Application of structured illumination microscopy in fast and accurate measurement of complex-surface and steep-edge

Abstract

With the wide application of micro-nano structures in various fields, micro-nano technology has been developed continuously. Among them, micro-nano surface morphology detection technology has become a research hotspot, because the surface geometry and morphology of micro-nano devices determine the functional level and service life of devices. With the increasing complexity of micro nano device surface morphology and the increasing sharp edges, the detection technologies are facing severe challenges. Among various detection methods, structured illumination microscopy (SIM) has attracted many research interests due to the characteristics of high accuracy, strong adaptability and high efficiency. The existing SIM are mainly based on phase-shift technique, Hilbert transform technique and global Fourier transform technique. However, for complex-surface and steep-edge measurements, it is difficult for traditional SIM to achieve both high accuracy and high efficiency. In this paper, a method based on SIM which combines vertical scan and phase-shift is proposed. In this proposed measurement system, vertical scanning of the object is synchronized with the switching of the phase-shifted fringe pattern and only one fringe pattern needs to be projected, which enables a point-to-point processing defined as local Fourier transform method in this paper to be utilized to extract the modulation information which will reserve high-frequency information of the image so it can be applied to both smooth and rough surfaces. Simulation and experiment are carried out to demonstrate that the proposed method can successfully realize fast and accurate detection of complex-surface and steep-edge.