基于纯相位空间光调试器的超高性能光束控制系统的性能研究

High precision laser beam steering is a very important topic, with applications of ultra-high precision manufacturing, free-space telecommunications system, fiber optic connectors, laser display and imaging process. Based on the diffraction theory and electrically controlled birefringence of the liquid crystal material electro-optic effect, the phase-only nematic liquid crystal on silicon device (LCOS) is to be used as an optical engine in this project to demonstrate the optical performance (steering resolution and diffraction efficiency) of the beam steering system by loading high precision gratings. First, the relationship between the resolution of beam steering and the distribution of liquid crystal in the phase-only nematic LCOS device is investigated; second, in order to improve the diffraction efficiency and the resolution of the beam steering system to the theoretical, a spatial phase grating compensation is proposed to optically optimize the space distribution of liquid crystal layer in the LCOS device; third, based on the characterization of nematic liquid crystal material and driving scheme of the phase-only nematic LCOS device, the development of dynamic response for the beam steering system is presented. In this project, the characterization for the performance of beam steering system is quantitatively analyzed through the angle of engineering the device itself and liquid crystal electro-optic effect, it is very significant result by using phase-only nematic LCOS devices for the fundamental industry, especially in the field of high quality laser communication, the adjustment and measurement for high precision instruments.

超高精度光束控制系统在高精度机械加工、自由空间光通信系统、光纤连接器、激光显示和图像处理等方面具有非常重要的研究意义。本项目创新性地提出利用光衍射理论和电信号控制双折率的向列型液晶材料的光电特性，以纯相控式硅基液晶器件为光学引擎，通过加载高精度位相光栅改变光线传播方向的方式实现超高精度的光束控制。具体研究内容包括：第一、研究纯相位式硅基液晶器件中液晶层的空间分布与光束控制系统的精度和光衍射效率关系；第二、研究光学空间相位补偿方法，对器件液晶层空间分布不均一性进行优化，以求提高光束控制系统的衍射效率和光束控制精度；第三、研究液晶材料的光电属性与硅基液晶背板的驱动方式，提出加速光束控制系统响应速度的方法。本项目从硅基液晶器件和液晶材料光电特性的角度出发对超高精度光束控制系统的性能进行定量分析，研究结果对以"纯相控式硅基液晶器件"为核心的激光通信、精密仪器测量和矫正等基础工业具有重要的科学意义。

本项目基于硅基液晶器件技术，通过集成激光器、准直扩束镜、偏振器、分光镜、反射镜、信号衰减器、光电二极管（或者相机）、透镜、数据采集系统、孔径可调节小孔、光纤耦合等，实现了1550nm波长的超高精度光束扫描系统：从向列型液晶材料光电特性的角度出发，阐述与论证了该扫描系统的光学衍射效率、光束控制精度、响应时间等主要性能参数的测试方法。研究结果1：从液晶材料的光电属性、粘稠性、双折射率以及硅基器件背板驱动方式的新角度揭示光束控制系统的动态响应速度的决定因素，科学分析和解决提高系统响应速度；研究结果2：通过分析与测量“液晶层空间分布的均匀性”，测量光控系统的扫描精度和光衍射效率；研究结果3：实现非机械超高精度的光束扫描系统——系统将“光衍射效率”值达到70%（近似于理论值）、“2π连续相位调试能力”、光控精度达到1.35×10-5rad、响应时间降低到几十毫秒以内、同时系统具有较低的驱动电压。本项目的研究成果，为开拓以硅基液晶空间光调试器技术为基础的“非机械式超高精度光学扫描系统”提供技术实施的参考，为波分复用的光信号传输以及安全领域的高精度光束识别等应用方向提供有力的基础理论和实践的支持。