Abstract
Liquid microlenses have emerged and played an important role in micro-optical systems in recent years. Compared to the conventional glass lenses, the liquid lenses have the deformable characteristic of liquids, which endows them unlimited potential of development. However, lack of measuring method on liquid lenses makes design and improvement difficult. In the present study, we demonstrate a measuring method using the Fizeau interferometer to characterize the dielectric liquid lenses consisting of two sample liquids. Furthermore, this study focuses on the behavior of liquid-liquid interface which may influence the quality and characteristic of dielectric liquid lenses. Two modes were used in the measuring experiments: reflective mode and transmission mode. The reflective mode is used to measure the profile of liquid-liquid interface including the symmetry, flatness, and quasi-static oscillation of the liquid drop, while the transmission mode can characterize the lens off-sphere aberrations. Some resonant frequencies were found in the presence of interferograms which are categorized into several modes at frequency below 500 Hz. When the drop oscillates, the number of nodal points and amplitude of ripple on the liquid-liquid interface at different frequencies were discussed. The measured phenomena in the study might be incomplete but it could provide some insights for further development of dielectric liquid lens. In addition, this work shared an idea of measuring liquid-liquid interface, which might be served as a reference in advancing opto-fluid systems.