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chi20191129上海光机所朱健强557645Inertial confinement fusion (ICF) driven by high power laser is one of the most important technologies to realize controllable fusion. The quality of laser beam is very important for the fusion experiment. From the seed light to the output before shooting, the millijoule laser needs to go through a large number of high-precision optical elements. The installation and correction stress, damage stress of optical elements, and the inhomogeneity of crystal refractive index will affect the wave front quality and frequency doubling effect of the beam transmission process, which will cause wave front distortion, affect the beam energy distribution, and have a great impact on the experiment. When it is serious, it will cause damage to the elements and failure of the experiment. Therefore, it is necessary to test and evaluate the stress, damage and the nonuniformity of the refractive index of the optical elements. In general, the beam birefringence is caused by the element stress and the inhomogeneity of the refractive index of the crystal material. In this paper, based on PIE, such as high precision of phase recovery, simple measuring light path and strong anti-interference ability, it is combined with polarization measurement to solve the problems of stress birefringence measurement and quantitative birefringence detection of plane polarimeter. It provides a new measurement method for the measurement of the nonuniformity of crystal refractive index, which is helpful for the realization of single exposure and fast measurement of mixed state polarization. The main contents include the following aspects: 1. A method of stress measurement in the whole field based on phase-shifting ptychography is proposed. The birefringence sample is placed in the light path formed by the probe light. The complex amplitude of the probe light in different polarization states is reconstructed by using pie. The isoclinic and isochromatic lines are extracted from the amplitude information, and the isochromatic lines are extracted from the phase information, thus the quantitative information of the whole field stress is obtained. The reason of phase jump in the detection light is analyzed in theory, and the problems of value range adjustment, half integer line removal and phase jump in the measurement of strong stress are solved in the experiment. The separation of the two principal stress components in the strong stress field is realized. The feasibility of the method is verified by the experiment of Mohr disk, and the error of the main stress parameters is given. This method is especially suitable for the stress measurement of large-diameter samples, and provides a practical measurement method for the stress research of large-diameter optical elements. 2. Aiming at the problem that the phase-shift pie has many measurements and the force vector is difficult to measure, a two beam stress vector measurement method based on pie is proposed. By recording the diffraction spots of two vertical polarization states in the far field with a spectroprism, the whole force vector information can be recorded in one measurement. Based on the complex amplitude, a new method to separate the stress information is proposed: the isopleth and isoclinic are extracted from the phase, and the isopleth is directly extracted from the complex amplitude division of two illumination lights, which avoids the complex interval judgment and improves the signal-to-noise ratio of the stress vector result. The feasibility of this method is verified by using the classical extrusion disk, and the error of the main stress parameters and the distribution of the force vector are given. This method can be further combined with the single measurement method to achieve the rapid measurement of the corresponding stress. 3. Aiming at the problem that the plane polarimeter is difficult to realize the quantitative measurement of birefringence, a plane polarized birefringence measurement method based on pie is proposed. The complex amplitude of dark field detection light formed in two different polarization states is reconstructed by phase recovery, and the phase delay and azimuth angle are extracted simply and accurately from the ratio of phase and complex amplitude of detection light respectively, so as to realize the two-dimensional quantitative measurement of birefringence samples. The experimental results show that the maximum error of phase delay is not more than 23.9 nm, and the azimuth error is 0.49 °. On this basis, aiming at the measurement of e-ray refractive index inhomogeneity of KDP crystal, a method of orthogonal polarization measurement based on pie is proposed. According to the phase of O and E, the refractive index of KDP crystal e is calculated, which is consistent with the measurement results of polarizing orthogonal interferometer (OPI). Compared with OPI, the sampling resolution of measurement is improved. Aiming at the problem of multiple measurements by orthogonal polarization method, a dark field method is proposed to detect the inhomogeneity of refractive index of KDP crystal. The results are in good agreement with those by orthogonal polarization method. The structure of the device is simple, which solves the problem that the traditional plane polarimeter can't measure the quantitative birefringence, reduces the number of pie scans, shortens the data acquisition time and processing flow, and provides a practical method for birefringence detection of large aperture optical devices.2020atalunwen221816293699phase retrieval;ptychographical iterative engine;polarization measurement;stress measurement; refractive index inhomogeneityThe Study of Optics Elements' Polarization Measurement Based on Ptychographical Iterative Engine基于PIE的光学元件偏振检测的研究高功率激光驱动的惯性约束核聚变(ICF)是目前实现可控核聚变的重要技术之一。驱动器输出的激光光束质量对聚变实验的实现至关重要。从种子光源到打靶前的输出中,毫焦级激光需要经过大量高精度的光学元件。光学元件的装校应力、损伤应力,晶体折射率的不均匀性都会影响光束传输过程的波前质量以及倍频效果,从而引起波前畸变,影响光束能量分布,对实验造成极大的影响,严重之时,导致元件损坏,实验失败。因此需要对光学元件的应力、损伤情况以及晶体折射率的不均匀性进行完整和高精度的检测评估。通常情况下,元件应力以及晶体材料折射率的不均匀性会引起光束双折射,通过偏振检测来定性和定量地测量。 本文基于PIE相位恢复精度高、测量光路简单、抗干扰能力强等优势,将其与偏振测量相结合,主要解决了应力双折射测量以及平面偏光仪进行定量双折射检测的问题,对晶体折射率非均匀性的检测提供了一种新的测量手段,为实现单次曝光、混合态偏振快速测量提供了新的思路,主要内容包括以下几个方面: 1. 提出了一种基于相移PIE的全场应力测量方法。将双折射样品置于探测光形成光路中,利用PIE重建了不同偏振状态下的探测光复振幅,并从振幅信息中提取出等倾线和等差线,相位信息中提取出等和线,从而获得了定量的全场应力信息。理论上分析了探测光中相位跃变存在的原因,实验上解决了强应力测量中面临的取值范围调整、半整数线移除、相位跃变等难题,实现了强应力场下的两个主应力分量的分离;采用摩尔圆盘实验验证了所提方法的可行性,并给出了主要应力参量的误差情况。该方法尤其适应于大口径样品的应力测量,为大口径光学元件的应力研究提供了一种实用测量手段。 2. 针对相移PIE测量次数多,力矢量难以测量的问题,提出了基于PIE的双光束应力矢量测量方法。用分光棱镜在远场记录两个垂直偏振态的衍射光斑,实现了在一次测量中对全部力矢量信息的记录。基于复振幅的角度,提出了新的分离应力信息的方法:从相位中提取了等和线和等倾线,利用两个照明光的复振幅相除中直接提取出了等差线,避免了避免了复杂的区间判断,提高了应力矢量结果的信噪比。利用经典挤压圆盘验证了该方法的可行性,并给出了主要应力参量的误差情况以及力矢量的分布。该方法可以进一步与单次测量方法结合以实现对应力的快速测量。 3. 针对平面偏光仪难以实现双折射定量测量的问题,提出了一种基于PIE的平面偏振双折射测量方法。通过相位恢复将样品在两种不同偏振状态下形成的暗场探测光复振幅重建出来,并分别从探测光相位及复振幅之比中将相位延迟量及方位角简单准确提取出来,实现了双折射样品的二维定量测量。采用双折射分辨率靶对所提方法进行实验验证,所得结果与分辨率靶实际分布完全相符,相位延迟量最大误差不超过23.9nm,方位角误差为0.49°。在此基础上,针对KDP晶体e光折射率非均匀性的测量问题,提出了基于PIE的正交偏振测量法。利用PIE进行相位恢复,根据得到的o光和e光的相位,求出了KDP晶体e光折射率,与偏振正交干涉仪(OPI)的测量结果相符;与OPI相比,基于PIE的正交偏振测量法,提升了测量的采样分辨率。针对正交偏振测量法测量多的问题,提出暗场检测KDP晶体折射率非均匀性的方法,所得结果与正交偏振测量法相符。该检测装置结构简单,解决了传统平面偏光仪无法进行定量双折射测量的难题,同时减少了PIE扫描的次数,缩短了数据采集时间及处理流程,为大口径光学器件的双折射检测提供了一种实用方法。相位恢复;衍射重叠术;偏振检测;应力检测;折射率非均匀性中国科学院上海光学精密机械研究所程北光学工程博士
中文题目: 基于PIE的光学元件偏振检测的研究
外文题目: The Study of Optics Elements' Polarization Measurement Based on Ptychographical Iterative Engine
作者: 程北
导师姓名: 朱健强
学位授予机构: 中国科学院上海光学精密机械研究所
答辩时间: 20191129
中文关键词:
相位恢复;衍射重叠术;偏振检测;应力检测;折射率非均匀性
英文关键词:
phase retrieval;ptychographical iterative engine;polarization measurement;stress measurement; refractive index inhomogeneity
中文摘要:
英文摘要:
文献类型:学位论文
学位级别: 博士
正文语种: chi
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