Research Progress on Evaluation Algorithms for Periodic Spacing Analysis of Nano Gratings Microscopy Images

Nano gratings are one of the five critical geometric nano standards in the Nanometric Working Group program of the International Organization for Weights and Measures. It is mainly used for value transfer and calibration of imaging system magnification and spatial distortion characterization. Before being used as a standard sample, its values must undergo strict and accurate evaluation. After obtaining grating images using metrological instruments, appropriate evaluation algorithms should be selected to reduce human errors introduced during manual measurement, thereby improving the accuracy and consistency between the measured values and results. This article provides an overview of the current research progress on grating evaluation algorithms, including the gravity center method, Fourier transform method, and periodic function fitting method, and summarizes and prospects the evaluation algorithms.