衍射透镜焦斑的非迭代相干检测研究
文献类型：学位论文
| 作者 | 王松贤 |
| 文献子类 | 硕士 |
| 导师 | 张艳丽 |
| 关键词 | 衍射透镜 diffractive lenses 数字全息 digital holography, 微光器件 micro-optical device, 光子筛 photon sieve, 自动对焦 autofocus |
| 其他题名 | Research on Non - iterative coherent measurement for focal spot of diffractive lenses |
| 英文摘要 | 衍射透镜是实现光束聚焦和成像的衍射光学元件，其在空间遥感、光学光刻、显微成像和生命科学等领域拥有广泛的应用前景，在系统性能改善及轻量化方面发挥了重要的作用。振幅型衍射透镜由于不受波长限制，在X射线和极紫外光波段具有很大的潜在应用价值。近年来一种新型的振幅型衍射透镜–光子筛备受关注，掀起了新的研究浪潮。通过多自由度的设计光子筛可以得到复杂、多样化的聚焦场形态和优越的性能，因此，在其实际应用之前对光子筛等衍射透镜的聚焦性能检测和分析具有重要意义。已有研究中主要应用直接成像法进行定性描述，操作要求较高。本论文针对光子筛类衍射透镜的焦斑检测，以实现快速和准确的定量检测为目标，探索研究了两种焦斑检测方法–数字全息测量技术和基于阵列抽样的相干检测技术，这两种方法都不需迭代过程。 数字全息是一种特殊的相干测量与成像技术，具有简单、快速、准确度较高、数字化处理等特点，被广泛应用于多种物理参数的测量，其独特特点在于可以直接得到被测物体的复振幅分布。另外，基于阵列抽样的检测技术也是一种能快速实现测量的非迭代相干衍射成像技术，是近年来提出的新方法，本论文尝试应用此方法进行聚焦焦斑测量。本论文从理论剖析和实验验证两个方面，对光子筛类衍射透镜的焦斑检测方法进行了探索研究，主要研究工作如下： 1. 全息技术理论分析和全息应用中的自动对焦算法研究。介绍了全息技术的基本理论，给出了全息应用中的几种自动对焦算法。针对双焦点光子筛的固有特性，本文中提出高阶变异系数距离自动对焦算法来实现其再现距离的自动获取。该算法是从数字全息的重建图像中减去平均值，对得到的高频信息重新进行计算，其评判标准最小值对应的距离就是较为准确的再现距离。相比于其它算法，该算法对双焦点光子筛的测量结果具有较高的准确性，同时适用于分辨率板等物体，具有适用性。 2. 基于数字全息的光子筛焦斑的检测技术研究。双焦点光子筛在微米量级的离焦面处能量会快速衰减，且无法通过一次测量同时获得其多个焦斑分布，本文中提出利用数字全息测量方法结合变采样间距的衍射传输算法实现该光子筛器件焦距及焦斑的同时精细测量。利用双曝光的离轴数字全息得到了离焦面处光场的复振幅分布，基于此光场通过变采样间距的衍射传输算法得到具有较高分辨率的双焦点光子筛的聚焦场特征。焦距等于自动对焦算法及强度最大值扫描方式分别求得的两段距离之和，实验结果表明实验所得焦距和焦斑大小与理论设计结果基本一致。另外，利用该测量方法实现了椭圆涡旋光子筛的焦斑检测，测量得到了椭圆中空焦斑和螺旋位相分布，实验结果和理论设计较为符合。该检测方法简单、快速，具有较高的分辨率，可适用于其它类衍射透镜元件的精细测量和性能分析。 3. 基于阵列抽样的光子筛焦斑的检测技术研究。该方法通过光场调制–记录图案–逆向传输–滤波过程–传输几个环节得到被测物体信息。本文建立了该方法的理论计算模型并给出了数值计算中需要注意的问题，实验验证了该方法用于焦斑分布检测的可行性。该方法光路简单，而且通过一幅衍射强度图可以快速获得物体的复振幅分布，使得测量方便、快捷。; The diffractive lens is a diffractive optical element that realizes beam focusing and imaging. It has a wide range of application prospects in space remote sensing, optical lithography, microscopic imaging, life science and so on, and plays an important role in the improvement of system performance and lightweight. Amplitude diffractive lenses have great potential applications in the X-ray and extreme-ultraviolet wavelength bands because they are not limited by wavelength. In recent years, a new type of amplitude diffractive lens, the photon sieve, has attracted attention and set off a new wave of research. Through the multi-degree of freedom design, the photon sieve can obtain complex and diversified focusing field structure and superior performance. Therefore, it is very important to detect and analyze the focusing performance of the diffractive lens such as the photon sieve before its practical application. In the existing research, simple direct qualitative imaging methods are mainly used to measure them, and the operation is cumbersome and requires high requirements. This dissertation focuses on the focal spot detection of diffractive lenses such as photon sieve and aims to achieve rapid and accurate quantitative detection. Two kinds of focal spot detection methods—digital holographic measurement technology and coherent detection technology based on array sampling—are explored and studied. Both methods do not require an iterative process. Digital holography is a special kind of coherent measurement and imaging technology. It has the characteristics of simple, fast, high accuracy and digital processing, and so on. It is widely used in the measurement of various physical parameters. Its unique feature is that it can directly obtain complex amplitude distribution of the measured object. In addition, the detection technology based on array sampling is also a kind of non-iteration coherent diffraction imaging technology that can quickly realize measurement. It is a new method proposed in recent years. This paper applies this method to try to measure the focused focal spot. This dissertation studies the focal spot detection method of diffraction lens such as photon sieve from two aspects: theoretical analysis and experimental verification. The main research work is as follows: 1. Theoretical analysis of holographic technology and auto focusing algorithm in holographic applications. The basic theory of digital holography is introduced, and several auto focusing algorithms in holographic applications are given. Because of the intrinsic characteristics of the bifocal photon sieve, a high-order coefficient of variation distance autofocus algorithm is proposed in this paper to realize the automatic acquisition of the reconstructed distance. The algorithm subtracts the average value from the reconstructed image of the digital hologram, and recalculates the high-frequency information obtained. The distance corresponding to the minimum value of the evaluation criterion is a relatively accurate reconstructed distance. Compared with other algorithms, this algorithm has high accuracy for the measurement results of bifocal photon sieves, and it is also suitable for objects such as resolution target and has strong applicability 2. Detection of the distribution of the focal spot of photon sieve based on digital holography. The energy of the bifocal photon sieve rapidly decays at the defocusing surface of the micrometer level and multiple focal spot distribution of it can't be obtained at the same time with one measurement. In this paper, the digital holographic measurement method combined with diffraction propagation algorithm of variable sampling interval is proposed to realize the simultaneous fine measurement of focal length and focal spot distribution of the photonic sieve. The double-exposure off-axis digital holography is used to obtain the complex amplitude distribution of the light field at the defocus surface. Based on this light field, the focusing field characteristics of bifocal photon sieve were obtained through the diffraction propagation algorithm of variable sampling interval. The focal length is equal to the sum of two distances obtained by the autofocus algorithm and the intensity maximum scanning method respectively. The experimental results show that the focal length and the focal spot distribution obtained by the experiment are basically consistent with the theoretical design results. The detection method is simple, rapid, and has high resolution, and can be applied to the fine measurement and performance analysis of other types of diffractive lens. In addition, using this measurement method, the focal spot detection of the elliptical vortex photon sieve was realized, and the elliptical hollow focal spot and helical phase distribution were measured. The experimental results and the theoretical design were in good agreement. 3. Detection of the focal spot distribution of photon sieves based on sampling array. The measured object information can be obtained through optical field modulation - recording patterns - reverse propagation - filtering process - propagation of several links. In this paper, the theoretical calculation model of the method is established and the problems that need attention in the numerical calculation are given. The feasibility of this method for the detection of focal spot distribution is verified by experiments. The optical path of the method is simple, and the complex amplitude distribution of the object can be quickly obtained through a diffraction intensity map, which makes the measurement more convenient and faster. |
| 学科主题 | 光学工程 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31076]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 王松贤. 衍射透镜焦斑的非迭代相干检测研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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