Applied phase-contrast radiography with polychromatic thermal neutrons

Instead of conventional radiography the phase-contrast imaging visualizes not only the beam absorption but also the phase shifts induced by the sample at the propagation of a coherent radiation through it. The strong phase changes on the borders between two media can be observed as sharp intensity variations on the radiography image. So the phase-contrast method is an edge-enhancement method which allows to visualize very fine structures where the conventional radiography provides unsatisfactory results. (orig.)