Patent ID: 8168693

Claim:
A BaO- and/or PbO-free X-ray opaque glass having a refractive index n d of about 1.54 to about 1.58 and an aluminum equivalent thickness of at least about 500%, the glass comprising in weight % of oxides: SiO 2 48-56 B 2 O 3 3-8 Al 2 O 3 0.5-4 Li 2 O 0-5 Na 2 O 1-4 K 2 O 2-7 Cs 2 O 10-16 CaO 5-9 MgO 0-5 ZrO 2 0.5-13 La 2 O 3 5-12 SnO 2 0-4 Σ alkali metal oxides 16-21 Cs 2 O + La 2 O 3 + SnO 2 ≧19.