针对空间光调制器系统中, 液晶在正常驱动电压下响应时间长, 拖慢系统响应速度等问题, 对影响液晶响应时间的因素、液晶的弛豫特性以及液晶的过驱动原理进行了分析, 提出了一种基于FPGA(Field－Programmable Gate Array)的液晶过驱动方法。其中, 相位量化、过驱动表查找、PWM(Pulse Width Modulation)产生均由FPGA完成, 该方法不占用CPU(Central Processing Unit)资源, 能够更快速响应CPU指令,在硬件方面进一步节省了液晶响应时间。最后搭建实验光路, 实验结果表明使用该过驱动方法后, 一个调制周期范围内, 在5 V过驱动电压下, 液晶调制相位上升过程响应时间从500 ms缩短至35 ms; 下降过程响应时间从300 ms缩短到36 ms。实现了液晶分子相位的快速偏转, 提高系统的响应速度近一个数量级。

In the system of the spatial light modulator, the response time of the liquid crystal under normal driving voltage is long, and the response speed of the system is slowed down. Considering these, the factors affecting the response time of the liquid crystal, the relaxation characteristics of the liquid crystal and the overdrive principle of the liquid crystal were analyzed. An overdriving method of liquid crystal based on the FPGA was put forward. Among them, phase quantization, overdriving look-up table, and PWM generation were all performed by the FPGA. This method did not occupy CPU resources and can respond to CPU instructions more quickly, and further saving LCD response time in terms of hardware. Finally, the experimental optical path was built. The experimental results show that after using the overdriving method, in a modulation period and under 5 V driving voltage, the response time of the liquid crystal modulation phase rise process is shortened from 500 ms to 35 ms, and the fall response time is shortened from 300 ms to 36 ms. The rapid deflection of the phase of the liquid crystal molecules is achieved, and the response speed of the system is improved by an order of magnitude.