Optical glass, preform for precision press molding, optical element, method for manufacturing optical element

An optical glass, comprising, denoted as cation percentages:

• 1 to 10% of Si4+,
• 25 to 45% of B3+,
• 0 to 10% of Li+,
• 0 to 5% of Na+,
• 0 to 5% of K+,
• 0 to 5% of Mg2+,
• 0 to 5% of Ca2+,
• 0 to 5% of Sr2+,
• 0 to 5% of Ba2+,
• 10 to 40% of Zn2+,
• 10 to 25% of La3+,
• 1 to 15% of Gd3+,
• 0 to 5% of Y3+,
• 0 to 5% of Yb3+,
• 0 to 3% of Zr4+,
• 1 to 15% of Ti4+,
• 0 to 5% of Nb5+,
• 0 to 5% of Ta5+,
• 1 to 20% of W6+,
• 0 to 5% of Te4+,
• 0 to 5% of Ge4+,
• 0 to 5% of Bi3+, and
• 0 to 5% of Al3+;
• wherein the cation ratio of (B3+/(B3++Si4+)) is 0.70 to 0.96;
• the cation ratio of (B3+/(La3++Gd3++Y3+)) is 1.0 to 2.0;
• the cation ratio of ((B3++Si4+)/(La3++Gd3++Y3+) is 1.0 to 3.0;
• the cation ratio of (B3+/(Ti4++Nb5++Ta5++W6+)) is 0.8 to 4.0;
• the cation ratio of ((B3++Si4+)/(Ti4++Nb5++Ta5++W6+)) is 1.5 to 5.0;
• the cation ratio of (Zn2+/(Zn2++Mg2++Ca2++Sr2++Ba2+)) is 0.8 to 1.0;
• the cation ratio of ((La3++Gd3++Y3+)/(Ti4++Nb5++Ta5++W6+)) is 1.0 to 3.0;
• the cation ratio of Ti4+/W6+ is 0.1 to 4.0;
• the cation ratio of ((Ti4++W6+)/(Ti4++Nb5++Ta5++W6+)) is 0.8 to 1.0;
• having a refractive index nd of 1.89 or higher and an Abbe number vd of 28 to 36.