Phase-shifting moireí method with an atomic force microscope.

Using a phase-shifting technique with an atomic force microscope (AFM), we propose a phase-shifting AFM scanning moiré method. The phase shifting is realized in four steps from 0 to 2pi by a piezoscanner in the AFM. The measurement method and experimental techniques are described in detail. For demonstration this method is applied to determine the phase distribution in the AFM moiré of a 1200-line/mm holographic grating used to measure the thermal deformation in a Quad FlatPack electronic package.