As shown in figures, three identical polaroids $$P_1$$, $$P_2$$ and $$P_3$$ are placed one after another. The pass axis of $$P_2$$ and $$P_3$$ are inclined at angle of $$60°$$ and $$90°$$ with respect to axis of $$P_1$$. The source $$S$$ has an intensity of $$256$$ W m$$^{-2}$$. The intensity of light at point $$O$$ is ______ W m$$^{-2}$$.