Experimental results of deep submicron lithography with a excimer laser are reported in this paper. With a free running KrF excimer laser, an illumination system including a light pipe uniformizer and a broadband catadioptric 1:1 projection lens with an aberration correcting planoparallel plate, the resolutions of 0.6 μm and 0.5 μm L/S patterns are produced on two resists respectively.