High-precision optical step detection

Due to the ongoing miniaturization of electronic, mechanic and optics components the precise position determination of surface profiles within optical measurement processes becomes more important. The investigation of diffraction pattern arise from the interaction of electromagnetic radiation with edges or rather steps with a height smaller than the incident wavelength is the focus of this work. By use of a supercontinuum laser source we study the diffraction signal of a step especially in the transition region where the step height becomes smaller than the wavelength. Furthermore, the effect of the surface material as well as the polarization state and direction of the incoming laser beam are subjects of the current work. The goal of this project is to become a detailed idea of the diffraction signal depending on the ratio of incoming wavelength to step height and to derive trends according to the aspect ratio and manufacturing related deviations of the steps shape. The results will serve as a basis for the development of an edge and step detection system within a nano-positioning-and-nano-measuring-machine (NPMM).