Implementation of phase-shifting moiré profilometry on a low-cost commercial data projector

In phase-shifting moiré profilometry, grid lines are projected onto an object, and the deformed projection is imaged onto a second grid to obtain moiré fringes. Grid noise is removed by translating both grids simultaneously in their own plane, and fringe phase-shifts are obtained by changing the relative distance between the two grids. From three or more phase-shifted moiré fringe patterns, object surface height is calculated on all pixel points of the camera which records the moiré fringe patterns. Classically, translation of the grids is performed mechanically. Recently, we have introduced a method using two liquid crystal light modulators to perform high-resolution phase-shifting moiré topography without any mechanically moving parts. We now describe, how this new method can be implemented using a low-cost consumer product LCD projector. We show how the different LCD panels can be addressed, and how fast grid noise averaging can be implemented using a standard computer graphics board. Resolution measurements and application examples are presented on objects of different sizes.