Optical Glass and Projection Exposure Apparatus Using the Same

Abstract

The optical glass of the present invention comprises a composition in terms of weight ratio within the range of 0 to 14.8 wt % of SiO2, 30 to 60 wt % of B2O3, 0 to 17.5 wt % of Al2O3, 0 to 0.4 wt % of Li2O, 0 to 3 wt % of Na2O, 0 to 3 wt % of K2O, 0 to 5 wt % of MgO, 0 to 30 wt % of CaO, 0 to 30 wt % of SrO, 0 to 35 wt % of BaO, where RO (MgO+CaO+SrO+BaO) is 8 to 35 wt %, 0 to 20 wt % of ZnO, 0 to 6.5 wt % of La2O3, 0 to 15 wt % of Gd2O3, 0 to 15 wt % of Y2O3, 0 to 10 wt % of Ta2O3, 0 to 9.5 wt % of ZrO2, 0 to 1 wt % of As2O3, and 0 to 0.5 wt % of Sb2O3; and has a refractive index (nd) of 1.52 to 1.65, an Abbe number (vd) of 55 to 61, and an 80% transmission wavelength (at a thickness of 10 mm including no reflection loss) of 330 nm or shorter.

Dependencies are inferred from the claim text.