精密位相主动控制技术研究

【作者】 王德恩；

【导师】 李小群；

【作者基本信息】 中国工程物理研究院 ， 光学工程， 2011， 硕士

【摘要】 高功率固体激光装置中有诸多因素导致波前畸变,影响光束质量；为实现高效的束靶耦合,必须精密控制波前以实现特定焦斑分布。本文通过对已有位相控制技术的充分调研,提出了精密位相主动控制的方法,并围绕这一方法展开了系统研究,主要研究内容如下：一、从波前频谱的角度出发,研究了中高频位相对焦斑能量集中度的影响；给出了变形镜控制能力的频谱评价方法,对比分析了不同驱动器数目下变形镜对装置性能的改善能力；明确了高空间分辨率变形镜的优势,如可控波前频段的扩展、峰值功率的有效提升等；研究了位相主动控制与空间滤波技术的耦合问题。二、针对易于实现高空间分辨率的压电薄膜变形镜开展了优化分析工作。建立了压电薄膜变形镜的数学模型,对其使用口径、交联值等参数做了优化分析,并明确了较大交联值变形镜用于像差校正的优势；建立压电薄膜变形镜的有限元模型,对各层厚度、材料参数、电极形状做了优化分析；通过有限元模型对变形镜的夹持方式做了研究,认为夹持带来的接触应力是造成变形镜不稳定工作的主要原因,提出了改进方式,并给予了理论验证；对压电薄膜变形镜样件进行了闭环校正实验,获得了较好的闭环校正效果；三、就采用高空间分辨率位相控制器件进行焦斑整形的可行性进行了模拟研究。首先,以传统高斯响函形式的变形镜作为模型,对AO系统用于焦斑整形的可行性进行了理论论证,并对交联值、波前畸变等的影响做了优化分析；其次,模拟验证了压电薄膜变形镜用于焦斑整形的可行性：第三,提出了多变形镜实现高空间分辨率的设想,对其可行性进行了理论论证,给出了多变形镜AO系统的控制算法,建立了双变形镜AO系统的模型；最后,给出了采用双变形镜实现焦斑整形的实验设计方案,并对结果进行了预估。四、对其他相关技术途径进行了思考与研究。首先,从ICF物理实验对激光束匀滑的要求出发,分析了离焦打靶对焦斑均匀性的控制能力；其次,分析对比了多种焦斑主动控制算法,指出了这类算法在现有装置上的潜在应用,并就SPGD算法、SA算法进行了详细的研究、对比,对其主要的控制参数做了优化分析,提出了一种通用的改进方法。更多还原

【Abstract】 There are a lot of factors leading to wavefront distortion, and influencing beam quality. In order to achieve high coupling efficiency between laser beam and target, the phase must be precisely controlled to achieve the special focal irradiance profile. This article is based on the idea of full frequency wavefront control, and proposes the concept of active precise phase control. The main contents are as follows:Firstly, basing on the phase spectrum method, we studied the influence of precise phase to the far-filed energy concentration. Then, we give the spectrum evaluation method of deformable mirror. The control results of DMs with different actuators are compared, and there are some advantages of high order DM:frequency expansion of control, and increasing of peak power. The coupling relation between DM and pin-hole is also studied.Secondly, the optimum study of piezoelectric film deformable mirror (PFDM) is done. We build a mathematical model of this DM, and the coupling coefficient and beam aperture are discussed based this model. Then, the finite element model is build, and the main material parameters are studied and optimized. The griping method is also studied based finite element model, and some improving methods are proposed and demonstrated.Thirdly, the method of focal irradiance profile control with high order DM is proposed. The influencing of coupling coefficient and wavefront distortion is discussed. Then a method to achieve high spatial frequency with dual-deformable mirror is proposed. The main questions of its application are discussed.Finally, some other technical approaches are studied. Firstly, from the ICF laser beam smoothing of physical requirements, analyzes the focal spot uniformity of defocus shooting; secondly, analyzes and compares a wide range of focal spot active control algorithms. The SPGD algorithm, SA algorithm are studied in detail. The main control parameters are optimized and a common improving method is proposed.更多还原