Dielectric-elastomer-driven long-wave infrared Alvarez lenses for continuous zooming imaging

With the concept of SWaP-C (size, weight, power, and cost), a light, small, low-cost, and high-performance uncooled infrared optical zooming imaging system is pursued. However, the traditional mechanical optical zooming method makes it difficult to meet those requirements. In this paper, a compact uncooled long-wave infrared continuous zooming imaging system using the Alvarez lens actuated by dielectric elastomer is proposed. The infrared zoom imaging system mainly consists of two pairs of infrared Alvarez lenses, an adjustable optical stop, focusing lenses, and an infrared detector. The first pair of infrared Alvarez lenses serves as the zoom group and the second pair serves as the compensation group. The infrared Alvarez lenses are fabricated by five-axis diamond turning and milling technology. The experiment results show that when the dielectric elastomer can provide a lateral displacement of 1.44 mm to the first pair of infrared Alvarez lenses and a lateral displacement of 1.03 mm to the second pair of infrared Alvarez lenses. The infrared continuous zooming imaging system covers the long-wave band of 8 ∼ 12 µm. The zoom ratio can be changed from 5 × to 15 × and the F-number is 2.0. The total optical length of the proposed system is less than 80 mm. The resolution of the infrared detector is 640 × 512 with a pixel spacing of 17 µm. The dynamic response time testing revealed that the rise and fall times are 132 ms and 92 ms, respectively. The proposed long-wave infrared continuous zooming imaging system can be used in miniaturized devices such as UAV equipment and thermal imaging cameras in the future.