高分辨率微球数字全息成像方法研究

发布时间：2018-06-07 00:29

  本文选题：数字全息 + 微球　； 参考：《北京工业大学》2016年硕士论文

【摘要】：数字全息成像具有实时、全视场、非接触和定量相衬成像的优势,在细胞形貌观测、微纳元件、温度场、粒子跟踪等方面,有着广泛的应用前景。随着生命科学、微加工技术、微电子技术等的飞速发展,对微小物体三维形貌测量的需求越来越迫切,因此开展超分辨数字全息成像方法研究具有重要的理论意义和应用价值。目前超分辨率数字全息成像方法主要包括:空间复用、亚像素微位移、多光束照明,光栅技术等技术。这些方法往往需要记录多幅全息图,并需要复杂的综合再现算法。研究者通过微球提高成像分辨率。但是,目前仅将微球应用到了白光显微成像系统中,而且只能得到二维成像结果。本文将微球与数字全息方法相结合,将二维成像拓展到高分辨率相衬成像,并进一步提高数字全息技术的分辨率,主要内容如下:研究了微球参数对微球成像特性的影响。首先,理论推导了微球直径,折射率等参数对成像系统球差和数值孔径的关系,研究表明微球的半径与球差成正比,数值孔径先会随着相对折射率的增大而增大,然后当数值孔径达到1后,会随着相对折射率的增大而减小,当半径和相对折射率适当选择,会得到较高的成像分辨率。然后给出了微球参数与微球傍轴焦距的关系式,结果表明微球傍轴焦距与微球半径成正比,与微球折射率成反比,并利用COMSOL Multiphysics软件进行仿真验证。最后通过仿真验证了微球具有收集近场倏逝波,并将其转换为远场传输波的能力。开展了基于微球的高分辨率数字全息显微成像研究。分析了微球与显微物镜组合的成像理论,并定量分析了微球与显微物镜组合以后系统的数值孔径。将预放大超分辨数字全息显微成像与微球结合,搭建了一套基于微球的预放大像面离轴菲涅耳数字全息显微成像系统。然后利用不同尺寸的样品进行实验,验证了微球可以通过一次曝光提高整个视场的横向分辨率,并通过相位解包裹与曲面拟合的相位畸变处理算法,得到物体相位像。最后进行了微球自组装实验,验证了自组装可以扩大微球成像的视场。
[Abstract]:Digital holographic imaging has the advantages of real-time, full field of view, non-contact and quantitative phase contrast imaging. It has a wide application prospect in cell morphology observation, micro and nano elements, temperature field, particle tracking and so on. With the rapid development of life science, micromachining and microelectronics, it is more and more urgent to measure the three-dimensional morphology of micro-objects. Therefore, the research of super-resolution digital holographic imaging has important theoretical significance and application value. At present, the super-resolution digital holographic imaging methods mainly include: spatial multiplexing, sub-pixel micro-displacement, multi-beam illumination, grating technology and so on. These methods often require multiple holograms to be recorded and complex synthetic reproduction algorithms. Researchers use microspheres to improve imaging resolution. However, only the microspheres are applied to white light microscopic imaging system, and only two-dimensional imaging results can be obtained. In this paper, the microsphere is combined with the digital holography method, and the two-dimensional imaging is extended to the high-resolution phase contrast imaging, and the resolution of the digital holographic technique is further improved. The main contents are as follows: the influence of the parameters of the microsphere on the imaging characteristics of the microsphere is studied. Firstly, the relationship between spherical aberration and numerical aperture of the imaging system is derived theoretically. The results show that the radius of the microsphere is proportional to the spherical aberration, and the numerical aperture increases with the increase of the relative refractive index. Then when the numerical aperture reaches 1, it will decrease with the increase of relative refractive index. When the radius and relative refractive index are properly selected, a higher imaging resolution will be obtained. Then the relationship between the microsphere parameters and the paraxial focal length of the microsphere is given. The results show that the paraxial focal length of the microsphere is proportional to the radius of the microsphere and inversely proportional to the refractive index of the microsphere. The simulation results are verified by COMSOL Multiphysics software. Finally, the capability of collecting near-field evanescent waves and converting them into far-field waves is verified by simulation. The high resolution digital holographic microimaging based on microspheres is studied. The imaging theory of the combination of the microsphere and the microobjective is analyzed, and the numerical aperture of the system after the combination of the microsphere and the microobjective is analyzed quantitatively. An off-axis Fresnel digital holographic imaging system based on microspheres was constructed by combining pre-amplification super-resolution digital holographic imaging with microspheres. Then the experiments with samples of different sizes show that the microsphere can improve the transverse resolution of the whole field of view by one exposure and obtain the phase image of the object by phase unwrapping and phase distortion processing algorithm fitting the curved surface. Finally, the self-assembly experiment is carried out to verify that self-assembly can enlarge the field of view of microsphere imaging.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN26
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本文编号：1988833