Optical glass and optical element

Abstract

To provide optical glass having superior thermal stability.SOLUTION: An optical glass comprises, on a mass basis, La2O3 content of 43.40% or more and 65.00% or less, (SiO2+B2O3) of 19.60% or less, (TiO2+Nb2O5+WO3+Ta2O5) of 20.00% or less, (SiO2 / B2O3) of 0.168 or more to 1.510 or less, (Ln2O3 / B2O3) of 5.100 or more, (Ln2O3-Nb2O5-ZrO2-TiO2-WO3-Ta2O5) of 34.20% or more, (TiO2 / (SiO2+B2O3)) of 0.081 or more,((Nb2O5+ZrO2+WO3) / TiO2) of 2.010 or more, and (Ln2O3 / (Ln2O3+SiO2+B2O3)) of 0.457x+0.396 or more, wherein x is (Ln2O3 / (Nb2O5+TiO2+WO3+Ln2O3)).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to optical glass and optical elements.

Background Art

[0002] Optical glass is useful as a material for optical elements such as lenses (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Desirable physical properties of optical glass include excellent thermal stability. Glass with excellent thermal stability is desirable from the viewpoint of maintaining the formability of the glass.

[0005] One aspect of the present invention aims to provide optical glass with excellent thermal stability.

Means for Solving the Problems

[0006] One aspect of the present invention is as follows. [1] On a mass basis, La 2 O 3 content is 43.40% or more and 65.00% or less, SiO 2 and B 2 O 3 total content with (SiO 2 + B 2 O 3 ) is 19.60% or less, TiO 2 , Nb 2 O 5 , WO 3 and Ta 2O 5 Total content of (TiO 2 + Nb 2 O 5 + WO 3 + Ta 2 O 5 ) is 20.00% or less, B 2 O 3 Mass ratio of SiO content to B 2 O content (SiO 2 / B 2 O 3 ) is 0.168 or more and 1.510 or less, Rare earth oxides (La 2 O 3 , Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 ) are denoted as Ln 2 O 3 , Ln 2 O 3 content is the total content of La 2 O 3 , Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 ), i.e., (La 2 O 3 + Gd 2 O 3 + Y 2 O 3 + Yb 2 O 3 ), and B 2 O 3 Mass ratio of Ln 2 O 3 content to B 2 O 3 content (Ln 2 O 3 / B Ln 2 O 3 content minus Nb 2 O 5 content, ZrO 2 content, TiO 2Content, WO 3 Content and Ta 2 O 5 The value obtained by subtracting the content (Ln 2 O 3 -Nb 2 O 5 -ZrO 2 -TiO 2 -WO 3 -Ta 2 O 5 ) is 34.20% or more, SiO 2 and B 2 O 3 The mass ratio of the TiO 2 content to the total content of SiO 2 / (SiO 2 +B 2 O 3 )) is 0.081 or more, TiO 2 The mass ratio of the Nb 2 O 5 , ZrO 2 and WO 3 total content to TiO 2 O 5 +ZrO 2 +WO 3 ) / TiO 2 ) is 2.010 or more, and Ln 2 O 3 , SiO 2 and B 2 O 3 The mass ratio of the Ln 2 O 3 content to the total content of Ln 2 O 3 / (Ln 2 O 3 +SiO 2 +B 2 O 3 )) is 0.457x + 0.396 or more, x is the Ln 2 O 5 , TiO 2 , WO 3 and Ln 2 O 3 total content to Ln 2 O 3The mass ratio of the content (Ln 2 O 3 / (Nb 2 O 5 +TiO 2 +WO 3 +Ln 2 O 3 )) is an optical glass. [2] The mass ratio of the content of Nb 2 to SiO 2 O 3 and B 2 O 5 to the total content of Nb 2 O 5 / (SiO 2 +B 2 O 3 )) is 0.200 or more and 0.900 or less, and the optical glass according to [1]. [3] The mass ratio of the content of Nb 2 O 5 to the total content of TiO 2 and WO 3 is 0.200 or more and 1.000 or less, and the optical glass according to [1] or [2]. 2 O 5 The mass ratio of the content of Nb 2 O 5 / (Nb 2 O 5 +TiO 2 +WO 3 )) is 0.200 or more and 1.000 or less, and the optical glass according to [1] or [2]. [4] The content of Ta 2 O 5 is 0.00% or more and 15.00% or less, and the optical glass according to any one of [1] to [3]. [5] The mass ratio of the total content of La 2 O 3 and Gd 2 O 3 to the total content of La 2 O 3 and Y 2 O 3 is ((La 2 O 3 +Y 2 O 3 ) / (La 2 O 3 +Gd 2 O 3The optical glass according to any one of [1] to [4], wherein ()) is 0.500 or more and 1.500 or less. [6] The refractive index nd is 1.89000 or more and 2.05000 or less, and The optical glass according to any one of [1] to [5], wherein the Abbe number νd is 25.00 or more and 45.00 or less. [7] The optical glass according to any one of [1] to [6], wherein the specific gravity is 5.30 or less. [8] The optical glass according to any one of [1] to [7], wherein the glass transition temperature Tg is 800 ° C or less. [9] The optical glass according to any one of [1] to [8], wherein the liquidus temperature is 1400 ° C or less.

[10] SiO 2 and B 2 O 3 The mass ratio of the content of Nb 2 O 5 to the total content of (Nb 2 O 5 / (SiO 2 + B 2 O 3 )) is 0.200 or more and 0.900 or less, Nb 2 O 5 , TiO 2 and WO 3 The mass ratio of the content of Nb 2 O 5 to the total content of (Nb 2 O 5 / (Nb 2 O 5 + TiO 2 + WO 3 )) is 0.200 or more and 1.000 or less, Ta 2 O 5 The content is 0.00% or more and 15.00% or less, La 2 O 3 and Gd 2 O 3 The mass ratio of the content of La 2 O 3 and Y 2 O 3 to the total content of ((La 2 O3 +Y 2 O 3 ) / (La 2 O 3 +Gd 2 O 3 )) is 0.500 or more and 1.500 or less, the refractive index nd is 1.89000 or more and 2.05000 or less, the Abbe number νd is 25.00 or more and 45.00 or less, the specific gravity is 5.30 or less, the glass transition temperature Tg is 800 °C or less, and the liquidus temperature is 1400 °C or less, the optical glass according to any one of [1] to [9].

[11] [1] An optical element made of the optical glass according to any one of [1] to

[10] . [Advantages of the Invention]

[0007] According to one aspect of the present invention, an optical glass excellent in thermal stability can be provided. Further, according to one aspect of the present invention, an optical element made of such an optical glass can also be provided. [Modes for Carrying Out the Invention]

[0008] [Optical Glass] [Glass Composition] In the present invention and this specification, the glass composition is expressed as a glass composition on an oxide basis. Here, the "glass composition on an oxide basis" means a glass composition obtained by converting all the glass raw materials into oxides present in the glass when melted. Further, unless otherwise specified, the glass composition is expressed on a mass basis (mass%, mass ratio). The glass composition of the present invention and in this specification can be determined by a method such as ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Quantitative analysis is performed for each element using ICP-AES. Thereafter, the analysis values are converted into oxide notation. The analysis values by ICP-AES may include a measurement error of about ±5% of the analysis values, for example. Therefore, the values in oxide notation converted from the analysis values may also include an error of about ±5% similarly. Also, in the present invention and in this specification, that the content of a constituent component is 0.0% or not included or not introduced means that this constituent component is substantially not included, and refers to that the content of this constituent component is at or below the impurity level. At or below the impurity level means, for example, less than 0.01%.

[0009] Hereinafter, the glass composition of the above optical glass (also simply referred to as "glass") will be described in more detail.

[0010] SiO 2 and B 2 O 3 are components that function to improve the thermal stability. SiO 2 and B 2 O 3 The total content of (SiO 2 +B 2 O 3 ) is 19.60% or less from the viewpoint of maintaining a high refractive index of the glass, preferably 19.50% or less, more preferably 19.40% or less, 19.30% or less, 19.20% or less, 19.10% or less, 19.00% or less, 18.90% or less, 18.80% or less, 18.70% or less, 18.60% or less, 18.50% or less, 18.40% or less, 18.30% or less, 18.20% or less, 18.10% or less, 18.00% or less, 17.90% or less, 17.80% or less, 17.70% or less, 17.60% or less, 17.50% or less, 17.40% or less, 17.30% or less, 17.20% or less, 17.10% or less, 17.00% or less in this order. From the viewpoint of maintaining the thermal stability of the glass, the total content (SiO 2 +B 2 O 3 ) is preferably 5.00% or more, more preferably 5.50% or more, 6.00% or more, 6.50% or more, 7.00% or more, 7.50% or more, 8.00% or more, 8.50% or more, 9.00% or more, 9.50% or more, 10.00% or more, 10.50% or more in this order.

[0011] B 2 O 3 The mass ratio (SiO 2 content / B 2 O 2 content) (SiO 3 / B 2 O 2 content) is 1.510 or less, preferably 1.500 or less, more preferably 1.480 or less, 1.450 or less, 1.420 or less, 1.400 or less, 1.380 or less, 1.350 or less, 1.320 or less, 1.300 or less, 1.280 or less, 1.250 or less, 1.220 or less, 1.200 or less, 1.180 or less, 1.150 or less, 1.120 or less, 1.100 or less, 1.090 or less, 1.080 or less, 1.070 or less, 1.060 or less, 1.050 or less, 1.040 or less, 1.030 or less, 1.020 or less, 1.010 or less, 1.000 or less, 0.990 or less, 0.980 or less in this order from the viewpoints of maintaining the thermal stability of the glass and maintaining a high refractive index. The mass ratio (SiO 2 / B 2 O 3 content) is 0.168 or more, preferably 0.170 or more, more preferably 0.190 or more, 0.210 or more, 0.230 or more, 0.250 or more, 0.270 or more, 0.290 or more, 0.310 or more, 0.330 or more, 0.350 or more, 0.370 or more, 0.400 or more in this order from the viewpoint of maintaining the thermal stability of the glass.

[0012] SiO 2The content is preferably 20.00% or less, more preferably 19.00% or less, 18.00% or less, 17.00% or less, 16.00% or less, 15.00% or less, 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.50% or less, 10.00% or less, 9.50% or less, 9.00% or less, from the viewpoint of maintaining the high refractive index of the glass. SiO 2 The content can be more than 0.00%, and is preferably 0.50% or more, more preferably 1.00% or more, 1.50% or more, 2.00% or more, 2.50% or more, 3.00% or more, 3.50% or more, 4.00% or more, from the viewpoint of maintaining the thermal stability of the glass.

[0013] B 2 O 3 The content is preferably 20.00% or less, more preferably 19.00% or less, 18.00% or less, 17.00% or less, 16.00% or less, 15.50% or less, 15.00% or less, 14.50% or less, 14.00% or less, 13.50% or less, 13.00% or less, 12.50% or less, 12.00% or less, 11.90% or less, 11.80% or less, 11.70% or less, 11.60% or less, from the viewpoint of maintaining the high refractive index of the glass. B 2 O 3 The content can be more than 0.00%, and is preferably 1.00% or more, more preferably 2.00% or more, 3.00% or more, 4.00% or more, 5.00% or more, 6.00% or more, 6.50% or more, 7.00% or more, 7.50% or more, 8.00% or more, from the viewpoint of maintaining the thermal stability of the glass.

[0014] La 2 O 3The content is 65.00% or less, preferably 64.50% or less, more preferably 64.00% or less, 63.50% or less, 63.00% or less, 62.50% or less, 62.00% or less, 61.50% or less, 61.00% or less, 60.50% or less, 60.00% or less, 59.50% or less, 59.00% or less, 58.50% or less, 58.00% or less, 57.50% or less, 57.00% or less, 56.50% or less, 56.00% or less from the viewpoint of maintaining the thermal stability of the glass. La 2 O 3 The content is 43.40% or more, preferably 43.70% or more, more preferably 43.90% or more, 44.10% or more, 44.30% or more, 44.50% or more, 44.70% or more, 44.90% or more, 45.10% or more, 45.30% or more, 45.50% or more, 45.70% or more, 45.90% or more, 46.10% or more, 46.30% or more, 46.50% or more from the viewpoint of maintaining the high refractive index and low dispersion of the glass.

[0015] In the present invention and this specification, rare earth oxides (La 2 O 3 , Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 ) are denoted as Ln 2 O 3 , and the content of Ln 2 O 3 is the total content of La 2 O 3 , Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 (La 2 O 3 +Gd 2 O 3 +Y 2 O 3 +Yb 2 O 3 ). In one embodiment, the rare earth oxide contained in the glass is La 2 O3 is only. In another embodiment, the rare earth oxide contained in the glass is Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 selected from the group consisting of one or more (one, two or three) and La 2 O 3 .

[0016] La 2 O 3 , Gd 2 O 3 , Y 2 O 3 and Yb 2 O 3 total content (La 2 O 3 +Gd 2 O 3 +Y 2 O 3 +Yb 2 O 3 ), that is, the Ln 2 O 3 content is preferably 43.50% or more, more preferably 44.00% or more, 45.00% or more, 46.00% or more, 47.00% or more, 48.00% or more, 49.00% or more, 50.00% or more, 51.00% or more, 52.00% or more, 53.00% or more, 54.00% or more, 55.00% or more, 56.00% or more, 57.00% or more, 58.00% or more from the viewpoint of maintaining the high refractive index and low dispersion of the glass. Ln 2 O 3 content is preferably 70.00% or less, more preferably 69.00% or less, 68.00% or less, 67.00% or less, 66.00% or less, 65.00% or less from the viewpoint of maintaining the thermal stability of the glass.

[0017] Gd 2 O 3 content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoint of maintaining the high refractive index and low dispersion of the glass, Gd 2 O 3The content is preferably 0.10% or more, more preferably 0.20% or more, 0.30% or more, 0.40% or more, 0.50% or more. From the viewpoint of maintaining the thermal stability of the glass, Gd 2 O 3 The content is preferably 20.00% or less, more preferably 19.00% or less, 18.00% or less, 17.00% or less, 16.00% or less, 15.50% or less, 15.00% or less, 14.50% or less, 14.00% or less, 13.50% or less, 13.00% or less, 12.50% or less, 12.00% or less in this order.

[0018] Y 2 O 3 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoint of maintaining the high refractive index and low dispersion of the glass, Y 2 O 3 The content is preferably 0.50% or more, more preferably 1.00% or more, 1.50% or more, 2.00% or more, 2.10% or more, 2.20% or more, 2.30% or more, 2.40% or more, 2.50% or more, 2.60% or more, 2.70% or more, 2.80% or more, 2.90% or more, 3.00% or more, 3.10% or more, 3.20% or more, 3.30% or more, 3.40% or more, 3.50% or more, 3.60% or more, 3.70% or more, 3.80% or more, 3.90% or more, 4.00% or more in this order. From the viewpoint of maintaining the thermal stability of the glass, Y 2 O 3The content is preferably 20.00% or less, more preferably 19.00% or less, 18.00% or less, 17.00% or less, 16.00% or less, 15.50% or less, 15.00% or less, 14.50% or less, 14.00% or less, 13.50% or less, 13.00% or less, 12.50% or less, 12.00% or less, 11.90% or less, 11.80% or less, 11.70% or less, 11.60% or less, 11.50% or less, 11.40% or less, 11.30% or less, 11.20% or less, 11.10% or less, 11.00% or less, 10.90% or less, 10.80% or less, 10.70% or less, 10.60% or less, 10.50% or less, 10.45% or less, 10.40% or less, 10.35% or less, 10.30% or less, 10.25% or less, 10.20% or less, 10.15% or less, 10.10% or less, 10.05% or less, 10.00% or less in this order.

[0019] Yb 2 O 3 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoint of maintaining the high refractive index and low dispersion of the glass, Yb 2 O 3 The content is preferably 0.10% or more, more preferably 0.20% or more, 0.30% or more, 0.40% or more, 0.50% or more. From the viewpoint of maintaining the thermal stability of the glass, Yb 2 O 3 The content is preferably 20.00% or less, more preferably 19.00% or less, 18.00% or less, 17.00% or less, 16.00% or less, 15.00% or less, 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.50% or less, 10.00% or less, 9.50% or less, 9.00% or less, 8.50% or less, 8.00% or less, 7.50% or less, 7.00% or less, 6.50% or less, 6.00% or less, 5.50% or less, 5.00% or less in this order.

[0020] La 2 O 3 and Gd 2 O 3 The content of La 2 O 3and Y 2 O 3 The mass ratio of the total content with ((La 2 O 3 +Y 2 O 3 )) / (La 2 O 3 +Gd 2 O 3 )) is preferably 0.500 or more, more preferably 0.520 or more, 0.540 or more, 0.560 or more, 0.580 or more, 0.600 or more, 0.620 or more, 0.640 or more, 0.660 or more, 0.680 or more, 0.700 or more, 0.710 or more, 0.720 or more, 0.730 or more, 0.740 or more, 0.750 or more, 0.760 or more, 0.770 or more, 0.780 or more, 0.790 or more, 0.800 or more, 0.810 or more, 0.820 or more, 0.830 or more, 0.840 or more, 0.850 or more, from the viewpoint of keeping the raw material cost low and maintaining the thermal stability of the glass. The mass ratio ((La 2 O 3 +Y 2 O 3 ) / (La 2 O 3 +Gd 2 O 3 )) is preferably 1.500 or less, more preferably 1.480 or less, 1.460 or less, 1.440 or less, 1.420 or less, 1.400 or less, 1.380 or less, 1.360 or less, 1.340 or less, 1.320 or less, 1.300 or less, 1.280 or less, 1.260 or less, 1.250 or less, 1.240 or less, 1.230 or less, 1.220 or less, 1.210 or less, 1.200 or less, 1.190 or less, from the viewpoints of maintaining the thermal stability of the glass and maintaining a high refractive index.

[0021] B 2 O 3 The mass ratio of the Ln 2 O 3 content to the B 2 O 3 content (Ln 2 O 3) is 5.100 or more, preferably 5.110 or more, more preferably 5.120 or more, 5.130 or more, 5.140 or more, 5.150 or more, 5.160 or more, 5.170 or more, 5.180 or more, 5.190 or more, 5.200 or more, 5.210 or more, 5.220 or more, 5.230 or more, 5.240 or more, 5.250 or more, 5.260 or more, 5.270 or more, 5.280 or more in order from the viewpoint of maintaining a high refractive index and low dispersion of the glass. Mass ratio (Ln 2 O 3 / B 2 O 3 ) is preferably 15.000 or less, more preferably 14.000 or less, 13.000 or less, 12.000 or less, 11.000 or less, 10.000 or less, 9.000 or less, 8.900 or less, 8.800 or less, 8.700 or less, 8.600 or less, 8.500 or less, 8.400 or less, 8.300 or less, 8.200 or less, 8.100 or less, 8.000 or less in order from the viewpoint of maintaining the thermal stability of the glass.

[0022] Ln 2 O 3 , SiO 2 and B 2 O 3 The mass ratio of the content of Ln 2 O 3 to the total content of Ln 2 O 3 / (Ln 2 O 3 +SiO 2 +B 2 O 3 )) is 0.457x + 0.396 or more, preferably 0.457x + 0.397 or more, more preferably 0.457x + 0.398 or more, 0.457x + 0.399 or more, 0.457x + 0.400 or more, 0.457x + 0.401 or more, 0.457x + 0.402 or more, 0.457x + 0.403 or more, 0.457x + 0.405 or more in order from the viewpoint of maintaining a high refractive index and low dispersion of the glass. The above "x" is Nb 2 O 5 , TiO 2 , WO 3 and Ln 2 O3 The mass ratio of Ln 2 O 3 content to the total content (Ln 2 O 3 / (Nb 2 O 5 +TiO 2 +WO 3 +Ln 2 O 3 )) is as follows. From the viewpoint of maintaining the thermal stability of the glass, the mass ratio (Ln 2 O 3 / (Ln 2 O 3 +SiO 2 +B 2 O 3 )) is preferably 0.457x + 0.470 or less, more preferably 0.457x + 0.469 or less, 0.457x + 0.468 or less, 0.457x + 0.467 or less, 0.457x + 0.466 or less, 0.457x + 0.465 or less, 0.457x + 0.464 or less, 0.457x + 0.463 or less, 0.457x + 0.462 or less, 0.457x + 0.461 or less, 0.457x + 0.460 or less in this order.

[0023] Ln 2 O 3 content minus the values of Nb 2 O 5 content, ZrO 2 content, TiO 2 content, WO 3 content and Ta 2 O 5 content ((Ln 2 O 3 -Nb 2 O 5 -ZrO 2 -TiO 2 -WO 3 -Ta 2 O 5) is, from the viewpoint of maintaining the low dispersion of the glass, 34.20% or more, preferably 34.50% or more, more preferably 34.70% or more, 34.90% or more, 35.10% or more, 35.30% or more, 35.50% or more, 35.70% or more, 35.90% or more, 36.10% or more, 36.30% or more, 36.50% or more, 36.70% or more, 36.90% or more, 37.10% or more, 37.30% or more, 37.50% or more, 37.70% or more, 37.90% or more, 38.10% or more, 38.30% or more, 38.50% or more, 38.70% or more, 38.90% or more, 39.10% or more, 39.30% or more, 39.50% or more, 39.70% or more, 39.90% or more, 40.00% or more in this order. From the viewpoints of maintaining the thermal stability of the glass and maintaining the high refractive index, the above value (Ln 2 O 3 -Nb 2 O 5 -ZrO 2 -TiO 2 -WO 3 -Ta 2 O 5 ) is preferably 60.00% or less, more preferably 59.00% or less, 58.00% or less, 57.00% or less, 56.00% or less, 55.00% or less, 54.00% or less, 53.00% or less, 52.00% or less, 51.00% or less, 50.00% or less, 49.00% or less, 48.00% or less in this order.

[0024] Ln 2 O 3 content, from the TiO 2 content, Nb 2 O 5 content, WO 3 content and Ta 2 O 5 content, the value obtained by subtracting the (Ln 2 O 3 -TiO 2 -Nb 2 O 5 -WO 3 -Ta 2 O 5) is preferably 32.00% or more, more preferably 32.50% or more, 33.00% or more, 33.50% or more, 34.00% or more, 34.50% or more, 35.00% or more, 35.50% or more, 36.00% or more, 36.50% or more, 37.00% or more, 37.50% or more, 38.50% or more, 39.00% or more, 39.20% or more, 39.40% or more, 39.60% or more, 39.80% or more, 40.00% or more, 40.20% or more, 40.40% or more, 40.60% or more, 40.80% or more, 41.00% or more in terms of maintaining the low dispersion of the glass. From the viewpoints of maintaining the thermal stability of the glass and maintaining the high refractive index, the above value (Ln 2 O 3 -TiO 2 -Nb 2 O 5 -WO 3 -Ta 2 O 5 ) is preferably 65.00% or less, more preferably 64.00% or less, 63.00% or less, 62.00% or less, 61.00% or less, 60.00% or less, 59.00% or less, 58.00% or less, 57.00% or less, 56.00% or less, 55.00% or less, 54.00% or less, 53.00% or less in terms of maintaining the thermal stability of the glass and maintaining the high refractive index.

[0025] Ln 2 O 3 The value obtained by subtracting the Nb 2 O 5 content, ZrO 2 content, ZnO content, TiO 2 content, WO 3 content and Ta 2 O 5 content from the Ln 2 O 3 -Nb 2 O 5 -ZrO 2 -ZnO-TiO 2 -WO 3 -Ta 2 O 5) is preferably 30.00% or more, more preferably 30.50% or more, 31.00% or more, 31.50% or more, 32.00% or more, 32.50% or more, 33.00% or more, 33.50% or more, 34.000% or more, 34.50% or more, from the viewpoint of maintaining low dispersion of the glass. From the viewpoints of maintaining the thermal stability of the glass and maintaining high refractive index, the above value (Ln 2 O 3 -Nb 2 O 5 -ZrO 2 -ZnO-TiO 2 -WO 3 -Ta 2 O 5 ) is preferably 60.00% or less, more preferably 59.0% or less, 58.0% or less, 57.0% or less, 56.0% or less, 55.0% or less, 54.0% or less, 53.0% or less, 52.0% or less, 51.0% or less, 50.0% or less, 49.0% or less, 48.0% or less, 47.0% or less, 46.0% or less, 45.0% or less, 44.0% or less.

[0026] SiO 2 and B 2 O 3 The mass ratio of the value obtained by subtracting the contents of Nb 2 O 3 content, ZrO 2 O 5 content, ZnO content, TiO 2 content, WO 2 content, and Ta 3 content and Ta 2 O 5 content from the content of Ln 2 O 3 -Nb 2 O 5 -ZrO 2 -ZnO-TiO 2 -WO 3 -Ta 2 O 5 ) / (SiO 2 + B 2 O 3)) is preferably 1.900 or more, more preferably 1.910 or more, 1.920 or more, 1.930 or more, 1.940 or more, 1.950 or more, 1.960 or more, 1.970 or more, 1.980 or more, 1.990 or more, 2.000 or more, 2.010 or more in order, from the viewpoint of maintaining the low dispersion of the glass. From the viewpoints of maintaining the thermal stability of the glass and maintaining the high refractive index, the mass ratio ((Ln 2 O 3 -Nb 2 O 5 -ZrO 2 -ZnO-TiO 2 -WO 3 -Ta 2 O 5 ) / (SiO 2 +B 2 O 3 )) is preferably 5.000 or less, more preferably 4.500 or less, 4.000 or less, 3.900 or less, 3.800 or less, 3.700 or less, 3.600 or less, 3.500 or less, 3.400 or less, 3.300 or less, 3.200 or less, 3.100 or less in order.

[0027] SiO 2 and B 2 O 3 The mass ratio of the Nb 2 O 5 content to the total content of SiO 2 O 5 / (SiO 2 +B 2 O 3 )) is preferably 0.100 or more, more preferably 0.150 or more, 0.170 or more, 0.190 or more, 0.200 or more, 0.220 or more, 0.240 or more, 0.260 or more, 0.270 or more, 0.280 or more, 0.290 or more, 0.300 or more, 0.310% or more, 0.320% or more, 0.330%, 0.340% or more, 0.350% or more in order, from the viewpoint of increasing the refractive index of the glass. From the viewpoint of maintaining the low dispersion of the glass, the mass ratio (Nb 2 O 5 / (SiO 2 +B 2 O 3)) is preferably 0.900 or less, more preferably 0.880 or less, 0.860 or less, 0.840 or less, 0.820 or less, 0.800 or less, 0.790 or less, 0.780 or less, 0.770 or less, 0.760 or less, 0.750 or less, 0.740 or less, 0.730 or less, 0.720 or less, 0.710 or less, 0.700 or less, 0.690 or less, 0.680 or less in this order.

[0028] SiO 2 and B 2 O 3 The mass ratio of the content of TiO 2 to the total content of 2 / (SiO 2 +B 2 O 3 )) is 0.081 or more from the viewpoint of increasing the refractive index of the glass, preferably 0.085 or more, more preferably 0.090 or more, 0.095 or more, 0.100 or more, 0.105 or more, 0.110 or more, 0.115 or more, 0.120 or more, 0.125 or more, 0.130 or more, 0.135 or more, 0.140 or more, 0.143 or more, 0.146 or more, 0.149 or more, 0.151 or more, 0.154 or more, 0.157 or more, 0.160 or more, 0.163 or more, 0.166 or more, 0.169 or more, 0.172 or more, 0.175 or more, 0.178 or more, 0.181 or more, 0.184 or more, 0.187 or more, 0.190 or more in this order. From the viewpoint of maintaining low dispersion of the glass, the mass ratio (TiO 2 / (SiO 2 +B 2 O 3 )) is preferably 0.800 or less, more preferably 0.780 or less, 0.760 or less, 0.740 or less, 0.720 or less, 0.700 or less, 0.680 or less, 0.660 or less, 0.640 or less, 0.620 or less, 0.600 or less, 0.580 or less, 0.560 or less, 0.540 or less, 0.520 or less, 0.510 or less, 0.500 or less, 0.490 or less, 0.480 or less, 0.470 or less, 0.460 or less, 0.450 or less, 0.440 or less, 0.430 or less, 0.420 or less, 0.410 or less in this order.

[0029] SiO2 and B 2 O 3 The mass ratio of NbO with respect to the total content of 2 O 5 , TiO 2 , WO 3 and Ta 2 O 5 ((NbO 2 O 5 +TiO 2 +WO 3 +Ta 2 O 5 ) / (SiO 2 +B 2 O 3 )) is preferably 0.100 or more, more preferably 0.150 or more, 0.200 or more, 0.250 or more, 0.300 or more, 0.350 or more, 0.400 or more, 0.450 or more, 0.500 or more, 0.550 or more, 0.600 or more, 0.610 or more, 0.620 or more, 0.630 or more, 0.640 or more, 0.650 or more, 0.660 or more, 0.670 or more, 0.680 or more, 0.690 or more, 0.700 or more, from the viewpoint of maintaining a high refractive index of the glass. From the viewpoint of maintaining a low dispersion of the glass, the mass ratio ((Nb 2 O 5 +TiO 2 +WO 3 +Ta 2 O 5 ) / (SiO 2 +B 2 O 3 )) is preferably 3.000 or less, more preferably 2.800 or less, 2.600 or less, 2.400 or less, 2.200 or less, 2.000 or less, 1.900 or less, 1.800 or less, 1.700 or less, 1.600 or less, 1.500 or less, 1.400 or less, 1.300 or less, 1.200 or less, 1.100 or less, 1.000 or less, from the viewpoint of maintaining a low dispersion of the glass.

[0030] B 2 O 3 The mass ratio of NbO with respect to the content of 2 O 5 , TiO 2 , WO 3 and Ta 2 O 5The mass ratio of the total content ((Nb 2 O 5 +TiO 2 +WO 3 +Ta 2 O 5 ) / B 2 O 3 ) is preferably 0.500 or more, more preferably 0.550 or more, 0.600 or more, 0.650 or more, 0.700 or more, 0.750 or more, 0.800 or more, 0.850 or more, 0.900 or more, 0.950 or more, 1.000 or more, 1.050 or more, 1.100 or more, from the viewpoint of maintaining a high refractive index of the glass. From the viewpoint of maintaining low dispersion of the glass, the mass ratio ((Nb 2 O 5 +TiO 2 +WO 3 +Ta 2 O 5 ) / B 2 O 3 ) is preferably 3.000 or less, more preferably 2.800 or less, 2.600 or less, 2.400 or less, 2.200 or less, 2.000 or less, 1.900 or less, 1.850 or less, 1.800 or less, 1.750 or less, in that order.

[0031] Ln 2 O 3 、SiO 2 、B 2 O 3 、Nb 2 O 5 、TiO 2 、WO 3 and Ta 2 O 5 The mass ratio of the total content of Ln 2 O 3 、SiO 2 and B 2 O 3 ((Ln 2 O 3 +SiO 2 +B 2 O 3 ) / (Ln 2 O 3 +SiO 2 +B 2 O 3+Nb 2 O 5 +TiO 2 +WO 3 +Ta 2 O 5 )) is preferably 0.150 or more, more preferably 0.200 or more, 0.250 or more, 0.300 or more, 0.350 or more, 0.400 or more, 0.450 or more, 0.500 or more, 0.550 or more, 0.600 or more, 0.610 or more, 0.620 or more, 0.630 or more, 0.640 or more, 0.650 or more, 0.660 or more, 0.670 or more, 0.680 or more, 0.690 or more, 0.700 or more, 0.710 or more, 0.720 or more, 0.730 or more, 0.740 or more, 0.750 or more, 0.760 or more, 0.770 or more, 0.780 or more, 0.790 or more, 0.800 or more, 0.810 or more, 0.820 or more, from the viewpoint of maintaining a high refractive index of the glass. From the viewpoint of maintaining low dispersion of the glass, the mass ratio ((Ln 2 O 3 +SiO 2 +B 2 O 3 ) / (Ln 2 O 3 +SiO 2 +B 2 O 3 +Nb 2 O 5 +TiO 2 +WO 3 +Ta 2 O 5)(()) is preferably 3,000 or less, more preferably 2,950 or less, 2,900 or less, 2,850 or less, 2,800 or less, 2,750 or less, 2,700 or less, 2,650 or less, 2,600 or less, 2,550 or less, 2,500 or less, 2,450 or less, 2,400 or less, 2,350 or less, 2,300 or less, 2,250 or less, 2,200 or less, 2,150 or less, 2,100 or less, 2,050 or less, 2,000 or less, 1,950 or less, 1,900 or less, 1,850 or less, 1,800 or less, 1,750 or less, 1,700 or less, 1,650 or less, 1,600 or less, 1,550 or less, 1,500 or less, 1,450 or less, 1,400 or less, 1,350 or less, 1,300 or less, 1,250 or less, 1,200 or less, 1,150 or less, 1,100 or less, 1,050 or less, 1,000 or less, 0,950 or less, 0,900 or less, 0,890 or less, 0,880 or less, in that order.

[0032] TiO 2 The Nb with respect to the content 2 O 5 The mass ratio of the content (Nb 2 O 5 / TiO 2 ) is preferably 0.500 or more, more preferably 0.600 or more, 0.700 or more, 0.800 or more, 0.900 or more, 0.950 or more, 1.000 or more, 1.05 or more, 1.100 or more, in that order, from the viewpoint of maintaining the low dispersion of the glass. From the viewpoint of maintaining the thermal stability of the glass, the mass ratio (Nb 2 O 5 / TiO 2 ) is preferably 15,000 or less, more preferably 14,000 or less, 13,000 or less, 12,000 or less, 11,000 or less, 10,500 or less, 10,000 or less, 9,500 or less, 9,000 or less, 8,500 or less, 8,000 or less, 7,500 or less, 7,000 or less, 6,800 or less, 6,600 or less, 6,400 or less, 6,200 or less, 6,000 or less, 5,900 or less, 5,800 or less, 5,700 or less, 5,600 or less, 5,500 or less, in that order.

[0033] Nb 2 O 5, TiO 2 and WO 3 The mass ratio of Nb 2 O 5 content to the total content of (Nb 2 O 5 / (Nb 2 O 5 +TiO 2 +WO 3 )) is preferably 0.200 or more, more preferably 0.220 or more, 0.240 or more, 0.260 or more, 0.280 or more, 0.300 or more, 0.320 or more, 0.340 or more, 0.360 or more, 0.380 or more, 0.400 or more, 0.420 or more, 0.440 or more, 0.460 or more, 0.480 or more, 0.500 or more, 0.510 or more, 0.520 or more, from the viewpoint of maintaining the high refractive index of the glass. From the viewpoint of maintaining the low dispersion of the glass, the mass ratio (Nb 2 O 5 / (Nb 2 O 5 +TiO 2 +WO 3 )) is preferably 1.000 or less, more preferably 0.980 or less, 0.960 or less, 0.940 or less, 0.920 or less, 0.900 or less, 0.880 or less, 0.860 or less, 0.840 or less, 0.820 or less, 0.800 or less, 0.790 or less, 0.780 or less, 0.770 or less, 0.760 or less, 0.750 or less, 0.740 or less, 0.720 or less, 0.700 or less, in this order.

[0034] TiO 2 The mass ratio of the total content of Nb 2 O 5 to TiO 2 and ZrO 2 O 5 +ZrO 2 ) / TiO 2) is preferably 2.010 or more, more preferably 2.090 or more, 2.100 or more, 2.110 or more, 2.120 or more, 2.130 or more, 2.140 or more, 2.150 or more, 2.160 or more, 2.170 or more, 2.180 or more, 2.190 or more, 2.200 or more, 2.210 or more, 2.220 or more, 2.230 or more, 2.240 or more, 2.250 or more, 2.260 or more, 2.270 or more, from the viewpoints of maintaining the thermal stability of the glass and maintaining low dispersion. From the viewpoint of maintaining the thermal stability of the glass, the mass ratio ((Nb 2 O 5 +ZrO 2 ) / TiO 2 ) is preferably 100.000 or less, more preferably 85.000 or less, 70.000 or less, 55.000 or less, 40.000 or less, 25.000 or less, 18.400 or less, 18.000 or less, 17.600 or less, 17.200 or less, 16.800 or less, 16.400 or less, 16.000 or less, 15.600 or less, 15.200 or less, 14.800 or less, 14.400 or less, 14.000 or less, 13.600 or less, 13.200 or less, 12.800 or less, 12.400 or less, 12.000 or less, 11.800 or less, 11.600 or less, 11.400 or less, 11.200 or less, 11.000 or less, 10.800 or less, 10.600 or less, 10.400 or less, 10.200 or less, 10.000 or less, 9.800 or less, 9.600 or less, 9.400 or less, 9.200 or less, 8.800 or less, 8.600 or less, 8.400 or less, 8.200 or less, 8.000 or less, 7.800 or less, 7.600 or less, 7.400 or less, 7.200 or less, 7.000 or less, 6.800 or less, 6.600 or less, 6.400 or less, 6.200 or less, 6.000 or less, 5.800 or less, 5.600 or less, 5.400 or less, in this order.

[0035] TiO 2 The mass ratio of the total content of Nb 2 O 5 , ZrO 2 and ZnO to the TiO 2 O 5 +ZrO 2 +ZnO) / TiO 2) is preferably 2.010 or more, more preferably 2.090 or more, 2.100 or more, 2.110 or more, 2.120 or more, 2.130 or more, 2.140 or more, 2.150 or more, 2.160 or more, 2.170 or more, 2.180 or more, 2.190 or more, 2.200 or more, 2.210 or more, 2.220 or more, 2.230 or more, 2.240 or more, 2.250 or more, 2.260 or more, 2.270 or more, 2.280 or more, 2.290 or more, 2.300 or more, 2.310 or more, 2.320 or more, 2.330 or more, 2.340 or more, 2.350 or more, 2.360 or more, 2.370 or more, from the viewpoints of maintaining the thermal stability of the glass and maintaining low dispersion. From the viewpoint of maintaining the thermal stability of the glass, the mass ratio ((Nb 2 O 5 +ZrO 2 +ZnO) / TiO 2 ) is preferably 100.000 or less, more preferably 85.000 or less, 70.000 or less, 55.000 or less, 40.000 or less, 25.000 or less, 18.400 or less, 18.000 or less, 17.600 or less, 17.200 or less, 16.800 or less, 16.400 or less, 16.000 or less, 15.600 or less, 15.200 or less, 14.800 or less, 14.400 or less, 14.000 or less, 13.600 or less, 13.200 or less, 12.800 or less, 12.400 or less, 12.000 or less, 11.800 or less, 11.600 or less, 11.400 or less, 11.200 or less, 11.000 or less, 10.800 or less, 10.600 or less, 10.400 or less, 10.200 or less, 10.000 or less, 9.800 or less, 9.600 or less, 9.400 or less, 9.200 or less, 8.800 or less, 8.600 or less, 8.400 or less, 8.200 or less, 8.000 or less, 7.800 or less, 7.600 or less, 7.400 or less, 7.200 or less, 7.000 or less, 6.800 or less.

[0036] TiO 2 content of Nb 2 O 5 、ZrO 2 、ZnO、TiO 2 、Ta 2 O 5 and WO3 The mass ratio of the total content ((Nb 2 O 5 +ZrO 2 +ZnO+TiO 2 +Ta 2 O 5 +WO 3 ) / TiO 2 ) is preferably 2.0×10 or more, more preferably 2.2×10 or more, 2.4×10 or more, 2.6×10 or more, 2.8×10 or more, 3.0×10 or more, 3.2×10 or more, 3.22×10 or more, 3.23×10 or more, 3.24×10 or more, 3.25×10 or more, 3.26×10 or more, 3.27×10 or more, 3.28×10 or more, 3.29×10 or more, 3.30×10 or more, 3.31×10 or more, 3.32×10 or more, 3.33×10 or more, 3.34×10 or more, 3.35×10 or more, 3.36×10 or more, 3.37×10 or more, 3.38×10 or more, 3.39×10 or more, 3.40×10 or more, from the viewpoints of maintaining the thermal stability of the glass and maintaining low dispersion. From the viewpoint of maintaining the thermal stability of the glass, the mass ratio ((Nb 2 O 5 +ZrO 2 +ZnO+TiO 2 +Ta 2 O 5 +WO 3 ) / TiO 2 ) is preferably 100.000 or less, more preferably 85.000 or less, 70.000 or less, 55.000 or less, 40.000 or less, 25.000 or less, 18.400 or less, 18.000 or less, 17.600 or less, 17.200 or less, 16.800 or less, 16.400 or less, 16.000 or less, 15.600 or less, 15.200 or less, 14.800 or less, 14.400 or less, 14.000 or less, 13.600 or less, 13.200 or less, 12.800 or less, 12.400 or less, 12.000 or less, 11.800 or less, 11.600 or less, 11.400 or less, 11.200 or less, 11.000 or less, 10.800 or less, 10.600 or less, 10.400 or less, 10.200 or less, 10.000 or less, 9.800 or less, 9.600 or less, 9.400 or less, 9.200 or less, 8.800 or less, 8.600 or less, 8.400 or less, 8.200 or less, 8.000 or less, 7.800 or less, from the viewpoints of maintaining the thermal stability of the glass.

[0037] TiO 2 Nb content relative to 2 O 5 、ZrO 2 and WO 3 The mass ratio of the total content of ((Nb 2 O 5 +ZrO 2 +WO 3 ) / TiO 2 ) is 2.010 or more, preferably 2.020 or more, more preferably 2.030 or more, 2.040 or more, 2.050 or more, 2.060 or more, 2.070 or more, 2.080 or more, 2.090 or more, 2.100 or more, 2.110 or more, 2.120 or more, 2.130 or more, 2.140 or more, 2.150 or more, 2.160 or more, 2.170 or more, 2.180 or more, 2.190 or more, 2.200 or more, 2.210 or more, 2.220 or more, 2.230 or more, 2.240 or more, 2.250 or more, 2.260 or more, 2.270 or more, from the viewpoint of maintaining the thermal stability of the glass and maintaining the low dispersion of the glass. From the viewpoint of maintaining the thermal stability of the glass, the mass ratio ((Nb 2 O 5 +ZrO 2 +WO 3 ) / TiO 2is preferably 100,000 or less, more preferably 85,000 or less, 70,000 or less, 55,000 or less, 40,000 or less, 25,000 or less, 18,400 or less, 18,000 or less, 17,600 or less, 17,200 or less, 16,800 or less, 16,400 or less, 16,000 or less, 15,600 or less, 15,200 or less, 14,800 or less, 14,400 or less, 14,000 or less, 13,600 or less, 13,200 or less, 12,800 or less, 12,400 or less, 12,000 or less, 11,800 or less, 11,600 or less, 11,400 or less, 11,200 or less, 11,000 or less, 10,800 or less, 10,600 or less, 10,400 or less, 10,200 or less, 10,000 or less, 9,800 or less, 9,600 or less, 9,400 or less, 9,200 or less, 8,800 or less, 8,600 or less, 8,400 or less, 8,200 or less, 8,000 or less, 7,800 or less, 7,600 or less, 7,400 or less, 7,200 or less, 7,000 or less, 6,800 or less in this order.

[0038] TiO 2 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoints of maintaining the thermal stability of the glass and increasing the refractive index, the TiO 2 content is preferably 0.00% or more, more preferably 0.50% or more, 1.00% or more, 1.50% or more, 2.00% or more, 2.20% or more, 2.40% or more, 2.60% or more, 2.80% or more, 3.00% or more, 3.20% or more, 3.40% or more in this order. From the viewpoint of maintaining the low dispersion of the glass, the TiO 2The content is preferably 15.00% or less, more preferably 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.50% or less, 10.00% or less, 9.80% or less, 9.60% or less, 9.40% or less, 9.20% or less, 9.00% or less, 8.80% or less, 8.60% or less, 8.40% or less, 8.20% or less, 8.10% or less, 8.00% or less, 7.90% or less, 7.80% or less, 7.70% or less, 7.60% or less, 7.50% or less, 7.45% or less, 7.40% or less, 7.30% or less, 7.20% or less, 7.10% or less, 7.00% or less, 6.90% or less, 6.80% or less, 6.70% or less, 6.60% or less in this order.

[0039] Nb 2 O 5 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoint of maintaining the high refractive index of the glass, Nb 2 O 5 The content is preferably 0.00% or more, more preferably 0.50% or more, 1.00% or more, 1.50% or more, 2.00% or more, 2.50% or more, 3.00% or more, 3.50% or more, 4.00% or more, 4.10% or more, 4.20% or more, 4.30% or more, 4.40% or more, 4.50% or more, 4.60% or more, 4.70% or more, 4.80% or more, 4.90% or more, 5.00% or more, 5.10% or more, 5.20% or more, 5.30% or more, 5.40% or more, 5.50% or more, 5.60% or more, 5.70% or more, 5.80% or more in this order. From the viewpoints of maintaining the thermal stability and low dispersion of the glass, Nb 2 O 5 The content is preferably 18.0% or less, more preferably 17.00% or less, 16.00% or less, 15.50% or less, 15.00% or less, 14.50% or less, 14.00% or less, 13.50% or less, 13.00% or less, 12.60% or less, 12.50% or less, 12.00% or less, 11.80% or less, 11.60% or less, 11.40% or less, 11.20% or less, 11.10% or less, 11.00% or less, 10.90 or less, 10.80 or less, 10.70% or less, 10.60% or less in this order.

[0040] ZrO 2 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoints of maintaining the thermal stability of the glass and maintaining high refractive index and low dispersion, ZrO 2 The content is preferably 0.00% or more, more preferably 0.50% or more, 1.00% or more, 1.50% or more, 2.00% or more, 2.50% or more, 3.00% or more, 3.10% or more, 3.20% or more, 3.30% or more, 3.40% or more, 3.50% or more in this order. From the viewpoint of maintaining the thermal stability of the glass, ZrO 2 The content is preferably 15.00% or less, more preferably 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.50% or less, 10.00% or less, 9.50% or less, 9.00% or less, 8.50% or less, 8.00% or less in this order.

[0041] WO 3 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoints of maintaining the thermal stability of the glass and increasing the refractive index, WO 3 The content is preferably 0.00% or more, more preferably 0.10% or more, 0.20% or more, 0.30% or more, 0.40% or more, 0.50% or more in this order. From the viewpoint of maintaining the low dispersion of the glass, WO 3 The content is preferably 10.00% or less, more preferably 9.50% or less, 9.00% or less, 8.50% or less, 8.00% or less, 7.50% or less, 7.00% or less, 6.50% or less, 6.00% or less, 5.50% or less, 5.00% or less, 4.50% or less, 4.00% or less, 3.50% or less in this order.

[0042] Ta 2 O 5 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoint of maintaining high refractive index and low dispersion of the glass, Ta 2 O 5The content can be 0.00% or more, 0.10% or more, 0.2% or more, 0.3% or more, 0.4% or more, or 0.5% or more. From the perspective of keeping the raw material cost of the glass low, it is preferable that the Ta 2 O 5 content is low. From such a perspective, it is preferable that the Ta 2 O 5 content is preferably 15.00% or less, more preferably 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.50% or less, 10.00% or less, 9.50% or less, 9.00% or less, 8.50% or less, 8.00% or less, 7.50% or less, 7.00% or less, 6.50% or less, 6.00% or less, 5.80% or less, 5.60% or less, 5.40% or less, 5.20% or less, 5.00% or less, 4.80% or less, 4.60% or less, 4.40% or less, 4.20% or less, 4.00% or less, 3.80% or less, 3.60% or less, 3.40% or less, 3.20% or less, 3.00% or less in this order.

[0043] TiO 2 、Nb 2 O 5 、WO 3 and Ta 2 O 5 The total content of (TiO 2 +Nb 2 O 5 +WO 3 +Ta 2 O 5 ) is 20.00% or less, preferably 19.50% or less, more preferably 19.00% or less, 18.50% or less, 18.40% or less, 18.30% or less, 18.20% or less, 18.10% or less, 18.00% or less, 17.90% or less, 17.80% or less, 17.70% or less, 17.60% or less, 17.50% or less, 17.40% or less, 17.30% or less, 17.20% or less, 17.10% or less, 17.00% or less, 16.90% or less, 16.80% or less, 16.70% or less, 16.60% or less, 16.50% or less in this order from the perspective of maintaining low dispersion of the glass. From the perspective of maintaining high refractive index of the glass, the total content (TiO 2 +Nb2 O 5 + WO 3 + Ta 2 O 5 ) is preferably 2.00% or more, more preferably 4.00% or more, 6.00% or more, 8.00% or more, 9.00% or more, 10.00% or more, 11.00% or more, 12.00% or more, 13.00% or more, 14.00% or more in this order.

[0044] The ZnO content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoint of maintaining the thermal stability of the glass and improving the meltability of the glass, the ZnO content is preferably 0.00% or more, more preferably 0.10% or more, 0.20% or more, 0.30% or more, 0.40% or more, 0.50% or more, more than 0.50%, 0.55% or more, 0.60% or more, 0.650% or more, 0.70% or more, 0.75% or more, 0.80% or more, 0.90% or more, 1.00% or more, 1.10% or more, 1.20% or more, 1.30% or more, 1.40% or more, 1.50% or more in this order. From the viewpoint of maintaining the high refractive index and low dispersion of the glass, the ZnO content is preferably 15.00% or less, more preferably 14.00% or less, 13.00% or less, 12.00% or less, 11.00% or less, 10.00% or less, 9.50% or less, 9.00% or less, 8.50% or less, 8.00% or less, 7.50% or less, 7.00% or less, 6.50% or less, 6.40% or less, 6.30% or less, 6.20% or less, 6.10% or less, 6.00% or less, 5.90% or less, 5.80% or less, 5.70% or less, 5.60% or less, 5.50% or less, 5.40% or less, 5.30% or less, 5.20% or less, 5.10% or less, 5.00% or less, 4.90% or less, 4.80% or less in this order.

[0045] P 2 O 5 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoint of maintaining the thermal stability of the glass, P 2 O 5The content is preferably 0.00% or more, more preferably 0.10% or more, 0.20% or more, 0.30% or more, 0.40% or more, and 0.50% or more in this order. From the perspective of maintaining the high refractive index of the glass, P 2 O 5 The content is preferably 5.00% or less, more preferably 4.50% or less, 4.00% or less, 3.50% or less, 3.00% or less, 2.50% or less, and 2.00% or less in this order.

[0046] Al 2 O 3 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the perspective of maintaining the thermal stability of the glass, Al 2 O 3 The content is preferably 0.10% or more, more preferably 0.20% or more, 0.30% or more, 0.40% or more, and 0.50% or more in this order. From the perspective of maintaining the high refractive index of the glass, Al 2 O 3 The content is preferably 5.00% or less, more preferably 4.50% or less, 4.00% or less, 3.50% or less, 3.00% or less, 2.50% or less, and 2.00% or less in this order.

[0047] Li 2 The Li2O content can be 0.00%, 0.00% or more, or more than 0.00%. From the perspective of maintaining the thermal stability of the glass, Li 2 The Li2O content is preferably 0.10% or more, more preferably 0.20% or more, 0.30% or more, 0.40% or more, and 0.50% or more in this order. From the perspective of maintaining the high refractive index and low dispersion of the glass and from the perspective of keeping the raw material cost of the glass low, Li 2 The Li2O content is preferably 5.00% or less, more preferably 4.50% or less, 4.00% or less, 3.50% or less, 3.00% or less, 2.50% or less, and 2.00% or less in this order.

[0048] The BaO content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoint of maintaining the thermal stability of the glass, the BaO content is preferably 0.00% or more, more preferably 0.10% or more, 0.20% or more, 0.30% or more, 0.40% or more, and 0.50% or more in this order. From the viewpoint of maintaining the high refractive index and low dispersion of the glass, the BaO content is preferably 10.00% or less, more preferably 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, and 4.00% or less in this order.

[0049] BiO 3 The content can be 0.00%, 0.00% or more, or more than 0.00%. From the viewpoints of maintaining the thermal stability of the glass and increasing the refractive index, the BiO 3 content is preferably 0.00% or more, more preferably 0.10% or more, 0.20% or more, 0.30% or more, 0.40% or more, and 0.50% or more in this order. From the viewpoint of maintaining the low dispersion of the glass, the BiO 3 content is preferably 10.00% or less, more preferably 9.50% or less, 9.00% or less, 8.50% or less, 8.00% or less, 7.50% or less, 7.00% or less, 6.50% or less, 6.00% or less, 5.50% or less, 5.00% or less, 4.50% or less, 4.00% or less, 3.50% or less, 3.00% or less, 2.50% or less, 2.40% or less, 2.30% or less, 2.20% or less, 2.10% or less, and 2.00% or less in this order.

[0050] Sb 2 O 3 is a component that can be added as a fining agent. Adding a small amount can also suppress the decrease in light transmittance due to the mixing of impurities such as Fe. However, when the addition amount of Sb 2 O 3 increases, the coloring of the glass tends to increase. Therefore, Sb 2 O 3The addition amount is preferably 0.00% or more and 0.10% or less on an external basis, more preferably 0.00% or more and 0.05% or less, and still more preferably 0.00% or more and 0.03% or less on an external basis. The Sb 2 O 3 content by external basis means the mass percentage of Sb 2 O 3 when the total content of glass components other than Sb 2 O 3 is taken as 100% by mass.

[0051] SnO 2 can also be added as a fining agent, but if added in excess of 1.00% on an external basis, the glass will be colored, or when the glass is heated and softened for reshaping such as press molding, Sn will become the starting point of crystal nucleation and a devitrification tendency will occur. Therefore, it is preferable that the addition amount of SnO 2 is 0.00% or more and 1.00% or less on an external basis, more preferably 0.00% or more and 0.50% or less, and particularly preferably not added. The SnO 2 content by external basis means the mass percentage of SnO 2 when the total content of glass components other than SnO 2 is taken as 100% by mass.

[0052] The above optical glass can be produced without containing components such as Lu and Hf. Since Lu 2 O 3 and HfO 2 are expensive components, it is preferable to suppress the content of each of them to 0.00% or more and 2.00% or less, more preferably to 0.00% or more and 1.00% or less, still more preferably to 0.00% or more and 0.80% or less, and even more preferably to 0.00% or more and 0.10% or less. It is particularly preferable not to introduce Lu 2 O 3 and not to introduce HfO 2 respectively. Also, considering environmental impact, it is preferable not to introduce Pb, and it is also preferable not to introduce As, U, Th, Te, and Cd. Furthermore, from the viewpoint of making the most of the excellent light transmittance of glass, it is preferable not to introduce substances that cause coloring, such as Cu, Cr, V, Fe, Ni, Co, etc.

[0053] F is a component that significantly increases the volatility of glass during melting and causes a decrease in the stability and homogeneity of the optical properties of glass. The F content can be defined as the content (unit: mass%) of the F element in terms of the external ratio with respect to the total content of 100 mass% of the glass composition based on oxides as required as described above. In the above optical glass, the F content thus defined is preferably less than 0.10%, more preferably less than 0.08%, and even more preferably less than 0.05%. The F content can be 0.00% or more, and may even be 0.00%.

[0054] <Glass physical properties> (Liquidus temperature) The thermal stability can be based on the liquidus temperature. Glass with a lower liquidus temperature can be said to be glass with better thermal stability. The liquidus temperature of the above optical glass is preferably 1400 °C or lower, and more preferably 1390 °C or lower, 1380 °C or lower, 1370 °C or lower, 1360 °C or lower, 1350 °C or lower in that order. The liquidus temperature can be, for example, 1100 °C or higher, 1150 °C or higher, 1200 °C or higher, 1210 °C or higher, 1220 °C or higher, but since it is preferable for the liquidus temperature to be low, it may exceed the values exemplified here. In this specification, the liquidus temperature is also denoted as "L.T." (liquidus temperature).

[0055] The "liquidus temperature" in the present invention and this specification is determined by the following method. A platinum crucible containing 5 cc of glass is covered and held in a furnace heated to a predetermined temperature for 2 hours. After cooling, the inside of the glass is observed with an optical microscope (magnification: 100 times), and the liquidus temperature is determined from the presence or absence of crystals. The temperature is changed in 10 °C increments.

[0056] (Refractive index nd) The above optical glass can be a glass with a high refractive index. The refractive index nd of the above optical glass is preferably 1.89000 or more, more preferably 1.89500 or more, 1.90000 or more, 1.90500 or more, 1.91000 or more, 1.91500 or more, 1.92000 or more in that order. The refractive index nd of the above optical glass can be, for example, 2.05000 or less, 2.04000 or less, 2.03000 or less, 2.02000 or less, 2.01000 or less, 2.00000 or less, 1.99000 or less, 1.98000 or less, 1.97000 or less, 1.96000 or less, 1.95500 or less, 1.95400 or less, 1.95300 or less, 1.95200 or less, 1.95100 or less, 1.95000 or less, 1.94900 or less, 1.94800 or less, 1.94700 or less, 1.94600 or less or 1.94500 or less. In the present invention and this specification, "refractive index" means "refractive index nd".

[0057] (Abbe number νd) The Abbe number νd is a value representing the property related to dispersibility, and is expressed as νd = (nd - 1) / (nF - nC) using the refractive indices nd, nF, and nC at the d-line, F-line, and C-line. From the viewpoint of the usefulness as a material for optical elements, the above optical glass is preferably a low-dispersion glass. From such a viewpoint, the Abbe number νd of the above optical glass is preferably 25.00 or more, more preferably 26.00 or more, 27.00 or more, 28.00 or more, 29.00 or more, 30.00 or more, 31.00 or more, 32.00 or more, 33.00 or more, 33.50 or more, 34.00 or more, 34.10 or more, 34.20 or more, 34.30 or more, 34.50 or more in that order. The Abbe number νd of the above optical glass can be, for example, 45.00 or less, 44.00 or less, 43.00 or less, 42.00 or less, 41.00 or less, 40.00 or less, 39.00 or less, 38.50 or less, 38.00 or less, 37.50 or less, 37.00 or less, 36.80 or less or 36.60 or less.

[0058] (Specific gravity) In an optical element that constitutes an optical system, the refractive power is determined by the refractive index of the glass that constitutes the optical element and the curvature of the optical functional surface of the optical element (the surface on which the light rays to be controlled are incident and exit). If one attempts to increase the curvature of the optical functional surface, the thickness of the optical element also increases. As a result, the optical element becomes heavier. On the other hand, if glass with a high refractive index is used, a large refractive power can be obtained without increasing the curvature of the optical functional surface. From the above, if it is possible to increase the refractive index while suppressing an increase in the specific gravity of the glass, it becomes possible to reduce the weight of an optical element having a certain refractive power. From the above viewpoints, the specific gravity of the above optical glass is preferably 5.30 or less, more preferably 5.29 or less, 5.28 or less, 5.27 or less, 5.26 or less, 5.25 or less, 5.24 or less, 5.23 or less, 5.22 or less, 5.21 or less, 5.20 or less, 5.19 or less, 5.18 or less, 5.17 or less, 5.16 or less, 5.15 or less, 5.14 or less, 5.13 or less, 5.12 or less, 5.11 or less, 5.10 or less in that order. Since a lower specific gravity is more preferable from the viewpoint of reducing the weight of the optical element, the lower limit of the specific gravity of the above optical glass is not particularly limited. In one embodiment, the specific gravity can be 4.40 or more, 4.50 or more, or 4.60 or more. In this specification, "specific gravity" is also denoted as "s.g." (specific gravity).

[0059] (Glass transition temperature Tg) From the viewpoint of reducing the burden on the annealing furnace and the molding die, the glass transition temperature Tg of the above optical glass is preferably 800°C or less, more preferably 790°C or less, 780°C or less, 770°C or less, 760°C or less, 750°C or less, 745°C or less, 740°C or less, 735°C or less, 730°C or less in that order. On the other hand, from the viewpoint of workability (specifically, the viewpoint of being less likely to break when performing mechanical processing of glass such as cutting, machining, grinding, polishing, etc.), the glass transition temperature Tg of the above optical glass is preferably 640°C or more, more preferably 650°C or more, and even more preferably 660°C or more. The glass transition temperature Tg is determined by the method described below.

[0060] <Manufacturing method of optical glass> The above optical glass can be obtained by weighing, mixing, and thoroughly blending raw materials such as oxides, carbonates, sulfates, nitrates, and hydroxides so as to obtain the target glass composition, forming a mixed batch, heating and melting it in a melting vessel, performing defoaming and stirring to produce a homogeneous and bubble-free molten glass, and then shaping this molten glass. Specifically, it can be produced using known melting methods.

[0061] [Glass Material for Press Molding, Optical Element Blank, and Methods for Producing the Same] Another aspect of the present invention is a glass material for press molding made of the above optical glass; an optical element blank made of the above optical glass, and relates to.

[0062] According to another aspect of the present invention, a method for producing a glass material for press molding, comprising a step of shaping the above optical glass into a glass material for press molding; a method for producing an optical element blank, comprising a step of producing an optical element blank by press molding the above glass material for press molding using a press mold; a method for producing an optical element blank, comprising a step of shaping the above optical glass into an optical element blank, is also provided.

[0063] An optical element blank is a base material of an optical element that approximates the shape of the target optical element and has a surface layer (a surface layer to be removed by polishing) and, if necessary, a grinding layer (a surface layer to be removed by grinding) added to the shape of the optical element. The optical element is finished by grinding and polishing the surface of the optical element blank. In one form, an optical element blank can be produced by a method of press molding (referred to as the direct press method) a molten glass obtained by melting an appropriate amount of the above glass. In another form, an optical element blank can also be produced by solidifying a molten glass obtained by melting an appropriate amount of the above glass.

[0064] In another embodiment, an optical element blank can be produced by preparing a glass material for press molding and press-molding the prepared glass material for press molding.

[0065] The press molding of the glass material for press molding can be carried out by a known method of pressing the glass material for press molding in a softened state by heating with a press mold. Both heating and press molding can be carried out in the atmosphere. By annealing after press molding to reduce the strain inside the glass, a homogeneous optical element blank can be obtained.

[0066] The glass material for press molding includes, in addition to what is called a glass gob for press molding that is directly used for press molding to produce an optical element blank in its as-received state, those that are subjected to machining such as cutting, grinding, and polishing and then used for press molding via the glass gob for press molding. As a cutting method, there are methods such as forming a groove by a method called scribing on the portion of the glass plate surface to be cut, applying local pressure to the groove portion from the back surface of the surface where the groove is formed to break the glass plate at the groove portion, and cutting the glass plate with a cutting blade. Also, as grinding and polishing methods, barrel polishing and the like can be mentioned.

[0067] The glass material for press molding can be produced, for example, by casting molten glass into a mold to form a glass plate and cutting this glass plate into a plurality of glass pieces. Or, an appropriate amount of molten glass can be formed to produce a glass gob for press molding. An optical element blank can also be produced by reheating, softening, and press molding the glass gob for press molding. The method of reheating, softening, and press molding the glass to produce an optical element blank is called the reheat press method as opposed to the direct press method.

[0068] [Optical Element and Method for Manufacturing the Same] Another aspect of the present invention is an optical element made of the above optical glass and relates to. The above optical element is fabricated using the above optical glass. In the above optical element, one or more coatings such as a multilayer film such as an antireflection film may be formed on the glass surface.

[0069] Also, according to one aspect of the present invention, A method for manufacturing an optical element includes a step of fabricating an optical element by grinding and / or polishing the above optical element blank. is also provided.

[0070] In the method for manufacturing the above optical element, machining such as grinding and polishing can be performed by applying known methods. By sufficiently cleaning and drying the surface of the optical element after processing, an optical element with high internal quality and surface quality can be obtained. In this way, an optical element made of the above optical glass can be obtained. Examples of the optical element include various lenses such as spherical lenses, aspherical lenses, and microlenses, and prisms.

[0071] Also, the optical element made of the above optical glass is also suitable as a lens constituting a cemented optical element. Examples of the cemented optical element include those obtained by cementing lenses together (cemented lenses), those obtained by cementing a lens and a prism, and the like. For example, the cemented optical element can be fabricated by precisely machining (e.g., spherical polishing) the cemented surfaces of two optical elements to be cemented so that the shapes are inverted, applying an ultraviolet curable adhesive used for cementing the cemented lens, laminating them, and then irradiating ultraviolet light through the lens to cure the adhesive. For fabricating such a cemented optical element, the above optical glass is preferable. By fabricating a plurality of optical elements to be cemented using a plurality of types of glasses having different Abbe numbers νd and then cementing them, an element suitable for correcting chromatic aberration can be obtained.

Examples

[0072] 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.

[0073] (Example 1) <Examples Nos. 1 to 190> As raw materials for introducing each component so as to obtain the glass compositions shown in the table below, corresponding nitrates, sulfates, carbonates, hydroxides, oxides, boric acid, etc. were used respectively. The raw materials were weighed and thoroughly mixed to obtain a prepared raw material. This prepared raw material was put into a platinum crucible and heated in a furnace set at 1400°C to 1450°C for 2 hours to be melted. After stirring and homogenizing the molten glass, the molten glass was poured into a preheated mold, cooled to near the glass transition temperature, and then immediately put into an annealing furnace. After holding at a temperature around the glass transition temperature for about 30 minutes, it was slowly cooled at a rate of -30°C / hour for 4 hours, and then cooled to room temperature in the furnace, whereby each of the optical glasses Nos. 1 to 190 shown in the following table was obtained. The physical properties of the optical glass thus obtained are shown in the following table. The physical properties of the optical glass were measured by the methods shown below.

[0074] (Physical Property Evaluation of Optical Glass) (1) Refractive index nd and Abbe number νd For the obtained glass, the refractive index nd and the Abbe number νd were measured by the refractive index measurement method of the Japan Optical Glass Industry Association Standard.

[0075] (2) Glass transition temperature Tg A sample obtained by thoroughly pulverizing the glass in a mortar was used as a sample, a platinum cell was used as a sample container, and the glass transition temperature Tg was measured at a heating rate of 10°C / min using a differential scanning calorimeter (DSC3300SA) manufactured by NETZSCH JAPAN.

[0076] (3) Specific gravity s.g. The specific gravity was measured by the Archimedes method.

[0077] (4) Liquidus temperature L.T. The liquidus temperature was determined by the method described above.

[0078] (Comparative Example 1) An optical glass having the composition of Example 11 of JP-A-2013-253013 (Patent Document 1) was produced by the method described above and evaluated by the method described above. For Comparative Example 1, since a homogeneous glass could not be produced, the refractive index nd and the Abbe number νd could not be measured.

[0079] [Table 1-1]

[0080] [Table 1-2]

[0081] [Table 1-3]

[0082] [Table 1-4]

[0083] [Table 1-5]

[0084] [Table 1-6]

[0085] [Table 1-7]

[0086] [Table 1-8]

[0087] [Table 1-9]

[0088]

Table 1-10

[0089]

Table 1-11

[0090]

Table 1-12

[0091]

Table 1-13

[0092]

Table 1-14

[0093]

Table 1-15

[0094]

Table 1-16

[0095]

Table 1-17

[0096]

Table 1-18

[0097]

Table 1-19

[0098]

Table 2-1

[0099]

Table 2-2

[0100]

Table 2-3

[0101]

Table 2-4

[0102]

Table 2-5

[0103]

Table 2-6

[0104]

Table 2-7

[0105]

Table 2-8

[0106]

Table 2-9

[0107]

Table 2-10

[0108]

Table 2-11

[0109]

Table 2-12

[0110]

Table 2-13

[0111]

Table 2-14

[0112]

Table 2-15

[0113]

Table 2-16

[0114]

Table 2-17

[0115]

Table 2-18

[0116]

Table 2-19

[0117] From the evaluation results shown in the above table, it can be confirmed that each optical glass of Example 1 is excellent in thermal stability (low liquidus temperature).

[0118] (Example 2) Using the various glasses obtained in Example 1, glass blocks (glass gobs) for press molding were produced. These glass blocks were heated and softened in the air and press-molded using a press mold to produce lens blanks (optical element blanks). The produced lens blanks were taken out from the press mold, annealed, and machined including polishing to produce spherical lenses made of the various glasses produced in Example 1.

[0119] (Example 3) A desired amount of the molten glass produced in Example 1 was press-molded using a press mold to produce lens blanks (optical element blanks). The produced lens blanks were taken out from the press mold, annealed, and machined including polishing to produce spherical lenses made of the various glasses produced in Example 1.

[0120] (Example 4) The glass blocks (optical element blanks) produced by solidifying the molten glass produced in Example 1 were annealed and machined including polishing to produce spherical lenses made of the various glasses produced in Example 1.

[0121] (Example 5) The spherical lenses produced in Examples 2 to 4 were bonded to spherical lenses made of other types of glass to produce bonded lenses. The bonding surfaces of the spherical lenses produced in Examples 2 to 4 were convex, and the bonding surfaces of the spherical lenses made of other types of glass were concave. The above two bonding surfaces were produced so that the absolute values of the radii of curvature were equal to each other. An ultraviolet curable adhesive for bonding optical elements was applied to the bonding surfaces, and the two lenses were bonded together at the bonding surfaces. Then, ultraviolet rays were irradiated onto the adhesive applied to the bonding surfaces through the spherical lenses produced in Examples 2 to 4 to solidify the adhesive. The bonded lenses were produced as described above. The bonding strength of the bonded lenses was sufficiently high, and the optical performance was also at a sufficient level.

[0122] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims be included. For example, with respect to the glass compositions exemplified above, by performing the composition adjustment described in the specification, an optical glass according to one aspect of the present invention can be obtained. In addition, it is of course possible to arbitrarily combine two or more of the matters exemplified or described as preferred ranges in the specification.

Claims

1. By mass, La ２ O ３ The content is 43.40% or more and 65.00% or less, SiO ２ and B ２ O ３ The total content of ２ +B ２ O ３ ) is 19.60% or less, TiO ２ , Nb ２ O ５ , W.O. ３ and Ta ２ O ５ The total content (TiO ２ +Nb ２ O ５ +W.O. ３ +Ta ２ O ５ ) is 20.00% or less, B ２ O ３ SiO content ２ Mass ratio of content (SiO ２ / B ２ O ３ ) is 0.168 or more and 1.510 or less, Rare earth oxide (La ２ O ３ , Gd ２ O ３ , Y ２ O ３ and Yb ２ O ３ ) to Ln ２ O ３ and Ln ２ O ３ The content is La ２ O ３ , Gd ２ O ３ , Y ２ O ３ and Yb ２ O ３ The total content (La ２ O ３ +Gd ２ O ３ +Y ２ O ３ +Yb ２ O ３ ) and B ２ O ３ Ln relative to content ２ O ３ Mass ratio of content (Ln ２ O ３ / B ２ O ３ ) is 5.100 or more, Ln ２ O ３ From the content, Nb ２ O ５ Content, ZrO ２ Content, TiO ２ Content, WO ３ Content and Ta ２ O ５ The value obtained by subtracting the content (Ln ２ O ３ -Nb ２ O ５ -ZrO ２ -TiO ２ -W.O. ３ -Ta ２ O ５ ) is 34.20% or more, SiO ２ and B ２ O ３ TiO relative to the total content ２ Mass ratio of content (TiO ２ / (SiO ２ +B ２ O ３ ) is 0.081 or more, TiO ２ Nb content ２ O ５ , ZrO ２ and W.O. ３ The mass ratio of the total content of (Nb ２ O ５ + ZrO ２ +W.O. ３ ) / TiO ２ ) is 2.010 or more, and Ln ２ O ３ , SiO ２ and B ２ O ３ Ln relative to the total content ２ O ３ Mass ratio of content (Ln ２ O ３ / (Ln ２ O ３ +SiO ２ +B ２ O ３ ) is equal to or greater than 0.457x + 0.396; x is Nb ２ O ５ , TiO ２ , W.O. ３ and Ln ２ O ３ Ln relative to the total content ２ O ３ Mass ratio of content (Ln ２ O ３ / (Nb ２ O ５ + TiO ２ +W.O. ３ + Ln ２ O ３ ) is an optical glass.

2. SiO ２ and B ２ O ３ Nb relative to the total content ２ O ５ Mass ratio of content (Nb ２ O ５ / (SiO ２ +B ２ O ３ 2. The optical glass according to claim 1 , wherein R 1 is 0.200 or greater and 0.900 or less.

3. Nb ２ O ５ , TiO ２ and W.O. ３ Nb content relative to the total content ２ O ５ Mass ratio of content (Nb ２ O ５ / (Nb ２ O ５ + TiO ２ +W.O. ３ 2. The optical glass according to claim 1 , wherein R 1 is 0.200 or greater and 1.000 or less.

4. T ２ O ５ 2. The optical glass according to claim 1, wherein the content is from 0.00% to 15.00%.

5. La ２ O ３ and G-d ２ O ３ La relative to the total content of ２ O ３ and Y ２ O ３ The mass ratio of the total content of (La ２ O ３ +Y ２ O ３ ) / (La ２ O ３ +Gd ２ O ３ 2. The optical glass according to claim 1 , wherein R 1 is 0.500 or greater and 1.500 or less.

6. The refractive index nd is 1.89000 or more and 2.05000 or less, and 2. The optical glass according to claim 1, having an Abbe number vd of 25.00 or greater and 45.00 or less.

7. 2. The optical glass according to claim 1, which has a specific gravity of 5.30 or less.

8. 2. The optical glass according to claim 1, which has a glass transition temperature Tg of 800° C. or lower.

9. 2. The optical glass according to claim 1, which has a liquidus temperature of 1400° C. or lower.

10. SiO ２ and B ２ O ３ Nb relative to the total content ２ O ５ Mass ratio of content (Nb ２ O ５ / (SiO ２ +B ２ O ３ ) is 0.200 or more and 0.900 or less, Nb ２ O ５ , TiO ２ and W.O. ３ Nb content relative to the total content ２ O ５ Mass ratio of content (Nb ２ O ５ / (Nb ２ O ５ + TiO ２ +W.O. ３ ) is 0.200 or more and 1.000 or less, T ２ O ５ The content is 0.00% or more and 15.00% or less, La ２ O ３ and G-d ２ O ３ La relative to the total content of ２ O ３ and Y ２ O ３ The mass ratio of the total content of (La ２ O ３ +Y ２ O ３ ) / (La ２ O ３ +Gd ２ O ３ ) is equal to or greater than 0.500 and equal to or less than 1.500, The refractive index nd is 1.89000 or more and 2.05000 or less, The Abbe number νd is 25.00 or more and 45.00 or less, The specific gravity is 5.30 or less, The glass transition temperature Tg is 800° C. or less, and 2. The optical glass according to claim 1, which has a liquidus temperature of 1400° C. or lower.

11. An optical element comprising the optical glass according to any one of claims 1 to 10.

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