光学多孔径成像系统成像性能研究

发布时间：2018-01-05 16:14

本文关键词：光学多孔径成像系统成像性能研究　出处：《北京工业大学》2013年博士论文　论文类型：学位论文

【摘要】：随着人们对外层空间的深入探索，担负探索任务的天文望远镜性能成为影响观测结果的重要因素。为了对更加遥远的天文目标进行观测，人们对天文望远镜的角分辨率提出了越来越高的要求。对于天文望远镜角分辨率的高要求必然导致天文望远镜的口径尺寸增大，对于反射式天文望远镜，这意味着需要制造超大尺寸的单镜面反射镜。对于超大尺寸单镜面反射镜，由于重量过大，镜面易形变，所以反射镜表面曲率半径的精度难以保证。另外，超大尺寸反射镜曲率半径检测方法也比较复杂。这些问题都会导致天文望远镜制造成本飞速增长。因此迫切需要提出新的方法，解决角高分辨率成像需求与制造困难之间的矛盾。光学多孔径成像系统既可以实现高角分辨率成像，又避免了制造超大单口径望远镜。光学多孔径成像系统的灵感来源于合成孔径雷达成像，利用若干较小口径的子望远镜收集遥远物体发出的光束。子望远镜按照一定形式排布，形成阵列，其收集的光束共同进入成像部分，相互干涉，共同成像。由于光学多孔径成像系统能够一次成像，因此非常适合观测快速变化的目标，例如超新星爆炸，外层空间的飞行器和卫星监测等，也可以在外层空间轨道实现对地面的高分辨率侦查，具有广阔的应用前景。目前，国内外关于光学多孔径成像系统的研究依然非常活跃。本文主要在三个方面阐述提高光学多孔径成像系统成像性能的方法，包括含噪声点扩展函数和光学传递函数对复原图像质量的影响，大气湍流对光学多孔径成像系统性能的影响，以及共相误差对成像性能的影响。通过一系列的理论分析，数值仿真以及光学实验，获得了大量的实验数据，得到了一些提高光学多孔径成像系统性能的方法。本文主要完成了如下的工作内容： 1．研究了光学多孔径成像系统的成像过程，物理模型和数学模型。分析并得到了由光学多孔径成像系统的阵列排布形式获得出瞳函数的方法，推导了利用光学多孔径成像系统的出瞳函数计算点扩展函数和光学传递函数的方法，研究了三者之间采样间隔的关系。对光学多孔径成像系统的出瞳函数在自由空间的传播进行了研究，获得了一种计算光学多孔径成像系统点扩展函数和光学传递函数的数值计算方法。在计算机中，仿真了光学多孔径成像系统的成像全过程，完成了几种常用图像复原算法在光学多孔径成像系统中的应用。 2．在光学多孔径成像系统的图像复原算法中，常用到点扩展函数和光学传递函数。对于光学多孔径成像系统，点扩展函数和光学传递函数可以通过实验测量得到，也可以根据阵列排布形式进行计算。这两种点扩展函数和光学传递函数都可以进行图像复原。利用实验方法测量得到的点扩展函数和光学传递函数包含噪声，在构建滤波器后对系统直接观测图像进行复原，会令复原图像质量下降。相反，计算的点扩展函数和光学传递函数因为不含有噪声，可以很好地复原光学多孔径成像系统的直接观测图像。本文通过理论分析、仿真和实验方法，确定当光学多孔径成像系统接近理想成像状态时，应采用计算的点扩展函数和光学传递函数构建滤波器进行图像复原，而实验测量的点扩展函数和光学传递函数，不适合在光学多孔径成像系统中使用。 3．研究了大气湍流对光学多孔径成像系统的影响。对于地基光学多孔径成像系统，大气湍流不可避免。因为大气湍流是一种随机介质，令大气折射率随机变化，所以导致光束波前在大气中传播受到随机影响。通过研究大气湍流随机相位屏理论和模型，在计算机中建立了大气湍流随机相位屏的数值仿真。在光学多孔径成像系统的成像过程中加入大气湍流随机相位屏，实现光学多孔径成像系统在大气湍流中的成像仿真。提出一种基于总变分(Total Variation, TV)准则的多帧盲解卷积图像复原算法，成功应用于仿真的受大气湍流影响的光学多孔径成像系统中。此外在实验室中搭建了有大气湍流的光学多孔径成像系统成像实验，通过实验获得有大气湍流的光学多孔径成像系统的直接观测图像序列，利用基于TV准则的多帧盲解卷积图像复原算法成功复原了直接观测图像，克服了大气湍流影响。 4．研究了光学多孔径成像系统的共相误差对成像性能的影响。光学多孔径成像系统的共相误差在光学多孔径成像系统的装配过程中产生。通过对光学多孔径成像系统的共相误差建模，得到包含共相误差分布的出瞳函数，从而利用角谱传播算法得到光学多孔径成像系统的点扩展函数和光学传递函数。通过分析光学传递函数，了解共相误差对光学多孔径成像系统的成像性能影响。共相误差会极大的降低光学多孔径成像系统的频率响应，导致最高分辨率降低，令光学多孔径成像系统无法高分辨率成像。为了校正共相误差，提出了一种基于数字全息波前探测技术的光学多孔径成像系统共相误差探测方法。推导了采用离轴数字全息记录和重构波前的过程，在计算机中实现完整的数字全息对光学多孔径成像系统的波前探测过程。根据重构的光学多孔径成像系统出瞳函数的相位分布，分析并得到了共相误差的相关信息。搭建了一套离轴数字全息波前探测光路，，成功测量了光学多孔径成像系统的出瞳函数相位分布，并且通过1/4波片模拟了包含共相误差的光学多孔径成像系统，利用重构出瞳函数分析得到了1/4波片模拟的共相误差信息。
[Abstract]:People with in-depth exploration of outer space, for astronomical telescope performance exploration mission has become an important factor to affect the observation result. In order to observe the more distant astronomical objects, demands more and more people the angular resolution of astronomical telescope for astronomical telescope. High angular resolution will inevitably lead to the telescope aperture size increases, for a reflecting telescope, which means that the single specular reflection mirror manufacturing large size. For large size single mirror mirror, because the weight is too large, easy to form variable mirror, so the mirror surface curvature radius is difficult to ensure the accuracy of detection methods. In addition, oversized mirror curvature is more complicated. These problems will lead to the rapid growth of the manufacturing cost of the telescope. There is an urgent need to put forward a new method to solve high resolution angle The optical multi aperture imaging system can both achieve high angular resolution imaging and avoid the manufacture of ultra large single aperture telescopes.
Optical multi aperture imaging system inspired by synthetic aperture radar imaging, the beam emitted by distant objects collected a number of smaller caliber sub sub telescope telescope. According to a certain form of arrangement, the formation of the beam array, collected together into the imaging section, mutual interference, common imaging. Because the optical multi aperture imaging system capable of imaging a therefore, very suitable for the observation of rapid change, such as a supernova explosion, outer space aircraft and satellite monitoring, also can realize high resolution detection of ground investigation in outer space orbit, and has broad application prospects. At present, the research on optical multi aperture imaging system at home and abroad is still very active.
This paper mainly discusses the methods to improve the imaging performance of multi aperture imaging system in three aspects, including the noise point spread function and the optical transfer function of image quality and the effect of atmospheric turbulence on the optical properties of multi aperture imaging system, and the influence is the phase error on the imaging performance. Through a series of theoretical analysis. Numerical simulation and optical experiment, obtained a large number of experimental data, this paper introduces some methods to improve the performance of multi aperture optical imaging system. The main contributions of the paper are as follows:
1. the study of the imaging process of optical multi aperture imaging system, the physical model and mathematical model. Analyzed and obtained by arrays of optical multi aperture imaging system to obtain a method for pupil function, derived by optical multi aperture imaging system exit pupil function to calculate the point spread function and the optical transfer function, study the sampling interval of the relationship between the three. The optical multi aperture imaging system to spread the pupil function in free space is studied, a calculation method of calculation of optical multi aperture imaging system point spread function and the optical transfer function value is obtained. In the computer, the whole process of imaging simulation of optical multi aperture imaging system complete the application, several commonly used image restoration algorithm in optical multi aperture imaging system.
2. algorithms of image restoration in optical multi aperture imaging system, commonly used to point spread function and the optical transfer function for optical multi aperture imaging system, point spread function and the optical transfer function can be obtained by experimental measurement, can also be calculated according to the array arrangement form. The two point spread function and the optical transfer function can be carried out image restoration. By using the experimental method of measuring the noise included point spread function and the optical transfer function, in the construction of the filter on image restoration system of direct observation, will make the image quality decline. Instead, the calculation of the point spread function and the optical transfer function does not contain noise, can well restore the optical images multi aperture imaging system. Through theoretical analysis, simulation and experimental methods to determine when the optical multi aperture imaging system close to the ideal image. When the state is used, we should use the point spread function and optical transfer function to reconstruct the image, and the point spread function and the optical transfer function measured by experiment are not suitable for optical multi aperture imaging system.
3. the influence of atmospheric turbulence on optical multi aperture imaging system for ground-based optical multi aperture imaging system, the atmospheric turbulence is inevitable. Because the atmospheric turbulence is a kind of random medium, the random variations of the refractive index, so the wavefront propagation by random effects in the atmosphere. Through the study of atmospheric turbulence phase screen theory and model and the numerical simulation of atmospheric turbulence phase screen based on the computer. Join the atmospheric turbulence phase screen in the imaging process of optical multi aperture imaging system, imaging simulation in atmospheric turbulence optical multi aperture imaging system. This paper proposes a total variation based on (Total, Variation, TV) multi frame blind criterion deconvolution image restoration algorithm, the influence of atmospheric turbulence on optical multi aperture imaging system was successfully applied in the simulation. In addition in the laboratory was built with atmospheric turbulence Optical multi aperture imaging system with optical flow experiment, the atmospheric turbulence multi aperture imaging system through the direct observation image sequence, using the TV criterion of multiframe blind deconvolution image restoration algorithm based on image restoration success observed directly, to overcome the influence of atmospheric turbulence.
A total of 4. of the effect of phase error of optical multi aperture imaging system for imaging performance. Optical multi aperture imaging system consists of phase error generated in the assembly process of optical multi aperture imaging system. Through the phase error on the optical multi aperture imaging system modeling, including total phase error distribution of exit pupil function, thus by using the angular spectrum propagation algorithm to obtain optical multi aperture imaging system point spread function and the optical transfer function of optical transfer function. Through the analysis, to understand the impact of common phase error on the performance of multi aperture imaging optical imaging system. Phase error will reduce the optical multi aperture imaging system wide frequency response, resulting in the highest resolution reduced to optical multi aperture imaging system to high-resolution imaging. In order to correct common phase error, presents an optical digital holographic wavefront detection technology based on multi aperture imaging system Method for detecting phase error is derived. The process of off-axis digital holographic recording and reconstruction of the wavefront, the realization process of digital holographic wavefront complete on optical multi aperture imaging detection system in the computer. According to the phase distribution of pupil function reconstruction of optical multi aperture imaging system, analysis and relevant information and phase error. A set of off-axis digital holographic wavefront detection optical path, optical multi aperture imaging system exit pupil function of the phase distribution was measured successfully, and through the 1/4 simulation of the optical wave plate multi aperture imaging system includes phase error, using the reconstructed pupil function analysis of the total phase error information of 1/4 wave plate simulation.

【学位授予单位】：北京工业大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH751

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