波前编码红外成像技术研究

发布时间：2018-02-21 01:03

本文关键词： 波前编码红外光学系统图像复原光学传递函数　出处：《北京理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：相对于可见光系统，红外成像系统应用的外界环境较为复杂，在若干环境因素中，由于红外光学材料自身的热效应比较灵敏，红外光学系统成像质量受环境温度的影响尤其明显。因此，为了保证其在工作温度范围内的良好成像，都要对红外光学系统进行无热化设计。波前编码系统是结合光学成像和数字图像处理的两步成像系统：通过在系统光瞳面上加入一块特殊的相位掩模板，对非相干光波波前进行调制，使得在一个较大焦深范围内，系统的光学传递函数（OTF）和点扩散函数（PSF）对离焦不敏感，因此所成的中间像为一系列等模糊图像；由于中间图像模糊程度近似一致，就可以通过后期图像处理，得到焦深延拓后的清晰图像。波前编码对离焦不敏感的特性与红外系统无热化的理念相同，如果波前编码扩展的焦深范围能够超越红外成像系统中由温度引起的焦面漂移，那么就可以将波前编码技术作为一种无热化手段应用到红外成像系统中，解决环境温度对红外成像系统的影响。论文首先介绍了课题的研究背景和意义，阐述了红外系统中无热化的必要性和波前编码技术作为无热化手段应用到红外成像系统的可行性，同时介绍了波前编码技术的应用，并且从国外和国内两方面介绍了波前编码的研究现状；其次，从理论方面详细阐述了波前编码系统的编码理论和解码理论，用稳相法推导了基于三次相位板的光学传递函数（OTF）表达式，并且分析了波前编码系统的离焦不变性；第三，通过分析波前编码系统DM（最大离焦处和零离焦处的MTF差值）和系统离焦不变性以及图像可复原性的关系，论文研究了一种基于MTF一致性的三次相位板优化方案，通过建立仿真实验，从光线结构分布、频域、空域三方面分析波前编码系统，，验证了该方案的可行性；第四，通过设计对照实验，说明将波前编码作为一种无热化手段应用到红外成像系统中，可以使系统在工作温度范围内成像质量不受环境温度变化影响，同时减小光学系统复杂度，降低成本。最后，通过对相位板进行加工，搭建实验平台，验证系统性能。
[Abstract]:Compared with the visible light system, the infrared imaging system is used in a more complex external environment. Among some environmental factors, the infrared optical material is sensitive to the thermal effect of its own. The imaging quality of infrared optical system is especially affected by ambient temperature. Therefore, in order to ensure good imaging in the range of working temperature, the infrared optical system should be designed without heat. The wavefront coding system is a two-step imaging system combining optical imaging and digital image processing. By adding a special phase mask on the pupil plane of the system, the incoherent optical wavefront is modulated to make it in a large range of focal depth. The optical transfer function (OTFF) and the point diffusion function (PSF) of the system are insensitive to defocus, so the intermediate image is a series of equal-blurred images. The defocus insensitivity of wave-front coding is the same as that of non-thermal infrared system. If the range of focal depth extended by wave-front coding can exceed the focal plane drift caused by temperature in infrared imaging system, Therefore, the wavefront coding technique can be applied to infrared imaging system as a non-thermal method, and the influence of ambient temperature on infrared imaging system can be solved. This paper first introduces the research background and significance of the subject, expounds the necessity of non-thermal in the infrared system and the feasibility of applying the wavefront coding technology to the infrared imaging system as a non-thermal means, and introduces the application of the wave-front coding technology at the same time. It also introduces the research status of wave-front coding from both foreign and domestic aspects. Secondly, the coding theory and decoding theory of wave-front coding system are described in detail from the theoretical point of view. The expression of optical transfer function (OTF) based on cubic phase plate is derived by using phase stabilization method, and the defocus invariance of wave-front coding system is analyzed. By analyzing the relationship between the MTF difference between the maximum defocus and zero defocus of the wavefront coding system, the defocus invariance of the system and the image recoverability, a cubic phase plate optimization scheme based on MTF consistency is studied in this paper. The feasibility of this scheme is verified by analyzing the wave-front coding system from three aspects of light structure distribution, frequency domain and spatial domain. It is shown that the application of wave-front coding as a non-thermal method to infrared imaging system can make the imaging quality of the system in the range of working temperature not affected by the change of ambient temperature, at the same time, reduce the complexity of optical system and reduce the cost. The performance of the system is verified by machining the phase plate and setting up the experimental platform.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TP391.41;TN219

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