激光雷达液晶相控阵波控数据优化算法研究

【作者】 尹晓虎；

【导师】 杨晓波；

【作者基本信息】 电子科技大学 ， 信号与信息处理， 2011， 硕士

【摘要】 激光雷达在现代高科技战争中具有不可替代的作用,光学相控阵激光雷达的出现是激光雷达体制的重大突破,使得激光雷达具有产生无惯性随机指向波束和可编程输出多路独立控制波束的能力,而且其波束指向精度和分辨率都优于传统机械扫描激光雷达。液晶相控阵作为光学相控阵技术的一种,具有驱动电压低、制作工艺成熟、成本低、体积小、能量消耗少等优点,成为近年来国内外光学相控阵研究领域中的热点。而如何有效地生成波控数据,产生高质量偏转光束亦成为液晶相控阵技术研究领域的重要方向。本论文依托具体的科研项目,针对液晶相控阵系统建模和波控数据优化算法研究开展如下工作。1、分析了液晶材料的光电特性、液晶移相器阵列结构以及液晶相控阵的波控原理,建立了液晶移相器的数学模型,为液晶相控阵波控数据优化算法的研究奠定了基础。2、针对目前项目中基于剪切干涉原理的相位测量系统难以测量高空间频率波阵面的问题,提出了基于能量约束的波控数据优化算法。该方法无需波前探测,能有效地实现对波控数据的闭环优化,提高激光束的偏转效率。3、实现了波控数据闭环优化实验平台的搭建,对基于能量约束的两种波控数据优化算法进行了实验验证,提高了液晶相控阵的衍射效率,抑制了液晶相控阵的旁瓣。并将优化后的电压代码与实测的液晶特性曲线进行比对,比对结果验证了算法的有效性。4、针对基于能量约束的波控数据优化算法迭代收敛慢,无法修正液晶移相器非均匀性对液晶阵列出射相位面影响的问题,采用了基于相位恢复的波控数据优化算法,该方法从光强分布中提取液晶移相器出射波阵面的信息,无需剪切干涉仪,光路简单,能克服液晶阵列的非均匀性,快速高效地实现对波控数据的优化。更多还原

【Abstract】 Laser radar (LIDAR) is playing an irreplaceable role in the modern high-tech warfare. As a major breakthrough in LIDAR system, the emergence of optical phased array (OPA) LIDAR enables LIDAR with programmable random-access pointing, multiple simultaneous beams. Besides, OPA is superior to conventional mechanical scanning laser radar in the beam pointing accuracy and resolution. As one of the beamsteering technologies for optical phased array, Liquid crystal phased array (LCPA) has many advantages, such as low driving voltage, mature production technology, low cost, small size, low power consumption, making LCPA the research hotspot in the field of OPA in recent years. How to generate the wave-control data correctly so as to produce high-quality deflected beam has become an important direction of research of LCPA.This paper is developed basing on a specific research project. The work of the dissertation on system modeling and optimization of wave-control data of the LCPA is as follows:1. The electrooptical properties of liquid crystal material, the structure of LCPA and the beam steering model of LCPA are analyzed. Mathematical model of the LCPA is set up, which is the basis of the research for the optimization algorithm of wave-control data.2. Aiming at the problem that the phase measurement system based shearing interferometry can not measure the wave front with high spatial frequency, an optimization algorithm for the wave-control data based on the energy constrained is proposed. This method does not need wave front sensing and can easily achieve the closed-loop optimization of the wave-control data to improve the efficiency of laser diffraction significantly.3. The closed-loop experimental platform is built to validate the effectiveness of the optimization algorithm for the wave-control data based on the energy constrained. The results have shown that this method can improve the efficiency of laser diffraction and suppress the sidelobe significantly. Then, the optimized voltage code and measured the characteristic curve of liquid crystal alignment are compared. The algorithm proves to be effective.4. Aiming at the problem that the optimization algorithm for the wave-control data based on the energy constrained needs a long time for convergence and can not modify the nonideal phase plane caused by the Non-uniform of LCPA, an optimization algorithm for the wave-control data based on phase retrieval is proposed. This method extracts the information of wave front from the light intensity distribution, which does not need the shearing interferometer and the optical structure of the system is simple. The algorithm can overcome the Non-uniform of LCPA and achieve the closed-loop optimization of the wave-control data rapidly and efficiently.更多还原