LARGE TRANSMISSIVE OPTICAL COMPONENT

An optical glass for the manufacture of large transmission optics, such as lenses having a thickness of 100 millimeters or more, comprises 35 to 70 wt.-% SiO2, 17 to 35 wt.-% Al2O3, 3 to 17 wt.-% P2O5, 0 to 6 wt.-% Li2O, 0.5 to 4 wt.-% MgO, 0.5 to 3 wt.-% ZnO, a maximum of 1 wt.-% CaO, a maximum of 0.5 wt. % BaO, 0.5 to 6 wt.-% TiO2, 0.5 to 3 wt.-% ZrO2, 0 to 1 wt.-% Na2O, 0 to 1 wt.-% K2O, a maximum of 1 wt.-% of refining agents (As2O3, SP2O3) and a maximum of 500 ppm of other contaminants. The glass composition may be equal to the composition of the glass ceramic Zerodur(R) and allows to manufacture large transmission optics in a cost-effective way, has a maximum of transmittance which is in the range of a He-Ne lasers and has a CTE of about 3.10-6/K.