Patent ID: 6413894
Filing Date: 2002-07-02
Classification: C03C,Y10S

Abstract:
A press shapeable glass preform in the form of a sphere, a marble, a flat plate, a column or a round loaf which is formed of an optical glass comprising silicon oxide, boron oxide, lithium oxide, calcium oxide, titanium oxide and niobium oxide, the total content of silicon oxide, boron oxide, lithium oxide, calcium oxide, titanium oxide and niobium oxide being at least 63% by weight,the content of the silicon oxide being 17 to 33% by weight, exclusive of 17% by weight, the content of the boron oxide being 1 to 25% by weight, the content of the lithium oxide being 5 to 1 1% by weight, the content of the calcium oxide being 5 to 27% by weight, exclusive of 5% by weight, the content of the titanium oxide being 1 to 20% by weight, the content of the niobium oxide being 13 to 30% by weight, exclusive of 13% by weight, the total content of the silicon oxide and the boron oxide being 20 to 50% by weight, the ratio of a content of the silicon oxide to a content of the boron oxide being greater than 0.78, the optical glass further comprising 0 to less than 16% by weight of lanthanum oxide, 0 to 12% by weight of zinc oxide, 0 to 15% by weight of barium oxide, 0 to 10% by weight of zirconium oxide, 0 to 10% by weight of strontium oxide, 0 to 6% by weight of tungsten oxide, 0 to 7% by weight of aluminum oxide, 0 to 5% by weight of sodium oxide, 0 to 5% by weight of potassium oxide, 0 to 5% by weight of yttrium oxide, 0 to 5% by weight of gadolinium oxide, 0 to 5% by weight of ytterbium oxide, 0 to 5% by weight of tantalum oxide, 0 to 2% by weight of arsenic oxide and 0 to 2% by weight of antimony oxide, wherein said press-shapeable preform has a form consistent with the form of a shaped article to be obtained by precision-press shaping.