Two-dimensional varifocal scanning imaging based on Alvarez and decentred lenses actuated by dielectric elastomer

A two-dimensional varifocal scanning imaging system has been employed broadly in various fields, such as biomedicine, holographic projection, and optical communication. As a core optical component of the aforementioned imaging system, the two-dimensional varifocal scanning element has intensively been investigated. Although many methods have been proposed for two-dimensional varifocal scanning imaging, they often suffer from several problems, such as small varifocal range, small scanning angle, bulky size, and slow response speed. This paper proposes a novel two-dimensional varifocal scanning element actuated by dielectric elastomer, which consists of two pairs of Alvarez lenses, and a pair of decentred lenses. By applying actuation voltages on the different quadrants of the dielectric elastomers, the two pairs of Alvarez lenses can be moved laterally to change the focal length and the pair of decentred lenses can be shifted to scan the imaging object in a two-dimension direction. The validity of the proposed two-dimensional varifocal scanning imaging is verified by the experiments. The results show that the focal length variation of the proposed two-dimensional varifocal scanning element is up to 3.75 times where the maximum and minimum focal lengths are 19.5 mm and 5.2 mm respectively. The maximum scanning angle is 14.18°. The rise and fall response times are 124 ms and 203 ms, respectively. The proposed varifocal scanning element is expected to be used in the fields of microscopy, biomedicine, virtual reality, etc.