Effects of transfer function of profilometer on roughness measurement of ultra-smooth surface

Root_mean_square roughness is one of the most important figures that is used to characterize the ultra-smooth surfaces. Many experimental results show that different types of profilometers usually give different results, which make it difficult to compare them. In this paper, the effects of the transfer function of a profilometer on the roughness measurement of ultra_smooth surfaces are analyzed based on linear system theory and simulated with the discrete Fourier transformation method. The results show that because of the limited bandpass of the profilometer, the measured root_mean_square roughness is always less than the real roughness of the surfaces.