Patent ID: 8268065

Claim:
A BaO- and/or PbO-free X-ray opaque glass having a refractive index n d of about 1.518 to about 1.533 and an aluminum equivalent thickness of at least about 180%, comprising (in % by weight based on oxide) SiO 2 51-<58 B 2 O 3 >10-<12 Al 2 O 3 3-<7 Li 2 O 0-3 Na 2 O 0-3 K 2 O 10.5-20 Cs 2 O 0-9 ZrO 2 >2-8 La 2 O 3 0-15 CaO 0-<0.5 Σ alkali metal oxides 10.5-25 Cs 2 O + La 2 O 3 >0.5.