Variable-Focus Liquid Lens Using Acoustic Radiation Force

With the development of science and technology,conventional lens is unable to meet people's need.A new type of lens was proposed called Liquid zoom lens,which is totally different from traditional lens and has the features of miniaturization,no mechanical components and variable focal lengths.The key technology of liquid lens is the micro-flow controlling.The current technologies about mainstream micro-flow controlling include hydraulic,electro-wetting and ultrasound.Based on the theory of ultrasonic vibration,a liquid zoom lens model driven by piezoelectric is proposed.The lens is composed by piezoelectric ceramics,optical film and aluminum cladding.The working mode of the piezoelectric ceramics is obtained by ANSYS simulation and macro measurements in this paper.By discussing the optical film vibration at the edge of excitation,the operating frequency and the vibration model of the optical thin film is calculated.In the aspect of the lens controlling,a new method which can control the liquid permeable surface model by varying the frequency of the input power is achieved.At the same time,the variation trends of the liquid lens center displacement,aperture,focal length and radius of curvature with the input power frequency variation is obtained.The research of the intrinsic connection between the impedance of the piezoelectric lens and the frequency of the driving power is studied.The method of volume controlling and voltage controlling is also studied except frequency.The problems of the self-heating of piezoelectric lens during the experiment,and solving the heat compensation coefficient to reduce error by setting the compensation device are studied.The study of power consumption and imaging performance of piezoelectric driven liquid zoom lens showed that its power consumption is very low and good zoom capability.Liquid lens have broad application prospects in the field of cameras,medical endoscopes and so on.But we also found that the liquid lens has geometric aberrations,the aberration compensation device can be installed within the lens.Law and results obtained above show that ultrasonic liquid zoom lens drive optimization and improvement has important theoretical and practical value.