Abstract: The stepped optical fiber has a core glass member and a surrounding cladding glass member. It has a high numerical aperture (NA)?0.50. The core glass member preferably has a zinc-containing composition including, in % by weight, SiO2, 42 to 53; ZnO, 16 to 38; PbO, 1 to 20; Na2O, <14; K2O, <12; with a sum of ZnO and PbO?30 and a sum of Na2O and K2O is ?2. The cladding glass composition, which is compatible with this core glass, includes, in percent by weight, SiO2, 60 to 72; B2O3, <20; Al2O3, <10; Na2O, <18; and K2O, <15. The resulting optical fiber has low attenuation, very neutral color transmission and low manufacturing costs. Other cladding glass compositions resulted in considerably poorer properties with too much crystallization at the core glass boundary layer. Environmentally-friendly, lead-free embodiments of the core glass were also prepared having even lower aperture values of ?0.48.

Abstract: The stepped optical fiber has a core glass member and a surrounding cladding glass member. It has a high numerical aperture (NA)?0.50. The core glass member preferably has a zinc-containing composition including, in % by weight, SiO2, 42 to 53; ZnO, 16 to 38; PbO, 1 to 20; Na2O, <14; K2O, <12; with a sum of ZnO and PbO?30 and a sum of Na2O and K2O is ?2. The cladding glass composition, which is compatible with this core glass, includes, in percent by weight, SiO2, 60 to 72; B2O3, <20; Al2O3, <10; Na2O, <18; and K2O, <15. The resulting optical fiber has low attenuation, very neutral color transmission and low manufacturing costs. Other cladding glass compositions resulted in considerably poorer properties with too much crystallization at the core glass boundary layer. Environmentally-friendly, lead-free embodiments of the core glass were also prepared having even lower aperture values of ?0.48.

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: A transparent or translucent inorganic material, especially a glass-ceramic and/or composite material, is provided with a low average thermal longitudinal expansion coefficient, .alpha., of from -1.times.10.sup.-6 K.sup.-1 to +2.times.10.sup.-6 K.sup.-1 in the temperature range of -50.degree.-700.degree. C., with the following composition (in weight percent):Li.sub.2 O, 2.5-6.0; Na.sub.2 O, 0-4.0; K.sub.2 O, 0-4.0; Na.sub.2 O+K.sub.2 O, 0.2-4.0; MgO, 0-3.0; ZnO, 0-3.0; BaO, 0-3.5; CaO, 0-1.0; SrO, 0-1.0; Al.sub.2 O.sub.3, 18-28; SiO.sub.2, 50-70; TiO.sub.2, 1.0-7.0; ZrO.sub.2, 0-3.5; TiO.sub.2 +ZrO.sub.2, 1.0-7.0; and P.sub.2 O.sub.5, 0-8.0,optionally with coloring components (in weight percent):V.sub.2 O.sub.5, 0-2.0; Cr.sub.2 O.sub.3, 0-2.0; MnO, 0-2.0; Fe.sub.2 O.sub.3, 0-2.0; CoO, 0-2.0; and NiO, 0-2.0,optionally, conventional refining agents, such as As.sub.2 O.sub.3, Sb.sub.2 O.sub.3, NaCl, and Ce.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 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.

Abstract: Glass composition ranges are described which permit the introduction of laser activators into fluorphosphate glass with exceptionally high fluorine content while forming glasses of high crystallization stability and permitting the realization of large melt volumes. The high fluorine content imparts to the glasses an exceptionally low nonlinear refractive index n.sub.2 down to O,4 .times.10.sup.-13 esu.

Abstract: A glass when in the form of an optical fiber having an optical loss of not more than 150 dB/km, high transparency, a high numerical aperture, and a high flexural strength, said glass being especially suitable for optical fibers and consisting essentially of:SiO.sub.2 : 65 - 75 mol-%; (38 - 46% by weight);R.sub.2 o: 4 - 17 mol-%; (4 - 13% by weight);PbO: 16 - 25 mol-%; (42 - 55% by weight); wherein R.sub.2 O is Na.sub.2 O, K.sub.2 O or Cs.sub.2 O or mixtures thereof, preferably not more than 3.0 mol % Na.sub.2 O, and with the provision that the molar ratio of SiO.sub.2 : PbO is 2.5 - 4.0.

Abstract: Arsenic pentoxide glasses characterized by containing 8 - 60 wt.% arsenic pentoxide and correspondingly 92 - 40 wt.% polyvalent metal fluorides exhibit improved processing characteristics while maintaining outstanding optical properties when prepared from a formula containing at least 0.5% of at least one member selected from the group consisting of bromides, chlorides, sulfates and metal oxides.