Large transmissive optical component

22325222222323−6An 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.-% SiO, 17 to 35 wt.-% AlO, 3 to 17 wt.-% PO, 0 to 6 wt.-% LiO, 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.-% TiO, 0,5 to 3 wt.-% ZrO, 0 to 1 wt.-% NaO, 0 to 1 wt.-% KO, a maximum of 1 wt.-% of refining agents (AsO, SPO) and a maximum of 500 ppm of other contaminants. The glass composition may be equal to the composition of the glass ceramic Zerodur® 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/K.