本發明之光學玻璃含有P5+
、Al3+
及Mg2+
作為陽離子成分，含有O2-
及F-
作為陰離子成分，相對折射率(589.29 nm)之溫度係數(20~40℃)為-6.0×10-6
(℃-1
)以上。除P5+
之外亦含有Al3+
及Mg2+
作為陽離子成分，且除O2-
之外亦含有F-
作為陰離子成分，藉此提高光學玻璃之相對折射率之溫度係數。因此，藉由於更廣泛之溫度範圍內高精度地獲得所需之成像特性等光學特性，可獲得可有助於光學系統之高解像度化及小型化的光學玻璃。
以下，亦將此種光學玻璃稱為「本發明之光學玻璃」。
以下，針對本發明之光學玻璃進行說明。本發明並不限定於以下之態樣，可於本發明之目標之範圍內施加適當變更而實施。再者，存在對於說明重複之處省略說明之情形，但並不限定發明之主旨。
＜玻璃成分＞
針對構成本發明之光學玻璃之各成分進行說明。
於本說明書中，各成分之含有率於無特別說明之情形時，全部記作以基於莫耳比之陽離子%或陰離子%所示者。此處，「陽離子%」及「陰離子%」(以下，存在記為「陽離子%(莫耳%)」及「陰離子%(莫耳%)」之情況)係：將本發明之光學玻璃之玻璃構成成分分離為陽離子成分及陰離子成分，並分別將合計比率設為100莫耳%而表記玻璃中所含之各成分之含有率的組成。
再者，各成分之離子價僅僅為方便而使用代表值，因此並不與其他離子價者進行區別。存在於光學玻璃中之各成分之離子價有為代表值以外之可能性。例如，P通常以離子價為5價之狀態存在於玻璃中，因此於本說明書中表示為「P5+
」，但有以其他離子價之狀態存在之可能性。如此，嚴格說來，即便為以其他離子價之狀態存在者，於本說明書中亦視為各成分以代表值之離子價存在於玻璃中者。
[關於陽離子成分]
本發明之光學玻璃包含P5+
。P5+
之含有率較佳為20~55%。
P5+
係玻璃形成成分，具有抑制玻璃之失透、提高折射率之性質。此種性質逐漸增強，因此P5+
之含有率之下限設為較佳為20.0%、更佳為25.0%、進而較佳為30.0%。
另一方面，P5+
具有若含有率較高則降低阿貝數之性質。此種性質逐漸增強，因此P5+
之含有率之上限設為較佳為55.0%、更佳為50.0%、更佳為45.0%、更佳為41.0%、進而較佳為37.0%。
P5+
可使用Al(PO3
)3
、Ca(PO3
)2
、Ba(PO3
)2
、Zn(PO3
)2
、BPO4
、H3
PO4
等作為原料而含有於玻璃內。
本發明之光學玻璃包含Al3+
。Al3+
之含有率較佳為1~20%。
Al3+
具有提高玻璃之耐失透性、降低磨耗度、提高相對折射率之溫度係數的性質。此種性質逐漸增強，因此Al3+
之含有率之下限設為較佳為1.0%、更佳為5.0%、更佳為7.0%、進而較佳為9.7%。
另一方面，Al3+
具有若含有率較高則降低玻璃之折射率的性質。此種性質逐漸增強，因此Al3+
之含有率之上限設為較佳為20.0%、更佳為18.0%、進而較佳為16.0%。
Al3+
可使用Al(PO3
)3
、AlF3
、Al2
O3
等作為原料而含有於玻璃內。
本發明之光學玻璃包含Mg2+
。Mg2+
之含有率較佳為0.1~30%。
Mg2+
具有提高玻璃之耐失透性、降低磨耗度、提高相對折射率之溫度係數的性質。此種性質逐漸增強，因此Mg2+
之含有率之下限設為較佳為0.1%、更佳為2.0%、更佳為5.0%、更佳為10.0%，進而較佳為設為超過11.0%。
另一方面，Mg2+
具有若含有率較高則降低玻璃之折射率的性質。此種性質逐漸增強，因此Mg2+
之含有率之上限設為較佳為30.0%、更佳為25.0%、進而較佳為20.0%。
Mg2+
可使用MgO、MgF2
等作為原料而含有於玻璃內。
本發明之光學玻璃亦可包含Ca2+
作為任意成分。Ca2+
之含有率較佳為30%以下。
Ca2+
具有提高玻璃之耐失透性、抑制折射率之降低、降低磨耗度、提高相對折射率之溫度係數的性質。此種性質逐漸增強，因此將Ca2+
之含有率之下限設為較佳為0.1%、更佳為5.0%，亦可進而較佳地設為超過10.0%。
另一方面，Ca2+
具有若含有率較高則反而降低玻璃之耐失透性、降低折射率的性質。此種性質逐漸增強，因此Ca2+
之含有率之上限設為較佳為30.0%、更佳為20.0%、進而較佳為16.0%。
Ca2+
可使用Ca(PO3
)2
、CaCO3
、CaF2
等作為原料而含有於玻璃內。
本發明之光學玻璃亦可包含Sr2+
作為任意成分。Sr2+
之含有率較佳為30%以下。
Sr2+
具有提高玻璃之耐失透性、抑制折射率之降低的性質。此種性質逐漸增強，因此亦可將Sr2+
之含有率之下限設為較佳為0.1%、更佳為1.0%、進而較佳為2.0%。
另一方面，Sr2+
具有若含有率較高則反而降低玻璃之耐失透性、降低折射率的性質。此種性質逐漸增強，因此Sr2+
之含有率之上限設為較佳為30.0%、更佳為20.0%、進而較佳為14.0%。
Sr2+
可使用Sr(NO3
)2
、SrF2
等作為原料而含有於玻璃內。
本發明之光學玻璃亦可包含Ba2+
作為任意成分。Ba2+
之含有率較佳為30%以下。
Ba2+
具有提高玻璃之耐失透性、維持較低之分散性、提高折射率的性質。此種性質逐漸增強，因此亦可將Ba2+
之含有率之下限設為較佳為0.1%、更佳為1.0%、更佳為5.0%、更佳為10.0%、更佳為12.0%、進而較佳為14.0%。
另一方面，Ba2+
具有若含有率較高則反而降低玻璃之耐失透性、降低相對折射率之溫度係數的性質。此種性質逐漸增強，因此Ba2+
之含有率之上限設為較佳為30.0%、更佳為25.0%、更佳為20.0%、進而較佳為17.1%以下。
Ba2+
可使用Ba(PO3
)2
、BaCO3
、Ba(NO3
)2
、BaF2
等作為原料而含有於玻璃內。
鹼土金屬於本發明中意指選自由Mg2+
、Ca2+
、Sr2+
及Ba2+
所組成之群中之一種以上。又，存在將選自由Mg2+
、Ca2+
、Sr2+
及Ba2+
所組成之群中之一種以上表示為R2+
之情形。
又，所謂R2+
之合計含有率，意指該等四個離子中之一種以上之合計含有率(例如，Mg2+
+Ca2+
+Sr2+
+Ba2+
)。
R2+
之合計含有率較佳為30~70%。藉由使R2+
之合計含有率為該範圍，可獲得耐失透性更高之玻璃。
R2+
之合計含有率之下限設為較佳為30.0%、更佳為35.0%、更佳為40.0%、進而較佳為44.0%。另一方面，R2+
之合計含有率之上限設為較佳為70.0%、更佳為65.0%、更佳為60.0%、進而較佳為55.0%。
本發明之光學玻璃較佳為Mg2+
及Ca2+
之合計含有率為7.5~50%。藉由該合計含有率較高，可提高相對折射率之溫度係數。因此，(Mg2+
+Ca2+
)之下限設為較佳為7.5%、更佳為12.5%、進而較佳為25.0%。
另一方面，若該合計含有率較高，則具有降低玻璃之耐失透性、降低折射率的性質。此種性質逐漸增強，因此(Mg2+
+Ca2+
)之上限設為較佳為50.0%、更佳為40.0%、進而較佳為35.0%。
本發明之光學玻璃較佳為Mg2+
含有率(陽離子%)及Ca2+
含有率(陽離子%)之合計相對於鹼土金屬之合計含有率(R2+
：陽離子%)的比((Mg2+
+Ca2+
)/R2+
)為0.25以上。
Mg2+
及Ca2+
之合計含有率相對於R2+
之比率較高，藉此可提高相對折射率之溫度係數，降低磨耗度。因此，(Mg2+
+Ca2+
)/R2+
之下限設為較佳為0.25、更佳為0.31、更佳為0.36、更佳為0.41、進而較佳為0.50。
另一方面，(Mg2+
+Ca2+
)/R2+
之上限亦可為1。然而，若Mg2+
及Ca2+
之合計含有率相對於R2+
之比率較高，則具有降低玻璃之耐失透性、降低折射率之性質。此種性質逐漸增強，因此可將(Mg2+
+Ca2+
)/R2+
之上限設為較佳為0.90、更佳為0.80、更佳為0.70、進而較佳為0.65。
又，本發明之光學玻璃較佳為Mg2+
含有率(陽離子%)相對於P5+
含有率(陽離子%)的比(Mg2+
/P5+
)為0.25以上。
藉由使提高相對折射率之溫度係數之作用較強的Mg2+
之含有率相對於玻璃形成成分P5+
之含有率的比率提高，可進一步提高玻璃之相對折射率之溫度係數。因此，(Mg2+
/P5+
)之下限設為較佳為0.25、更佳為0.30、更佳為0.35、進而較佳為0.42。
另一方面，若Mg2+
之含有率相對於該比率之P5+
之含有率的比率較高，則具有降低玻璃之耐失透性、降低折射率之性質。此種性質逐漸增強，因此可將(Mg2+
/P5+
)之上限設為較佳為1.00、更佳為0.90、更佳為0.80、進而較佳為0.70。
La3+
、Gd3+
、Y3+
、Yb3+
及Lu3+
具有維持較低之分散性、提高折射率、進一步提高耐失透性的性質。為增強此種性質，本發明之光學玻璃亦可包含選自由La3+
、Gd3+
、Y3+
、Yb3+
及Lu3+
所組成之群中之一種以上成分作為任意成分。
另一方面，La3+
、Gd3+
、Y3+
、Yb3+
及Lu3+
之含有率分別較佳為10%以下。La3+
、Gd3+
、Y3+
、Yb3+
及Lu3+
具有若含有率較高則反而因玻璃之穩定性惡化而變得容易失透的性質。此種性質逐漸增強，因此La3+
、Gd3+
、Y3+
、Yb3+
及Lu3+
之含有率各自之上限設為較佳為10.0%、更佳為8.0%、更佳為5.0%、進而較佳為3.0%。
La3+
、Gd3+
、Y3+
、Yb3+
及Lu3+
可使用La2
O3
、LaF3
、Gd2
O3
、GdF3
、Y2
O3
、YF3
、Yb2
O3
、Lu2
O3
等作為原料而含有於玻璃內。
Ln3+
於本發明中意指選自由Y3+
、La3+
、Gd3+
、Yb3+
及Lu3+
所組成之群中之至少一種。又，所謂Ln3+
之合計含有率，意指該等五個離子之合計含有率(Y3+
+La3+
+Gd3+
+Yb3+
+Lu3+
)。
於本發明之光學玻璃中，Ln3+
之合計含有率較佳為20%以下。Ln3+
具有若含有率較高則變得容易失透之性質。此種性質逐漸增強，因此Ln3+
之合計含有率之上限設為較佳為20.0%、更佳為15.0%、更佳為10.0%、更佳為5.0%、進而較佳為3.0%。Ln3+
之合計含有率可設為未達2.0%，亦可設為未達1.0%。再者，Ln3+
為任意成分，因此本發明之光學玻璃亦可不含Ln3+
。
Li+
、Na+
及K+
具有維持玻璃形成時之耐失透性、且降低玻璃轉移點(Tg)之性質。為增強此種性質，本發明之光學玻璃亦可包含選自由Li+
、Na+
及K+
所組成之群中之一種以上作為任意成分。
另一方面，Li+
之含有率較佳為20%以下，Na+
及K+
之含有率分別較佳為10%以下。Li+
、Na+
及K+
具有若含有率較高則使玻璃之磨耗度變大、化學耐久性惡化之性質。此種性質逐漸增強，因此Li+
之含有率之上限設為較佳為20.0%、更佳為15.0%、進而較佳為10.0%。又，Na+
及K+
之含有率各自之上限設為較佳為10.0%、更佳為8.0%、進而較佳為5.0%。
Li+
、Na+
及K+
可使用Li2
CO3
、LiNO3
、LiF、Na2
CO3
、NaNO3
、NaF、Na2
SiF6
、K2
CO3
、KNO3
、KF、KHF2
、K2
SiF6
等作為原料而含有於玻璃內。
於本發明中，Rn+
意指選自由Li+
、Na+
及K+
所組成之群中之至少一種。又，所謂Rn+
之合計含有率，意指該等三個離子之合計含有率(Li+
+Na+
+K+
)。
於本發明之光學玻璃中，Rn+
之合計含有率較佳為20%以下。若Rn+
之合計含有率較高，則具有使玻璃之磨耗度變大、化學耐久性惡化之性質。此種性質逐漸增強，因此Rn+
之合計含有率之上限設為較佳為20.0%、更佳為15.0%、進而較佳為10.0%。
Si4+
具有提高玻璃之耐失透性、提高折射率、降低磨耗度之性質。因此，本發明之光學玻璃亦可包含Si4+
作為任意成分。
另一方面，Si4+
之含有率較佳為10%以下。Si4+
具有若含有率較高則反而使玻璃變得容易失透之性質。此種性質逐漸增強，因此Si4+
之含有率之上限設為較佳為10.0%、更佳為8.0%、進而較佳為5.0%。
Si4+
可使用SiO2
、K2
SiF6
、Na2
SiF6
等作為原料而含有於玻璃內。
B3+
具有提高玻璃之耐失透性、提高折射率、降低磨耗度之性質。因此，本發明之光學玻璃亦可包含B3+
作為任意成分。
另一方面，B3+
之含有率較佳為15%以下。B3+
具有若含有率較高則使化學耐久性惡化之性質。此種性質逐漸增強，因此B3+
之含有率之上限設為較佳為15.0%、更佳為8.0%、更佳為5.0%、進而較佳為3.0%。
B3+
可使用H3
BO3
、Na2
B4
O7
、BPO4
等作為原料而含有於玻璃內。
Zn2+
具有提高玻璃之耐失透性之性質。因此，本發明之光學玻璃亦可包含Zn2+
作為任意成分。
另一方面，Zn2+
之含有率較佳為30%以下。Zn2+
具有若含有率較高則使玻璃之磨耗度惡化、折射率降低之性質。此種性質逐漸增強，因此Zn2+
之含有率之上限設為較佳為30.0%、更佳為12.0%、更佳為8.0%、更佳為4.0%、進而較佳為2.0%。
Zn2+
可使用Zn(PO3
)2
、ZnO、ZnF2
等作為原料而含有於玻璃內。
Nb5+
、Ti4+
及W6+
具有提高玻璃之折射率之性質。此外，Nb5+
具有提高化學耐久性之性質，W6+
具有降低玻璃轉移點之性質。因此，本發明之光學玻璃亦可包含選自由Nb5+
、Ti4+
及W6+
所組成之群中之一種以上作為任意成分。
另一方面，Nb5+
、Ti4+
及W6+
之含有率分別較佳為10%以下。Nb5+
、Ti4+
及W6+
具有若含有率較高則使阿貝數降低之性質。此外，Ti4+
及W6+
具有若含有率較高則使玻璃著色之性質。此種性質逐漸增強，因此Nb5+
、Ti4+
及W6+
之含有率各自之上限設為較佳為10.0%、更佳為8.0%、進而較佳為5.0%。
Nb5+
、Ti4+
及W6+
可使用Nb2
O5
、TiO2
、WO3
等作為原料而含有於玻璃內。
Zr4+
具有提高玻璃之折射率之性質。因此，本發明之光學玻璃亦可包含Zr4+
作為任意成分。
另一方面，Zr4+
之含有率較佳為10%以下。Zr4+
具有若含有率較高則由於玻璃中成分之揮發而產生條紋之性質。此種性質逐漸增強，因此Zr4+
之含有率之上限設為較佳為10.0%、更佳為8.0%、進而較佳為5.0%。
Zr4+
可使用ZrO2
、ZrF4
等作為原料而含有於玻璃內。
Ta5+
具有提高玻璃之折射率之性質。因此，本發明之光學玻璃亦可包含Ta5+
作為任意成分。
另一方面，Ta5+
之含有率較佳為10%以下。Ta5+
具有若含有率較高則使玻璃變得容易失透之性質。此種性質逐漸增強，因此Ta5+
之含有率之上限設為較佳為10.0%、更佳為8.0%、進而較佳為5.0%。
Ta5+
可使用Ta2
O5
等作為原料而含有於玻璃內。
Ge4+
具有提高玻璃之折射率、提高耐失透性之性質。因此，本發明之光學玻璃亦可包含Ge4+
作為任意成分。
另一方面，Ge4+
之含有率較佳為10%以下。若Ge4+
之含有率較高，則玻璃之材料成本上升。因此，Ge4+
之含有率之上限設為較佳為10.0%、更佳為8.0%、進而較佳為5.0%。
Ge4+
可使用GeO2
等作為原料而含有於玻璃內。
Bi3+
及Te4+
具有提高玻璃之折射率、降低玻璃轉移點之性質。本發明之光學玻璃亦可包含Bi3+
或Te4+
作為任意成分。
另一方面，Bi3+
之含有率較佳為10%以下，Te4+
之含有率較佳為15%以下。Bi3+
及Te4+
具有若含有率較高則使玻璃著色、變得容易失透之性質。此種性質逐漸增強，因此Bi3+
之含有率之上限設為較佳為10.0%、更佳為8.0%、進而較佳為5.0%。又，Te4+
之含有率之上限設為較佳為15.0%、更佳為10.0%、更佳為8.0%、進而較佳為5.0%。
Bi3+
及Te4+
可使用Bi2
O3
、TeO2
等作為原料而含有於玻璃內。
[關於陰離子成分]
本發明之光學玻璃包含F-
。F-
之含有率較佳為20~70%。
F-
具有提高玻璃之異常分散性及阿貝數使玻璃不易失透之性質。此種性質逐漸增強，因此F-
之含有率之下限設為較佳為20.0%、更佳為30.0%、更佳為35.0%、進而較佳為38.0%。
另一方面，F-
具有若含有率較高則過度提高玻璃之阿貝數、降低磨耗度之性質。此種性質逐漸增強，因此F-
之含有率之下限設為較佳為70.0%、更佳為60.0%、更佳為50.0%、進而較佳為48.0%。
F-
可使用AlF3
、MgF2
、BaF2
等各種陽離子成分之氟化物作為原料而含有於玻璃內。
本發明之光學玻璃包含O2-
。O2-
之含有率較佳為30~80%。
O2-
具有抑制玻璃之失透、抑制磨耗度之上升之性質。此種性質逐漸增強，因此O2-
之含有率之下限設為較佳為30.0%、更佳為40.0%、更佳為45.0%、進而較佳為50.0%。
另一方面，為容易地獲得由其他陰離子成分所引起之效果，O2-
之含有率之上限設為更佳為80.0%、更佳為70.0%、更佳為66.0%、進而較佳為62.0%。
又，就抑制玻璃之失透之觀點而言，O2-
之含有率與F-
之含有率的合計以較佳為98.0%、更佳為99.0%為下限，進而較佳為設為100%。
O2-
可使用Al2
O3
、MgO、BaO等各種陽離子成分之氧化物或Al(PO)3
、Mg(PO)2
、Ba(PO)2
等各種陽離子成分之磷酸鹽等作為原料而含有於玻璃內。
[關於其他成分]
於本發明之光學玻璃中，於無損本案發明之玻璃之特性的範圍內可視需要添加其他成分。
[關於不應含有之成分]
繼而，針對本發明之光學玻璃中不應含有之成分及不宜含有之成分進行說明。
除Ti、Zr、Nb、W、La、Gd、Y、Yb、Lu以外，V、Cr、Mn、Fe、Co、Ni、Cu、Ag及Mo等過渡金屬之陽離子具有如下性質：即便於單獨或複合地少量含有各者之情形時，亦會使玻璃著色，對可見光區域之特定波長發生吸收；因此尤其於使用可見光區域之波長之光學玻璃中，較佳為實質上不含該等。
Pb、Th、Cd、Tl、Os、Be及Se之陽離子近年來存在作為有害之化學物質而控制使用之傾向，不僅玻璃之製造步驟，甚至加工步驟及製品化後之處理中，認為必需環境對策上之措施。因此，於重視環境上之影響之情形時，較佳為除不可避免之混入以外實質上不含該等。藉此，光學玻璃實質上不含污染環境之物質。因此，即便不採取特別之環境對策上之措施，亦可對該光學玻璃進行製造、加工及廢棄。
Sb或Ce之陽離子作為消泡劑較為有用，但作為對環境造成不利影響之成分，近年來存在使之不含於光學玻璃中之傾向。因此，就上述方面而言，本發明之光學玻璃較佳為不含Sb或Ce。
[製造方法]
本發明之光學玻璃之製造方法並無特別限定。例如，可藉由如下方法製造：以使各成分成為特定含有率之範圍內之方式均勻地混合上述原料，將製作而成之混合物投入至石英坩堝或氧化鋁坩堝或鉑坩堝中進行部分熔融後，添加至鉑坩堝、鉑合金坩堝或銥坩堝中，於900~1200℃之溫度範圍內熔融2~10小時，進行攪拌使之均質化並消泡等之後，降低至850℃以下之溫度後進行完工攪拌除去條紋，鑄入至模具中進行緩冷。
[物性]
本發明之光學玻璃具有較高之相對折射率之溫度係數(dn/dT)。更具體而言，本發明之光學玻璃的相對折射率(589.29 nm)之溫度係數(20~40℃)之下限較佳為-6.0×10-6
℃-1
，更佳為-5.5×10-6
℃-1
，進而較佳為-5.0×10-6
℃-1
。藉此，即便於光學元件之溫度產生較大變動之環境下，折射率之變動亦會減小，因此可於更廣泛之溫度範圍內，高精度地發揮所需之光學特性。
另一方面，若相對折射率之溫度係數於正方向上過大，則由光學元件之溫度變化所引起之折射率之變化反而變大。因此，亦可將本發明之光學玻璃的相對折射率之溫度係數之上限設為較佳為6.0×10-6
℃-1
、更佳為5.5×10-6
℃-1
、進而較佳為5.0×10-6
℃-1
。本發明之光學玻璃所具有之相對折射率之溫度係數絕對值越小越佳，最佳為0。
再者，關於相對折射率之溫度係數，於與光學玻璃相同溫度之空氣中，一面照射波長589.29 nm之光一面改變光學玻璃之溫度，相對折射率之溫度係數即以此時平均1℃溫度之折射率之變化量(×10-6
/℃)表示。
本發明之光學玻璃只要為含有P5+
及F-
之氟磷酸鹽玻璃，則其光學常數並無特別限定，尤佳為具有較高之折射率(nd)、並且具有較低之分散性(較高之阿貝數)。
本發明之光學玻璃較佳為折射率(nd)為1.50以上1.60以下。更具體而言，本發明之光學玻璃之折射率之下限較佳為1.50，更佳為1.51，更佳為1.52。又，本發明之光學玻璃之折射率之上限較佳為1.58，更佳為1.57，更佳為1.55。
本發明之光學玻璃較佳為阿貝數(νd)為60以上80以下。更具體而言，本發明之光學玻璃之阿貝數之下限較佳為60，更佳為65，更佳為70，進而較佳為73。另一方面，本發明之光學玻璃之阿貝數之上限較佳為80，更佳為78，進而較佳為77。
藉此，光學設計之自由度擴大，進而即便謀求元件之薄型化亦可獲得所需之光之折射量，因此可謀求光學系統之高精度化及小型化。
再者，折射率(nd)及阿貝數(νd)意指基於日本光學玻璃工業會規格JOGIS01-2003進行測定而獲得之值。
本發明之光學玻璃磨耗度越低越佳。藉此，光學玻璃之必需以外之磨耗或損傷降低，對光學玻璃之研磨加工中之操作變得容易，因此可容易地進行研磨加工。本發明之光學玻璃之磨耗度之上限較佳為600，更佳為550，更佳為500，更佳為450，進而較佳為430。
另一方面，若磨耗度過低則存在反而難以進行研磨加工之傾向。因此，本發明之光學玻璃之磨耗度之下限亦可設為較佳為80、更佳為100、進而較佳為120。
再者，所謂磨耗度，意指依據「JOGIS10-1994光學玻璃之磨耗度之測定方法」進行測定而獲得之值。
[預成形體及光學元件]
本發明之光學玻璃於各種光學元件及光學設計中較為有用，其中尤佳為使用如下等方法製作透鏡或稜鏡、反射鏡等光學元件：由本發明之光學玻璃形成預成形體，並對該預成形體進行研磨加工或精密加壓成形。藉此，於用於如相機或投影儀等使可見光穿透光學元件之光學機器時，可實現高精細且高精度之成像特性。尤其是，本發明之光學玻璃由溫度變化所引起之折射率之變動較小，因此例如即便用於如投影儀般於使用時成為高溫之用途中，亦可實現高精細且高精度之成像特性。此處，製造預成形體材料之方法並無特別限定，例如亦可使用日本專利特開平8-319124中記載之玻璃坯之成形方法，或如日本專利特開平8-73229中記載之光學玻璃之製造方法及製造裝置般由熔融玻璃直接製造預成形體材料之方法。又，亦可使用對由光學玻璃形成之條狀材料進行研削研磨等冷加工而製造的方法。
[實施例]
將本發明之光學玻璃即實施例1~3及比較例1之玻璃的組成(以表示陽離子%或表示陰離子%之莫耳%表示)、折射率(nd)、阿貝數(νd)、相對折射率之溫度係數(dn/dT)及磨耗度(Aa)示於表1。再者，以下之實施例僅用於例示，並不僅限定於該等實施例。
本發明之實施例1~3及比較例1之光學玻璃均以如下方式進行製作：作為各成分之原料，選定各自相應之氧化物、碳酸鹽、硝酸鹽、氟化物、偏磷酸化合物等通常用於氟磷酸鹽玻璃之高純度原料，以成為表1所示之各實施例之組成比率之方式進行稱量並均勻地混合之後，投入至鉑坩堝中，依據玻璃組成之熔融難易度利用電爐於900~1200℃之溫度範圍內熔解2~10小時，進行攪拌使之均質化並消泡等之後，將溫度降至850℃以下後鑄入至模具中，進行緩冷而製作玻璃。
此處，實施例1~3及比較例1之光學玻璃之折射率(nd)及阿貝數(νd)係基於日本光學玻璃工業會規格JOGIS01-2003進行測定。再者，作為用於本測定之玻璃，使用退火條件為將緩冷降低速度設為-25℃/hr而利用緩冷爐進行處理者。
又，實施例1~3及比較例1之光學玻璃之相對折射率之溫度係數(dn/dT)係以日本光學玻璃工業會規格JOGIS18-1994「光學玻璃之折射率之溫度係數之測定方法」中記載之方法中的干涉法進行測定。
又，磨耗度係依據「JOGIS10-1994光學玻璃之磨耗度之測定方法」進行測定。即，將30×30×10 mm大小之玻璃方板之試樣置於每分鐘水平旋轉60次之鑄鐵製平面盤(250 mmϕ)自中心起80 mm之起始位置上，一面垂直施加9.8 N(1 kgf)之荷重，一面以同樣之方式將於水20 mL中添加有#800(平均粒徑20 μm)之研磨材料(氧化鋁質A研磨粒)10 g之研磨液供給5分鐘進行摩擦，測定研磨前後之試樣質量，求出磨耗質量。以相同之方式求出日本光學玻璃工業會所指定之標準試樣之磨耗質量，根據下式進行計算：
磨耗度={(試樣之磨耗質量/比重)/(標準試樣之磨耗質量/比重)}×100。
[表1]
如表1所示，本發明之實施例1~3之光學玻璃相對折射率之溫度係數(20~40℃)均為-6.0×10-6
℃-1
以上，為所需之範圍內。另一方面，作為本發明之範圍以外之比較例1，其相對折射率之溫度係數低於-6.0×10-6
℃-1
。因此，可明確本發明之實施例之光學玻璃與比較例1之玻璃相比，相對折射率之溫度係數較高。
又，本發明之實施例之光學玻璃折射率均為1.50以上，更詳細而言為1.53以上，為所需之範圍內。又，本發明之實施例之光學玻璃阿貝數均為60以上，更詳細而言為74以上，為所需之範圍內。又，本發明之實施例之光學玻璃磨耗度均為600以下，為所需之範圍內。
因此，可明確，本發明之實施例之光學玻璃折射率及阿貝數為所需之範圍內，相對折射率之溫度係數較高，且，磨耗度較小。由此推測，本發明之實施例之光學玻璃可於更廣泛之溫度範圍內高精度地獲得所需之成像特性等光學特性，藉此可有助於光學系統之高解像度化及小型化。
進而，使用本發明之實施例之光學玻璃，於形成研磨加工用預成形體之後進行研削及研磨，加工成透鏡及稜鏡之形狀。又，使用本發明之實施例之光學玻璃，形成精密加壓成形用之預成形體，對該預成形體進行精密加壓成形加工而加工成透鏡及稜鏡之形狀。於任一情形時，均可加工成各種透鏡及稜鏡之形狀。
以上，為例示已詳細地說明本發明，但希望理解，本實施例僅為用於例示者，業者可於不脫離本發明之思想及範圍而進行多種變更。The optical glass of the present invention contains P 5+ , Al 3+ and Mg 2+ as cationic components, O 2 and F - as anionic components, and the temperature coefficient (20 ~ 40 ° C) of the relative refractive index (589.29 nm) is- 6.0 × 10 -6 (° C -1 ) or more. In addition to P 5+ , it also contains Al 3+ and Mg 2+ as cationic components, and in addition to O 2- it also contains F - as an anionic component, thereby increasing the temperature coefficient of the relative refractive index of the optical glass. Therefore, by obtaining optical characteristics such as required imaging characteristics with high accuracy over a wider temperature range, an optical glass that can contribute to high resolution and miniaturization of the optical system can be obtained.
Hereinafter, such an optical glass is also referred to as "the optical glass of the present invention".
Hereinafter, the optical glass of this invention is demonstrated. The present invention is not limited to the following aspects, and can be implemented with appropriate changes within the scope of the object of the present invention. In addition, there may be cases where the description is omitted, but the gist of the invention is not limited.
＜ Glass composition ＞
Each component which comprises the optical glass of this invention is demonstrated.
In the present specification, unless otherwise specified, the content rate of each component is expressed as a cation% or an anion% based on the molar ratio. Here, the "cationic%" and "anionic%" (hereinafter, sometimes referred to as "cationic% (mole%)" and "anionic% (mole%)") are: the glass of the optical glass of the present invention The constituent components are separated into a cationic component and an anionic component, and the total ratio is 100 mol%, and the composition expresses the content rate of each component contained in the glass.
In addition, the ionic valence of each component is used for convenience only, so it is not distinguished from other ionic valences. The ionic valence of each component present in the optical glass may be other than the representative value. For example, P is usually present in glass in a state where the valence of the ion is 5 valences. Therefore, P is expressed as "P 5+ " in this specification, but may exist in a state of other ion valences. In this way, strictly speaking, even if it exists in a state with other ionic valences, it is considered in this specification that each component exists in glass with an ionic valence of a representative value.
[About cationic ingredients]
The optical glass of the present invention contains P 5+ . The content of P 5+ is preferably 20 to 55%.
P 5+ is a glass-forming component that has properties of suppressing devitrification of glass and increasing refractive index. This property is gradually enhanced, so the lower limit of the content rate of P 5+ is preferably 20.0%, more preferably 25.0%, and even more preferably 30.0%.
On the other hand, P 5+ has a property of lowering the Abbe number when the content rate is high. This property is gradually enhanced, so the upper limit of the content rate of P 5+ is preferably 55.0%, more preferably 50.0%, more preferably 45.0%, more preferably 41.0%, and even more preferably 37.0%.
P 5+ can be contained in glass using Al (PO 3 ) 3 , Ca (PO 3 ) 2 , Ba (PO 3 ) 2 , Zn (PO 3 ) 2 , BPO 4 , H 3 PO 4 and the like as raw materials.
The optical glass of the present invention contains Al 3+ . The content of Al 3+ is preferably 1 to 20%.
Al 3+ has the properties of improving the devitrification resistance of glass, reducing the abrasion degree, and increasing the temperature coefficient of relative refractive index. This property is gradually enhanced, so the lower limit of the content rate of Al 3+ is preferably 1.0%, more preferably 5.0%, more preferably 7.0%, and still more preferably 9.7%.
On the other hand, Al 3+ has a property of lowering the refractive index of glass when the content rate is high. This property is gradually enhanced, so the upper limit of the content rate of Al 3+ is preferably 20.0%, more preferably 18.0%, and still more preferably 16.0%.
Al 3+ can be contained in glass using Al (PO 3 ) 3 , AlF 3 , Al 2 O 3 and the like as raw materials.
The optical glass of the present invention contains Mg 2+ . The content of Mg 2+ is preferably 0.1 to 30%.
Mg 2+ has the properties of improving the devitrification resistance of glass, reducing the abrasion degree, and increasing the temperature coefficient of relative refractive index. This property is gradually enhanced, so the lower limit of the content of Mg 2+ is set to preferably 0.1%, more preferably 2.0%, more preferably 5.0%, more preferably 10.0%, and more preferably more than 11.0%. .
On the other hand, Mg 2+ has a property of lowering the refractive index of glass when the content is high. This property is gradually enhanced, so the upper limit of the content rate of Mg 2+ is preferably 30.0%, more preferably 25.0%, and even more preferably 20.0%.
Mg 2+ can be contained in glass using MgO, MgF 2 or the like as a raw material.
The optical glass of the present invention may contain Ca 2+ as an optional component. The content of Ca 2+ is preferably 30% or less.
Ca 2+ has the properties of improving the devitrification resistance of glass, suppressing the decrease in refractive index, reducing the degree of abrasion, and increasing the temperature coefficient of relative refractive index. This property is gradually enhanced, so the lower limit of the content rate of Ca 2+ is preferably 0.1%, more preferably 5.0%, and further preferably more than 10.0%.
On the other hand, if Ca 2+ is high, the devitrification resistance and the refractive index of the glass are reduced. This property is gradually enhanced, so the upper limit of the content of Ca 2+ is preferably 30.0%, more preferably 20.0%, and even more preferably 16.0%.
Ca 2+ can be contained in glass using Ca (PO 3 ) 2 , CaCO 3 , CaF 2 or the like as a raw material.
The optical glass of the present invention may also contain Sr 2+ as an optional component. The content of Sr 2+ is preferably 30% or less.
Sr 2+ has properties of improving the devitrification resistance of glass and suppressing the decrease in refractive index. This property is gradually enhanced, so the lower limit of the content ratio of Sr 2+ can also be set to preferably 0.1%, more preferably 1.0%, and even more preferably 2.0%.
On the other hand, if the content of Sr 2+ is high, the devitrification resistance and the refractive index of the glass are reduced. This property is gradually enhanced, so the upper limit of the content ratio of Sr 2+ is preferably 30.0%, more preferably 20.0%, and even more preferably 14.0%.
Sr 2+ can be contained in glass using Sr (NO 3 ) 2 , SrF 2 or the like as a raw material.
The optical glass of the present invention may contain Ba 2+ as an optional component. The content of Ba 2+ is preferably 30% or less.
Ba 2+ has the properties of improving the devitrification resistance of glass, maintaining a low dispersion, and increasing the refractive index. This property is gradually enhanced, so the lower limit of the Ba 2+ content rate can also be set to preferably 0.1%, more preferably 1.0%, more preferably 5.0%, more preferably 10.0%, more preferably 12.0%, It is more preferably 14.0%.
On the other hand, if Ba 2+ is high, the devitrification resistance of the glass is lowered, and the temperature coefficient of the relative refractive index is lowered. This property is gradually enhanced, so the upper limit of the content rate of Ba 2+ is preferably 30.0%, more preferably 25.0%, more preferably 20.0%, and even more preferably 17.1% or less.
Ba 2+ can be contained in glass using Ba (PO 3 ) 2 , BaCO 3 , Ba (NO 3 ) 2 , BaF 2 or the like as a raw material.
The alkaline earth metal in the present invention means one or more members selected from the group consisting of Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ . In addition, there is a case where one or more members selected from the group consisting of Mg 2+ , Ca 2+ , Sr 2+, and Ba 2+ are expressed as R 2+ .
The total content of R 2+ means the total content of one or more of the four ions (for example, Mg 2+ + Ca 2+ + Sr 2+ + Ba 2+ ).
The total content of R 2+ is preferably 30 to 70%. When the total content of R 2+ is within this range, a glass having higher devitrification resistance can be obtained.
The lower limit of the total content of R 2+ is preferably 30.0%, more preferably 35.0%, more preferably 40.0%, and still more preferably 44.0%. On the other hand, the upper limit of the total content of R 2+ is preferably 70.0%, more preferably 65.0%, more preferably 60.0%, and still more preferably 55.0%.
In the optical glass of the present invention, the total content of Mg 2+ and Ca 2+ is preferably 7.5 to 50%. The higher the total content rate, the higher the temperature coefficient of the relative refractive index. Therefore, the lower limit of (Mg 2+ + Ca 2+ ) is preferably 7.5%, more preferably 12.5%, and even more preferably 25.0%.
On the other hand, if the total content is high, it has properties of reducing the devitrification resistance of the glass and reducing the refractive index. This property is gradually enhanced, so the upper limit of (Mg 2+ + Ca 2+ ) is preferably 50.0%, more preferably 40.0%, and even more preferably 35.0%.
The optical glass of the present invention is preferably a ratio of the total of the Mg 2+ content rate (% cation) and the Ca 2+ content rate (% cation) to the total content rate (R 2+ : cation%) of the alkaline earth metal ((Mg 2+ + Ca 2+ ) / R 2+ ) is 0.25 or more.
The ratio of the total content of Mg 2+ and Ca 2+ to R 2+ is relatively high, thereby increasing the temperature coefficient of the relative refractive index and reducing the degree of abrasion. Therefore, the lower limit of (Mg 2+ + Ca 2+ ) / R 2+ is preferably 0.25, more preferably 0.31, more preferably 0.36, more preferably 0.41, and even more preferably 0.50.
On the other hand, the upper limit of (Mg 2+ + Ca 2+ ) / R 2+ may also be 1. However, if the ratio of the total content of Mg 2+ and Ca 2+ to R 2+ is high, it has properties of reducing the devitrification resistance of the glass and the refractive index. This property is gradually enhanced, so the upper limit of (Mg 2+ + Ca 2+ ) / R 2+ can be set to preferably 0.90, more preferably 0.80, more preferably 0.70, and even more preferably 0.65.
The optical glass of the present invention is preferably such that the ratio (Mg 2+ / P 5+ ) of the Mg 2+ content rate (% cation) to the P 5+ content rate (% cation) is 0.25 or more.
By increasing the ratio of the content rate of Mg 2+ which is relatively strong to increase the temperature coefficient of the relative refractive index to the content rate of the glass forming component P 5+ , the temperature coefficient of the relative refractive index of the glass can be further increased. Therefore, the lower limit of (Mg 2+ / P 5+ ) is preferably 0.25, more preferably 0.30, more preferably 0.35, and still more preferably 0.42.
On the other hand, if the ratio of the content ratio of Mg 2+ to the content ratio of P 5+ is high, it has the properties of reducing the devitrification resistance of glass and the refractive index. This property is gradually enhanced, so the upper limit of (Mg 2+ / P 5+ ) can be set to preferably 1.00, more preferably 0.90, more preferably 0.80, and even more preferably 0.70.
La 3+ , Gd 3+ , Y 3+ , Yb 3+ and Lu 3+ have the properties of maintaining low dispersion, increasing refractive index, and further improving devitrification resistance. In order to enhance this property, the optical glass of the present invention may also include, as an arbitrary component, one or more components selected from the group consisting of La 3+ , Gd 3+ , Y 3+ , Yb 3+, and Lu 3+ .
On the other hand, the contents of La 3+ , Gd 3+ , Y 3+ , Yb 3+ and Lu 3+ are each preferably 10% or less. La 3+ , Gd 3+ , Y 3+ , Yb 3+, and Lu 3+ have properties such that when the content rate is high, the stability of the glass is deteriorated and devitrification is liable to occur. This property is gradually enhanced, so the upper limits of the content ratios of La 3+ , Gd 3+ , Y 3+ , Yb 3+, and Lu 3+ are preferably 10.0%, more preferably 8.0%, and more preferably 5.0. %, More preferably 3.0%.
La 3+ , Gd 3+ , Y 3+ , Yb 3+ and Lu 3+ can use La 2 O 3 , LaF 3 , Gd 2 O 3 , GdF 3 , Y 2 O 3 , YF 3 , Yb 2 O 3 , Lu 2 O 3 and the like are contained in the glass as a raw material.
Ln 3+ in the present invention means at least one selected from the group consisting of Y 3+ , La 3+ , Gd 3+ , Yb 3+ and Lu 3+ . The total content of Ln 3+ means the total content of the five ions (Y 3+ + La 3+ + Gd 3+ + Yb 3+ + Lu 3+ ).
In the optical glass of the present invention, the total content of Ln 3+ is preferably 20% or less. Ln 3+ has a property of being easily devitrified if the content rate is high. This property is gradually enhanced, so the upper limit of the total content of Ln 3+ is preferably 20.0%, more preferably 15.0%, more preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%. The total content of Ln 3+ may be set to less than 2.0%, or may be set to less than 1.0%. Furthermore, Ln 3+ is an arbitrary component, so the optical glass of the present invention may not contain Ln 3+ .
Li + , Na + and K + have the property of maintaining devitrification resistance during glass formation and reducing the glass transition point (Tg). In order to enhance such properties, the optical glass of the present invention may further include, as an optional component, one or more members selected from the group consisting of Li + , Na + and K + .
On the other hand, the content rate of Li + is preferably 20% or less, and the content rates of Na + and K + are each preferably 10% or less. Li + , Na +, and K + have properties such that if the content ratio is high, the abrasion degree of the glass is increased and the chemical durability is deteriorated. This property is gradually enhanced, so the upper limit of the content rate of Li + is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%. The upper limits of the content ratios of Na + and K + are preferably 10.0%, more preferably 8.0%, and even more preferably 5.0%.
Li + , Na + and K + can use Li 2 CO 3 , LiNO 3 , LiF, Na 2 CO 3 , NaNO 3 , NaF, Na 2 SiF 6 , K 2 CO 3 , KNO 3 , KF, KHF 2 , K 2 SiF 6 and the like are contained in the glass as a raw material.
In the present invention, Rn + means at least one selected from the group consisting of Li + , Na + and K + . The total content rate of Rn + means the total content rate of these three ions (Li + + Na + + K + ).
In the optical glass of the present invention, the total content of Rn + is preferably 20% or less. When the total content ratio of Rn + is high, it has the property of increasing the abrasion degree of glass and deteriorating chemical durability. This property is gradually enhanced, so the upper limit of the total content ratio of Rn + is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%.
Si 4+ has the properties of improving the devitrification resistance of glass, increasing the refractive index, and reducing the abrasion degree. Therefore, the optical glass of the present invention may also contain Si 4+ as an optional component.
On the other hand, the Si 4+ content is preferably 10% or less. Si 4+ has a property that if the content rate is high, the glass becomes easily devitrified. This property is gradually enhanced, so the upper limit of the content rate of Si 4+ is preferably 10.0%, more preferably 8.0%, and even more preferably 5.0%.
Si 4+ can be contained in glass using SiO 2 , K 2 SiF 6 , Na 2 SiF 6 and the like as raw materials.
B 3+ has the properties of improving the devitrification resistance of glass, increasing the refractive index, and reducing the degree of abrasion. Therefore, the optical glass of the present invention may also contain B 3+ as an optional component.
On the other hand, the content of B 3+ is preferably 15% or less. B 3+ has a property of deteriorating chemical durability if the content rate is high. This property is gradually enhanced, so the upper limit of the content rate of B 3+ is preferably 15.0%, more preferably 8.0%, more preferably 5.0%, and even more preferably 3.0%.
B 3+ can be contained in glass using H 3 BO 3 , Na 2 B 4 O 7 , BPO 4 and the like as raw materials.
Zn 2+ has the property of improving the devitrification resistance of glass. Therefore, the optical glass of the present invention may also contain Zn 2+ as an arbitrary component.
On the other hand, the content of Zn 2+ is preferably 30% or less. Zn 2+ has a property that if the content ratio is high, the abrasion degree of glass is deteriorated and the refractive index is reduced. This property is gradually enhanced, so the upper limit of the content rate of Zn 2+ is preferably 30.0%, more preferably 12.0%, more preferably 8.0%, more preferably 4.0%, and even more preferably 2.0%.
Zn 2+ can be contained in glass using Zn (PO 3 ) 2 , ZnO, ZnF 2 or the like as a raw material.
Nb 5+ , Ti 4+ and W 6+ have the property of increasing the refractive index of glass. In addition, Nb 5+ has the property of improving chemical durability, and W 6+ has the property of reducing the glass transition point. Therefore, the optical glass of the present invention may also contain, as an optional component, one or more members selected from the group consisting of Nb 5+ , Ti 4+ and W 6+ .
On the other hand, the content ratios of Nb 5+ , Ti 4+ and W 6+ are each preferably 10% or less. Nb 5+ , Ti 4+ and W 6+ have the property of lowering the Abbe number if the content ratio is high. In addition, Ti 4+ and W 6+ have the property of coloring glass when the content ratio is high. This property is gradually strengthened, so the upper limits of the content rates of Nb 5+ , Ti 4+ and W 6+ are preferably 10.0%, more preferably 8.0%, and even more preferably 5.0%.
Nb 5+ , Ti 4+ and W 6+ can be contained in glass using Nb 2 O 5 , TiO 2 , WO 3 and the like as raw materials.
Zr 4+ has the property of increasing the refractive index of glass. Therefore, the optical glass of the present invention may also contain Zr 4+ as an optional component.
On the other hand, the content of Zr 4+ is preferably 10% or less. Zr 4+ has a property that if the content is high, streaks are generated due to volatilization of components in the glass. This property is gradually enhanced, so the upper limit of the content rate of Zr 4+ is preferably 10.0%, more preferably 8.0%, and even more preferably 5.0%.
Zr 4+ can be contained in glass using ZrO 2 , ZrF 4 or the like as a raw material.
Ta 5+ has the property of increasing the refractive index of glass. Therefore, the optical glass of the present invention may contain Ta 5+ as an optional component.
On the other hand, the content of Ta 5+ is preferably 10% or less. Ta 5+ has a property of making glass easily devitrified if the content is high. This property is gradually enhanced, so the upper limit of the content rate of Ta 5+ is preferably 10.0%, more preferably 8.0%, and even more preferably 5.0%.
Ta 5+ can be contained in glass using Ta 2 O 5 or the like as a raw material.
Ge 4+ has the property of increasing the refractive index of glass and improving the devitrification resistance. Therefore, the optical glass of the present invention may also contain Ge 4+ as an arbitrary component.
On the other hand, the content of Ge 4+ is preferably 10% or less. If the content rate of Ge 4+ is high, the material cost of glass increases. Therefore, the upper limit of the content rate of Ge 4+ is preferably 10.0%, more preferably 8.0%, and still more preferably 5.0%.
Ge 4+ can be contained in glass using GeO 2 or the like as a raw material.
Bi 3+ and Te 4+ have the properties of increasing the refractive index of glass and reducing the glass transition point. The optical glass of the present invention may also contain Bi 3+ or Te 4+ as an optional component.
On the other hand, the content rate of Bi 3+ is preferably 10% or less, and the content rate of Te 4+ is preferably 15% or less. Bi 3+ and Te 4+ have properties such that if the content ratio is high, the glass is colored and easily devitrified. This property is gradually enhanced, so the upper limit of the content rate of Bi 3+ is preferably 10.0%, more preferably 8.0%, and even more preferably 5.0%. The upper limit of the content of Te 4+ is preferably 15.0%, more preferably 10.0%, more preferably 8.0%, and even more preferably 5.0%.
Bi 3+ and Te 4+ can be contained in glass using Bi 2 O 3 , TeO 2 or the like as a raw material.
[About anionic ingredients]
The optical glass of the present invention comprises F -. F - The content ratio is preferably 20 to 70%.
F -It has the property of improving the abnormal dispersibility of glass and Abbe's number, making glass not easily devitrified. Such properties gradually increased, so F - is set to the lower limit of the content ratio is preferably 20.0%, more preferably 30.0%, more preferably 35.0%, and further preferably 38.0%.
On the other hand, F - if the content has a higher Abbe number of the glass is excessively increased, the decrease of the degree of wear properties. Such properties gradually increased, so F - is set to the lower limit for the ratio is preferably 70.0%, more preferably 60.0%, more preferably 50.0%, and further preferably 48.0%.
F - Fluoride compounds of various cationic components such as AlF 3 , MgF 2 , and BaF 2 can be contained in the glass as raw materials.
The optical glass of the present invention contains O 2- . The content of O 2- is preferably 30 to 80%.
O 2- has the property of suppressing devitrification of glass and suppressing an increase in abrasion. This property is gradually enhanced, so the lower limit of the content rate of O 2- is preferably 30.0%, more preferably 40.0%, more preferably 45.0%, and still more preferably 50.0%.
On the other hand, in order to easily obtain the effects caused by other anionic components, the upper limit of the content rate of O 2 is set to 80.0%, 70.0%, 66.0%, or 62.0%. %.
From the viewpoint of suppressing devitrification of glass, the total limit of the content of O 2 and the content of F - is preferably 98.0%, more preferably 99.0% as the lower limit, and more preferably 100%. .
O 2-It can be used as a raw material by using oxides of various cationic components such as Al 2 O 3 , MgO, and BaO, or phosphates of various cationic components such as Al (PO) 3 , Mg (PO) 2 , and Ba (PO) 2 . In glass.
[About other ingredients]
In the optical glass of the present invention, other components may be added as needed within a range that does not impair the characteristics of the glass of the present invention.
[About ingredients that should not be contained]
Next, components which should not be contained in the optical glass of the present invention and components which should not be contained will be described.
In addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu, the cations of transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo have the following properties: When a small amount of each is contained in combination, the glass is also colored and absorbs a specific wavelength in the visible light region; therefore, it is preferable that the optical glass, which uses wavelengths in the visible light region, is substantially free of these.
The cations of Pb, Th, Cd, Tl, Os, Be, and Se have tended to be controlled as harmful chemical substances in recent years. Not only glass manufacturing steps, but even processing steps and post-productive treatment, environmental measures are considered necessary. On measures. Therefore, in the case of attaching importance to environmental influences, it is preferable that these are substantially not included except for inevitable incorporation. As a result, the optical glass is substantially free of substances that pollute the environment. Therefore, the optical glass can be manufactured, processed, and discarded without taking special environmental measures.
Sb or Ce cations are useful as defoamers, but as a component that adversely affects the environment, in recent years, there has been a tendency to exclude them from optical glass. Therefore, in terms of the above aspects, the optical glass of the present invention is preferably free of Sb or Ce.
[Production method]
The manufacturing method of the optical glass of this invention is not specifically limited. For example, it can be manufactured by uniformly mixing the above-mentioned raw materials so that each component falls within a specific content range, and putting the prepared mixture into a quartz crucible, an alumina crucible, or a platinum crucible for partial melting. , Add to a platinum crucible, a platinum alloy crucible or an iridium crucible, melt in a temperature range of 900 to 1200 ° C for 2 to 10 hours, stir to homogenize and defoam, and then reduce to a temperature below 850 ° C Stirring is completed to remove streaks, and it is cast into a mold for slow cooling.
[Physical properties]
The optical glass of the present invention has a relatively high temperature coefficient of relative refractive index (dn / dT). More specifically, the lower limit of the relative refractive index of the optical glass of the present invention (589.29 nm) of the temperature coefficient (20 ~ 40 ℃) of preferably -6.0 × 10 -6 ℃ -1, more preferably -5.5 × 10 - 6 ℃ -1 , more preferably -5.0 × 10 -6 ℃ -1 . Thereby, even in the environment where the temperature of the optical element fluctuates greatly, the variation of the refractive index is reduced, so that the required optical characteristics can be exhibited with high accuracy in a wider temperature range.
On the other hand, if the temperature coefficient of the relative refractive index is too large in the positive direction, the change in the refractive index caused by the temperature change of the optical element becomes large instead. Therefore, the upper limit of the temperature coefficient of the relative refractive index of the optical glass of the present invention may be preferably 6.0 × 10 -6 ℃ -1 , more preferably 5.5 × 10 -6 ℃ -1 , and further preferably 5.0. × 10 -6 ℃ -1 . The smaller the absolute value of the temperature coefficient of the relative refractive index of the optical glass of the present invention, the better, and most preferably 0.
Furthermore, regarding the temperature coefficient of the relative refractive index, in the air at the same temperature as the optical glass, the temperature of the optical glass is changed while irradiating light with a wavelength of 589.29 nm. The change in refractive index (× 10 -6 / ° C) is shown.
The optical glass of the present invention is not particularly limited as long as it is a fluorophosphate glass containing P 5+ and F − , and it is particularly preferred that it has a high refractive index (nd) and a low dispersibility ( Higher Abbe number).
The optical glass of the present invention preferably has a refractive index (nd) of 1.50 or more and 1.60 or less. More specifically, the lower limit of the refractive index of the optical glass of the present invention is preferably 1.50, more preferably 1.51, and even more preferably 1.52. The upper limit of the refractive index of the optical glass of the present invention is preferably 1.58, more preferably 1.57, and even more preferably 1.55.
The optical glass of the present invention preferably has an Abbe number (νd) of 60 or more and 80 or less. More specifically, the lower limit of the Abbe number of the optical glass of the present invention is preferably 60, more preferably 65, more preferably 70, and even more preferably 73. On the other hand, the upper limit of the Abbe number of the optical glass of the present invention is preferably 80, more preferably 78, and even more preferably 77.
As a result, the degree of freedom in optical design is expanded, and the required amount of light refraction can be obtained even if the thickness of the device is reduced. Therefore, the precision and miniaturization of the optical system can be achieved.
The refractive index (nd) and Abbe number (νd) mean values obtained by measurement based on the specifications of the Japan Optical Glass Industry Association JOGIS01-2003.
The lower the abrasion degree of the optical glass of the present invention, the better. Thereby, abrasion or damage other than the necessity of the optical glass is reduced, and operations in polishing processing of the optical glass are facilitated, so that the polishing processing can be easily performed. The upper limit of the abrasion degree of the optical glass of the present invention is preferably 600, more preferably 550, more preferably 500, more preferably 450, and even more preferably 430.
On the other hand, if the degree of wear is too low, it tends to be difficult to perform polishing. Therefore, the lower limit of the abrasion degree of the optical glass of the present invention can also be set to preferably 80, more preferably 100, and even more preferably 120.
In addition, the abrasion degree means a value obtained by measuring in accordance with the "measurement method of the abrasion degree of JOGIS10-1994 optical glass".
[Preforms and Optical Elements]
The optical glass of the present invention is useful in various optical elements and optical designs, and among them, it is particularly preferable to use the following methods to make optical elements such as lenses, mirrors, and mirrors: a preform is formed from the optical glass of the present invention, and The formed body is subjected to grinding or precision press forming. This makes it possible to realize high-definition and high-precision imaging characteristics when used in an optical device such as a camera or a projector that allows visible light to pass through the optical element. In particular, the optical glass of the present invention has a small change in refractive index due to temperature changes, and therefore, it can achieve high-definition and high-accuracy imaging characteristics, for example, even in applications such as a projector that becomes hot during use. . Here, the method for manufacturing the preform material is not particularly limited, and for example, a method for forming a glass blank described in Japanese Patent Laid-Open No. 8-319124 or an optical glass as described in Japanese Patent Laid-Open No. 8-73229 can be used. A method of manufacturing a preform material directly from molten glass like a manufacturing method and a manufacturing apparatus. Alternatively, a method of manufacturing a strip-shaped material made of optical glass by cold working, such as grinding, may be used.
[Example]
The optical glass of the present invention, that is, the composition of the glasses of Examples 1 to 3 and Comparative Example 1 (represented by Moore% indicating cationic% or anionic%), refractive index (nd), Abbe number (νd), relative The temperature coefficient (dn / dT) and abrasion degree (Aa) of the refractive index are shown in Table 1. In addition, the following embodiments are only for illustration, and are not limited to these embodiments.
The optical glasses of Examples 1 to 3 and Comparative Example 1 of the present invention were prepared as follows: As the raw materials of each component, the corresponding oxides, carbonates, nitrates, fluorides, metaphosphoric acid compounds, etc. were selected. The high-purity raw materials of the fluorophosphate glass were weighed and uniformly mixed so as to have a composition ratio of each of the examples shown in Table 1, and then put into a platinum crucible. After melting in a temperature range of 900 to 1200 ° C for 2 to 10 hours, after stirring to homogenize and defoam, etc., the temperature is lowered to 850 ° C or lower, and then cast into a mold, followed by slow cooling to produce glass.
Here, the refractive index (nd) and Abbe number (νd) of the optical glass of Examples 1 to 3 and Comparative Example 1 were measured based on the specifications of the Japan Optical Glass Industry Association JOGIS01-2003. In addition, as a glass used for this measurement, the annealing conditions were used, and the slow cooling rate was set to -25 degreeC / hr, and it processed using the slow cooling furnace.
In addition, the temperature coefficient of the relative refractive index (dn / dT) of the optical glass of Examples 1 to 3 and Comparative Example 1 is based on the Japan Optical Glass Industry Association JOGIS18-1994 "Method for Measuring the Temperature Coefficient of the Refractive Index of Optical Glass" The interference method in the method described in the measurement.
In addition, the abrasion degree was measured according to "JOGIS10-1994 measuring method of abrasion degree of optical glass". That is, a sample of a 30 × 30 × 10 mm square glass plate is placed at a starting position of 80 mm from the center of a cast-iron flat plate (250 mmϕ) that rotates horizontally 60 times per minute, with 9.8 N applied vertically on one side With a load of (1 kgf), in the same manner, 10 g of a polishing liquid (alumina-based A abrasive particles) of # 800 (average particle size 20 μm) was added to 20 mL of water for 5 minutes for rubbing. , Measure the mass of the sample before and after grinding to obtain the abrasion quality. In the same way, the abrasion quality of the standard sample specified by the Japan Optical Glass Industry Association was calculated and calculated according to the following formula:
Abrasion degree = {(Abrasion mass / specific gravity of the sample) / (Abrasion mass / specific gravity of the standard sample)} × 100.
[Table 1]
As shown in Table 1, the temperature coefficients (20-40 ° C) of the relative refractive indices of the optical glasses of Examples 1 to 3 of the present invention are all -6.0 × 10 -6 ℃ -1 or more, which are within the required range. On the other hand, as Comparative Example 1 outside the scope of the present invention, the temperature coefficient of the relative refractive index was lower than -6.0 × 10 -6 ° C -1 . Therefore, it is clear that the temperature coefficient of the relative refractive index of the optical glass of the example of the present invention is higher than that of the glass of Comparative Example 1.
In addition, the refractive indices of the optical glasses in the examples of the present invention are all 1.50 or more, more specifically 1.53 or more, which are within a required range. In addition, the Abbe numbers of the optical glass in the examples of the present invention are all 60 or more, more specifically 74 or more, which are within a required range. In addition, the abrasion degrees of the optical glass in the examples of the present invention are all 600 or less, which is within a required range.
Therefore, it is clear that the refractive index and Abbe number of the optical glass in the embodiments of the present invention are within the required ranges, the temperature coefficient of the relative refractive index is high, and the degree of wear is small. It is speculated that the optical glass according to the embodiment of the present invention can obtain optical characteristics such as required imaging characteristics with high accuracy over a wider temperature range, thereby contributing to high resolution and miniaturization of the optical system.
Furthermore, the optical glass according to the embodiment of the present invention was used to grind and polish the preform for polishing processing, and then processed it into the shape of a lens and a cymbal. In addition, the optical glass according to the embodiment of the present invention is used to form a preform for precision press forming, and the preform is subjected to a precision press forming process to be processed into the shapes of a lens and a cymbal. In either case, it can be processed into various lens and 稜鏡 shapes.
The present invention has been described in detail as an example, but it is to be understood that this embodiment is only for illustration, and the industry can make various changes without departing from the spirit and scope of the present invention.