Study On A Droplet Driving And Wavefrontcorrection Lens Based On Electrowetting-on-dielectric

Optofluidic device based on electrowetting-on-dielectric(EWOD)has a wide range of applications in optical systems,which benefit from its advantages of simple structure,high sensitivity and fast response.Such device adjusts the optical properties only by liquid driving,which is different from the traditional.In view of the characteristic,this paper mainly carries out two researches.First,an EWOD driving model of an insulating droplet is established and the reliability of the model is tested through simulations and experiments.Second,a stacked liquid lens based on EWOD for wavefront correction is presented,and its capability of wavefront correction is analyzed by simulating in COMSOL and ZEMAX.The main work is as follows:(1)The research background and status of optofluidics and adaptive optics are summarized,the theoretical development and application of EWOD are introduced,the generation and correction methods of wavefront distortion are expounded.At last,several common wavefront correctors are listed.(2)The driving characteristics of an insulating droplet on a planar electrode is studied,the theoretical model of the droplet driving by EWOD is constructed.The relationship between droplet contact angle and droplet height with working voltage is deduced.Then,using COMSOL software to build the theoretical model and simulating the deformation of the insulating droplet with different voltages.After that,the experimental platform is set up to test the driving ability of the plane electrode for the droplet,and the droplet contact angle and droplet height under different working voltages are recorded.Finally,the theoretical curve and the experimental curve are drawn for comparative analysis.(3)A stacked liquid lens based on EWOD is designed,which is applied to the correction of distorted wavefront.First,the working principle of presented device is described in detail.Then,the simulation model is established in COMSOL software,and its curvature of the liquid interface in each unit under different voltages can be obtained.At last,the wavefront correction system is structured by ZEMAX software,and the wavefront correction ability of the device is analyzed by wavefront phase distribution and point spread function distributionThe results show that:(1)The working threshold voltage is about 30 V in the process of the insulating droplet driving.When the driving AC voltage is lower than 30 V,the silicone oil droplet keeps stable and its contact angle and height remain unchanged.As the voltage increases,the droplet begins to deform.In the voltage range of 30～110V,its contact angle increases from 42.5° to134°,and its height rises from 1.38 mm to 3.46 mm.If the voltage continues to increase,the droplet eventually escapes from the bottom.(2)The stacked liquid lens can simultaneously correct three kinds of distorted wavefronts.After correcting,the peak to valley value of the distorted wavefront is reduced from 19.7856λ to 0.18λ,the root mean square value is also reduced from 5.6638λ to0.0355λ and the strehl ratio is restored from the initial 0 value to 0.962,which is close to the ideal state.