Orthogonal modulated computer-generated moiré profilometry

An orthogonal modulated computer-generated moire profilometry is proposed. Only one composite grating in which two sinusoidal fringe patterns with a π phase difference are modulated by two other orthogonal sinusoidal fringe patterns with different frequencies respectively is projected on the object. While a single-shot deformed composite pattern is captured, the two sinusoidal deformed patterns with a π phase difference are demodulated from the deformed composite pattern. The AC component of deformed pattern is calculated by subtraction of the two demodulated deformed patterns. If this AC component of deformed pattern is respectively multiplied by the two AC components of fringe patterns of reference plane with a π ∕ 2 phase difference prepared and saved in computer in advance, two computer generated moire fringes which just respectively stand for sine and cosine of phase modulated by the height of the object relative to the reference plane are extracted. The tangent of the modulated phase is obtained by the ratio of these two moire fringes. So the three-dimensional (3D) shape of object can be reconstructed using only one deformed composite pattern. Both simulation and experimental results demonstrate the feasibility and validity of the proposed method. It has potential in real-time 3D measurement due to its single-shot feature.