Highly refractive and highly transparent optical glass
The optical glass has a refractive index n d of 1.945≦n d ≦1.97, an Abbe number ν d of 33≦ν d ≦36, and a composition with the following components in amounts expressed in % of their cations, with respect to the total number of cations in the composition: B 3+ , 35-46; La 3+ , 25-35; Ta 5+ , 6-14; W 6+ , 6-13; Zr 4+ , 1-7; Gd 3+ , 0-5; Nb 5+ , 0-4; Y +3 , 0-4; Ba 2+ , 0-2; Σ alkaline earth metal cations, 0-2, Σ La 3+ +Ta 3+ +W 6+ +Zr 4+ +Gd 3+ +Nb 5+ +Y 3+ ≧50; and at least one fining agent, 0-0.3. Also a ratio of B 3+ to La +3 is 1.1 to 1.6 and a ratio of B 3+ to Σ Si +4 +B 3+ is ≧0.5. The glass is free of lead, arsenic, Ti 4+ , Th 4+ , Zn 2+ , F − , and Hf +4 .
1. A lead-free and arsenic-free optical glass having a refractive index n d of 1.945≦n d ≦1.97, an Abbe number ν d of 33≦ν d ≦36, and an internal transmittance of >80% at 410 nm and at a thickness of 10 mm, wherein said optical glass has a composition comprising respective components in the following amounts expressed in % of corresponding cations of said respective components in said composition, with reference to a sum of all cations in the composition:
B 3+
35-46
La 3+
25-35
Ta 5+
6-14
W 6+
6-13
Zr 4+
1-7
Gd 3+
0-5
Nb 5+
0-4
Y 3+
0-4
Ba 2+
0-2
Σalkaline earth metal cations
0-2
ΣLa 3+ + Ta 5+ + W 6+ + Zr 4+ + Gd 3+ + Nb 5+ + Y 3+
≧50
cations of at least one fining agent
0-0.3,
wherein a ratio of B 3+ to La 3+ is 1.1 to 1.6, a ratio of B 3+ to Σ Si 4+ +B 3+ is greater than 0.5, and the glass is free of Ti 4+ , Th 4+ , Zn 2+ , F − and Hf 4+ , and wherein the glass contains less than 6 ppm of platinum.
2. The glass according to claim 1 , having a coefficient of expansion α (20, 300° C.) that is less than 9×10 −6 /K.
3. The glass according to claim 1 , wherein the respective components are contained in the following amounts expressed in % of the corresponding cations in said composition, with reference to the sum of the cations in the composition:
B 3+
36-45
La 3+
26-34
Ta 5+
7-13
W 6+
7-12
Zr 4+
2-6
Gd 3+
0-4
Nb 5+
0.1-3
Y 3+
0-3
Ba 2+
0-1
Σalkaline earth metal cations
0-2
ΣLa 3+ + Ta 5+ + W 6+ + Zr 4+ + Gd 3+ + Nb 5+ + Y 3+
≧52
cations of at least one fining agent
0-0.2,
wherein a ratio of B 3+ to La 3+ is 1.2 to 1.5, a ratio of B 3+ to Σ Si 4+ +B 3+ is greater than 0.7, and the glass is free of Ti 4+ , Th 4+ , Zn 2+ , F − and Hf 4+ , and wherein the glass contains less than 6 ppm of platinum.
4. The glass according to claim 1 , wherein said at least one fining agent comprises at least one of the following components, each in an amount expressed in % of cations of the at least one component in the total number of cations in the composition of:
Sb 2 O 3
0-0.3
and/or
SnO
0-0.3
5. Optical element, comprising a glass according to claim 1 .
6. A method of producing an optical glass according to claim 1 , comprising the step of direct inductive heating of a mixture of raw materials with an electromagnetic alternating field.
7. A method of producing an optical element, said method comprising the step of pressing a glass according to claim 1 .
8. A lead-free and arsenic-free optical glass having a refractive index n d of 1.945≦n d ≦1.97, an Abbe number ν d of 33≦ν d ≦36, and an internal transmittance of >80% at 410 nm and at a thickness of 10 mm, wherein said optical glass has a composition comprising respective components are contained in the following amounts expressed in % of the corresponding cations in said composition, with reference to the sum of the cations in the composition:
B 3+
37-44
La 3+
27-33
Ta 5+
8-12
W 6+
8-11
Zr 4+
2-5
Gd 3+
0.5-4
Nb 5+
0.5-2
Y 3+
0-2.5
Ba 2+
0-1
Σalkaline earth metal cations
0-2
ΣLa 3+ + Ta 5+ + W 6+ + Zr 4+ + Gd 3+ + Nb 5+ + Y 3+
≧53
cations of at least one fining agent
0-0.1,
wherein a ratio of B 3+ to La 3+ is 1.2 to 1.5, a ratio of B 3+ to Σ Si 4+ +B 3+ is greater than 0.8, and the glass is free of Ti 4+ , Th 4+ , Zn 2+ , F − and Hf 4+ , and wherein the glass contains less than 6 ppm of platinum.