High-speed liquid lens for computer vision

We report a high-speed liquid lens, called a Dynamorph Lens (DML), and its applications in the field of computer vision. The developed lens uses a liquid-liquid interface as a variable refractive surface. The interface shape is controlled by the volume of a liquid chamber using a high-speed piezostack actuator. A developed prototype demonstrated both millisecond-order response speed and practical optical performance. A high-speed focusing vision system that can adaptively control its focal length in based on visual feedback by using the DML prototype coupled with a high-speed imager is also proposed. High-speed autofocusing within 15.8 ms and focus tracking of a moving object were demonstrated using the developed system. The DML prototype was also applied to high-speed focus scanning of a camera lens at 500 Hz. An image sequence was captured at 8000 fps through the lens so that every eight images were captured with a different focus, and a 1000 fps video with extended depth of field was successfully synthesized.