Steep Geometric Grating for Use in Moire Interferometry

The theoretical background and the procedure of executing a new moire interferometry method, which combines the advantages of geometric moire method with the traditional moire interferometry, is reported. The method uses a steep geometric grating of about 40 linesmm on a mirror finished specimen surface to achieve high contrast moire fringes. A special four beam moire interferometry bench is designed for the low grating frequency used. An application to experimental fracture mechanics analysis is briefly discussed.