The application of moiré inversion technique in the characterization of micro-scale 3D periodic structures

The characterization of micro/nano periodic structures is of great importance in the micro/nano manufacturing field. Existing characterization methods based on inversion technique are mostly for planar structures. An effective method for the characterization of three-dimensional (3D) periodic structures based on inversion technique is proposed in this paper. The inversion technique is based on the stereo vision technique and the digital phase shifting method. The 3D micro/nano periodic structures were imaged and captured under the microscope from two relative camera angles. Digital reference grating were superimposed with the periodic structures as specimen gratings. Consequently, the shape and periodic structures of the specimen can be characterized by the phase shifting method. A simulation test was performed and the results indicate that the proposed method is reliable. Simultaneously, an experiment for the characterization of the periodic structure on the bulged polyimide films was carried out on an optical microscope. The method is verified effective and has potential for the characterization of various 3D periodic structures. With the aid of various high-resolution microscopes, the proposed method can be applied to characterize the 3D periodic structures from nano-scale to micro-scale.