Extended depth-of-field stereo imaging system based on high-speed dual cameras embedded with variable focus lenses

Extended depth-of-field (DoF) technology is widely used in three-dimensional (3D) depth measurement. However, it is hard to achieve extended DoF imaging for conventional stereoscopic vision systems in dynamic scenes. Here, we propose an extended DoF vision system based on variable-focus lenses for target motion scenes. This system operates at two synergistic levels: optical-level focal sweeping and computational-level all-in-focus synthesis dynamically. Specifically, we introduce a temporally adaptive focal calibration model that precisely predicts curvature variations of varifocal lenses under non-linear electromechanical responses, ensuring sub-millisecond focal accuracy across a depth range of 0.45∼1.2 m. In addition, an adaptive homography-based multi-plane remapping mechanism is designed to compensate for disparity drift and distortion artifacts induced by rapid focus change, followed by a sharpness-weighted fusion strategy that synthesizes an all-in-focus image with preserved high-frequency details. The depth measurement performance was improved by approximately 6.2%, the relative depth error rate is optimized to 5.82%, and the RMSE is reduced to 0.0505 compared to conventional stereo vision systems in images obtained. The proposed system has the advantage of a compact form factor and dynamic extended DoF imaging. The potential applications include biomedical imaging, industrial vision inspection, robotic vision with navigation, and AR/VR.