本文關(guān)鍵詞： 波前編碼 紅外光學(xué)系統(tǒng) 圖像復(fù)原 光學(xué)傳遞函數(shù)　出處：《北京理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：相對于可見光系統(tǒng)，紅外成像系統(tǒng)應(yīng)用的外界環(huán)境較為復(fù)雜，在若干環(huán)境因素中，由于紅外光學(xué)材料自身的熱效應(yīng)比較靈敏，紅外光學(xué)系統(tǒng)成像質(zhì)量受環(huán)境溫度的影響尤其明顯。因此，為了保證其在工作溫度范圍內(nèi)的良好成像，都要對紅外光學(xué)系統(tǒng)進(jìn)行無熱化設(shè)計(jì)。 波前編碼系統(tǒng)是結(jié)合光學(xué)成像和數(shù)字圖像處理的兩步成像系統(tǒng)：通過在系統(tǒng)光瞳面上加入一塊特殊的相位掩模板，對非相干光波波前進(jìn)行調(diào)制，使得在一個較大焦深范圍內(nèi)，系統(tǒng)的光學(xué)傳遞函數(shù)（OTF）和點(diǎn)擴(kuò)散函數(shù)（PSF）對離焦不敏感，因此所成的中間像為一系列等模糊圖像；由于中間圖像模糊程度近似一致，就可以通過后期圖像處理，得到焦深延拓后的清晰圖像。波前編碼對離焦不敏感的特性與紅外系統(tǒng)無熱化的理念相同，如果波前編碼擴(kuò)展的焦深范圍能夠超越紅外成像系統(tǒng)中由溫度引起的焦面漂移，那么就可以將波前編碼技術(shù)作為一種無熱化手段應(yīng)用到紅外成像系統(tǒng)中，解決環(huán)境溫度對紅外成像系統(tǒng)的影響。 論文首先介紹了課題的研究背景和意義，闡述了紅外系統(tǒng)中無熱化的必要性和波前編碼技術(shù)作為無熱化手段應(yīng)用到紅外成像系統(tǒng)的可行性，同時(shí)介紹了波前編碼技術(shù)的應(yīng)用，并且從國外和國內(nèi)兩方面介紹了波前編碼的研究現(xiàn)狀；其次，從理論方面詳細(xì)闡述了波前編碼系統(tǒng)的編碼理論和解碼理論，用穩(wěn)相法推導(dǎo)了基于三次相位板的光學(xué)傳遞函數(shù)（OTF）表達(dá)式，并且分析了波前編碼系統(tǒng)的離焦不變性；第三，通過分析波前編碼系統(tǒng)DM（最大離焦處和零離焦處的MTF差值）和系統(tǒng)離焦不變性以及圖像可復(fù)原性的關(guān)系，論文研究了一種基于MTF一致性的三次相位板優(yōu)化方案，通過建立仿真實(shí)驗(yàn)，從光線結(jié)構(gòu)分布、頻域、空域三方面分析波前編碼系統(tǒng)，，驗(yàn)證了該方案的可行性；第四，通過設(shè)計(jì)對照實(shí)驗(yàn)，說明將波前編碼作為一種無熱化手段應(yīng)用到紅外成像系統(tǒng)中，可以使系統(tǒng)在工作溫度范圍內(nèi)成像質(zhì)量不受環(huán)境溫度變化影響，同時(shí)減小光學(xué)系統(tǒng)復(fù)雜度，降低成本。最后，通過對相位板進(jìn)行加工，搭建實(shí)驗(yàn)平臺，驗(yàn)證系統(tǒng)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.
【學(xué)位授予單位】：北京理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TP391.41;TN219

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