Curvature of bending shells by moire interferometry

There are many kinds of moire interferometry. But, they are used to obtain the displacement and strain of object especially for in-plane deformation. And, most of all, the grating must be put on to the object which will be measured. It is inconvenient. Now, we proposed a moire interferometry, which can measure the curvature of object for out-of-plane deformation, and need not put the grating on to the object. In the schematic of the method, there are one grating (106Lines/in, or 300Lines/in, or 500Lines/in), and the coherent-optimal processor. Between the two-exposures, the recorded plate is moved by lx along the direction of perpendicular to the grating line, and the curvature of the object can be measured directly. In the schematic of the method, spatial filter is used, for allowing the ± orders of the diffracted wave of the grating formed by the collimated wavefront. This method is accuracy, sensitivity, convenience, and can be used for quantitative analysis. A group of shallow shells with different shapes and boundary conditions are measured by this method. The experimental results agree with the theoretical values very well.