Large-depth-range dual-color π-phase-shifted fringe projection based on sinusoidal phase grating

Achieving high-precision three-dimensional (3D) measurement from a single-frame image has become the ultimate goal in phase-shifting profilometry (PSP). However, current methods of sinusoidal fringe generation involve a trade-off between projection speed and depth range, thereby limiting the capability of PSP for dynamic and large-scale measurements. To address this problem, we propose a novel sinusoidal fringe projection method based on sinusoidal phase grating (SPG). Experimental results confirmed that the proposed method can project dual-color π-phase-shifted fringes within a depth range of 300 mm to 1000 mm and enables single-frame 3D measurement of complex objects in PSP, effectively overcoming the inherent trade-off. Featuring a compact architecture, the SPG-based projector also provides a promising approach for developing miniaturized and robust PSP systems, with broad prospects in portable devices, machine vision, and other structured-illumination-based technologies.