Variable-focus fluid lens using an electromagnetic actuator

A variable-focus fiuid lens controlled by an electromagnetic actuator and its characteristics are presented in this paper. The repulsive force between an NdFeB magnet and a solenoid through electromagnetic induction causes deffections in the elastomeric membranes integrated in the lens resulting in a focal-length change. The controllability of the focal length of the fabricated lens with an aperture size of 2 mm was approximately from infinity to 15 mm (with input current of 100 mA). The actuator including the solenoid was carefully designed to avoid thermal crosstalk of the lens fiuid and magnet from the electromagnetic induction of the solenoid. The settling time to form a convex shape of the lens membrane was approximately 2.5 ms at an input current of 20 mA.