We report a new optical element which diffuses the one-dimensional laser beam into an omnidirectional plane beam. We name it as a hollow tube prism based on its tubular structure. By numerical simulation and experiment we have shown that the rays of the transmitted light propagate to all directions in the two-dimensional plane through infinite refractions and reflections at the inner and the outer surfaces of the hollow tube. With a proper dielectric multilayer coating on the outer surface, the transmitted light becomes uniform over all angles. The uniformity of the intensity distribution is evaluated by the contrast. We have obtained the contrast of 0.467 for the coated hollow tube prism while the uncoated one has the contrast of 0.953. (C) 2005 American Institute of Physics.