基于VA液晶的激光扫描器件及响应速度调制  

Laser scanning device and response speed modulation based on VA liquid crystal

作　　者：刘红均 邱成峰 刘召军 LIU Hong-jun;QIU Cheng-feng;LIU Zhao-jun(Department of Electrical and Electronic Engineering,Southern University of Science and Technology,Shenzhen 518055,China)

机构地区：[1]南方科技大学电子与电气工程系,广东深圳518055

出　　处：《液晶与显示》2023年第9期1178-1184,共7页Chinese Journal of Liquid Crystals and Displays

基　　金：深圳市科技计划项目(No.JCYJ20190812141803608)。

摘　　要：本文在带有锯齿型ITO电极的基底上制备垂直排列(Vertical Aligned,VA)的液晶器件,将激光耦合在液晶层中,调制ITO电极的电压,出射激光实现了偏转并且偏转角随电压的增加而增大直至饱和。在两个顶角为20°的锯齿电极下,激光光斑偏转了约4°。用于液晶驱动的电压为交流电信号,通过调整最低驱动电压即偏置电压,使得液晶分子从一定的起始角度开始转动,同时也是在其可快速旋转的区间内进行驱动,从而提高液晶分子的响应速度。在此策略的指导下,通过在液晶分子转动时对其偏振态的表征,来确定液晶分子的状态与驱动速度。在平衡好折射率与驱动速度的前提下,对比了不同偏置电压下液晶层分子整体的响应速度。在有一定偏置电压的情况下,液晶层驱动的响应时间从55 ms下降至2.5 ms,而断电后的弛豫时间从18 ms下降至8.5 ms。这为后续采用这种液晶层方案的激光偏转器件获得更快速的扫描频率和扫描角度提供了新的方案。In this work,the vertically aligned(VA)liquid crystal devices are prepared on a substrate with serrated ITO electrodes,the laser is coupled into the liquid crystal layer,and the voltage of the ITO electrodes is modulated.The output laser achieves deflection and the deflection angle increases with the increase of voltage until saturation.Under two serrated electrodes with a top angle of 20°,the laser spot deflects by about 4°.At the same time,since the voltage used for driving liquid crystals is an AC signal,by adjusting the minimum driving voltage,which is the bias voltage,the liquid crystal molecules start to rotate from a certain starting angle and are also driven within their fast rotation range,thereby improving the response speed of the liquid crystal molecules.Under the guidance of this strategy,the state and driving speed of liquid crystal molecules are determined by characterizing their polarization state during their rotation.Under the premise of balancing the refractive index and driving speed,the overall response speed of liquid crystal layer molecules under different bias voltages is compared.Under a certain bias voltage,the response time driven by the liquid crystal layer decreases from 55 ms to 2.5 ms,while the relaxation time after power outage decreases from 18 ms to 8.5 ms.This provides a new solution for laser deflection devices using this liquid crystal layer scheme to achieve faster scanning frequency and scanning angle in the future.

关 键 词：激光偏转 液晶器件 液晶分子驱动 

分 类 号：TN27[电子电信—物理电子学] TN383.1