A High-Speed Variable-Focus Imaging System Based on Ultrafast Angular Modulation of Mirrors

Abstract

This letter presents a novel optical approach for high-speed variable-focus imaging utilizing ultrafast angular control of switching mirrors. By rapidly adjusting the optical path through high-speed mirror actuation, the system achieves millisecond-level focus response times, allowing high-speed focal scanning across multiple focal depths. Unlike traditional mechanical focusing or specialized lens-based methods, this system seamlessly integrates with standard camera-lens setups without requiring any lens movement or complex correction procedures. It effectively overcomes limitations caused by environmental factors such as temperature fluctuations and gravity-induced deformation, as well as constraints from fixed lens parameters including aperture size and optical diameter. The imaging performance and focus adaptability of the system were validated by conducting the all-in-focus imaging experiment, in which a full-focus image was generated from a series of images captured at different focal depths at high speed. By performing 500 Hz high-speed focal scanning with 20 focal planes per stack, the proposed system achieves 25 Hz in-focus imaging of the moving target without requiring iterative autofocus algorithms or active ranging sensors.