Research On Driving Technology Of Liquid Crystal Optical Phased Array For Beam Steering

As a new kind of device used for beam steering, liquid crystal optical phased array (LCOPA) can use all-electric and non-inertial scanning technology, with advantages of electrical addressing, high control precision, low power consumption, small size, light weight and high efficient payload, and illustrates a good prospect of application in such fields as national defense, information, aeronautics and astronautics. LCOPA has its unique theory and methodology because of its special optical material, and it's necessary to do research and development on its driving technology.Firstly, this paper introduces theoretical basis and operation principle of LCOPA, and determines to drive the LCOPA by applying stair-like periodic voltages to its transparent electrodes, so LCOPA can be made to a liquid crystal grating and modulate the phase of incidence light to control the output beam direction in high precision. On this basis, overall driving scheme of LCOPA is designed and detailed parameters of driving voltages are determined.Secondly, the driving circuit board is designed based on FPGA chip EP2C25F672C8N of CycloneII series and USB chip CY7C68013 of EZ-USB FX2. FPGA internal logic program, USB transmission program and PC application software are designed using VHDL and C languages. Based on this, the driving circuit board can receive controlling data through the USB interface, and generate 256 adjustable voltages to drive the LCOPA designed by our laboratory according to received controlling data.Finally, test device is established based on the driving circuit board designed in this paper and LCOPA equipment. In the experiment, accuracy of the 25 output voltages is tested quantitatively, and the operating characteristics of LCOPA are analyzed. The experimental results show that the driving scheme is right and the driving circuit board designed in this paper can work pretty well.