本發明之光學玻璃含有SiO2
40～75%、B2
O3
1～30%、Al2
O3
0～15%、RO 0.1～10%(R為選自Mg、Ca、Sr、Ba及Zn中之至少1種)、Li2
O 0.1～10%、Na2
O＋K2
O 0.5～15%、ZrO2
0～3%、F2
0～5%，實質上不含Sb2
O3
。以下，對將各成分之含量特定為如上所述之理由進行詳細說明。再者，於無特別說明之情形時，以下之「%」意指「質量%」。SiO2
具有使紫外線透射率與耐候性提昇，又使折射率降低，進而提高液相黏度之效果。SiO2
之含量為40～75%，較佳為45～70%、尤其是50～65%。若SiO2
之含量過少，則有變得難以使折射率降低，或紫外線透射率降低之傾向。另一方面，若SiO2
之含量過多，則有玻璃轉移點上升，加壓成型性降低之傾向。又，玻璃之熔解性變得容易惡化，或變得容易析出含有SiO2
之失透物。B2
O3
具有使折射率降低，又提高液相黏度，進而使耐候性提昇之效果。B2
O3
之含量為1～30%，較佳為3～26%、尤其是5～22%。若B2
O3
之含量過少，則變得難以使折射率降低。另一方面，若B2
O3
之含量過多，則耐候性變得容易惡化，或成形時容易蒸發故而變得容易產生條紋。Al2
O3
具有使折射率降低，又提高液相黏度，進而使耐候性提昇之效果。Al2
O3
之含量為0～15%，較佳為1～13%、2～11%、尤其是3～9%。若Al2
O3
之含量過多，則玻璃之熔解性變得容易惡化，或變得容易析出含有Al2
O3
之失透物。再者，SiO2
/B2
O3
較佳為10以下、7.5以下、5以下、4以下、尤其是3以下。若SiO2
/B2
O3
過大，則玻璃之熔解性惡化，變得容易析出含有SiO2
之失透物。又，SiO2
/B2
O3
之下限並無特別限定，現實上較佳為1以上。再者，「SiO2
/B2
O3
」係指用SiO2
之含量除以B2
O3
之含量而獲得之值。又，SiO2
/Al2
O3
較佳為10以下、7.5以下、5以下、4以下、尤其是3以下。若SiO2
/Al2
O3
過大，則玻璃之熔解性惡化，變得容易析出含有SiO2
之失透物。又，SiO2
/Al2
O3
之下限並無特別限定，現實上較佳為1以上。再者，「SiO2
/Al2
O3
」係指用SiO2
之含量除以Al2
O3
之含量而獲得之值。RO(R為選自Mg、Ca、Sr、Ba及Zn中之至少1種)係使玻璃轉移點降低，又使玻璃之高溫黏性降低之成分。RO之含量(合計量)為0.1～10%，較佳為1～8%、尤其是2～5%。若RO之含量過少，則變得難以使玻璃轉移點降低。另一方面，若RO之含量過多，則失透傾向加強，變得難以進行玻璃化，於加壓成型時玻璃容易熔接於加壓模具上。再者，RO之各成分之含量亦較佳為分別為上述範圍。Li2
O係使玻璃轉移點降低，又使玻璃之高溫黏性降低之成分。Li2
O之含量為0.1～10%，較佳為1～8%、尤其是2～6%。若Li2
O之含量過少，則變得難以使玻璃轉移點降低。另一方面，若Li2
O之含量過多，則紫外線透射率變得容易降低，或耐候性變得容易惡化。又，於加壓成型時玻璃容易熔接於加壓模具上。Na2
O及K2
O係使玻璃轉移點降低，又使玻璃之高溫黏性降低之成分。Na2
O＋K2
O之含量為0.5～15%，較佳為1～10%、1～8%、2～7%、尤其是3～6%。若Na2
O＋K2
O之含量過少，則變得難以獲得上述效果。另一方面，若Na2
O＋K2
O之含量過多，則紫外線透射率變得容易降低，或耐候性變得容易惡化。再者，Na2
O及K2
O之含量之較佳範圍如下所述。Na2
O之含量較佳為0～10%、0.5～8%、1～7%、尤其是2～6%。K2
O之含量較佳為0～10%、0.5～8%、1～7%、尤其是2～6%。Li2
O＋Na2
O＋K2
O之含量較佳為0.6～25%、2～18%、尤其是5～12%。若Li2
O＋Na2
O＋K2
O之含量過少，則變得難以使玻璃轉移點降低。另一方面，若Li2
O＋Na2
O＋K2
O之含量過多，則紫外線透射率變得容易降低，或耐候性變得容易惡化。再者。「Li2
O＋Na2
O＋K2
O」意指Li2
O、Na2
O及K2
O之含量之合計量。Li2
O/(Na2
O＋K2
O)較佳為10以下、5以下、3以下、2以下、尤其是1以下。若Li2
O/(Na2
O＋K2
O)過大，則於加壓成型時玻璃容易熔接於加壓模具上。Li2
O/(Na2
O＋K2
O)之下限較佳為0.01以上。再者，「Li2
O/(Na2
O＋K2
O)」係指用Li2
O之含量除以Na2
O＋K2
O之含量而獲得之值。(Li2
O＋Na2
O＋K2
O)/RO較佳為100以下、50以下、30以下、25以下、尤其是20以下。若(Li2
O＋Na2
O＋K2
O)/RO過大，則紫外線透射率變得容易降低，或耐候性變得容易惡化。(Li2
O＋Na2
O＋K2
O)/RO之下限較佳為0.1以上。再者，「(Li2
O＋Na2
O＋K2
O)/RO」係指用Li2
O＋Na2
O＋K2
O之含量除以RO之含量而獲得之值。ZrO2
具有使耐候性提昇之效果。ZrO2
之含量為0～3%，較佳為0～2%、尤其是0.1～2%。若ZrO2
之含量過多，則紫外線透射率變得容易降低，或液相黏度變得容易降低而失透。F2
係提高紫外線透射率之成分。F2
之含量為0～5%，較佳為0.5～3%、尤其是1～2%。若F2
之含量過多，則熔融時之蒸發增加而產生條紋等，玻璃容易變得不均質。又，於加壓成型時玻璃容易熔接於加壓模具上。Sb2
O3
由於容易使紫外線透射率降低，故而較佳為實質上不含有。除上述成分以外，亦可含有以下所示之各種成分。La2
O3
、Nb2
O5
、Bi2
O3
及WO3
係提高耐侯性及化學耐候性之成分。又，藉由含有該等成分，可調整折射率。La2
O3
＋Nb2
O5
＋Bi2
O3
＋WO3
之含量較佳為0～0.05%。若該等成分之含量過多，則變得容易發生耐失透性之降低、熔融溫度之上升、或者紫外線透射率之降低等不良情況。再者，La2
O3
、Nb2
O5
、Bi2
O3
及WO3
之各成分之含量亦較佳為分別為上述範圍。TiO2
由於容易使紫外線透射率降低，故而較佳為其含量儘可能少。具體而言，TiO2
之含量較佳為100 ppm以下、尤其是50 ppm以下。容易作為雜質而混入之Fe2
O3
由於容易使紫外線透射率降低，故而較佳為其含量儘可能少。具體而言，Fe2
O3
之含量較佳為50 ppm以下、尤其是30 ppm以下。於將玻璃熔融時，亦可添加1%以下之成為還原劑之碳或金屬錫等成分。又，Cu、Ag、Pr、Br係使玻璃著色之成分，因而較佳為實質上不含有。關於Cd，考慮到對環境之影響，較佳為實質上不含有。再者，所謂「實質上不含Cu、Ag、Pr、Br、Cd」意指不有意地作為原料而含有，客觀上係指Cu、Ag、Pr、Br、Cd之含量未達0.1%。具有以上之組成之光學玻璃較佳為折射率nd為1.45～1.55、1.48～1.53、尤其是1.49～1.52。又，較佳為阿貝數為50～65、52～63、尤其是54～60。本發明之光學玻璃如上所述由於折射率相對較低，故而光入射效率較高。因此，即便不設置抗反射膜，實質上亦無問題。但是，視需要形成抗反射膜亦無妨。本發明之光學玻璃較佳為玻璃轉移點為550℃以下、530℃以下、尤其是500℃以下。玻璃轉移點之下限並無特別限定，現實上為400℃以上。又，較佳為軟化點為700℃以下、680℃以下、尤其是650℃以下。軟化點之下限並無特別限定，現實上為550℃以上。由於玻璃轉移點、軟化點較低，故而加壓成型溫度變低，而容易抑制加壓模具之劣化。本發明之光學玻璃較佳為玻璃轉移點與軟化點之差為245℃以下、220℃以下、尤其是200℃以下。若玻璃轉移點與軟化點之差較小，則於加壓成型並冷卻時玻璃容易迅速固化，因而玻璃難以熔接於加壓模具上。本發明之光學玻璃較佳為30～300℃之範圍之熱膨脹係數為40×10-7
/℃以上、50×10-7
/℃以上、60×10-7
/℃以上、尤其是70×10-7
/℃以上。若熱膨脹係數過低，則於加壓成型並冷卻後，玻璃容易自加壓模具脫模。再者，熱膨脹係數之上限並無特別限定，現實上為150×10-7
/℃以下。本發明之光學玻璃對於大致波長350 nm以下之深紫外區域具有良好之透光率。具體而言，關於本發明之光學玻璃於厚度1 mm、且波長為270 nm時之透射率，較佳為透光率為50%以上、60%以上、尤其是70%以上。又，於厚度1 mm、且波長為300 nm時之透光率較佳為80%以上、85%以上、尤其是90%以上。其次，對製造本發明之光學玻璃透鏡的方法進行說明。首先，以成為所需組成之方式調配玻璃原料後，於玻璃熔爐中進行熔融。玻璃之熔融溫度較佳為1150℃以上、1200℃以上、尤其是1250℃以上。再者，就防止因自構成熔融容器之鉑金屬熔解Pt引起之玻璃著色的觀點而言，熔融溫度較佳為1450℃以下、1400℃以下、1350℃以下、尤其是1300℃以下。又，若熔融時間過短，則可能無法充分地脫泡，因此熔融時間較佳為2小時以上，尤佳為3小時以上。其中，就防止因自熔融容器熔解Pt引起之玻璃著色的觀點而言，熔融時間較佳為8小時以內，尤佳為5小時以內。其次，自噴嘴之前端滴加熔融玻璃，製作液滴狀玻璃，而獲得光學玻璃。或者，將熔融玻璃進行驟冷鑄造，暫時製作玻璃磚，並進行研削、研磨、洗淨，而獲得光學玻璃。繼而，向實施過精密加工之模具中投入光學玻璃，一邊加熱至成為軟化狀態為止一邊進行加壓成型，而將模具之表面形狀轉印至光學玻璃。如此可獲得光學玻璃透鏡。[實施例]以下，基於實施例對本發明之光學玻璃進行詳細說明。表1及表2表示本發明之實施例(試樣No.1～12)及比較例(試樣No.13)。 [表1]
[表2]
各試樣係藉由如下方式製作。首先，將以成為表1及表2所記載之組成之方式調配之玻璃原料加入至鉑坩堝中，於1300℃下分別熔融2小時。其次，將熔融玻璃流出至碳板上，加以冷卻固化後，進行退火而製作玻璃磚。其後，進行研削、研磨、洗淨而獲得光學玻璃。針對如此而獲得之光學玻璃評價各種特性。將結果示於各表。其後，向實施過精密加工之模具中投入光學玻璃，一邊於軟化點下進行加熱一邊進行加壓成形，將模具之表面形狀轉印至光學玻璃，而獲得前面曲率半徑20 mm且中心厚度4 mm之平凸透鏡、前面曲率半徑10 mm且中心厚度0.5 mm之平凸透鏡、及前面曲率半徑10 mm、後面曲率半徑10 mm、中心厚度0.5 mm之雙凸透鏡。折射率nd係以使用折射率計並利用d線(波長：587.6 nm)所獲得之測定值表示。玻璃轉移點係使用熱膨脹計進行測定。軟化點係使用纖維伸長法進行測定。熱膨脹係數係使用熱膨脹計而測定30～300℃之溫度範圍之值。透光率係利用分光光度計(島津製作所製造之UV-3100)進行測定。TiO2
及Fe2
O3
之含量係利用感應耦合電漿質譜分析儀(ICP-MS)進行分析。由表明確得知，本發明之實施例No.1～12之各試樣之折射率nd為1.46～1.54，玻璃轉移點為440～540℃，軟化點為600～699℃，熱膨脹係數為42～90×10-7
/℃，透光率(270 nm)為55～78%，透光率(300 nm)為81～94%。相對於此，比較例No.13之試樣之玻璃轉移點為630℃，軟化點為785℃之較高值，加壓成形性差。The optical glass of the present invention contains SiO 2 40 to 75%, B 2 O 3 1 to 30%, Al 2 O 3 0 to 15%, and RO 0.1 to 10% (R is selected from the group consisting of Mg, Ca, Sr, Ba, and Zn). At least one of them), Li 2 O 0.1 to 10%, Na 2 O+K 2 O 0.5 to 15%, ZrO 2 0 to 3%, and F 2 0 to 5%, and substantially no Sb 2 O 3 . Hereinafter, the reason why the content of each component is specified as described above will be described in detail. In addition, in the case of no particular explanation, the following "%" means "% by mass". SiO 2 has an effect of improving ultraviolet transmittance and weather resistance, and lowering the refractive index, thereby increasing the viscosity of the liquid phase. The content of SiO 2 is 40 to 75%, preferably 45 to 70%, particularly 50 to 65%. When the content of SiO 2 is too small, it tends to be difficult to lower the refractive index or to lower the ultraviolet transmittance. On the other hand, when the content of SiO 2 is too large, the glass transition point increases and the press formability tends to decrease. Further, the meltability of the glass is likely to be deteriorated, or the devitrified substance containing SiO 2 is easily precipitated. B 2 O 3 has the effect of lowering the refractive index, increasing the viscosity of the liquid phase, and further improving the weather resistance. The content of B 2 O 3 is from 1 to 30%, preferably from 3 to 26%, especially from 5 to 22%. When the content of B 2 O 3 is too small, it becomes difficult to lower the refractive index. On the other hand, when the content of B 2 O 3 is too large, the weather resistance is likely to be deteriorated, or it is likely to evaporate during molding, and streaks are likely to occur. Al 2 O 3 has an effect of lowering the refractive index, increasing the viscosity of the liquid phase, and further improving the weather resistance. The content of Al 2 O 3 is from 0 to 15%, preferably from 1 to 13%, from 2 to 11%, especially from 3 to 9%. When the content of Al 2 O 3 is too large, the meltability of the glass is likely to be deteriorated, or the devitrified substance containing Al 2 O 3 is easily precipitated. Further, SiO 2 /B 2 O 3 is preferably 10 or less, 7.5 or less, 5 or less, 4 or less, or particularly 3 or less. When SiO 2 /B 2 O 3 is too large, the meltability of the glass is deteriorated, and it is easy to precipitate a devitrified substance containing SiO 2 . Further, the lower limit of SiO 2 /B 2 O 3 is not particularly limited, but is preferably 1 or more in reality. Further, "SiO 2 /B 2 O 3 " means a value obtained by dividing the content of SiO 2 by the content of B 2 O 3 . Further, SiO 2 /Al 2 O 3 is preferably 10 or less, 7.5 or less, 5 or less, 4 or less, or particularly 3 or less. When SiO 2 /Al 2 O 3 is too large, the meltability of the glass is deteriorated, and it is easy to precipitate a devitrified substance containing SiO 2 . Further, the lower limit of SiO 2 /Al 2 O 3 is not particularly limited, but is preferably 1 or more in reality. Further, "SiO 2 /Al 2 O 3 " means a value obtained by dividing the content of SiO 2 by the content of Al 2 O 3 . RO (R is at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn) is a component which lowers the glass transition point and lowers the high temperature viscosity of the glass. The content of RO (total amount) is 0.1 to 10%, preferably 1 to 8%, particularly 2 to 5%. If the content of RO is too small, it becomes difficult to lower the glass transition point. On the other hand, when the content of RO is too large, the devitrification tendency is strengthened, and it becomes difficult to vitrify, and the glass is easily welded to the press mold at the time of press molding. Further, the content of each component of RO is preferably in the above range. Li 2 O is a component that lowers the glass transition point and lowers the high temperature viscosity of the glass. The content of Li 2 O is from 0.1 to 10%, preferably from 1 to 8%, especially from 2 to 6%. If the content of Li 2 O is too small, it becomes difficult to lower the glass transition point. On the other hand, when the content of Li 2 O is too large, the ultraviolet transmittance is likely to be lowered, or the weather resistance is likely to be deteriorated. Further, the glass is easily welded to the press mold during press molding. Na 2 O and K 2 O are components which lower the glass transition point and lower the high temperature viscosity of the glass. The content of Na 2 O+K 2 O is from 0.5 to 15%, preferably from 1 to 10%, from 1 to 8%, from 2 to 7%, especially from 3 to 6%. If the content of Na 2 O+K 2 O is too small, it becomes difficult to obtain the above effects. On the other hand, when the content of Na 2 O+K 2 O is too large, the ultraviolet transmittance is likely to be lowered, or the weather resistance is likely to be deteriorated. Further, a preferred range of the contents of Na 2 O and K 2 O is as follows. The content of Na 2 O is preferably 0 to 10%, 0.5 to 8%, 1 to 7%, especially 2 to 6%. The content of K 2 O is preferably 0 to 10%, 0.5 to 8%, 1 to 7%, especially 2 to 6%. The content of Li 2 O+Na 2 O+K 2 O is preferably from 0.6 to 25%, from 2 to 18%, especially from 5 to 12%. When the content of Li 2 O+Na 2 O+K 2 O is too small, it becomes difficult to lower the glass transition point. On the other hand, when the content of Li 2 O+Na 2 O+K 2 O is too large, the ultraviolet transmittance is likely to be lowered, or the weather resistance is likely to be deteriorated. Again. "Li 2 O+Na 2 O+K 2 O" means the total amount of the contents of Li 2 O, Na 2 O, and K 2 O. Li 2 O/(Na 2 O+K 2 O) is preferably 10 or less, 5 or less, 3 or less, 2 or less, or particularly 1 or less. When Li 2 O/(Na 2 O+K 2 O) is too large, the glass is easily welded to the press mold at the time of press molding. The lower limit of Li 2 O/(Na 2 O+K 2 O) is preferably 0.01 or more. Further, "Li 2 O/(Na 2 O+K 2 O)" means a value obtained by dividing the content of Li 2 O by the content of Na 2 O + K 2 O. (Li 2 O+Na 2 O+K 2 O)/RO is preferably 100 or less, 50 or less, 30 or less, 25 or less, or particularly 20 or less. When (Li 2 O+Na 2 O+K 2 O)/RO is too large, the ultraviolet transmittance is likely to be lowered, or the weather resistance is likely to be deteriorated. The lower limit of (Li 2 O+Na 2 O+K 2 O)/RO is preferably 0.1 or more. In addition, "(Li 2 O+Na 2 O+K 2 O)/RO" means a value obtained by dividing the content of Li 2 O+Na 2 O+K 2 O by the content of RO. ZrO 2 has an effect of improving weather resistance. The content of ZrO 2 is from 0 to 3%, preferably from 0 to 2%, especially from 0.1 to 2%. When the content of ZrO 2 is too large, the ultraviolet transmittance is liable to lower, or the liquidus viscosity is liable to be lowered to devitrify. F 2 is a component that increases the transmittance of ultraviolet light. The content of F 2 is from 0 to 5%, preferably from 0.5 to 3%, especially from 1 to 2%. When the content of F 2 is too large, evaporation at the time of melting increases to cause streaks or the like, and the glass tends to be uneven. Further, the glass is easily welded to the press mold during press molding. Since Sb 2 O 3 is likely to lower the ultraviolet transmittance, it is preferably substantially not contained. In addition to the above components, various components shown below may also be contained. La 2 O 3 , Nb 2 O 5 , Bi 2 O 3 and WO 3 are components which improve weather resistance and chemical weather resistance. Further, the refractive index can be adjusted by including these components. The content of La 2 O 3 + Nb 2 O 5 + Bi 2 O 3 + WO 3 is preferably from 0 to 0.05%. When the content of these components is too large, problems such as a decrease in devitrification resistance, an increase in melting temperature, or a decrease in ultraviolet transmittance are likely to occur. Further, the contents of the respective components of La 2 O 3 , Nb 2 O 5 , Bi 2 O 3 and WO 3 are also preferably in the above ranges. Since TiO 2 tends to lower the ultraviolet transmittance, it is preferable that the content thereof is as small as possible. Specifically, the content of TiO 2 is preferably 100 ppm or less, particularly 50 ppm or less. Since Fe 2 O 3 which is easily mixed as an impurity tends to lower the ultraviolet transmittance, it is preferable that the content is as small as possible. Specifically, the content of Fe 2 O 3 is preferably 50 ppm or less, particularly 30 ppm or less. When the glass is melted, a component such as carbon or tin metal which is a reducing agent may be added in an amount of 1% or less. Further, since Cu, Ag, Pr, and Br are components for coloring the glass, they are preferably substantially not contained. Regarding Cd, in consideration of the influence on the environment, it is preferable that it is substantially not contained. In addition, "substantially free of Cu, Ag, Pr, Br, and Cd" means that it is contained unintentionally as a raw material, and objectively means that the content of Cu, Ag, Pr, Br, and Cd is less than 0.1%. The optical glass having the above composition preferably has a refractive index nd of 1.45 to 1.55, 1.48 to 1.53, particularly 1.49 to 1.52. Further, the Abbe number is preferably 50 to 65, 52 to 63, and particularly 54 to 60. Since the optical glass of the present invention has a relatively low refractive index as described above, the light incident efficiency is high. Therefore, even if an anti-reflection film is not provided, there is substantially no problem. However, it is also possible to form an antireflection film as needed. The optical glass of the present invention preferably has a glass transition point of 550 ° C or less, 530 ° C or less, and especially 500 ° C or less. The lower limit of the glass transition point is not particularly limited, and is actually 400 ° C or higher. Further, the softening point is preferably 700 ° C or lower, 680 ° C or lower, and particularly 650 ° C or lower. The lower limit of the softening point is not particularly limited, and is actually 550 ° C or higher. Since the glass transition point and the softening point are low, the press molding temperature becomes low, and deterioration of the press mold is easily suppressed. The optical glass of the present invention preferably has a difference between a glass transition point and a softening point of 245 ° C or less, 220 ° C or less, and particularly 200 ° C or less. If the difference between the glass transition point and the softening point is small, the glass is easily solidified rapidly upon press molding and cooling, so that it is difficult to weld the glass to the press mold. The optical glass of the present invention preferably has a thermal expansion coefficient in the range of 30 to 300 ° C of 40 × 10 -7 / ° C or more, 50 × 10 -7 / ° C or more, 60 × 10 -7 / ° C or more, especially 70 × 10 -7 / °C or more. If the coefficient of thermal expansion is too low, the glass is easily released from the press mold after press molding and cooling. Further, the upper limit of the coefficient of thermal expansion is not particularly limited, and is actually 150 × 10 -7 / ° C or less. The optical glass of the present invention has a good light transmittance for a deep ultraviolet region having a wavelength of approximately 350 nm or less. Specifically, the transmittance of the optical glass of the present invention at a thickness of 1 mm and a wavelength of 270 nm is preferably 50% or more, 60% or more, and particularly 70% or more. Further, the light transmittance at a thickness of 1 mm and a wavelength of 300 nm is preferably 80% or more, 85% or more, and particularly 90% or more. Next, a method of manufacturing the optical glass lens of the present invention will be described. First, the glass raw material is blended so as to have a desired composition, and then melted in a glass melting furnace. The melting temperature of the glass is preferably 1150 ° C or higher, 1200 ° C or higher, and particularly 1250 ° C or higher. Further, from the viewpoint of preventing coloring of the glass due to melting of Pt from the platinum metal constituting the melting vessel, the melting temperature is preferably 1450 ° C or lower, 1400 ° C or lower, 1350 ° C or lower, or particularly 1300 ° C or lower. Further, if the melting time is too short, the defoaming may not be sufficiently performed. Therefore, the melting time is preferably 2 hours or longer, and more preferably 3 hours or longer. Among them, from the viewpoint of preventing coloring of the glass due to melting of Pt from the molten container, the melting time is preferably within 8 hours, and particularly preferably within 5 hours. Next, molten glass was dropped from the front end of the nozzle to prepare a droplet-shaped glass to obtain an optical glass. Alternatively, the molten glass is subjected to rapid cooling casting, and the glass brick is temporarily produced, ground, polished, and washed to obtain an optical glass. Then, the optical glass is placed in a mold that has been subjected to precision machining, and is subjected to press molding while being heated to a softened state, and the surface shape of the mold is transferred to the optical glass. An optical glass lens can thus be obtained. [Examples] Hereinafter, the optical glass of the present invention will be described in detail based on examples. Tables 1 and 2 show examples (samples No. 1 to 12) and comparative examples (sample No. 13) of the present invention. [Table 1] [Table 2] Each sample was produced as follows. First, the glass raw materials blended so as to have the compositions described in Tables 1 and 2 were placed in a platinum crucible and melted at 1300 ° C for 2 hours. Next, the molten glass was discharged onto a carbon plate, cooled and solidified, and then annealed to prepare a glass brick. Thereafter, grinding, polishing, and washing were carried out to obtain an optical glass. Various characteristics were evaluated for the optical glass thus obtained. The results are shown in the respective tables. Thereafter, the optical glass was placed in a mold subjected to precision machining, and pressure molding was performed while heating at a softening point, and the surface shape of the mold was transferred to the optical glass to obtain a front curvature radius of 20 mm and a center thickness of 4 A plano-convex lens of mm, a plano-convex lens with a front radius of curvature of 10 mm and a center thickness of 0.5 mm, and a lenticular lens with a front radius of curvature of 10 mm, a back radius of curvature of 10 mm, and a center thickness of 0.5 mm. The refractive index nd is represented by a measured value obtained by using a refractometer and using a d-line (wavelength: 587.6 nm). The glass transfer point was measured using a thermal dilatometer. The softening point was measured using a fiber elongation method. The coefficient of thermal expansion is a value measured in a temperature range of 30 to 300 ° C using a thermal dilatometer. The light transmittance was measured by a spectrophotometer (UV-3100 manufactured by Shimadzu Corporation). The contents of TiO 2 and Fe 2 O 3 were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). It is clear from the table that the refractive index nd of each of the samples Nos. 1 to 12 of the present invention is 1.46 to 1.54, the glass transition point is 440 to 540 ° C, the softening point is 600 to 699 ° C, and the thermal expansion coefficient is 42. ～90×10 -7 /°C, the light transmittance (270 nm) is 55 to 78%, and the light transmittance (300 nm) is 81 to 94%. On the other hand, the sample of Comparative Example No. 13 had a glass transition point of 630 ° C, a softening point of a high value of 785 ° C, and poor press formability.