【作者】 李大海；

【导师】 陈祯培；

【作者基本信息】 四川大学 ， 光学， 2002， 博士

【摘要】 波前畸变的检测和控制一直是ICF激光驱动器等其它高功率固体激光器关心的重要课题，它将直接对光束的质量和激光器的造价产生影响。本论文在激光光束波前畸变检测和控制上进行了新的探索，主要就空间相位调制环路径向剪切干涉仪以及它对波前畸变的检测和液晶空间光调制器及其对中频段波前畸变的控制进行了研究，其研究的内容和取得的成果如下： 一、根据标量衍射理论，结合低频波前畸变的高斯随机位相分布模型，研究了不同均方根梯度低频畸变波前对激光光束焦斑聚焦性的影响，并采用描述中频段波前畸变的功率谱密度概念，模拟计算了它对激光焦斑旁瓣的贡献。 二、为了实现激光光束在确定平面上的波前畸变的准确检测，采用中继成像技术建立了一套基于空间相位调制的环路径向剪切干涉波前传感硬件系统，实验证明，它可用于中低频段波前畸变的检测。 三、为实现任意波前的环路径向剪切干涉条纹图的解释，提出了一种新的波前重建算法，并对其收敛性进行了分析，数值计算和实验结果都证明了该算法的正确性。此外，还对台阶波前的环路径向剪切干涉条纹图进行了解释，从中发现了环路径向剪切干涉仪在一定条件下检测陡变波前畸变上的困难和台阶波前在光路调整中的应用。 四、从光学系统衍射效应的角度分析了本文建立的环路径向剪切干涉仪的空间分辨率，并利用波前功率谱密度的概念对该干涉仪的空间频率响应特性进行了标定，分析了限制该干涉仪测量精度的主要因素以及径向剪切比与测量精度的关系，并指出了该干涉仪的测量范围，结果显示该干涉仪基本上可用于准确测量中低频段的波前畸变。 五、利用环路径向剪切干涉仪共光路、双光束干涉的特点，全场准确测量了液晶空间光调制器的位相调制特性，并且利用它的位相调制特性实现了台阶位相板畸变波前的补偿，由此证明了液晶空间光调制器可用于控制波前畸变。 六、通过利用液晶空间光调制器的位相调制特性，成功地模拟产生了任意畸变波前，指出若该器件有更大的位相调制动态范围和均匀性，将有可能成为校验波前传感设备和波前畸变控制系统性能的有力工具。 七、采用已建立的空间相位调制环路径向剪切干涉仪及其波前重建算法，和位相调制持性已知的两块液晶空间光调制器，创建了一套用于模拟产生任意畸变波前并加以检测和反馈控制的自适应光学硬件系统，并通过台阶波前对该系统实现了像素级校准。特别地，还在此基础上验证了LCSLM对中频段任意波前畸变的控制和校正，并且验证了环路径向剪切干涉结合双LCSLM的波前传感与控制系统的自适应波前控制能力。 通过以上研究，说明我们建立的环路径向剪切干涉仪可以用于ICF激光驱动器的中低段波前畸变的检测，并且液晶空间光调制器可用于它的前级中存在的中频段波前畸变的校正。更多还原

【Abstract】 The diagnosis and control of distorted wavefront is a key issue in thefield of high power laser system, Which will directly decide the laser beamquality and the cost of a laser system. In this doctOral dissertation, a newresearch of the diagnosis and control of laser wavefront distortion hasbeen imPlemented. A cyclic radial shearing interferometer was used todiagnose the wavefront distortion of a laser system and an LCSLM(liquidcrysnd spatial ligh modulator) was used to control it. Some results havebeen summarized as follows:l. According tO the theory of scalar quanity diffeaction and the modelof the random Gaussian phase screen of low frequency wavefront, theeffect of the low frequency wavefront with different RMS gradient on thefocal sPot of a laser beam was stUdied. And a numerical simulation whichthe portion of the PSD(power spectral density) contributes to the tail of themain focal spot was studied too. -2. In order to accomPlish the eXtraction measuremellt of distOrtedwavefrOnt on specific plane of a laser beam, a CRSI(cyc1ic radial shearinginterferometer) based on relay imaging technique was built. TheeXPeriInental result on this CRSI shows it can used to test the spatial midand low frequency wavefront distortion.3. A new algorithIn to be used to recontrict the distorted wavefrontfrom itS CRSI ffinge pattem has been presented. It can be used to exactlyexPlain the CRSI funge pattem of an arbitrary wavefront. And theconvergence of this algorithm was analyzed too. The results of numericalcomplltaion and eaperiment show that our algorithIn is correct. Moreovef,the CRS interferogram of a step wavefront was exPlained. It shows that adisadvantag ekistS when a CRSI is used to measure a steP strUcture in awavefrOnt, but it is useful tO adjust a CRSI system with LCSLM.4.According to the didriction effect of an aPertUre, the spatialresolution of our CRSI was analyzed and the transform function of ourCRSI was calibrated by using the PSD method of a step wavefront. Andsome factOrs Which are associated with the accuracy of our CRSI wereanalyzed too. The relationship betWeen radial sheared ratio and theaccuray of ffos CRSI was investigated. Furthermore, the range ofmeasurement of it was pointed out. All the analysis shows that our CRSI1Ilcan be used to measure the spatial mid and low frequency wavefront distortion.5.Based on our CRSI and algorithm, the phase modulation characteristic of an LCSLM was measured. And the correction of a step wavefront produced by a step phase plate is accomplished successfully.6.According to the phase modulation characteristic of an LCSLM, arbitrary complicated wavefronts were modeled. The result shows that LCSLM can be use to test the wavefront sensors and controller if LCSLM has wider dynamic range and perfect optical quality.7.Based on our CRSI and algorithm and double LCSLM, an adaptive optical hardware system which c&n be used to model arbitrary complicated wavefront and the compensation of the wavefront can be accomplished was built. And according to the characteristic of a CRS interferogram of a step wavefront produced by an LCTV, the pixel-level calibration of this system is implemented. The control of the spatial mid frequency wavefront distortion was achieved based on our CRI wavefront sensing and LCTV wavefront correcting system.The results of our research show that CRS interferometer can be used to diagnosing the mid and low frequency wavefront distortion of a laser beam and LCSLM can be used to availably controlled it.更多还原