In order to damage the airframe of an ICBM, an estimated 3kJ/cm2 would need to hit it. The laser is essentially a focusing device, taking the radiation falling along the length of the rod and turning some small amount of it into a beam traveling out the end. One can consider the effect as increasing the brightness of the X-rays falling on the target compared to the X-rays released by the bomb itself. The enhancement of the brightness compared to the unfocused output from the bomb is formula_1, where formula_2 is the efficiency of conversion from bomb X-rays to laser X-rays, and formula_3 is the dispersion angle.