Abstract: The invention provides a method by which a crystal glass composition which employs TiO.sub.2 as a raw material substituted for PbO can be produced while effectively preventing development of a yellowish color of the glass composition which is caused by TiO.sub.2. In the production method, to a batch composition which is composed of 50 to 60 percent by weight of SiO.sub.2, 4 to 14 percent by weight of K.sub.2 O, 10 to 20 percent by weight of BaO and 3 to 10 percent by weight of TiO.sub.2, NaNO.sub.3 (sodium nitrate) is added by 1.0 to 5.0 percent by weight or BaO.sub.2 (barium peroxide) is added by 0.3 to 2.0 percent by weight for elimination of development of a color which arises from the 3 to 10 percent by weight of TiO.sub.2, and also one of Sb.sub.2 O.sub.3 (antimony oxide) and As.sub.2 O.sub.3 (arsenious acid) is added by 0.2 to 1.0 percent by weight for defoaming. Instead, NaSb(OH).sub.6 (sodium antimonate) having color development elimination and defoaming actions may be added by 0.5 to 2.

Abstract: An optical glass having optical constants of refractive index within the range of 1.55-1.75 and Abbe number (.nu. d) within the range of 25-51 and having large negative anomalous dispersion which is substantially free of lead and arsenic compounds includes as its essential ingredients in weigth percent 10->40% SiO.sub.2, 12.5-35% B.sub.2 O.sub.3, 3-20% ZrO.sub.2 and 6-30% Nb.sub.2 O.sub.5.

Abstract: An optical glass containing, as glass components,30.about.55 wt % of SiO.sub.2,5.about.30 wt % of B.sub.2 O.sub.3,the total amount of SiO.sub.2 and B.sub.2 O.sub.3 being 56.about.70 wt % and the SiO.sub.2 /B.sub.2 O.sub.3 weight ratio being 1.3.about.12.0,7.about.12 wt % of Li.sub.2 O, in which 7 wt % is excluded,0.about.5 wt % of Na.sub.2 O,0.about.5 wt % of K.sub.2 O,the total amount of Li.sub.2 O, Na.sub.2 O and K.sub.2 O being 7 to 12 wt % in which 7 wt % is excluded,10.about.30 wt % of BaO,0.about.10 wt % of MgO,0.about.20 wt % of CaO,0.about.20 wt % of SrO, and0.about.20 wt % of ZnOthe total amount of BaO, MgO, CaO, SrO and ZnO being 10.about.30 wt %, and the total amount of SiO.sub.2, B.sub.2 O.sub.3, Li.sub.2 O and BaO being at least 72 wt %.

Abstract: An optical glass having optical constants of a refractive index (Nd) from 1.50 to 1.60 and an Abbe number (.nu.d) ranging from 62 to 73, a transformation temperature (Tg) of 550.degree. C. or below, and barely cracks or sticks to metal molds when the glass is subjected to mold pressing, maintains excellent chemical durability, and having softening capability at a low temperature which can be obtained by restricting the composition of the glass in weight percents within a specific range of a SiO.sub.2 --Al.sub.2 O.sub.3 --P.sub.2 O.sub.5 --R.sub.2 O system.

Abstract: The invention relates to a glass of high refractive index suitable for the close-vision part of multifocal, in particular phototropic multifocal, spectacle lenses. The glass has a composition (in % by weight, based on oxide) of:SiO.sub.2 28-40; B.sub.2 O.sub.3 0-8.5; Li.sub.2 O 0-1; Na.sub.2 O 0-2.5; K.sub.2 O 0-5; CaO 0-6; SrO 0-6; BaO 6-12; ZnO 9-16; PbO 32-40; TiO.sub.2 0.3-7; ZrO.sub.2 0.4-5; .SIGMA. Li.sub.2 O+Na.sub.2 O+K.sub.2 O 0-5, anda refractive index n.sub.e of 1.66-1.81, an expansion coefficient .alpha..sub.20-300 of 5.7-6.8.times.10.sup.-6 K.sup.-1, a softening point of 650.degree.-700.degree. C. and a glass transition temperature Tg of 520.degree.-560.degree. C.

Abstract: This invention is directed to the production of glasses essentially free of Nb.sub.2 O.sub.5, and having refractive index close to 1.7, an Abbe number of about 35 and a density close to 3.2. The glasses consist essentially in weight percent on the oxide basis, of______________________________________ SiO.sub.2 38-45 TiO.sub.2 15-<20 ZrO.sub.2 6-10 La.sub.2 O.sub.3 0.5-4 BaO 12-19 CaO 3-8 BaO + CaO + SrO 17-25 Na.sub.2 O 2-6 K.sub.2 O 4-8 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 6-10.

Abstract: This invention is directed to the production of glasses useful for ophthalmic applications which exhibit excellent resistance to the development of coloration upon being exposed to x-radiation and excellent resistance to the development of solarization. The glass compositions are essentially free of lead and consist essentially, in weight percent, of______________________________________ SiO.sub.2 60-70 ZrO.sub.2 0.5-2 TiO.sub.2 0-1.5 B.sub.2 O.sub.3 0.5-5 CeO.sub.2 0.1-0.3 Sb.sub.2 O.sub.3 0-0.5 Al.sub.2 O.sub.3 2-6 Li.sub.2 O 0-2 SO.sub.3 0-0.3 Na.sub.2 O 9-14 MgO 0-5 Br 0-0.5 K.sub.2 O 3-10 SrO 0-5 Cl 0-0.5 CaO 0.5-4 BaO 0-5 F 0-0.5.

Abstract: An optical glass including as its main ingredients in weight percent 25-50% SiO.sub.2, 16-40% B.sub.2 O.sub.3, 5-25% SrO and 1-10% Li.sub.2 O has optical constants of refractive index (Nd) of 1.55-1.65 and Abbe number (.nu.d) of 55-63 and a yield point (At) below 600.degree. C. which is suited for mold pressing.

Abstract: Lead- and barium-free crystal glass for the production of high-quality glasses and domestic articles, having high optical transmission, a refractive index n.sub.D of greater than 1.52, a density of at least 2.45 g/cm.sup.3, high hydrolytic resistance, good solarization resistance, and a K.sub.2 O+ZnO content of greater than 10% by weight, the glass system being based on an alkali-lime-silicate glass containing TiO.sub.2, ZrO.sub.2, Nb.sub.2 O.sub.3 and possibly Ta.sub.2 O.sub.5 and/or combinations thereof.

Abstract: A glass composition is disclosed wherein the density and the refraction index and the dispersion value of light are equal to or higher than those of conventional lead-containing crystal glass while no lead is contained therein at all. The glass composition comprises 50 to 60% by weight of SiO.sub.2, 5 to 13% by weight of K.sub.2 O, 5 to 8% by weight of TiO.sub.2, 10 to 15% by weight of BaO, 5 to 10% by weight of ZnO, 3 to 10% by weight of Na.sub.2 O, 1 to 5% by weight of CaO, and 0.3 to 0.8% by weight of Sb.sub.2 O.sub.3.

Abstract: An optical crown glass having a negative anomalous partial dispersion .DELTA.P.sub.g,F, a refractive index n.sub.d of greater than 1.52, an Abbe number .nu..sub.d of greater than 57, and a high UV transmission has a composition (in % by weight) 40-72 B.sub.2 O.sub.3, 9-31 Al.sub.2 O.sub.3, 0-15 SiO.sub.2, 0.1-0.5 H.sub.2 O, 0-12 Li.sub.2 O, wherein the total of R.sub.2 O (R=Li, Na, K, Rb, Cs) is 0-20 and the total of MO (M=Mg, Ca, Sr, Ba) is 0-30, and wherein the total of R.sub.2 O and MO is greater than 5, and the molar ratio between Al.sub.2 O.sub.3 and B.sub.2 O.sub.3 is 0.2-0.3 and the molar ratio between (R.sub.2 O+MO) and B.sub.2 O.sub.3 is 0.1-0.4.

Abstract: An optical glass which is a SiO.sub.2 -Nb.sub.2 O.sub.5 -R'.sub.2 O (where R' is an alkali metal element)-F system of a specific composition range exhibits optical constants of a refractive index (Nd) of about 1.52-1.67 and an Abbe number (.upsilon. d) of about 32-50, is free of PbO and has an improved light transmissivity.

Abstract: An optical glass which is a SiO.sub.2 --TiO.sub.2 --K.sub.2 O--RO (where R represents Mg, Ca, Sr, Ba and Zn metal elements) system glass of a specific content range exhibits optical constants of a refractive index (Nd) of about 1.58-1.78 and Abbe number (.nu.d) of about 28-45, is free of PbO and has an improved property against devitrification.

Abstract: An optical glass which is a SiO.sub.2 --Nb.sub.2 O.sub.5 --R'.sub.2 O (R' being an alkali metal element)-F system of a specific composition range exhibits optical constants of a refractive index (Nd) of about 1.60 or below and an Abbe number (.nu.d) of about 57-40, is free of PbO and has an improved light transmissivity.

Abstract: An optical glass which is a SiO.sub.2 --B.sub.2 O.sub.3 --(TiO.sub.2 +ZrO.sub.2)--SrO--BaO--R'.sub.2 O system of a specific composition range exhibits optical constants of a refractive index (Nd) of 1.57-1.75 and Abbe number (.nu.d) of 30-55, is free of PbO and has improved stability against devitrification and tinting and improved chemical durability.

Abstract: A highly refractive, low-density phototropic glass in which the carriers of phototropy are precipitates containing silver, halogens and copper oxide, and which has a density equal to or less than 3.0 g/cm.sup.3, a refractive index equal to or greater than 1.60 and an Abbe number equal to or greater than 40, consisting essentially of, in % by weight on an oxide basis:______________________________________ SiO.sub.2 35-50 B.sub.2 O.sub.3 13.5-21 .SIGMA.SiO.sub.2 and B.sub.2 O.sub.3 50-70 Li.sub.2 O 0.0-2.5 Na.sub.2 O 0.0-4.0 K.sub.2 O 0.0-10.0 .SIGMA.Alkali metal oxides 4-14 BaO.sub.2 5.0-10.5 TiO.sub.2 3.5-6.5 ZrO.sub.2 4.5-9.5 Nb.sub.2 O.sub.3 5.0-11.5, ______________________________________the total of the foregoing oxides being 100% by weight, and in addition to the basic glass composition, carriers of phototropy consisting essentially of, in % by weight: ______________________________________ Ag.sub.2 O 0.05-0.25 Br 0.07-0.25 Cl 0.06-0.35 .SIGMA.Br and Cl .ltoreq.0.5 CuO 0.003-0.015.

Abstract: An optical glass for a press lens composed of 25 to 41 mol % of SiO.sub.2, 10 to 30 mol % of B.sub.2 O.sub.3, 18 to 40 mol % of PbO, 1 to 10 mol % of Na.sub.2 O, 1 to 15 mol % of K.sub.2 O, 2 to 20 mol % of Li.sub.2 O, and 0.3 to 3 mol % of Al.sub.2 O.sub.3.

Abstract: A colored, chemstrengthenable contrast enhancement, UV attenuated glass (e.g., for sunglasses) comprises, in weight percent,______________________________________ Oxide Wt. % ______________________________________ SiO.sub.2 40-72 B.sub.2 O.sub.3 0-13 Al.sub.2 O.sub.3 0.5-3 Li.sub.2 O 0-3 Na.sub.2 O 8-13 K.sub.2 O 1-10 TiO.sub.2 8.0-9.5 CeO.sub.2 2.6-3.5 Nd.sub.2 O.sub.3 5-17 Fe.sub.2 O.sub.3 1.40-2.10 CoO 0-0.07 NiO 0-0.4 CuO 0-0.5 Er.sub.2 O.sub.3 0-2 V.sub.2 O.sub.5 0-0.5 Cr.sub.2 O.sub.3 0-0.25 ______________________________________and has the following properties% T (2.0 mm) 400 nm: .ltoreq.2.2%% T (2.0 mm) 380 nm: 0.0%a: -1.0 to -7.5b: +1.0 to +10.0.

Abstract: This invention relates to the production of glasses exhibiting a refractive index between about 1.66-1.81, a softening point between about 625.degree.-675.degree. C., a strain point between about 455.degree.-490.degree. C., a linear coefficeint of thermal expansion (25.degree.-300.degree. C.) between about 53-65.times.10.sup.-7 /.degree.C., and good chemical durability which consist essentially, in weight percent, of:______________________________________ SiO.sub.2 24-42 Li.sub.2 O 0.2 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 0-3.5 Al.sub.2 O.sub.3 3-7.5 Na.sub.2 O 0-2 ZrO.sub.2 0-2.5 B.sub.2 O.sub.3 2-7.5 K.sub.2 O 0-3 TiO.sub.2 0-8 PbO 35-57 La.sub.2 O.sub.3 0-8 La.sub.2 O.sub.3 + ZrO.sub.2 4-12.sub.

Abstract: A chemically resistant glass which can be produced at relatively low melting temperatures and has anomalous negative partial dispersion P.sub.g,F, a refractive index n.sub.d of from 1.73 to 1.83 and an Abbe coefficient v.sub.d of from 31 to 38 preferably contains (in % by weight, based on oxides):______________________________________ 0-4 SiO.sub.2 + GeO.sub.2 0-2 GeO.sub.2 0-10 MgO 26-33 B.sub.2 O.sub.3 0-1 Li.sub.2 O 0-16 CaO 19-50 PbO 0-1 Na.sub.2 O 0-16 BaO 1-6 ZrO.sub.2 0-1 K.sub.2 O 0-16 SrO 4-16 Ta.sub.2 O.sub.5 0-2 .SIGMA. alkaline earth 0-6 Al.sub.2 O.sub.3 metal oxides 0-16 ZnO 0-4 TiO.sub.2 1.5-20 .SIGMA. alkaline earth metal oxides + ZnO 0-1 WO.sub.3 0-11 La.sub.2 O.sub.3 0-7 Nb.sub.2 O.sub.5 0-5.5 Y.sub.2 O.sub.3 0-5.5 Gd.sub.2 O.sub.3 4-11 .SIGMA. La.sub.2 O.sub.3 + Y.sub.2 O.sub.3 + Gd.sub.2 O.sub.3 ______________________________________with the proviso that the .SIGMA.(SiO.sub.2 +GeO.sub.2 +B.sub.2 O.sub.3)/.SIGMA.(ta.sub.2 O.sub.5 +ZrO.sub.2 +HfO.sub.2) ratio is less than 5 and the PbO/.

Abstract: A highly refractive, low-density phototropic glass in which the carriers of phototropy are precipitates containing silver, halogens and copper oxide, and which has a density equal to or less than 3.0 g/cm.sup.3, a refractive index equal to or greater than 1.60 and an Abbe number equal to or greater than 40, consisting essentially of, in % by weight on an oxide basis:SiO.sub.2 : 35-50B.sub.2 O.sub.3 : 13.5-21.SIGMA.SiO.sub.2 and B.sub.2 O.sub.3 : 50-70Li.sub.2 O: 0.0-2.5Na.sub.2 O: 0.0-4.0K.sub.2 O: 0.0-10.0.SIGMA.Alkali metal oxides: 4-14BaO: 5.0-10.5TiO.sub.2 : 3.5-6.5ZrO.sub.2 : 4.5-9.5Nb.sub.2 O.sub.3 : 5.0-11.5,and in addition to the basic glass composition, carriers of phototropy consisting essentially of, in % by weight:Ag.sub.2 O; 0.05-0.25Br: 0.07-0.25Cl: 0.06-0.35.SIGMA.Br and Cl: .ltoreq.0.5CuO: 0.003-0.015.

Abstract: A glass having a negative anomalous partial dispersion .DELTA.P.sub.g,F, an index of refraction of n.sub.d .gtoreq.1.67 and an Abbe number of .nu..sub.d >36 has the following composition, in % by weight, 3-11 of SiO.sub.2, 0-3 of GeO.sub.2, .SIGMA. SiO.sub.2 +GeO.sub.2, 4.5-11; B.sub.2 O.sub.3, 29-35; 5-13 of Al.sub.2 O.sub.3 ; 1-3 of ZrO.sub.2 ; 0.2-3 of TiO.sub.2 ; 0.2-1.5 of Ta.sub.2 O.sub.5 ; 30-45 of PbO; 0-3 each of Li.sub.2 O, Na.sub.2 O, K.sub.2 O, Rb.sub.2 O, Cs.sub.2 O, .SIGMA. alkali metal oxide 0-3; 0-3.5 each of MgO, CaO, BaO, SrO, .SIGMA. alkaline-earth oxide 0-6, if .SIGMA. SiO.sub.2 and GeO.sub.2 .gtoreq.9; .SIGMA. alkaline-earth oxide 0-3.5, if .SIGMA. SiO.sub.2 and GeO.sub.2 <9; 0-14 of ZnO, 0-3 of La.sub.2 O.sub.3 ; 0-7 of Nb.sub.2 O.sub.3 ; 0-1 of Sb.sub.2 O.sub.3 ; 0-0.3 of As.sub.2 O.sub.3 ; 0-1.5 of WO.sub.3 ; 0-1 of F. This glass is inexpensive and can be produced in high quality, and has a high crystalization stability and good transmission values.

Abstract: This invention is directed to the preparation of silver halide-containing photochromic glasses exhibiting refractive indices between 1.585-1.610, Abbe numbers higher than 41, and densities less than 2.80 g/cm.sup.3 generally consisting essentially, in weight percent, of:______________________________________ SiO.sub.2 43-52 SrO 0.8-9 B.sub.2 O.sub.3 12.5-18 BaO 1-9 Al.sub.2 O.sub.3 0-3 K.sub.2 O 2-9 ZrO.sub.2 3-8 TiO.sub.2 2-8 Li.sub.2 O 1.5-3.5 Ag 0.100-0.175 Na.sub.2 O 0.3-3 Cl 0.140-0.350 Nb.sub.2 O.sub.5 4-9 Br 0.093-0.180 MgO 0-5 CuO 0.0080-0.

Abstract: This invention is drawn particularly to the production of glasses having essentially fluorine-free compositions consisting essentially, in mole percent, of:______________________________________ Li.sub.2 O 5-10 P.sub.2 O.sub.5 30-36 Na.sub.2 O 5-15 Al.sub.2 O.sub.3 0-5 K.sub.2 O 0-6 CeO.sub.2 0-2 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 15-25 SnO 0-20 ZnO 10-33 PbO 0-20 CaO 0-20 Sb.sub.2 O.sub.3 0-12 SrO 0-20 Bi.sub.2 O.sub.3 0-6 BaO 0-20 SnO + PbO + 0-20. Sb.sub.2 O.sub.3 + Bi.sub.2 O.sub.

Abstract: The optical glass of the present invention comprising SiO.sub.2, alkali metal oxides, P.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 has optical properties of 1.70 or more in refractive index nd and 30 or less in Abbe's number .nu.d and is superior in devitrification resistance and stability.

Abstract: A fluorophosphate optical glass having optical constants, i.e. refractive index (nd) of 1.54 to 1.60 and Abbe number (.nu.d) of 68 to 75 and having abnormal partial dispersion represented by a relative partial dispersion of at least 0.537 is provided, which has a chemical composition (% by weight) comprising:______________________________________ Al(PO.sub.3).sub.3 15-32% Ba(PO.sub.3).sub.2 0-10% Sr(PO.sub.3).sub.2 0-10% Ca(PO.sub.3).sub.2 0-10% Mg(PO.sub.3).sub.2 0-10% sum of metaphosphates 20-32% BaF.sub.2 20-70% SrF.sub.2 5-40% CaF.sub.2 0-15% MgF.sub.2 0-10% AlF.sub.3 0-5% GdF.sub.3 0-5% sum of fluorides 55-75% Gd.sub.2 O.sub.3 5-22% La.sub.2 O.sub.3 0-7% Y.sub.2 O.sub.3 0-10% Yb.sub.2 O.sub.

Abstract: There are disclosed fluoroborosilicate glasses that are particularly adapted to being drawn with lead silicate core glasses to produce clad glass fibers useful in forming fiber optic bundles to be incorporated in night vision equipment. The cladding glass has a refractive index not over about 1.465 and a coefficient of thermal expansion not over about 80.times.10.sup.-7 /.degree.C. The clad fiber has a numerical aperture approximating or equal to one.

Abstract: There are disclosed fluoroborosilicate glasses that are particularly adapted to being drawn with lead silicate core glasses to produce clad glass fibers useful in forming fiber optic bundles to be incorporated in night vision equipment. The cladding glass has a refractive index not over about 1.45 and a coefficient of thermal expansion not over about 120.times.10.sup.-7 /.degree.C. The clad fiber has a numerical aperture approximating or equal to one.

Abstract: This invention is directed to the production of glasses especially suitable for use as ophthalmic lenses which exhibit indices of refraction between about 1.699-1.703, Abbe numbers equal to or greater than 41.0, densities less than 3.25 g/cm.sup.3, and good resistance to attack by acids. The glasses are essentially free of Al.sub.2 O.sub.3 and consist essentially, in weight percent on the oxide basis, of:______________________________________ SiO.sub.2 33-37 CaO 8-9.5 B.sub.2 O.sub.3 7.5-13 SrO 2-4 SiO.sub.2 + B.sub.2 O.sub.3 44-48 La.sub.2 O.sub.3 12.3-14.5 Li.sub.2 O 5-8 ZrO.sub.2 4-6 Na.sub.2 O 0-2.5 Nb.sub.2 O.sub.5 8-10.5 K.sub.2 O 0-2 TiO.sub.2 5-7 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 5-8 As.sub.2 O.sub.3 0-0.8.

Abstract: A new, CdO-and ThO.sub.2 -free optical glass with refractive indices of 1.73-1.78 and Abbe numbers of 30-34 and with particularly good devitrification stability comprises (in weight %):______________________________________ SiO.sub.2 12-20, B.sub.2 O.sub.3 10-18, PbO 50-60 Al.sub.2 O.sub.3 2-7, ZnO 0-4, ZrO.sub.2 0.5-3 La.sub.2 O.sub.3 2-10, Cs.sub.2 O 0-5, M.sub.2 O 0-1 (M.sub.2 O.dbd. Na.sub.2 O, K.sub.2 O, Li.sub.2 O) TiO.sub.2 0-5 with the SiO.sub.2 /B.sub.2 O.sub.3 -ratio being about 1.0 to ______________________________________ 1.5.

Abstract: This invention is related to glasses particularly useful in the fabrication of multifocal lenses for ophthalmic applications. The inventive glasses exhibit a refractive index between 1.599-1.602, an Abbe number between 40.5-41.5, a density between 2.64-2.66 g/cm.sup.3, a transmission of visible radiation at 400 nm through a thickness of 10 mm greater than 83%, a softening point between 670.degree.-680.degree. C., a birefringence upon sealing, measured as described, between -150 and +150 nm/cm, and consist essentially, expressed in terms of weight percent on the oxide basis, of:______________________________________ SiO.sub.2 52-57 K.sub.2 O 11.0-16.0 B.sub.2 O.sub.3 2.5-7.0 CaO 2-3.5 Al.sub.2 O.sub.3 0-1 ZrO.sub.2 1-1.5 Li.sub.2 O 0.3-0.8 TiO.sub.2 15.0-16.2 Na.sub.2 O 5.4-8.2 As.sub.2 O.sub.3 0.1-0.

Abstract: An optical glass, n.sub.d .gtoreq.1.60 and v.sub.d .gtoreq.58, having a high chemical stability as well as resistance to phase separation and crystallization, comprises in percent by weight:______________________________________ SiO.sub.2 21.5-27.0; B.sub.2 O.sub.3 23.5-30.0 SrO 16.0-24.0; La.sub.2 O.sub.3 10.0-20; Al.sub.2 O.sub.3 1.5-5.0; BaO 5.0-14.0; ZrO.sub.2 0-4.0; Li.sub.2 O 0.5-5.0; Na.sub.2 O 0.8-2.5; K.sub.2 O 0-2.0.

Abstract: This specification discloses optical light-weight glass having a composition of SiO.sub.2 47--70, Li.sub.2 O 5.5-21, K.sub.2 O 2-30, Na.sub.2 O 0-30 (Li.sub.2 O+Na.sub.2 O+K.sub.2 O 21-50), TiO.sub.2 9.5-24, B.sub.2 O.sub.3 0-20, CaO 0-20, MgO+SrO+BaO+ZnO 0-4, Al.sub.2 O.sub.3 0-5 and ZrO.sub.2 +La.sub.2 O.sub.3 +Ta.sub.2 O.sub.5 +WO.sub.3 0-3, all being in % by weight, and having a refractive index (n.sub.d) of 1.58-1.65, an Abbe number (.gamma..sub.d) of 35-50 and a specific gravity of 2.69 or less. This optical glass is light in weight, high in transparency and low in dispersion, and is particularly suitable for spectacle lenses, but can also be utilized for photographic lenses.

Abstract: Reduced boron containing glass fibers are provided which have a refractive index similar to that of higher boron-containing glass fiber compositions. The glass fibers with a refractive index in the range of greater than 1.5495 to around 1.57 have in weight percent SiO.sub.2 - 55-56.5, CaO - 20-23, Al.sub.2 O.sub.3 14.5-15.5, B.sub.2 O.sub.3 - 5 to 5.8, R.sub.2 O - 1-1.5, wherein R is an alkali metal and F.sub.2 - 0.4 to 0.6. In addition, the glass fiber composition can have minor constituents such as TiO.sub.2 of up to around 0.6 weight percent and an MgO of up to around 0.3 weight percent and ferric oxide of up to around 0.3 weight percent. Basically, the glass fibers have a reduced content of both B.sub.2 O.sub.3 and CaO over standard glass fiber compositions such as E-glass and 621-glass and also has elevated amounts of alkali and of refractory constituents such as SiO.sub.2 and Al.sub.2 O.sub.3. The glass fibers are formed with an elevated temperature of 40.degree. to 50.degree. F. (22.degree.-28.degree.

Abstract: This invention is concerned with a glass for optical and/or ophthalmic applications having an index of refraction between about 1.78-1.82, an Abbe number greater or equal to 31, and a density less than about 3.80 g/cm.sup.3 consisting essentially, expressed in terms of weight percent on the oxide basis, of:______________________________________ SiO.sub.2 15-30 CaO 15-28 B.sub.2 O.sub.3 2-17 SrO 0-11 SiO.sub.2 + B.sub.2 O.sub.3 24-36 BaO 0-11 Al.sub.2 O.sub.3 0-6.5 MgO + CaO + 16-33 SrO + BaO Li.sub.2 O 0-5 ZnO 0-11 Na.sub.2 O 0-5 La.sub.2 O.sub.3 16-30 K.sub.2 O 0-5 ZrO.sub.2 0-10 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 0-6 Nb.sub.2 O.sub.5 5-26 MgO 0-6 TiO.sub.2 0-14.

Abstract: An Ophthalmic and optical glass which is a B.sub.2 O.sub.3 - SiO.sub.2 - Li.sub.2 O - CaO - La.sub.2 O.sub.3 - TiO.sub.2 - ZrO.sub.2 -Nb.sub.2 O.sub.5 system in which relatively large amounts of B.sub.2 O.sub.3 and La.sub.2 O.sub.3 ingredients coexist has improved resistivity to devitrification while maintaining desirable optical constants, i.e., a refractive index (.eta.d) in the range of 1.75 to 1.84, Abbe number (.nu.d) in the range of 33 to 40 and specific gravity of 4.0 or less. Besides, the range of content of the Li.sub.2 O ingredient which is effective for the chemical strengthening treatment can be enlarged by this system of glass.

Abstract: High PbO-content glass in the optical range of flint and heavy flint glasses from the system SiO.sub.2 --PbO--M.sub.2 O wherein M.sub.2 O=alkali metal oxides, said glass having a minimum PbO content of 30 wt. % and a minimum M.sub.2 O content of 0.5 wt. %, are provided with enhanced chemical stability without loss of the desired optical position by replacing a portion of the SiO.sub.2 and PbO such that the glass contains 1.5-6 wt. % (TiO.sub.2 +ZrO.sub.2) and the ratio of TiO.sub.2 :ZrO.sub.2 is about 0.3-2.0.

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: A phototropic glass with the optical characteristics of n.sub.d greater than to or equal to 1.59 and v.sub.d greater than or equal to 44, and with a density less than or equal to 3.0 g/cm.sup.-3 is provided having a composition comprising:______________________________________ SiO.sub.2 42-56 B.sub.2 O.sub.3 11-18 Al.sub.2 O.sub.3 0-5 sum of SiO.sub.2, B.sub.2 O.sub.3, and Al.sub.2 O.sub.3 55-75 Li.sub.2 O 3-9 Na.sub.2 O 0-7.98 K.sub.2 O 0-8.22 sum of alkaki metal oxides 7-15 MgO 3-12 CaO 0-3 SrO 0-3 BaO 0-6 ZnO 0-2 sum of alkali earth metal 3-12 oxides amd ZnO TiO.sub.2 3.06-6.74 ZrO.sub.2 2-11 Nb.sub.2 O.sub.5 2.28-8 La.sub.2 O.sub.3 0-3 Er.sub.2 O.sub.

Abstract: Neodymium-doped phosphate glasses having a refractive index, nd>1.520; an Abbe number, Vd, <60; a density <3.0 g/cm.sup.3, a thermal expansion coefficient, .alpha., .ltoreq.110.times.10.sup.-7 .degree.C..sup.-1 ; a Young's Modulus, E, <70.times.10.sup.3 N/mm.sup.2 ; a Poisson's Ratio, .nu., <0.28; a thermal conductivity, K, >0.5 W/m.multidot.K, a thermal FOM=(1-.nu.).multidot.K/.alpha.E>0.7, consisting essentially of, in mol. %:P.sub.2 O.sub.5 : 40-70%SiO.sub.2 : 0-20%B.sub.2 O.sub.3 : 5-20%Sum SiO.sub.2 +B.sub.2 O.sub.3 : 5-35%Sum Li.sub.2 O+Na.sub.2 O+K.sub.2 O: 5-20%Sum La.sub.2 O.sub.3 +Nd.sub.2 O.sub.3 : 3-10%Sum MgO+CaO+SrO+BaO+ZnO: 0-10%and preferably containing an amount of Nd.sub.2 O.sub.3 effective for laser activity having an emission cross-section, .sigma., >3.5.times.10.sup.-20 cm.sup.2 ; a fluorescence linewidth (.DELTA..lambda..sub.f1)<23.5 nm; a first e-folding time of the Nd.sup.3+ fluorescence at 0.5 wt. % Nd.sub.2 O.sub.3 >375 .mu.

Abstract: Optical glass compositions having refractive indexes of 1.60-1.69 and Abbe numbers higher than 54 as well as with a density of less than 3.4 g/cm.sup.3, and which are distinguished in that they have good chemical stability, comprising (in percent by weight): 5-30 percent SiO.sub.2 ; 20-55 percent B.sub.2 O.sub.3 ; 13-40 percent CaO; 3-25 percent La.sub.2 O.sub.3 ; and optionally one or more of the following: up to 7 percent ZrO.sub.2, up to 2 percent TiO.sub.2, up to 9 percent Al.sub.2 O.sub.3, up to 11 percent MgO, up to 10 percent ZnO, up to 10 percent SrO, and up to 12 percent BaO.

Abstract: A glass for an eye glass lens comprising a SiO.sub.2 (or B.sub.2 O.sub.3)-CaO-Nb.sub.2 O.sub.5 system as a basic system and having a refractive index of 1.79 or more, an Abbe number of 32 to 38 and a specific gravity of less than 3.6 is disclosed.

Abstract: A glass for multi-focal eyeglass having a refractive index (n.sub.d) of 1.74 to 1.78, an Abbe number (.nu..sub.d) of 31 or more, a coefficient of thermal expansion of 82 to 95.times.10.sup.-7 and a softening point of 560.degree. to 640.degree. C., comprising, in % by weight,26 to 34% SiO.sub.2 +B.sub.2 O.sub.3 +Al.sub.2 O.sub.3 ;14 to 24% SiO.sub.2 ;6 to 14% B.sub.2 O.sub.3 ;0 to 4% Al.sub.2 O.sub.3 ;38 to 50% PbO;15 to 30% BaO+SrO+CaO+MgO+ZnO;2 to 24% BaO;0 to 17% SrO;0 to 15% CaO;0 to 10% MgO;0 to 12% ZnO; and0 to 3% ZrO.sub.2 ;wherein a weight ratio of B.sub.2 O.sub.3 /SiO.sub.2 ranges from 0.3 to 0.8 and a weight ratio of alkaline earth oxides/PbO ranges from 0.2 to 0.6.

Abstract: This invention is concerned with the production of glasses suitable for ophthalmic applications having refractive indices of 1.523.+-.0.004, Abbe number between 51-59, densities less than 2.43 g/cm.sup.3, transmissions at 400 nm in 2 mm thickness greater than 89%, and a UV cutoff between 310-335 nm, said glasses consisting essentially, in weight percent on the oxide basis, of:______________________________________ SiO.sub.2 49-71 Li.sub.2 O + Na.sub.2 O + K.sub.2 O 8-20 B.sub.2 O.sub.3 5-26 TiO.sub.2 1.8-6 Al.sub.2 O.sub.3 0-14 ZrO.sub.2 0-5.5 Li.sub.2 O 0-4 As.sub.2 O.sub.3 and/or Sb.sub.2 O.sub.3 0-0.7 Na.sub.2 O 0-16 Cl and/or Br 0-1 K.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 glass for multi-focal eyeglass having a refractive index (n.sub.d) of 1.67 to 1.73, an Abbe number (.nu..sub.d) of 33 or more, a coefficient of thermal expansion of 82 to 95.times.10.sup.-7 and a softening point of 560.degree. to 640.degree. C., comprising, in % by weight,32 to 40% SiO.sub.2 +B.sub.2 O.sub.3 +Al.sub.2 O.sub.3 ;22 to 40% SiO.sub.2 ;0 to 10% B.sub.2 O.sub.3 ;0 to 4% Al.sub.2 O.sub.3 ;4 to 10% Li.sub.2 O+Na.sub.2 O+K.sub.2 O;0 to 4% Li.sub.2 O;0 to 7% Na.sub.2 O;0 to 7% K.sub.2 O;30 to 47% PbO;3 to 24% BaO+SrO+CaO+MgO+ZnO;0 to 20% BaO;0 to 15% SrO;0 to 10% CaO;0 to 8% MgO;0 to 15% ZnO; and1 to 7% ZrO.sub.2 ;wherein a weight ratio of alkali metal oxides/PbO ranges from 0.1 to 0.3.

Abstract: Alkali-free borosilicate glass have been developed having coefficients of thermal expansion (+20.degree. C. to +200.degree. C.) below 40.5.times.10.sup.-7, densities less than 3.0 g/cm.sup.3 and good visible and UV transmission, and can be produced by conventional continuous melting techniques. These glasses are particularly suitable for photomask, photovoltaic and mirror substrate applications. Their compositions comprise, in weight percent:______________________________________ SiO.sub.2 50-60% B.sub.2 O.sub.3 1-6% Al.sub.2 O.sub.3 12-15% MgO 0-2.5% CaO 0-5.1% BaO 9-10% ZnO 12-18% CeO.sub.2 0-5% As.sub.2 O.sub.3 + 0-1.5% Sb.sub.2 O.sub.3 PbO 0-1% ______________________________________Sum MgO+CaO+BaO+ZnO=21-33.5.

Abstract: A glass suitable for use in optical fibre cores has a refractive index of 1.540-1.610, Na.sub.2 O and B.sub.2 O.sub.3 in a molar ratio of 1.05-2:1, 2-12 mole percent BaO, 40-63 mole percent SiO.sub.2, and 1.5-15 mole percent ZrO.sub.2, the proportion of SiO.sub.2 and ZrO.sub.2 together not exceeding 65 mole percent. The glass can be prepared in a highly reduced state by the use of CO and a redox buffering agent. The glass is especially suitable for the production of high numerical aperture wide cored fibres.

Abstract: This invention relates to glasses especially suitable for optical and ophthalmic applications which exhibit densities less than about 2.65 g/cm.sup.3, refractive indices between about 1.595-1.607, and Abbe numbers between about 40-47, and which consist essentially, in weight percent on the oxide basis, of______________________________________ SiO.sub.2 45-55 MgO and/or BaO and/or B.sub.2 O.sub.3 5-13 SrO and/or La.sub.2 O.sub.3 0-6 Al.sub.2 O.sub.3 0-5 CaO 0-12 Li.sub.2 O 1-7.5 ZnO 0-8 Na.sub.2 O 1-9 ZrO.sub.2 0-7 K.sub.2 O >10-24 TiO.sub.2 9.5-17.5 As.sub.2 O.sub.3 and/or Sb.sub.2 O.sub.3 0-1 and 13.5 < TiO.sub.2 + ZrO.sub.2 + La.sub.2 O.sub.3 + MgO <23.

Abstract: An optical glass with the familiar optical position of n.sub.d >1.70 and v.sub.d >22, which differs from the familiar optical glasses of the optical position due to its lower density and good chemical stability, and is composed of (in percent by weight): SiO.sub.2 25-42, TiO.sub.2 15-35, B.sub.2 O.sub.3 0.5-7, BaO 3-13, CaO 1-3, Nb.sub.2 O.sub.5 1-20, GeO.sub.2 0-2, Al.sub.2 O.sub.3 0-4, Na.sub.2 O 7.5-15, Li.sub.2 O 0-9, K.sub.2 O 2-10, SrO 0-6, ZnO 0-5, ZrO.sub.2 0-3, and WO.sub.3 0-3.