Toward Compact Motorized Lens: Switch and Focus a Filter Wheel with Single Piezoelectric Tube

Multispectral cameras (MSCs) have the capability of detecting and analyzing features invisible to human eyes and are of interest for many applications. However, the traditional MSC suffers from bulkiness since the light filtering and optical focusing mechanisms are independent. Herein, it proposed an integrated strategy that implements two functions through a tunable filtering-focusing mechanism (TFFM), driven by two degrees of freedom (two-DOF) piezoelectric tube actuator (PTA). The TFFM can realize light filtering and optical focusing through the rotary and linear motions of PTA. The configuration of PTA is presented, and the working principle is discussed. Then, prototypes of PTA and TFFM are developed, weighing merely 5.5 and 8 g, sizing of Ø7 × 21.4 mm and Ø35 × 7 mm, demonstrating the merits of lightweight and miniaturization. Experiments validate the effectiveness of TFFM, including multispectral images acquired with 0.1 s through rotary motion, focused images obtained with a linear speed of 60.2 mm⁻¹s, and a series of images with different sharpness and wavelengths. The sharpness evaluation algorithms are adopted to determine the sharpest image. The work contributes to reducing the volume of MSC systems with multifunctionalities while keeping the devices simple, providing a practical and effective solution for the integrated design of MSC.