Optical glass - contg. oxide(s) of silicon, germanium, boron, aluminium, zinc, magnesium, sodium, potassium, lithium, strontium, barium, calcium, gadolinium, tantalum, lead, etc.

摘要

Optical glass compsn. comprises (wt%) SiO2 0-2; CuO2 0-2; SiO2+GeO2 0-2; B2O3 0-2; Al2O3 6-13.5%; Li2O 0-3; Na2O 0-3; K2O 0-3; sum of alkali oxides 0-3; (a) MgO 0-10 (b) CaO 0-10; (c) SrO 0-10; (d) BaO 30-46; (e) ZnO 0-10; a+b+c+d+e 44-61; Gd2O3 0.3-5; PbO 0-3' Ta2O5 0-3; WO3 0-3; ZrO2 0-3; TiO2 0-3; P2O5 8-22; F2O 13-18; F 23-31; and up to 0.5 refining assistants. The glass has a positive anomalous particle dispersion in the blue region of the spectrum Pg.F with refractive index nd of 1.49-1.54, nu(d) of 71-84 and deviation from the normal of lambda Pg.F of at least 0.200; where nu(d) = nd1(nF-nC) and pg.F = ng-nF/(nF-nC), where nd = refractive index (ri) at 587.56 nm; nf = ri at 486.13 nm; nC ri at 656-27 nm, and ng = ri at 435.83 nm. ADVANTAGE - The glass has good crystallisation stability and transmission.