Fabrication of micro-scale gratings for moiré method with a femtosecond laser

Fabrication of micro gratings using a femtosecond laser exposure system is experimentally investigated for the electron moiré method. Micro holes and lines are firstly etched for parameter study. Grating profile is theoretically optimized to form high quality moiré patterns. For a demonstration, a parallel grating is fabricated on a specimen of quartz glass. The minimum line width and the distance between two adjacent lines are both set to be 1μm, and the frequency of grating is 500lines/mm. The experimental results indicate that the quality of gratings is good and the relative error of the gratings pitch is about 1.5%. Based on moiré method, scanning electron microscope (SEM) moiré patterns are observed clearly, which manifests that gratings fabricated with the femtosecond laser exposure is suitable for micro scale deformation measurement.