Fabrication of aspherical liquid lens controlled by electrostatic force

Aspherical micro lens is becoming more and more important due to their excellent optical quality. A novel method for fabricating aspherical liquid lens from UV curable polymer with on-line measurement is proposed. Electrostatic forces are employed to manipulate the shape of liquid polymer lens. Surface profile distortion of the liquid lens results in its focus variability. An experimental system which can fabricate tunable aspherical liquid lens and real-time detect its surface profile and focal spot is developed. The MTF of the liquid lens is calculated via detecting the lens profile image, polynomial fitting and ray tracing. The experiment system can also image the focal spot of the liquid lens and calculate its PSF. These provide a novel method for the control of the pre-cured lens properties and hence the final solid lens optical performance. UV light is employed to cure the liquid lens when its surface profile and focal spot are desirable. Therefore, aspherical lens with better optical imaging and focusing ability can be fabricated. Experiment results show that the surface profiles and focal spots of liquid lens varying with the increase of the electrostatic force. Near-cone shaped surface profile with smaller and more circular focal spot are achieved in strong electrostatic field. Fine aspherical surface profiles and focal spots of the liquid lens demonstrate the feasibility of fabricating aspherical micro-lens by using this method.