Phase retrieval for dual-projection pattern based on orthogonal frequency encoding to suppress superposing effects

When grating patterns are simultaneously projected by a dual-projection structured-light system, interference-like blur and brightness overexposure in the superposed area often cause miscalculation of the phase of the grating pattern. In this study, we proposed a novel method, to the best of our knowledge, that utilizes orthogonal grating encoding to retrieve the phases of superposed grating patterns. Specifically, we determined the frequency of the dual-projection pattern based on the condition that enabled the separation of superposed orthogonal signals in wireless communication. Additionally, the maximum intensity of the projected pattern was determined using the intensity-saturation relationship. By performing a discrete Fourier transform on a series of superposed grating patterns, we obtained the wrapped phase of the corresponding projected grating patterns in the space-time dimension. Finally, we reconstructed the measured object by fusing the point clouds obtained from the dual-projection structured-light system. The experimental results demonstrated that the encoded orthogonal grating patterns could eliminate interference-like blurring and brightness overexposure during superposition and obtain high-precision phase maps and 3D reconstruction results, which provides the possibility for the simultaneous reconstruction of multiprojection structured light.