Displaceable and focus-tunable electrowetting optofluidic lens.

A conventional optofluidic lens usually has one liquid-liquid (L-L) interface, which can be deformed to achieve variable focal length. Such a single lens cannot be used alone to realize optical zooming because its back focal distance keeps changing. Here, we report a novel displaceable and focus-tunable electrowetting optofluidic lens. In comparison with the conventional optofluidic lens, our new lens has a different working principle and it can function as an optical zoom lens. The L-L interface can be displaced by a voltage. The object distance and image distance can be adjusted by shifting the L-L interface position to achieve the desired magnification, yet the lens can refocus the image by reshaping the L-L interface with another voltage. Under such condition, only one lens is adequate to realize the zooming functionality. To prove the concept, we fabricate an optofluidic lens whose largest displaceable distance is ~8.3 mm and the zooming ratio is ~1.31 ×. The proposed optofluidic lens greatly simplifies the zoom lens system. Widespread application of such an adaptive zoom lens is foreseeable.