Baseline-free structured light 3D imaging using a metasurface double-helix dot projector.

Structured light is a widely used 3D imaging method with a drawback that it typically requires a long baseline length between the laser projector and the camera sensor, which hinders its utilization in space-constrained scenarios. On the other hand, the application of passive 3D imaging methods, such as depth from depth-dependent point spread functions (PSFs), is impeded by the challenge in measuring textureless scenes. Here, we combine the advantages of both structured light and depth-dependent PSFs and propose a baseline-free structured light 3D imaging system. A metasurface is designed to project a structured dot array and encode depth information in the double-helix pattern of each dot simultaneously. Combined with a straightforward and fast algorithm, we demonstrate accurate 3D point cloud acquisition for various real-world scenarios including multiple cardboard boxes and a living human face. Such a technique may find application in a broad range of areas including consumer electronics and precision metrology.