###### Abstract  
As the core element of adaptive optical systems, tuneable lenses are essential in adaptive optics. Dielectric elastomer-driven tuneable lenses offer significant advantages in tuning range, response speed, and lightweight design compared to traditional mechanical zoom lenses. This paper systematically reviews the working mechanisms and research advancements of these lenses. Firstly, based on the two driving modes of deformation zoom and displacement zoom, the tuning principle of dielectric elastomer-driven tuneable lenses is analysed in depth. Secondly, the design methodology and current status of the research are systematically elaborated for four typical structures: monolithic, composite, array, and metalenses. Finally, the potential applications of this technology are discussed in the fields of auto-zoom imaging, microscopic imaging, augmented reality display, and infrared imaging, along with an analysis of the key technological challenges faced by this technology, such as material properties, modelling and control, preparation processes, and optical performance. This paper aims to provide a systematic reference for researchers in this field and to help promote the engineering application of dielectric elastomer tuneable lens technology.  
tuneable lenses; dielectric elastomers; liquids; soft solids; review 22 May 202516 June 20 to change the optical medium's arrangement to form a gradient refractive index distribution, commonly found in liquid crystal lenses [8; 9]. Through variable curvature zoom lenses, the interior of the lens is mainly liquid or solid. The shape of the lens is directly or indirectly changed by the electric wetting effect [10], memory alloy actuator [11; 12], piezoelectric actuator [13; 14; 15], or dielectric elastomer actuator (DEA), which directly or indirectly changes the shape of the lens to achieve zoom.  
Dielectric elastomers (DEs) are flexible polymer materials (e.g., silicone rubber, acrylic elastomers) driven by the electric field-induced Maxwell stress effect. When an electric field is applied, the electrostatic pressure generated by the electrodeposition compresses the thickness and expands the area of the film, resulting in a large strain output. Dielectric elastomer-driven tuneable lenses (DETLs) have the advantages of fast response, light weight, vibration resistance, low power consumption, and high energy density and show great potential in optical systems [16; 17].  
Although tuneable lenses have been previously introduced in the review literature [7; 18], this review mainly focuses on DETLs and systematically comprehends the recent advances, applications, and challenges in this field. This review not only analyses the driving principle and driving mechanism of DETL in detail but also focuses on the advantages and limitations of DETL with different structures and synthesises the research trends in materials, structures and optics. The full text is structured as follows: Chapter 2 classifies and analyses the zoom working principle of DETLs; Chapter 3 introduces the structural types of DETLs; Chapter 4 compares the performance of several classical DETLs; and Chapter 5 reviews innovative applications in areas such as auto-zoom imaging systems, micro-imaging, and augmented reality displays, while summarising the technical challenges facing DETL concerning materials, modelling and control, processes, and optical properties. Through this review, we aim to provide theoretical support and technical reference for the innovative research and development of DETL.