Research On A Novel Tunable Microlens

The tunable microlens is a novel optical component with many advantages, such astunable optical performance, small size, light weight, no mechanical moving, goodstability, which has wide potential application in many fields ranging from imaging tomicrofluidic sensing and adaptive optics. However, there are still some shortcomings inthe published reports about various tunable microlenses, and these are still in their earlystage of research and application. As a result, many opportunities for exploring variousnovel devices with high performance exist across this field.In this paper, a detailed review and analysis about the various tunable microlenseshas been carried out, including tunable microlens based on adjusting liquid volume,electrowetting-driven tunable microlens, thermal actuated tunable microlens and theliquid crystal tunable microlens based on electro-optical effect. Their advantages anddisadvantages about the tunable microlens have been discussed. In this thesis, theproposal for the thermal actuated tunable microlens and the liquid crystal tunablemicrolens has been presented.For the thermal actuated tunable polymer microlens, there is only experimentalresults without theoretical analysis and numerical simulation in the reports, manypeople only consider the thermal expansion effects on the performance of microlens, butthe impact on its focusing performance resulting from the thermo-optic effect has beenneglected. In this thesis, the physical model for controllable polymer microlens causedby thermal effect is established. The finite element method has been used to accuratelysimulate and analyze the optical properties of the microlens. Through simulation andanalysis, the thermal effect on the performance of the microlens focusing has beeninvestigated in detail.For the tunable liquid crystal microlens based on electro-optical effect, the tunablemicrolens with single and dual focus has been designed by using the blue phase liquidcrystal material. The finite element method has been adopted to simulate theperformance of these microlenses, including the distribution of electric field, therefractive index and the optical field. Then, the simulation results have been discussed, which can provide a theoretical guideline for the experimental fabrication.Finally, design and fabrication for tunable microlens array have been performed byusing the polymer dispersed liquid crystal. The properties of mocrolens have been tested,including the electro-optical effect of liquid crystal, the optical transmission, imagingquality and focusing performance. The results show that the focal length of microlenscan be tuned by controlling the applied voltage, and it exihibits good opticalperformance.