Fabrication technique of micro/nano-scale speckle patterns with focused ion beam

The fabrication technique of micro/nano-scale speckle patterns with focused ion beam (FIB) system is studied for digital image correlation (DIC) measurement under a scanning electron microscope (SEM). The speckle patterns are fabricated by directly etching the counterpart of the specimen to the black part of a template. Mean intensity gradient is used to evaluate the quality of these SEM images of speckle patterns fabricated based on different templates to select an optimum template. The pattern size depending on the displacement measurement sensitivity is adjusted by altering the magnification of FIB according to the relation curve of the etching size versus magnification. The influencing factors including etching time and ion beam current are discussed. Rigid body translation tests and rotation tests are carried out under SEM to verify the reliability of the fabricated speckle patterns. The calculated values are in good agreement with the imposed ones.