A variable-focus lens with 1 kHz bandwidth applied to axial-scan of a confocal scanning microscope

This paper proposes a new structure of variable-focus lens aimed at 1 kHz bandwidth. Two kinds of prototypes are developed to validate the structure. The 1 kHz bandwidth is confirmed by the frequency response measurements. One prototype is applied to the axial high-speed scan of a confocal laser scanning microscope. Depth information measurements of a microscopic object in 1 ms and automated focusing to keep the focus on a randomly moving object are successfully achieved.