability at the time of reheating, and an optical element made of the optical glass. With the goal.

The gist of the present invention is as follows.
(1) _{The content of SiO 2} is 10 to 50% by mass,
The content of Nb ₂ O ₅ is 10 to 50% by mass,
The total content of TiO _{2 and BaO [TiO 2} + BaO] is 10% by mass or less, and the total content is 10% by mass or less.
The mass ratio of the content of _B 2 _{O 3} to the content of _{SiO 2 [B 2 O 3 /} SiO 2] is 0.15 or less, optical glass.

(2) The optical glass according to (1), which satisfies any one or more of (a) to (g).
(A) _{The content of La 2} O ₃ is 15% by mass or less.
(B) the mass ratio of the content of ZrO ₂ to the content of _{Nb 2 O 5 [ZrO 2 /} Nb 2 O 5] is greater than 0.1.
(C) Mass ratio of the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 to} the total content of _{B 2} O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO) ₂ )] is smaller than 1.7.
(D) _{The mass ratio [R'O / R 2} O] of the total content R'O of MgO, CaO, SrO and BaO to the total content R _{2 O of Li 2} O, Na ₂ O and K _{2 O is 5} It is as follows.
(E) The mass ratio of the content _{of Ta 2} O ₅ to the total content of _{Nb 2} O ₅ and TiO _{2 [Ta 2} O ₅ / (Nb ₂ O ₅ + TiO ₂ )] is 0.15 or less.
(F) The mass ratio of the content _{of TiO 2} to the total content of _{Nb 2} O ₅ , TiO ₂ and ZrO _{2 [TiO 2} / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ )] is greater than 0 and less than 0.3. ..
(G) The total content R _{2 O of Li 2} O, Na ₂ O and K ₂ O is larger than 0% by mass.

(3) The refractive index nd is 1.69 to 1.77, and the refractive index nd is 1.69 to 1.77.
The optical glass according to (1) or (2), wherein the Abbe number νd is 34 to 37.

(4) The specific gravity is 3.45 or less,
The deviation ΔPg, F of the partial dispersion ratios Pg and F is −0.0015 or less, and
The liquidus temperature LT is 1250 ° C or lower,
When heated at the glass transition temperature Tg for 10 minutes and further heated at a temperature 180 to 200 ° C. higher than the Tg for 10 minutes, the number of crystals observed per gram is 20 or less.
The refractive index nd is 1.69 to 1.77, and the refractive index nd is 1.69 to 1.77.
Optical glass having an Abbe number νd of 34 to 37.

(5) An optical element made of the optical glass according to any one of (1) to (4) above.

According to the present invention, there is provided an optical glass having a desired optical constant, small specific gravity and partial dispersion ratios Pg and F, and excellent stability at the time of reheating, and an optical element made of the optical glass. Can be done.

Hereinafter, embodiments of the present invention will be described. In addition, in this invention and this specification, the glass composition of an optical glass is represented by an oxide standard unless otherwise specified. Here, the "oxide-based glass composition" refers to a glass composition obtained by converting all glass raw materials into those that are decomposed at the time of melting and exist as oxides in optical glass, and the notation of each glass component is According to the custom, SiO ₂ , TiO _2, etc. are described. Unless otherwise specified, the content and total content of the glass component are based on mass, and "%" means "mass%".

The content of the glass component can be quantified by known methods such as inductively coupled plasma emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). Further, in the present specification and the present invention, the content of the constituent component is 0%, which means that the constituent component is substantially not contained, and the component is allowed to be contained at an unavoidable impurity level.

Further, in the present specification, the refractive index refers to the refractive index nd at the d-line (wavelength 587.56 nm) of helium unless otherwise specified.

The Abbe number νd is used as a value representing a property related to dispersion, and is expressed by the following equation. Here, nF is the refractive index of blue hydrogen at the F line (wavelength 486.13 nm), and nC is the refractive index of red hydrogen at the C line (656.27 nm).
νd = (nd-1) / (nF-nC)

The partial dispersion ratios Pg and F are expressed as follows using the refractive indexes ng, nF and nC of the g-line, F-line and c-line.
Pg, F = (ng-nF) / (nF-nC)
The normal line is represented by the following equation in a plane in which the horizontal axis is the Abbe number νd and the vertical axis is the partial dispersion ratios Pg and F.
Pg, F (0) = 0.6483- (0.0018 × νd)
Further, the deviations ΔPg and F of the partial dispersion ratios Pg and F from the normal line are expressed as follows.
ΔPg, F = Pg, F-Pg, F (0)

Hereinafter, the optical glass of the present invention will be described as the first embodiment based on the glass composition, and the optical glass of the present invention will be described as the second embodiment based on the physical property values.

1st Embodiment The optical glass according to the 1st embodiment is
The content of SiO ₂ is 10 to 50% by mass,
The content of Nb ₂ O ₅ is 10 to 50% by mass,
The total content of TiO _{2 and BaO [TiO 2} + BaO] is 10% by mass or less, and the total content is 10% by mass or less.
The mass ratio of the content of _B 2 _{O 3} to the content of _{SiO 2 [B 2 O 3 /} SiO 2] is 0.15 or less.

In the optical glass according to the first embodiment, _{the content of SiO 2} is 10 to 50%. The lower limit of the content of SiO ₂ is preferably 15%, more preferably 20%, 25%, and 30%. The upper limit of the content of SiO ₂ is preferably 47%, more preferably 45% and 43%. If _{the content of SiO 2} is too small, vitrification becomes difficult. If _{the content of SiO 2} is too large, it is difficult to obtain the desired optical constant.

In the optical glass according to the first embodiment, _{the content of Nb 2} O ₅ is 10 to 50%. The lower limit of the content of Nb ₂ O ₅ is preferably 14%, more preferably 16%, 18%, and 20% in that order. The upper limit of the content of Nb ₂ O ₅ is preferably 44%, more preferably 41%, 38%, and 35% in that order. If _{the content of Nb 2} O ₅ is too small, the target high refractive index may not be achieved. If _{the content of Nb 2} O ₅ is too large, the thermal stability may decrease and the raw material cost of glass may increase.

In the optical glass according to the first embodiment, the total content of _{TiO 2 and BaO [TiO 2} + BaO] is 10% or less. The upper limit of the total content [TiO ₂ + BaO] is preferably 9%, more preferably 8%, 7%, and 6% in that order. The total content [TiO ₂ + BaO] is preferably small, and the lower limit thereof is preferably 0%. The total content [TiO ₂ + BaO] may be 0%. TiO ₂ is a component that increases the partial dispersion ratios Pg and F, and BaO is a component that increases the specific gravity. Therefore, by setting the total content [TiO ₂ + BaO] in the above range, it is possible to suppress an increase in the partial dispersion ratios Pg and F and the specific gravity.

In the optical glass according to the first embodiment, the mass ratio of the content of _B 2 _{O 3} to the content of _{SiO 2 [B 2 O 3 /} SiO 2] is 0.15 or less. The upper limit of the mass ratio [B ₂ O ₃ / SiO ₂ ] is preferably 0.14, and more preferably 0.13, 0.12, and 0.11. The lower limit of the mass ratio [B ₂ O ₃ / SiO ₂ ] is preferably 0, more preferably 0.01, 0.02, 0.03. If the mass ratio [B ₂ O ₃ / SiO ₂ ] is too large, the glass raw material is melted and melted, and when the glass melt is molded and vitrified, or after vitrification, the glass is heated, softened and re-formed. Crystals may precipitate during molding.

In the first embodiment, it is preferable to satisfy any one or more of the following (a) to (g).
(A) _{The content of La 2} O ₃ is 15% or less.
(B) the mass ratio of the content of ZrO ₂ to the content of _{Nb 2 O 5 [ZrO 2 /} Nb 2 O 5] is greater than 0.1.
(C) Mass ratio of the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 to} the total content of _{B 2} O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO) ₂ )] is smaller than 1.7.
(D) _{The mass ratio [R'O / R 2} O] of the total content R'O of MgO, CaO, SrO and BaO to the total content R _{2 O of Li 2} O, Na ₂ O and K _{2 O is 5} It is as follows.
(E) The mass ratio of the content _{of Ta 2} O ₅ to the total content of _{Nb 2} O ₅ and TiO _{2 [Ta 2} O ₅ / (Nb ₂ O ₅ + TiO ₂ )] is 0.15 or less.
(F) The mass ratio of the content _{of TiO 2} to the total content of _{Nb 2} O ₅ , TiO ₂ and ZrO _{2 [TiO 2} / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ )] is greater than 0 and less than 0.3. ..
_(G) Li 2 O, the total content _{R 2} O Na ₂ O and _{K 2} O is greater than 0%.
The above (a) to (g) will be described in detail below.

(A) In the optical glass according to the first embodiment, _{the upper limit of the content of La 2} O ₃ is preferably 15%, more preferably 13%, 11%, and 9% in that order. The lower limit of the content of La ₂ O ₃ is preferably 0%, more preferably 0.5%, 1.0%, and 1.5% in that order. The content of La ₂ O ₃ may be 0%. By _{setting the upper limit of the content of La 2} O ₃ to the above range, an increase in specific gravity can be suppressed.

(B) In the optical glass according to the first embodiment, the mass ratio of the content of ZrO ₂ to the content of _{Nb 2 O 5 [ZrO 2 /} Nb 2 O 5] is preferably greater than 0.1, more preferably Is greater than 0.3. The upper limit of the mass ratio [ZrO ₂ / Nb ₂ O ₅ ] is preferably 0.8, and more preferably 0.7, 0.6, 0.5. By setting the lower limit of the mass ratio [ZrO ₂ / Nb ₂ O ₅ ] to the above range, the partial dispersion ratios Pg, F and ΔPg, F can be reduced. By setting the upper limit of the mass ratio [ZrO ₂ / Nb ₂ O ₅ ] to the above range, glass can be stably obtained.

(C) In the optical glass according to the first embodiment, the mass ratio of the total contents of Nb ₂ O ₅ , TIO ₂ and ZrO _{2 to} the total contents of _{B 2} O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO _2). + ZrO ₂ ) / (B ₂ O ₃ + SiO ₂ )] is preferably smaller than 1.7, and more preferably 1.5 or less, 1.4 or less, and 1.3 or less. The lower limit of the mass ratio [(Nb ₂ O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO ₂ )] is preferably 0.5, and further 0.6, 0.7, 0.8. It is more preferable in the order of. By setting the mass ratio [(Nb ₂ O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO ₂ )] in the above range, an optical glass having a desired optical constant can be obtained.

(D) In the optical glass according to the first embodiment, the mass ratio of the total content R'O of MgO, CaO, SrO and BaO to the total content R _{2 O of Li 2} O, Na ₂ O and K _{2 O [} The upper limit of R'O / R ₂ O] is preferably 5, and more preferably 4.0, 3.5, and 3.0. The lower limit of the mass ratio [R'O / R ₂ O] is preferably 0, and more preferably 0.2, 0.4, and 0.6 in that order. The mass ratio [R'O / R ₂ O] may be 0. By setting the mass ratio [R'O / R ₂ O] in the above range, an optical glass having a low specific gravity and a high dispersion can be obtained.

(E) In the optical glass according to the first embodiment, the mass ratio of the content of _{Ta 2} O ₅ to the total content of _{Nb 2} O ₅ and TiO _{2 [Ta 2} O ₅ / (Nb ₂ O ₅ + TiO ₂ )]. Is 0.15 or less. The upper limit of the mass ratio [Ta ₂ O ₅ / (Nb ₂ O ₅ + TiO ₂ )] is preferably 0.12, and more preferably 0.10, 0.08, 0.06 in that order. The mass ratio [Ta ₂ O ₅ / (Nb ₂ O ₅ + TiO ₂ )] is preferably small, and its lower limit is preferably 0. Further, the mass ratio [Ta ₂ O ₅ / (Nb ₂ O ₅ + TiO ₂ )] may be 0. By setting [Ta ₂ O ₅ / (Nb ₂ O ₅ + TiO ₂ )] in the above range, an increase in specific gravity can be suppressed, and the raw material cost of glass can be reduced.

(F) In the optical glass according to the first embodiment, the mass ratio of the content _{of TiO 2} to the total content of _{Nb 2} O ₅ , TiO ₂ and ZrO _{2 [TiO 2} / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ )). ] Is preferably larger than 0, and more preferably 0.01 or more, 0.02 or more, and 0.03 or more. Further, the mass ratio [TiO ₂ / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ )] is preferably smaller than 0.3, and more preferably 0.25 or less, 0.20 or less, and 0.15 or less in that order. By setting the mass ratio [TiO ₂ / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ )] to the above range, an increase in specific gravity can be suppressed and the partial dispersion ratios Pg and F can be reduced. Moreover, the raw material cost of glass can be reduced.

(G) In the glass according to the first embodiment, the total content of _{Li 2} O, Na ₂ O and K _{2 O R 2} O [Li ₂ O + Na ₂ O + K ₂ O] is preferably larger than 0%, and further 3 It is more preferable in the order of 0.0% or more, 6.0% or more, and 8.0% or more. The total content _{R 2} O is preferably 30% or less, further 25% or less, 23% or less, preferably by 20% following order. By setting the total content R ₂ O in the above range, the meltability and thermal stability of the glass can be improved, and the liquidus temperature LT can be lowered.

The glass components other than the above in the optical glass according to the first embodiment will be described in detail below.

In the optical glass according to the first _embodiment, the upper limit of the content of B 2 _{O 3} is preferably 10%, more 8.0%, 6.0%, preferably by 5.0% sequentially. The lower limit of the content of B ₂ O ₃ is preferably 0%, more preferably 1.0%, 1.5%, and 2.0% in that order. The content of B ₂ O ₃ may be 0%. By _{setting the content of B 2} O _{3 in} the above range, the specific gravity of the glass can be reduced and the thermal stability of the glass can be improved.

In the optical glass according to the first _embodiment, the upper limit of the content of P 2 _{O 5} is preferably 10%, more 8.0%, 6.0%, preferably by 5.0% sequentially. The lower limit of the content of P ₂ O _{5 is preferably 0%.} The content of P ₂ O ₅ may be 0%. By _{setting the content of P 2} O _{5 in} the above range, it is possible to suppress an increase in the partial dispersion ratios Pg and F and maintain the thermal stability of the glass.

In the glass according to the first embodiment, _{the upper limit of the content of Al 2} O ₃ is preferably 10%, more preferably 8.0%, 6.0%, and 5.0% in that order. The content of Al ₂ O ₃ may be 0%. By _{setting the content of Al 2} O _{3 in} the above range, the devitrification resistance and thermal stability of the glass can be maintained.

In the glass according to the first embodiment, _{the lower limit of the content of ZrO 2} is preferably 1.0%, more preferably 2.0%, 2.5%, and 3.0% in that order. The upper limit of the ZrO ₂ content is preferably 15%, more preferably 14%, 13%, and 12%. By _{setting the content of ZrO 2 in} the above range, a desired optical constant can be realized and the partial dispersion ratios Pg and F can be reduced.

In the optical glass according to the first embodiment, _{the upper limit of the TiO 2} content is preferably 10%, more preferably 9.0%, 8.0%, and 7.0% in that order. The lower limit of the content of TiO ₂ is preferably 0.5%, more preferably 1.0%, 1.5%, and 2.0% in that order. The content of TiO ₂ may be 0%. By _{setting the content of TiO 2 in} the above range, a desired optical constant can be realized, an increase in specific gravity can be suppressed, and the raw material cost of glass can be reduced.

In the glass according to the first embodiment, _{the upper limit of the content of WO 3} is preferably 5%, more preferably 4%, 3%, and 2%. The content of WO ₃ may be 0%. By _{setting the content of WO 3 in} the above range, the transmittance can be increased, and the partial dispersion ratios Pg, F and specific gravity can be reduced.

In the first embodiment, _{the upper limit of the content of Bi 2} O ₃ is preferably 5%, more preferably 4%, 3%, and 2%. The lower limit of the Bi ₂ O ₃ content is preferably 0%. By _{setting the content of Bi 2} O _{3 in} the above range, the thermal stability of the glass can be improved, and the partial dispersion ratios Pg, F and specific gravity can be reduced.

In the glass according to the first embodiment, _{the upper limit of the Li 2} O content is preferably 12%, more preferably 10%, 9.0%, and 8.0% in that order. The lower limit of the Li ₂ O content is preferably 1.0%, more preferably 2.0%, 3.0%, and 4.0%.

In the glass according to the first embodiment, _{the upper limit of the Na 2} O content is preferably 20%, more preferably 18%, 16%, and 14% in that order. The lower limit of the Na ₂ O content is preferably 0%, more preferably 1.0%, 1.5%, and 2.0% in that order.

In the glass according to the first embodiment, the upper limit of the content of _{K 2} O is preferably 10%, more 5.0%, 3.0%, preferably by 2.0% order. The lower limit of the K ₂ O content is preferably 0%, more preferably 0.2%, 0.4%, and 0.6% in that order.

Li ₂ O, Na ₂ O and K ₂ O are components that reduce the partial dispersion ratios Pg and F, and have a function of lowering the liquidus temperature and improving the thermal stability of the glass, and their contents. The higher the amount, the lower the chemical durability, weather resistance, and stability during reheating. Therefore, the _{contents of Li 2} O, Na ₂ O, and K ₂ O are preferably in the above ranges.

In the glass according to the first embodiment, _{the upper limit of the content of Cs 2} O is preferably 10%, more preferably 5%, 3%, and 1%. The lower limit of the content of cs ₂ O is preferably 0%.

Cs ₂ O has a function of improving the thermal stability of glass, but when the content is increased, the chemical durability and weather resistance are lowered. Therefore _{, each content of Cs 2} O is preferably in the above range.

In the glass according to the first embodiment, the upper limit of the MgO content is preferably 20%, more preferably 10%, 5%, and 3%. The lower limit of the MgO content is preferably 0%.

In the glass according to the first embodiment, the upper limit of the CaO content is preferably 20%, more preferably 18%, 16%, and 14% in that order. The lower limit of the CaO content is preferably 0%, more preferably 1.0%, 1.5%, and 2.0%.

In the glass according to the first embodiment, the upper limit of the SrO content is preferably 20%, more preferably 10%, 5%, and 3%. The lower limit of the SrO content is preferably 0%.

In the optical glass according to the first embodiment, the upper limit of the BaO content is preferably 10%, more preferably 5.0%, 3.0%, and 2.0% in that order. The lower limit of the BaO content is preferably 0%. By setting the BaO content within the above range, an increase in specific gravity can be suppressed.

MgO, CaO, SrO, and BaO are all glass components having a function of improving the thermal stability and devitrification resistance of the glass. However, when the content of these glass components is increased, the specific gravity is increased, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass are lowered. Therefore, the content of each of these glass components is preferably in the above range.

Further, in the glass according to the first embodiment, the upper limit of the total content R'O [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is preferably 20%, and further 18%, 16% and 14%. More preferred in order. The lower limit of the total content R'O is preferably 0%, more preferably 1.0%, 1.5%, and 2.0% in that order. The total content R'O is preferably in the above range from the viewpoint of suppressing an increase in specific gravity and maintaining thermal stability without hindering high dispersion.

In the glass according to the first embodiment, the upper limit of the ZnO content is preferably 10%, more preferably 5.0%, 3.0%, and 2.0% in that order. The lower limit of the ZnO content is preferably 0%.

ZnO is a glass component having a function of improving the thermal stability of glass. However, if the ZnO content is too high, the specific gravity will increase. Therefore, from the viewpoint of improving the thermal stability of the glass and maintaining the desired optical constant, the ZnO content is preferably in the above range.

In the glass according to the first embodiment, _{the upper limit of the content of Ta 2} O ₅ is preferably 10%, more preferably 5.0%, 3.0%, and 2.0% in that order. The lower limit of the content of Ta ₂ O _{5 is preferably 0%.}

Ta ₂ O ₅ is a glass component having a function of improving the thermal stability of glass, and is a component that lowers the partial dispersion ratios Pg and F. On the other hand, when _{the content of Ta 2} O ₅ is increased, the thermal stability of the glass is lowered, and when the glass is melted, unmelted glass raw material is likely to occur. In addition, the specific gravity increases. Therefore, _{the content of Ta 2} O ₅ is preferably in the above range.

In the glass according to the first _embodiment, the upper limit of the content of Y 2 _{O 3} is preferably 20%, even 10%, 5%, preferably by 3% sequentially. The lower limit of the content of Y ₂ O _{3 is preferably 0%.}

If _{the content of Y 2} O ₃ is too high, the thermal stability of the glass is lowered, and the glass is liable to be devitrified during production. Therefore, from the viewpoint of suppressing a decrease in the thermal stability of the glass, the content of Y ₂ O ₃ is preferably in the range.

In the glass according to the first embodiment, _{the content of Sc 2} O ₃ is preferably 2% or less. The lower limit of the Sc ₂ O ₃ content is preferably 0%.

In the glass according to the first embodiment, _{the content of HfO 2} is preferably 2% or less. The lower limit of the HfO ₂ content is preferably 0%.

Sc ₂ O ₃ and HfO ₂ have a function of enhancing the high dispersibility of glass, but are expensive components. Therefore, the _{contents of Sc 2} O ₃ and HfO ₂ are preferably in the above range.

In the glass according to the first embodiment, _{the content of Lu 2} O ₃ is preferably 2% or less. The lower limit of the content of Lu ₂ O _{3 is preferably 0%.}

Lu ₂ O ₃ has a function of enhancing the high dispersibility of glass, but is also a glass component that increases the specific gravity of glass due to its large molecular weight. Therefore, _{the content of Lu 2} O ₃ is preferably in the above range.

In the glass according to the first embodiment, _{the content of GeO 2} is preferably 2% or less. The lower limit of the content of GeO _{2 is preferably 0%.}

GeO ₂ has a function of enhancing the high dispersibility of glass, but is a prominently expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of glass, _{the content of GeO 2} is preferably in the above range.

In the glass according to the first embodiment, _{the content of Gd 2} O ₃ is preferably 2% or less. The lower limit of the content of Gd ₂ O _{3 is preferably 0%.}

If _{the content of Gd 2} O ₃ is too high, the thermal stability of the glass will decrease. Further, if _{the content of Gd 2} O ₃ becomes too large, the specific gravity of the glass increases, which is not preferable. _{Therefore, the content of Gd 2} O ₃ is preferably in the above range from the viewpoint of suppressing an increase in specific gravity while maintaining good thermal stability of the glass.

In the glass according to the first embodiment, _{the content of Yb 2} O ₃ is preferably 2% or less. The lower limit of the content of Yb ₂ O _{3 is preferably 0%.}

Since Yb ₂ O ₃ has a _{larger molecular weight than La 2} O ₃ , Gd ₂ O ₃ , and Y ₂ O ₃ , it increases the specific gravity of glass. As the specific gravity of glass increases, the mass of the optical element increases. For example, if a lens having a large mass is incorporated into an autofocus type imaging lens, the power required to drive the lens during autofocus increases, and the battery consumption increases. Therefore, _{it is desirable to reduce the content of Yb 2} O ₃ to suppress the increase in the specific gravity of the glass.

Further, _{if the content of Yb 2} O ₃ is too large, the thermal stability of the glass is lowered. _{The content of Yb 2} O ₃ is preferably in the above range from the viewpoint of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.

The glass according to the first embodiment mainly contains the above-mentioned glass components, that is, SiO ₂ and Nb ₂ O _{5 as essential components, and La 2} O ₃ , B ₂ O ₃ , P ₂ O ₅ , and Al ₂ O ₃ as optional components. , ZrO ₂ , TiO ₂ , WO ₃ , Bi ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, MgO, CaO, SrO, BaO, ZnO, Ta ₂ O ₅ , Y ₂ O ₃ , Sc ₂ O ₃ , HfO ₂ , Lu ₂ O ₃ , GeO ₂ , Gd ₂ O ₃ , and Yb ₂ O ₃ , and the total content of the above glass components is more than 95%. It is preferably more, more preferably more than 98%, even more preferably more than 99%, even more preferably more than 99.5%.

The glass according to the first embodiment is basically composed of the above glass components, but other components may be contained as long as the effects of the present invention are not impaired. Further, in the present invention, the inclusion of unavoidable impurities is not excluded.

(Other ingredients)
In addition to the above components, the above optical glass may also contain a small amount _{of Sb 2} O ₃ , CeO _{2, etc. as a fining agent.} The total amount of the fining agent (external split addition amount) is preferably 0% or more and less than 1%, and more preferably 0% or more and 0.5% or less.

The external split addition amount is expressed as a weight percentage when the total content of all glass components excluding the fining agent is 100%.

Pb, Cd, As, Th and the like are components that are concerned about environmental load. Therefore, the contents of PbO, CdO, and ThO ₂ are preferably 0 to 0.1%, more preferably 0 to 0.05%, and 0 to 0.01%, respectively. Is more preferable, and it is particularly preferable that PbO, CdO, and ThO _{2 are substantially not contained.}

The content of As ₂ O ₃ is preferably 0 to 0.1%, more preferably 0 to 0.05%, further preferably 0 to 0.01%, and As ₂ O. It is particularly preferable that _{3 is substantially not contained.}

Further, the optical glass can obtain high transmittance over a wide range of the visible region. In order to take advantage of these features, it is preferable that no coloring element is contained. Examples of the coloring element include Cu, Co, Ni, Fe, Cr, Eu, Nd, Er, and V. Each element is preferably less than 100 mass ppm, more preferably 0 to 80 mass ppm, further preferably 0 to 50 mass ppm or less, and particularly preferably not substantially contained. ..

Further, Ga, Te, Tb and the like are components that do not need to be introduced and are also expensive components. Therefore, _{the range of the contents of Ga 2} O ₃ , TeO ₂ , and TbO ₂ in terms of mass% is preferably 0 to 0.1%, and more preferably 0 to 0.05%, respectively. Preferably, it is more preferably 0 to 0.01%, further preferably 0 to 0.005%, further preferably 0 to 0.001%, and substantially not contained. Especially preferable.

(Glass characteristics)
<Refractive index nd>

In the optical glass according to the first embodiment, the refractive index nd is preferably 1.69 to 1.77. The refractive index nd can also be 1.695 to 1.765, or 1.70 to 1.76. The refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component. The components (high-refractive index-increasing components) having a function of relatively increasing the refractive index nd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , La ₂ O _{3, and the} like. On the other hand, the components having a function of relatively lowering the refractive index nd (lowering the refractive index component) are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O and the like. Further, for example, the total content of the high refractive index components Nb ₂ O ₅ , TiO ₂ and ZrO _{2 ) (Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) and the total content of the low refractive index components B ₂ O ₃ and SiO ₂ mass ratio of _{[(Nb 2 O 5 + TiO} 2 + ZrO 2) / (B 2 O 3 + SiO 2)]) can increase the refractive index nd by increasing the mass ratio _{[(Nb 2 O 5 + TiO} 2 The refractive index nd can be lowered by reducing + ZrO ₂ ) / (B ₂ O ₃ + SiO _2)]).

<Abbe number νd>
In the optical glass according to the first embodiment, the Abbe number νd is preferably 34 to 37. The Abbe number νd can also be 34.3 to 36.7, or 34.5 to 36.5. The Abbe number νd can be set to a desired value by appropriately adjusting the content of each glass component. The components that relatively lower the Abbe number νd, that is, the highly dispersed components, are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O _{5, and the} like. On the other hand, the components that relatively increase the Abbe number νd, that is, the low dispersion components, are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, SrO. And so on. Since work TiO ₂ Among highly dispersed component _Nb 2 _{O 5,} TiO 2, ZrO ₂ is to reduce the Abbe number [nu (serves to highly dispersed) is large, the content of TiO ₂ and _Nb 2 _O 5, TiO ₂ And the Abbe number νd can be reduced (highly dispersed) by increasing the mass ratio to the total content of ZrO _{2 ([TiO 2} / (Nb ₂ O ₅ + TiO ₂ + ZrO _{2)]), and the mass.} The Abbe number νd can be increased (decreased) by decreasing the ratio ([TiO ₂ / (Nb ₂ O ₅ + TiO ₂ + ZrO _2)]).

<Specific gravity of glass>
The specific gravity of the optical glass according to the first embodiment is preferably 3.45 g / cc or less, more preferably 3.40 g / cc or less, and more preferably 3.35 g / cc or less.
The components having a relatively high specific gravity are BaO, La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O _{5, and the} like. On the other hand, components having a relatively low specific gravity, such as SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. The specific gravity can be controlled by appropriately adjusting the content of these components.

<Partial dispersion ratio Pg, F>
In the optical glass according to the first embodiment, the upper limit of the partial dispersion ratios Pg and F is preferably 0.5870, and more preferably 0.5856, 0.5851, and 0.5846 in that order. By setting the partial dispersion ratios Pg and F in the above range, optical glass suitable for high-order chromatic aberration correction can be obtained. On the other hand, the lower limit of the partial dispersion ratios Pg and F is not particularly limited, but is set to 0.5717 as a guide.

Further, in the optical glass according to the first embodiment, the upper limit of the deviations ΔPg and F is preferably −0.0015, and more preferably −0.0020 and −0.0025. By setting the deviations ΔPg and F in the above range, optical glass suitable for high-order chromatic aberration correction can be obtained. On the other hand, the lower limit of the deviations ΔPg and F is not particularly limited, but is set to −0.0080 as a guide.

<Liquid phase temperature LT>
The liquidus temperature LT of the optical glass according to the first embodiment is preferably 1250 ° C. or lower, more preferably 1220 ° C. or lower and 1200 ° C. or lower. By setting the liquidus temperature LT in the above range, the melting and molding temperatures of glass can be lowered, and the corrosion of glass melting equipment (for example, a crucible, a stirring equipment for molten glass, etc.) in the melting step can be reduced. .. The liquidus temperature LT is determined by the balance of the contents of all glass components. _{Among them, the content of SiO 2} , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, etc. has a large influence on the liquidus temperature LT.

The liquidus temperature is determined as follows. 10 cc (10 ml) of glass is put into a platinum crucible, melted at 1250 ° C to 1350 ° C for 20 to 30 minutes, cooled to a glass transition temperature of Tg or less, and the glass is placed in a melting furnace at a predetermined temperature together with the platinum crucible and held for 2 hours. To do. The holding temperature is 1000 ° C. or higher in 5 ° C. or 10 ° C. increments, and after holding for 2 hours, the glass is cooled and the presence or absence of crystals inside the glass is observed with a 100x optical microscope. The lowest temperature at which crystals do not precipitate is defined as the liquidus temperature.

<Stability during reheating>
In the optical glass according to the first embodiment, the number of crystals observed per gram when heated at a glass transition temperature Tg for 10 minutes and further heated at a temperature 180 to 200 ° C. higher than the Tg for 10 minutes is preferable. Is 20 or less, more preferably 10 or less.

The stability during reheating is measured as follows. A glass sample having a size of 1 cm × 1 cm × 1 cm is heated for 10 minutes in a first test furnace set to a glass transition temperature Tg of the glass sample, and further raised to a temperature 180 to 200 ° C. higher than the glass transition temperature Tg. After heating in the set second test furnace for 10 minutes, the presence or absence of crystals is confirmed with an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1 g is measured. Also, visually check the presence or absence of white turbidity of the glass.

<Glass transition temperature Tg>
The upper limit of the glass transition temperature Tg of the optical glass according to the first embodiment is preferably 650 ° C, more preferably 620 ° C, 600 ° C, and 580 ° C. The lower limit of the glass transition temperature Tg is preferably 450 ° C., more preferably 480 ° C., 500 ° C., and 520 ° C. The glass transition temperature Tg can be controlled by adjusting each of them.
The components that relatively lower the glass transition temperature Tg are Li ₂ O, Na ₂ O, K ₂ O, and the like. The components that relatively increase the glass transition temperature Tg are La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , and the like. The glass transition temperature Tg can be controlled by appropriately adjusting the content of these components.

<Light transmission of glass>
The light transmittance of the optical glass according to the first embodiment can be evaluated by the degree of coloring λ80, λ70 and λ5.
The spectral transmittance of a glass sample having a thickness of 10.0 mm ± 0.1 mm is measured in the wavelength range of 200 to 700 nm. The wavelength at which the external transmittance is 80% is λ80, and the wavelength at which the external transmittance is 70% is λ70. Let λ5 be the wavelength at which the external transmittance is 5%.

The λ80 of the optical glass according to the first embodiment is preferably 500 nm or less, more preferably 470 nm or less, and further preferably 450 nm or less. λ70 is preferably 450 nm or less, more preferably 420 nm or less, and further preferably 400 nm or less. Further, λ5 is preferably 370 nm or less, more preferably 360 nm or less, and further preferably 350 nm or less.

(Manufacturing of optical glass)
The glass according to the first embodiment may be produced by blending a glass raw material so as to have the above-mentioned predetermined composition, and using the blended glass raw material according to a known glass manufacturing method. For example, a plurality of types of compounds are mixed and sufficiently mixed to obtain a batch raw material, and the batch raw material is placed in a quartz crucible or a platinum crucible for rough melting. The melt obtained by crude melting is rapidly cooled and crushed to prepare a cullet. Further, the cullet is placed in a platinum crucible, heated and remelted to obtain molten glass, and after further clarification and homogenization, the molten glass is formed and slowly cooled to obtain an optical glass. A known method may be applied to the molding and slow cooling of the molten glass.

As long as a desired glass component can be introduced into the glass so as to have a desired content, the compound used when preparing the batch raw material is not particularly limited, and examples of such a compound include oxides and carbonates. Examples thereof include salts, nitrates, hydroxides and fluorides.

(Manufacturing of optical elements, etc.)
In order to manufacture an optical element using the optical glass according to the first embodiment, a known method may be applied. For example, in the production of the above optical glass, the molten glass is poured into a mold and formed into a plate shape to produce a glass material made of the optical glass according to the present invention. The obtained glass material is appropriately cut, ground, and polished to produce a cut piece having a size and shape suitable for press molding. The cut piece is heated and softened, and press-molded (reheat-pressed) by a known method to produce an optical element blank that approximates the shape of the optical element. An optical element blank is annealed and ground and polished by a known method to produce an optical element.

The optical functional surface of the produced optical element may be coated with an antireflection film, a total reflection film, or the like, depending on the purpose of use.

According to one aspect of the present invention, it is possible to provide an optical element made of the above optical glass. Examples of the types of optical elements include lenses such as spherical lenses and aspherical lenses, prisms, and diffraction gratings. As the shape of the lens, various shapes such as a biconvex lens, a plano-convex lens, a biconcave lens, a plano-concave lens, a convex meniscus lens, and a concave meniscus lens can be exemplified. The optical element can be manufactured by a method including a step of processing a glass molded body made of the above optical glass. Examples of processing include cutting, cutting, rough grinding, fine grinding, and polishing. By using the above glass when performing such processing, damage can be reduced and high-quality optical elements can be stably supplied.

2nd Embodiment The optical glass according to the 2nd embodiment is
The specific gravity is 3.45 or less,
The deviation ΔPg, F of the partial dispersion ratios Pg and F is −0.0015 or less, and
The liquidus temperature LT is 1250 ° C or lower,
When heated at the glass transition temperature Tg for 10 minutes and further heated at a temperature 180 to 200 ° C. higher than the Tg for 10 minutes, the number of crystals observed per gram is 20 or less.
The refractive index nd is 1.69 to 1.77, and the refractive index nd is 1.69 to 1.77.
The Abbe number νd is 34 to 37.

In the optical glass according to the second embodiment, the refractive index nd is 1.69 to 1.77. The refractive index nd can also be 1.695 to 1.765, or 1.70 to 1.76. The refractive index nd can be controlled by adjusting the mass ratio [(Nb ₂ O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO _2)].
The components that relatively increase the refractive index nd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ , and La ₂ O ₃ . The components that relatively lower the refractive index nd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, and K ₂ O. The refractive index nd can be controlled by appropriately adjusting the content of these components.

In the optical glass according to the second embodiment, the Abbe number νd is 34 to 37. The Abbe number νd can also be 34.3 to 36.7, or 34.5 to 36.5. The Abbe number νd can be controlled by adjusting the _{mass ratio [TiO 2} / (Nb ₂ O ₅ + TiO ₂ + ZrO _2)].
The components that relatively lower the Abbe number νd are Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . The components that relatively increase the Abbe number νd are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, La ₂ O ₃ , BaO, CaO, and SrO. The Abbe number νd can be controlled by appropriately adjusting the content of these components.

In the optical glass according to the second embodiment, the specific gravity is 3.45 or less, preferably 3.40 or less, and more preferably 3.35 or less.
The components having a relatively high specific gravity are BaO, La ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and the like. The components having a relatively low specific gravity are SiO ₂ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O and the like. The specific gravity can be controlled by adjusting the content of these components.

In the optical glass according to the second embodiment, the deviations ΔPg and F are −0.0015 or less, preferably −0.0020 or less, and more preferably −0.0025 or less. The lower limit of the deviations ΔPg and F is preferably −0.0100, and more preferably −0.0080, −0.0060, and −0.0050. By setting the deviations ΔPg and F in the above range, optical glass suitable for high-order chromatic aberration correction can be obtained. The deviations ΔPg and F can be calculated by the same method as in the first embodiment.

In the optical glass according to the second embodiment, the liquidus temperature LT is 1250 ° C. or lower, preferably 1220 ° C. or lower, and more preferably 1200 ° C. or lower. By setting the liquidus temperature LT in the above range, the melting and molding temperatures of glass can be lowered, and the corrosion of glass melting equipment (for example, a crucible, a stirring equipment for molten glass, etc.) in the melting step can be reduced. .. The liquidus temperature LT is determined by the balance of the contents of all glass components. _{Among them, the content of SiO 2} , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, etc. has a large influence on the liquidus temperature LT. The liquidus temperature LT can be measured by the same method as in the first embodiment.

In the optical glass according to the second embodiment, when the glass is heated at the glass transition temperature Tg for 10 minutes and further heated at a temperature 180 to 200 ° C. higher than the Tg for 10 minutes, the number of crystals observed per 1 g is 20. The number is less than, preferably 10 or less.
The number of crystals can be measured by the same method as the stability at the time of reheating in the first embodiment.

In the second embodiment, the partial dispersion ratios Pg and F, the glass transition temperature Tg, and the light transmittance of the glass can be the same as those in the first embodiment.

(Glass component)
In the optical glass according to the second embodiment, _{the lower limit of the content of SiO 2} is preferably 10%, more preferably 15%, 20%, 25%, and 30%. The upper limit of the content of SiO ₂ is preferably 50%, more preferably 48%, 46%, 44%, and 43%. If _{the content of SiO 2} is too small, vitrification becomes difficult. If _{the content of SiO 2} is too large, it is difficult to obtain the desired optical constant.

In the optical glass according to the second embodiment, _{the lower limit of the content of Nb 2} O ₅ is preferably 10%, more preferably 14%, 16%, 18%, and 20% in that order. The upper limit of the content of Nb ₂ O ₅ is preferably 50%, more preferably 44%, 41%, 38%, and 35%. If _{the content of Nb 2} O ₅ is too small, the increase in the refractive index of the glass is suppressed. If _{the content of Nb 2} O ₅ is too large, the thermal stability may decrease and the raw material cost of glass may increase.

In the optical glass according to the second embodiment, the upper limit of the total content of _{TiO 2 and BaO [TiO 2} + BaO] is preferably 10%, and further in the order of 9%, 8%, 7%, and 6%. preferable. The total content [TiO ₂ + BaO] is preferably small, and the lower limit thereof is preferably 0%. The total content [TiO ₂ + BaO] may be 0%. TiO ₂ is a component that increases the partial dispersion ratios Pg and F, and BaO is a component that increases the specific gravity. Therefore, by setting the total content [TiO ₂ + BaO] in the above range, it is possible to suppress an increase in the partial dispersion ratios Pg and F and the specific gravity.

In the optical glass according to the second embodiment, the upper limit of the mass ratio of the content of _B 2 _{O 3} to the content of _{SiO 2 [B 2 O 3 /} SiO 2] is preferably 0.15, more 0 It is more preferable in the order of .14, 0.13, 0.12, 0.11. The lower limit of the mass ratio [B ₂ O ₃ / SiO ₂ ] is preferably 0, more preferably 0.01, 0.02, 0.03. If the mass ratio [B ₂ O ₃ / SiO ₂ ] is too large, the glass raw material is melted and melted, and when the glass melt is molded and vitrified, or after vitrification, the glass is heated, softened and re-formed. Crystals may precipitate during molding.

In the optical glass according to the second embodiment, the glass components and composition ratios other than the above can be the same as those in the first embodiment.

Further, the production of the optical glass and the production of the optical element and the like according to the second embodiment can be the same as those of the first embodiment.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the embodiments shown in the examples.

(Example 1)
Glass samples having the glass compositions shown in Tables 1-1 to 1-2 and Tables 2-1 to 2-2 were prepared by the following procedure and evaluated in various ways.

[Manufacturing of optical glass]
First, oxides, hydroxides, carbonates, and nitrates corresponding to the constituents of the glass are prepared as raw materials, and the glass composition of the obtained optical glass is each composition shown in Tables 1-1 to 1-4. The above raw materials were weighed and mixed as described above, and the raw materials were thoroughly mixed. The compounding raw material (batch raw material) thus obtained is put into a platinum crucible and heated at 1350 ° C. to 1400 ° C. for 2 to 4 hours to obtain molten glass. Was cast into a mold preheated to an appropriate temperature. The cast glass was heat-treated for 30 minutes at an arbitrary temperature between the glass transition temperature Tg and Tg, which was 100 ° C. lower than the glass transition temperature, and allowed to cool to room temperature in a furnace to obtain a glass sample.

[Confirmation of glass component composition]
For the obtained glass sample, the content of each glass component was measured by inductively coupled plasma emission spectroscopy (ICP-AES), and it was confirmed that the composition was as shown in Tables 1-1 to 1-2. ..

[Stability during reheating]
The obtained glass sample is cut into a size of 1 cm × 1 cm × 1 cm, heated in a first test furnace set to a glass transition temperature Tg of the glass sample for 10 minutes, and further 180 to 180 to 180 to higher than the glass transition temperature Tg. It was heated for 10 minutes in a second test furnace set to a temperature 200 ° C. higher. Then, the presence or absence of crystals was confirmed with an optical microscope (observation magnification: 10 to 100 times). Then, the number of crystals per 1 g was measured. The presence or absence of white turbidity of the glass was visually confirmed. When the number of crystals per 1 g was 20 or less and no white turbidity was confirmed, it was judged as ◯, and when the number of crystals per 1 g was more than 20 or at least one of the white turbidity was confirmed, it was judged as ×.

[Measurement of optical characteristics]
The obtained glass sample was further annealed at a glass transition temperature of about Tg for about 30 minutes to about 2 hours, and then cooled to room temperature at a temperature lowering rate of −30 ° C./hour in a furnace to obtain an annealed sample. The refractive indexes nd, ng, nF and nC, Abbe number νd, partial dispersion ratio Pg, F, specific gravity, and glass transition temperature Tg, λ80, λ70 and λ5 were measured for the obtained annealed sample. The results are shown in Tables 3-1 to 2-3.
(I) Refractive index nd, ng, nF, nC and Abbe number νd
The refractive indexes nd, ng, nF, and nC of the above annealed sample were measured by the refractive index measurement method of JIS standard JIS B 7071-1, and the Abbe number νd was calculated based on the following formula.
νd = (nd-1) / (nF-nC)

(Ii) Partial dispersion ratio Pg, F
The partial dispersion ratios Pg and F were calculated based on the following formulas using the refractive indexes ng, nF and nC of the g-line, F-line and c-line.
Pg, F = (ng-nF) / (nF-nC)

(Iii) Deviation ΔPg, F of partial dispersion ratio Pg, F
It was calculated based on the following formula using the partial dispersion ratios Pg and F and the Abbe number νd.
ΔPg, F = Pg, F + (0.0018 × νd) -0.6483

(Iv) Specific gravity The specific gravity was measured by the Archimedes method.

(V) Liquid phase temperature LT
The glass was placed in a furnace heated to a predetermined temperature and held for about 2 hours, and after cooling, the inside of the glass was observed with an optical microscope of 40 to 100 times, and the liquidus temperature was determined from the presence or absence of crystals.

(Vi) Glass transition temperature Tg
The glass transition temperature Tg was measured at a heating rate of 10 ° C./min using a differential scanning calorimetry device (DSC3300SA) manufactured by NETZSCH JAPAN.

(Vii) λ80, 70, λ5
The annealed sample was processed so as to have a plane having a thickness of 10 mm, parallel to each other and optically polished, and the spectral transmittance in the wavelength range from 280 nm to 700 nm was measured. The spectral transmittance B / A was calculated with the intensity of the light beam perpendicularly incident on one plane that was optically polished as the intensity A and the intensity of the light beam emitted from the other plane as the intensity B. The wavelength at which the spectral transmittance is 80% is λ80, the wavelength at which the spectral transmittance is 70% is λ70, and the wavelength at which the spectral transmittance is 5% is λ5. The spectral transmittance also includes the reflection loss of light rays on the sample surface.

(Example 2)
Using each optical glass produced in Example 1, a lens blank was produced by a known method, and the lens blank was processed by a known method such as polishing to produce various lenses.
The manufactured optical lenses are various lenses such as a biconvex lens, a biconcave lens, a plano-convex lens, a plano-concave lens, a concave meniscus lens, and a convex meniscus lens.
By combining various lenses with lenses made of other types of optical glass, secondary chromatic aberration could be satisfactorily corrected.

In addition, since glass has a low specific gravity, each lens is lighter in weight than a lens having the same optical characteristics and size, and is suitable for various imaging devices, especially for autofocus type imaging devices because it can save energy. is there. Similarly, a prism was produced using various optical glasses produced in Example 1.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

For example, the optical glass according to one aspect of the present invention can be produced by adjusting the composition described in the specification with respect to the glass composition exemplified above.
In addition, it is of course possible to arbitrarily combine two or more of the items described in the specification as an example or a preferable range.

Claims (7)

The content of SiO ₂ is 10 to 50% by mass,
The content of Nb ₂ O ₅ is 10 to 35 % by mass,
The total content of TiO _{2 and BaO [TiO 2} + BaO] is 10% by mass or less, and the total content is 10% by mass or less.
The mass ratio of the content of _B 2 _{O 3} to the content of _{SiO 2 [B 2 O 3 /} SiO 2] is 0.15 or less,
The BaO content is 5.0% by mass or less,
The content of Ta ₂ O ₅ is 2.0% by mass or less,
Mass ratio of the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 to} the total content of B ₂ O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO ₂ )] Is 0.92 or more and less than 1.7,
The content of ZrO ₂ is 6.29% by mass or more, and the content is 6.29% by mass or more.
The content of B ₂ O ₃ is 1.0% by mass or more,
The ZnO content is 2.0% by mass or less,
The refractive index nd is 1.69 to 1.77, and the refractive index nd is 1.69 to 1.77.
The Abbe number νd is 34 to 37,
Optical glass having ΔPg and F of −0.0015 or less. The content of SiO ₂ is 10 to 50% by mass,
The content of Nb ₂ O ₅ is 10 to 35 % by mass,
The total content of TiO _{2 and BaO [TiO 2} + BaO] is 10% by mass or less, and the total content is 10% by mass or less.
The mass ratio of the content of _B 2 _{O 3} to the content of _{SiO 2 [B 2 O 3 /} SiO 2] is 0.15 or less,
The BaO content is 3.0% by mass or less,
The content of Ta ₂ O ₅ is 2.0% by mass or less,
The total content of Li ₂ O, Na ₂ O and K _{2 O R 2} O [Li ₂ O + Na ₂ O + K ₂ O] is 25% by mass or less.
Mass ratio of the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 to} the total content of B ₂ O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO ₂ )] Is 0.8 or more and less than 1.7,
The content of ZrO ₂ is 6.29% by mass or more, and the content is 6.29% by mass or more.
The content of B ₂ O ₃ is 1.0% by mass or more,
The ZnO content is 2.0% by mass or less,
The refractive index nd is 1.69 to 1.77, and the refractive index nd is 1.69 to 1.77.
The Abbe number νd is 34 to 37,
Optical glass having ΔPg and F of −0.0015 or less. The content of SiO ₂ is 10 to 50% by mass,
The content of Nb ₂ O ₅ is 10 to 35 % by mass,
The total content of TiO _{2 and BaO [TiO 2} + BaO] is 10% by mass or less, and the total content is 10% by mass or less.
The mass ratio of the content of _B 2 _{O 3} to the content of _{SiO 2 [B 2 O 3 /} SiO 2] is 0.15 or less,
The BaO content is 5.0% by mass or less,
The content of Ta ₂ O ₅ is 2.0% by mass or less,
Mass ratio of the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 to} the total content of B ₂ O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO ₂ )] Is 0.8 or more and less than 1.7,
The mass ratio of the content _{of TiO 2} to the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 [TiO 2} / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ )] is greater than 0 and less than 0.3.
The content of ZrO ₂ is 6.29% by mass or more, and the content is 6.29% by mass or more.
The content of B ₂ O ₃ is 1.0% by mass or more,
The ZnO content is 2.0% by mass or less,
The refractive index nd is 1.69 to 1.77, and the refractive index nd is 1.69 to 1.77.
The Abbe number νd is 34 to 37,
Optical glass having ΔPg and F of −0.0015 or less. The optical glass according to any one of claims 1 to 3, which satisfies any one or more of (a) to (g).
(A) _{The content of La 2} O ₃ is 15% by mass or less.
(B) the mass ratio of the content of ZrO ₂ to the content of _{Nb 2 O 5 [ZrO 2 /} Nb 2 O 5] is greater than 0.1.
(C) Mass ratio of the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 to} the total content of _{B 2} O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO) ₂ )] is smaller than 1.7.
(D) _{The mass ratio [R'O / R 2} O] of the total content R'O of MgO, CaO, SrO and BaO to the total content R _{2 O of Li 2} O, Na ₂ O and K _{2 O is 5} It is as follows.
(E) The mass ratio of the content _{of Ta 2} O ₅ to the total content of _{Nb 2} O ₅ and TiO _{2 [Ta 2} O ₅ / (Nb ₂ O ₅ + TiO ₂ )] is 0.15 or less.
(F) The mass ratio of the content _{of TiO 2} to the total content of _{Nb 2} O ₅ , TiO ₂ and ZrO _{2 [TiO 2} / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ )] is greater than 0 and less than 0.3. ..
(G) The total content R _{2 O of Li 2} O, Na ₂ O and K ₂ O is larger than 0% by mass. The specific gravity is 3.45 or less,
The deviation ΔPg, F of the partial dispersion ratios Pg and F is −0.0015 or less, and
The liquidus temperature LT is 1250 ° C or lower,
When heated at the glass transition temperature Tg for 10 minutes and further heated at a temperature 180 to 200 ° C. higher than the Tg for 10 minutes, the number of crystals observed per 1 g is 20 or less.
The refractive index nd is 1.69 to 1.77, and the refractive index nd is 1.69 to 1.77.
The Abbe number νd is 34 to 37,
The content of Nb ₂ O ₅ is 10 to 35% by mass,
The mass ratio of the content of _B 2 _{O 3} to the content of _{SiO 2 [B 2 O 3 /} SiO 2] is 0.15 or less,
The content of ZrO ₂ is 6.29% by mass or more, and the content is 6.29% by mass or more.
The content of B ₂ O ₃ is 1.0% by mass or more,
The ZnO content is 2.0% by mass or less,
An optical glass that satisfies any of (1) to (3).
(1) The content of BaO is 5.0% by mass or less, and the content is 5.0% by mass or less.
The content of Ta ₂ O ₅ is 2.0% by mass or less,
Mass ratio of the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 to} the total content of B ₂ O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO ₂ )] Is 0.92 or more and less than 1.7.
(2) The content of BaO is 3.0% by mass or less, and the content is 3.0% by mass or less.
The content of Ta ₂ O ₅ is 2.0% by mass or less,
The total content of Li ₂ O, Na ₂ O and K _{2 O R 2} O [Li ₂ O + Na ₂ O + K ₂ O] is 25% by mass or less.
Mass ratio of the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 to} the total content of B ₂ O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO ₂ )] Is 0.8 or more and smaller than 1.7.
(3) The content of BaO is 5.0% by mass or less, and the content is 5.0% by mass or less.
The content of Ta ₂ O ₅ is 2.0% by mass or less,
Mass ratio of the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 to} the total content of B ₂ O ₃ and SiO _{2 [(Nb 2} O ₅ + TiO ₂ + ZrO ₂ ) / (B ₂ O ₃ + SiO ₂ )] Is 0.8 or more and less than 1.7,
The mass ratio of the content _{of TiO 2} to the total content of Nb ₂ O ₅ , TiO ₂ and ZrO _{2 [TiO 2} / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ )] is greater than 0 and less than 0.3. The optical glass according to claim 1 to 5, wherein the content of La ₂ O _{3 is 4.70% by mass or less.} An optical element made of optical glass according to any one of claims 1 to 6.