Design And Fabrication Of Liquid Crystal Micro-optics Structures Based On Patterned Electrodes

Liquid crystal (LC) is a kind of special material composed of molecules with orderedorientation. It has both birefringence characteristics and the electrically respondingproperty of LC molecular reorientation driven and controlled by external electrical fieldapplied. Currently, LC materials have been employed widely in many kinds ofopto-electronic devices such as LC lenses. The obvious advantages of the opto-electronicdevices based on liquid crystal material are the low control signal voltage, very low powerconsumption, small volume, and the electrically tunable optical property. In this paper, wehave done much basic research on using the LC micro-optics structures with complexpatterned electrodes to manufacture the diffractive or refractive devices. Athree-dimensional model of the LC micro-optics structures with complex patternedelectrodes is set up. We design and fabricate a number of LC micro-optics functionalstructures.In this paper, we set up a three-dimensional model for the functioned LC micro-opticsstructures, and use the over-relaxation method to model the dynamic response behavior ofLC directors driven by applied signal voltage. This method is based on the Frank-Oseencontinuum elastic theory. The software is written in the Matlab. The distribution of LCdirectors in LC layers, the distribution of electric potential in LC layers, and thedistribution of phase retardation are able to be calculated. This method can deal withliquid crystal structures with arbitrary patterned electrodes. Different numerical resultsobtained according the method are as follows:(1) the nematic LC structures with complexpatterned electrodes applied by a constant voltage signal, and (2) the nematic LCstructures with different thickness of LC layer, and (3) the nematic LC structures withdifferent signal voltage. A number of micro-optics structures are designed according tothose results.The fabrication of the LC micro-optics structures is carried out according to thephotolithography and wet etching technology. Firstly, we use the AutoCAD to design thephotomask. Secondly, the reasonable size of the ITO (Indium-Tin Oxide) glass is designedbased on the photomask. And then the patterned ITO electrodes are fabricated through the steps including photolithography, developing and wet etching process. The technologicalprocesses of curing and rubbing wafer coated by polyimideen is performed, and thedevice fabrication is finished after infusing the LC and sealing the device. An opticalmeasuring system is constructed for testing the LC devices fabricated. We test the imagingproperties using different signal voltage and setting different distance between the devicesand the CCD camera. Besides, the interference behaviors of monochrome incident laserincident upon the LC device are also acquired. The experimental results demonstrate thecorrectness and validity of the model simulated.