A Window Based Graphics Interface for Phase Shifting Analysis in Moire Interferometry

A window based graphics interface for phase shifting in a moiré interferometry system is introduced in this paper. VISUAL C++ is used in the software programming. The phase shifting is accomplished by driving the reference grating in the moiré interfermetry system with a low voltage piezo stack. Four images from three shifts and one original image are used to derive the phase diagram, which is used for displacement and strain calculations. Automatic fringe numbering is achieved by the phase shifting, which significantly simplifies the traditional fringe-counting process. The strain calculation is also automatic by space derivative of displacement. The displacement distribution is obtained by unwrapping the phase diagram. Various help menu functions are provided, facilitating the ease use of the software. A 3-point bending beam is used for the demonstration. The technique is also applied to the analysis of thermal deformations in a flip-chip electronic package.