Achromatic Metalens for Three-Dimensional Depth Sensing

Depth imaging, which provides crucial information about the distance of objects, plays a vital role in broad applications, such as autonomous driving, industrial manufacturing, and robotics. Traditional 3D imaging methods, for example, Time-of-Flight (ToF), usually require active illumination, which increases the complexity of the whole optical system. Passive depth imaging can be achieved using methods including stereo vision, light-field imaging, and point spread function engineering. Here, we have demonstrated a broadband achromatic double-helix metalens by employing the integrated resonant unit elements in metasurface, combining both the propagation phase with linear phase compensation and geometric phase. This broadband achromatic flat optical device effectively eliminated the chromatic aberration that occurs in the depth-sensing process of an existing double-helix metalens in the 1200–1400 nm wavelength range and achieved a 14.39-fold enhancement in energy utilization efficiency. Our work holds potential applications in various fields, including microscopic imaging, autonomous driving, and robotic perception.