Depth from focus with electrowetting liquid lens

Depth from focus and defocus is an effective technique to extract depth information from a set of images, which is called focal stack. In prior studies, this technology was commonly operated on complex laboratory imaging equipment. In this paper, a new imaging system based on electrowetting liquid lens is proposed. Electrowetting liquid lens is one of the adaptive lens which has adjustable focal length controlled by voltage signal. The focal stack can be easily got by sweeping the applied voltage without mechanical moving part. To eliminate the field of view (FOV) variations during the process of capturing focal stack, which is called focal breathing, we proposed an algorithm based on conventional flow concatenation to align focal stack images. We test the proposed imaging system on both laboratory scene and mobile phones, and the experiments demonstrate this imaging system can capture high quality images and shows excellent performance in extracting depth information without complex mechanical structure.