A deceleration system for a parallel ion beam in the energy range of 50 to 500 eV is described. The system is used for sputtering yield measurements as a function of the angle of ion incidence. Measured yield data for Cu and Au sputtered by 100‐ and 300‐eV D+ions are reported and compared to computer calculations. Experimental and calculated data show only a weak dependence on the angle of incidence. However, at glancing incidence the experimental values are larger up to a factor of 2 compared to the calculated ones. This is attributed to the surface roughness not included in the calculations.