Rapid characterization of nano-scale structures in large-scale ultra-precision surfaces

Characterizations of nano-scale structures using conventional stylus profilometer and optical microscopy are respectively restricted by tip radius and diffraction limit. Atomic force microscope (AFM) can measure smaller structures but it is difficult and time-consuming to find them in large-scale ultra-precision surfaces. In this paper, a new profilometer for rapid positioning and measurement of nano-scale structures in large-scale ultra-precision surfaces is proposed. A technique based on white light interference is integrated into an AFM to detect probe deflection. The adapted profilometer has two measurement modes: a white light interferometry mode used to find an area of interest, an AFM mode for high-resolution measurement. Using this profilometer, the time of positioning an area of interest can be significantly reduced and the measurement efficiency is thus improved. Furthermore, a tracking measurement method is proposed to improve the measurement range of the AFM mode, which can enhance the measuring ability of the profilometer for complex large-scale surfaces. Experiments demonstrate that the profilometer can quickly positioning nano-scale structures in large-scale surfaces and achieve three-dimensional measurement with nanometer resolution.