Mo/Si and W/C multilayer films were fabricated by magnetron sputtering. Cross‐section transmission electron microscopy shows that these multilayers have a well‐formed layer structure. The modulation wavelength of the multilayer can be precisely determined from the spacing of the satellites in the low‐angle regions of both electron and x‐ray‐diffraction patterns. Experimental results show that the refraction corrections to the Bragg condition for electron and x‐ray diffractions are in opposite directions. The physical significance of the difference between the two corrections is discussed. ©1995 American Institute of Physics.