Ultrathin Microlens Array Camera for Passive High-Speed 3D Imaging

Abstract

High-speed three-dimensional imaging is essential for the quantitative analysis of rapidly evolving dynamic phenomena such as combustion, fluid flow, and biological motion. However, conventional approaches suffer from the bulky form factor of multi-camera systems, limited frame rates, or a reliance on active illumination. Here we present an ultrathin high-speed three-dimensional microlens array camera (HS3D-MAC) that simultaneously acquires spatial parallax and high-frame-rate image sequences on a single image sensor. HS3D-MAC comprises double-period offset microlens arrays (doMLAs) and a rolling-shutter CMOS image sensor. The double-period structure of doMLAs simultaneously provides channels with distinct viewpoints at a common time instant and channels at various positions with different time instants. High-frame-rate three-dimensional image sequences are recovered through spatio-temporal reconstruction based on 4D Gaussian splatting. Depth estimation accuracy is validated over an object distance range of 6 to 38.5 cm both within the single-pixel resolution limit. Our camera successfully estimated trajectories of a rotating ball at 400 rpm on a 45°-tilted plate with 2 ms intervals, confirming that HS3D-MAC quantitatively recovers the three-dimensional trajectory of rapidly moving objects. HS3D-MAC will open a new route to compact, passive, high-speed three-dimensional imaging, with applications including combustion diagnostics, fluid visualization, and high-speed biological motion analysis.