Abstract: The present invention relates to a novel process for the production of sequences of interference layers composed of layers i of prescribed thicknesses d(i) and refractive indices n(i). In this process a stack of at least two layers i of glasses having refractive indices n(i) and thicknesses d0(i), which are each larger than the predetermined thicknesses d(i) by the same multiplying factor, is provided. The stack is heated to a temperature above the transformation temperature of the glasses and during or after heating, the stack is drawn in such a manner that the individual layers obtain the prescribed thicknesses d(i). After this the drawn stack is cooled.

Abstract: An optical and ophthalmic glass with high refractive index, high Abbe number and low density, which is distinguished by good chemical stability, good crystallization behavior and capability of chemical hardening, comprises (in % by weight):______________________________________ SiO.sub.2 50-63 B.sub.2 O.sub.3 4-8 Al.sub.2 O.sub.3 1-2 Li.sub.2 O 4-8 Na.sub.2 O 4-8 K.sub.2 O 3-7 sum of M.sub.2 O 11-20 (M = Li, Na, K) MgO 0.5-2 CaO 2-5 sum of MO 0-3 (M = Mg, Ca) TiO.sub.2 8-12.5 ZrO.sub.2 1-3 F.sup.- 0-1 As.sub.2 O.sub.3 0.05-0.15 (optional refining agent) Sb.sub.2 O.sub.3 0.0-0.

Abstract: Infrared-transparent bi- or multicomponent chalcogenide glasses based on germanium and selenium are improved by doping with 0.05 to 1.0 atom % of at least one of the alkaline earth metals calcium or strontium and/or one of their compounds. Optical fibers and optical elements can be made from these glasses.

Abstract: A colorless, cerium-and phosphorous-containing barium silicate glass, with a density of >3.3 g/cm.sup.2, a radiation length <43.5 mm, with strong fluorescence at 415-430 nm and with good scintillation properties, consisting essentially of (in percent by weight):______________________________________ SiO.sub.2 20-60 B.sub.2 O.sub.3 0-18 21-60 P.sub.2 O.sub.5 1-10 Li.sub.2 O 0-10 Na.sub.2 O 0-10 K.sub.2 O 0-15 MgO 0-10 SrO 0-12 BaO 30-60 30-60 La.sub.2 O.sub.3 0-10 Ce.sub.2 O.sub.3 0.5-8 Other oxides 0-20 Al.sub.2 O.sub.

Abstract: An optical and ophthalmic glass with high refractive index, high Abbe number and low density, which is distinguished by good chemical stability, good crystallization behavior and capability for chemical hardening, comprises (in % by weight):SiO.sub.2 --47 to 75B.sub.2 O.sub.3 --1 to 20Al.sub.2 O.sub.3 --0 to 10P.sub.2 O.sub.5 --0 to 5Li.sub.2 O--0 to 15Na.sub.2 O--0 to 10K.sub.2 O--0 to 10CaO--0 to 20MgO--0 to 15SrO--0 to 4BaO--0 to 4ZnO--0 to 5TiO.sub.2 --1 to 15ZrO.sub.2 --0 to 8Nb.sub.2 O.sub.5 --0 to 5 andF----0 to 5.

Abstract: A spectacle glass which is colorless in the visible spectrum range, not transmissive in the ultraviolet spectrum range below 350 nm, has a refractive index n.sub.d higher than 1.56 and an Abbe number of more than 45, and which has an extremely low density, has the following composition (in % by weight):______________________________________ 12-40 P.sub.2 O.sub.5 13-34 Al.sub.2 O.sub.3 8-30 SiO.sub.2 0-16 B.sub.2 O.sub.3 4-12 TiO.sub.2 0-4 ZrO.sub.2 2-18 CaO 0-4 MgO 0-15 Na.sub.2 O 0-11 K.sub.2 O 0-6 Li.sub.2 O 0-12 Nb.sub.2 O.sub.5 0-8 ZnO.

Abstract: A new phototropic glass in which the phototropic properties arise from precipitations of silver halide and which in the unirradiated condition is slightly tinted or completely colorless while showing a brown color in the light-exposed condition, comprises, in known phototropic glass compositions, an additional content of at least 0.001 wt % of TeO.sub.2 and/or Yb.sub.2 O.sub.3.