Fig. 1. Tunable liquid lens based on dielectric elastomer. (a) Three-dimensional cross-sectional structure; (b) planar structure and parameters; (c) middle film bulges upward when liquid volume fraction of upper cavity is relatively small; (d) middle film bulges downward when liquid volume fraction of upper cavity is relatively large

Fig. 2. Establishment of liquid lens model. (a) Lens model without liquid filling; (b) deformation of each DE film at specific liquid volume filling

Fig. 3. Profile of upper and middle films varies with driving voltage at specific liquid volume filling (V=3.15 mL, V1∶V=0.21). (a) Changes in profile of upper film; (b) changes in profile of middle film

Fig. 4. Curves of maximum focal length change |Δfm| with volume ratio (V1∶V) at different total volumes

Fig. 5. Flow chart of fabrication process of dielectric elastomer liquid lens. (a) SLA laser printing cavity; (b) pasting optical glass; (c) fixing side film; (d) installing copper foil; (e) fixing upper film; (f) injecting liquid

Fig. 6. Focal length variation curves of liquid lens with different driving voltages (V=3.15 mL, V1∶V=0.21)

Fig. 7. Testing focusing ability of liquid lens on objects at different distances. (a) Optical setup diagram; (b) focusing situation in initial state (U=0 kV); (c) focusing situation in driving state (U=5 kV)

Fig. 8. Resolution test results and simulated MTF curve of lens at different voltages. (a) 0 kV; (b) 3 kV; (c) 5 kV; (d) MTF curve driven by 5 kV

Fig. 9. Focal spot images and corresponding intensity distribution curves of liquid lens under different driving voltages. (a)(d) 0 kV; (b)(e) 3 kV; (c)(f) 5 kV

Fig. 10. Dynamic response test of liquid lens