The near field patterns in the direction parallel to the target surface of prepulse which induces J=0→1 lasers in neonlike Fe and Zn were investigated under three different focusing conditions of the pump laser, i.e. optimum focusing, prepulse laser beam defocused alone, and prepulse and main pulse defocused simultaneously. The experiment was performed at the Asterix IV iodine laser with a prepulse 5 ns before the main pulse. Under optimum focusing conditions for main pulse and prepulse the X-ray laser beam splits into two beamlets along the target surface (vertical direction) at its output end of the 2.5 cm long plasma column. The splitting was still observed when the prepulse alone was defocused. Defocusing the prepulse and the main pulse simultaneously eliminated the splitting, resulting in a very narrow half-maximum width of the vertical near field pattern of 40 μm (FWHM).