Interferometric Phase Measurement Using Spatial Synchronous Detection

A family of three phase measurement techniques are described that are spatial analogs of the popular temporal phase-shift methods. For these spatial techniques, the need for an active element such as a piezoelectric translator or an electro-optic crystal is eliminated simply by adding tilt to the fringe pattern. Measurements are obtained over a uniform grid with an accuracy comparable to temporal phase-shift interferometry. Advantages and disadvantages are discussed.