【作者】 王东；

【导师】 张健；

【作者基本信息】 哈尔滨工业大学 ， 仪器科学与技术， 2013， 博士

【摘要】 激光束敏捷控制技术指的是研究激光束分束数量、扫描位置、光斑形状以及能量变化规律和可控性规律的技术。其特点是可实现对于激光束的数量、光斑形状、指向及聚焦位置的无机械惯量控制，充分发挥激光能量集中、指向性和相干性好的特性，在诸多领域得到应用并正显现出巨大的应用潜力。该技术的关键是设计加载于空间光调制器上的相位分布，使得经过空间光调制器调制的激光束数量、光斑形状、指向以及聚焦位置预期被控。然而，目前基于液晶空间光调制器的激光束敏捷控制技术仍然存在以下两个问题：第一，如何在控制区域内无显著“鬼影光斑”及“噪声光斑”的情况下，动态实现一束入射激光分成多个激光束，并且每个激光束焦点在三维空间可预期独立程控；第二，如何在保持高衍射效率的前提下，按照预期的任意形状强度分布对每个激光束进行较高精度远场整形。针对上述两个问题，本课题展开了如下相关理论及实验研究：首先，针对第一个问题，提出一种基于多个独立迭代平面的相位分布设计方法，并对该方法进行理论仿真和初步实验验证。该方法把远场分为工作区和噪声区且限制相位平面的频谱带宽，抑制工作区中的“噪声光斑”；采用并行设计多个相位分布拼接形成用于多个光束独立控制的最终相位分布，从而避免由串行设计多个相位分布引入的“鬼影光斑”，同时，多相位分布拼接解决了抑制工作区中的“噪声光斑”时造成的衍射效率降低的问题。其次，针对第二个问题，提出一种适用于远场不同形状、不同口径平顶光束整形的自适应权重优化相位分布设计方法，并对该方法进行理论仿真。该方法以被整形光束的光强分布均方根误差（RMSE）和衍射效率（DE）两个参数作为评价标准进行自适应权重优化，在保证较高衍射效率前提下，大大减小光束强度分布的波动。为进一步提高光束整形能力，能将激光束强度分布整形成任意预期的形状，提出一种对被控光波前振幅、相位进行独立调控的双相分布级联设计方法，并对该方法进行理论仿真。该方法不同于常规相位恢复算法，它将传统的一个相位迭代面改成两个相位迭代面，第一个相位迭代面控制光波前的振幅分布，第二个相位迭代面控制光波前的相位分布，由此克服传统相位恢复算法中，只对振幅优化而不能对相位加以控制的缺点。因为该方法能对被控光场振幅、相位进行独立调控，所以可高精度地在目标平面构建任意期望的强度分布。最后，搭建实验装置，采用上述三种方法设计相位分布图加载于纯相位液晶空间光调制器LCSLM（Liquid Crystal Spatial Llight Modulator），分别进行实验研究，实验结果与理论仿真一致，进一步证明上述方法的可行性和正确性。更多还原

【Abstract】 Laser beam agility control technology researches the variation law andcontrollability law of laser beam’s splitting number, shape distribution, energydistribution. Splitting number, shape distribution, energy distribution， pointorientation and focus position of an incident laser beam can be programmablecontrolled by using the technology without mechanical-inertia, in which thecharacteristic (i.e. Energy concentrated, good directional and good coherence) of alaser is fully utilized. It has been applied in many fields and is showing greatpotential applications.The key of this technology is the design of phase distribution loaded onto aspatial light modulator, which makes the splitting number, shape distribution,energy distribution，Point orientation and focus position of a modulated laser beamcontrolled as expected. However, so far, laser beam agility control technologybased on liquid crystal spatial light modulator still exist the following two problems:First, how to dynamically realized that a incident laser beam is split into multiplelaser beams and focus spot of each of the beams can be independently programmedto move as expected in3D space domain without other significant "ghosting spot"and "noise spot". Second, How to make each of the beams tailored into arbitraryintensity distribution as expected in far-field with high accuracy and highdiffraction efficiency.Intend to solve the above two problems, the dissertation make the relevanttheoretical and experimental researches, as follows:First, in order to solve the first problem, a phase distribution design methodbased on multiple independent iterations plane is proposed. And then, necessarytheoretical simulations and preliminary experimental validations of the proposedmethod are conducted. Far-field is divided into the work area and the noise zone, atthe same time, spectral bandwidth of the phase plane is limited, which arecombined to suppress the "noise spot" in the work area. Phase distribution splicingmethod is adopted to form the phase distributions for multiple beam independentcontrol, thereby, the "ghosting spot" and "noise spot introduced by the phasemultiple distributions’ superposition can be avoided and suppressed.Second, in order to solve the second problem, an adaptive weight optimizationphase distribution design method is proposed for far-field variable shape or variablecaliber flat-top beam shaping. And then, necessary theoretical simulations of theproposed method are conducted. Root mean square error (RMSE) and thediffraction efficiency (DE) of the shaped intensity distribution are used as evaluation criteria during the adaptive weights optimization process of the methodfor beam shaping, which not only greatly reduces fluctuations of the shapeddistribution, but also keeps high diffraction efficiency.Then, in order to further enhance the beam shaping capabilities, which canshape the intensity distribution of incident laser beam into arbitrary desired shapeintensity distribution, a double phase distributions cascade design method, whichcan independently code the amplitude and phase the controlled wave-front, isproposed. And then, necessary theoretical simulations of the proposed method areconducted. This method is different from the conventional phase retrieval algorithm,it has two-phase iterative plane, the first phase iterative plane determines theamplitude distribution of the controlled wave-front, the second phase iterative planedetermines the phase distribution of the controlled wave-front, thus avoids thedrawback of traditional phase retrieval algorithm, in which only amplitude isoptimize as expected but the phase can not be controlled. Because the amplitudeand phase of the controlled wave-front can be independently coded, the method canshape the Gauss intensity distribution of incident laser beam into arbitrary desiredshape intensity distribution with high accuracy on the target plane.Finally, experimental setup is established. Using the above proposed threemethods to design phase distributions, the design phase distributions are loadedonto a phase-only liquid crystal spatial light modulator for the experimentalverification of each above methods. Experimental results consistent with thetheoretical simulation, which further proves the feasibility and correctness of theproposed methods.更多还原