Optical glass and projection exposure apparatus using the same

The present invention relates to an optical glass, composed of a basic composition of B O -RO (where R indicates Mg, Ca, Sr and Ba), having 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; and a projection exposure apparatus using the same. 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 SiO, 30 to 60 wt % of BO, 0 to 17.5 wt % of AlO, 0 to 0.4 wt % of LiO, 0 to 3 wt % of NaO, 0 to 3 wt % of KO, 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 LaO, 0 to 15 wt % of GdO, 0 to 15 wt % of YO, 0 to 10 wt % of TaO, 0 to 9.5 wt % of ZrO, 0 to 1 wt % of AsO, and 0 to 0.5 wt % of SbO; 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.