Optical characterization of electro-optics lenses for researching in optics

Today, multiple technological instruments facilitate the work of the researcher. These instruments are provided with some features given by the manufacturer. However, it is important to verify these features to be sure that the instrument works properly and does not have any influence on the results of an experiment. In this study, we consider the electrically focus-tunable lenses (EFTL), whose main feature is the fast and efficient control of its focal length. This feature has allowed its use in several areas of optics like visual optics, and nonlinear optics, where precision is an important requirement. In this context, it is important to guarantee that the programmed focal length on the EFTL matches with the actual focal length driven on the lens. Recently, it was shown that the EFTL presents a hysteresis effect, which, according to the datasheet, should not exist. In this work, we develop a complete optical calibration of some EFTLs to evaluate the performance of the lenses. Three EFTLs were studied. Two of them had an optical power variation from +8.3 to +20 Diopter (D), while it was from -10 to +10 D for the other one. It was confirmed the existence of hysteresis for all these EFTLs. Additionally, we present an experiment that intends to answer the question about whether all the lenses of the same reference will have the same hysteresis curves. Finally, we study the behavior of several aberration terms as a function of the induced current, to explore the existence of hysteresis in other aberrations terms different from the defocus.