title: Numerical simulation for meniscus shape and optical performance of a MEMS-based liquid micro-lens.
abstract: It is very difficult to fabricate tunable optical systems having an aperture below 1000 micrometers with the conventional means on macroscopic scale. Krogmann et al. (J. Opt. A 8, S330-S336, 2006) presented a MEMS-based tunable liquid micro-lens system with an aperture of 300 micrometers. The system exhibited a tuning range of back focal length between 2.3mm and infinity by using the electrowetting effect to change the contact angle of the meniscus shape on silicon with a voltage of 0-45 V. However, spherical aberration was found in their lens system. In the present study, a numerical simulation is performed for this same physical configuration by solving the Young-Laplace equation on the interface of the lens liquid and the surrounding liquid. The resulting meniscus shape produces a back focal length that agrees with the experimental observation excellently. To eliminate the spherical aberration, an electric field is applied on the lens. The electric field alters the Young-Laplace equation and thus changes the meniscus shape and the lens quality. The numerical result shows that the spherical aberration of the lens can be essentially eliminated when a proper electric field is applied.
authors.affiliation: Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. sllee@pme.nthu.edu.tw
authors.forename: Shong-Leih
authors.initials: SL
authors.lastname: Lee
authors.forename: Chao-Fu
authors.initials: CF
authors.lastname: Yang