本文關(guān)鍵詞： 波前編碼 調(diào)制傳遞函數(shù) 相位掩膜板 光學(xué)傳遞函數(shù) 點(diǎn)擴(kuò)散函數(shù)　出處：《哈爾濱工業(yè)大學(xué)》2016年博士論文　論文類型：學(xué)位論文

【摘要】：大景深(DOF)光學(xué)成像系統(tǒng)可以獲取物體更為豐富的信息,使獲得的景物信息更接近于真實(shí)的世界,在過(guò)去的近半個(gè)世紀(jì)里,人們努力尋求著各種各樣的方法來(lái)擴(kuò)大光學(xué)系統(tǒng)的DOF。波前編碼(WFC)技術(shù)是近年新興的光學(xué)成像技術(shù),其重要的應(yīng)用之一便是擴(kuò)展光學(xué)系統(tǒng)DOF。WFC技術(shù)作為一種光學(xué)數(shù)字混合成像技術(shù),其通過(guò)在傳統(tǒng)非相干成像系統(tǒng)光瞳位置進(jìn)行相位調(diào)制來(lái)記錄編碼圖像,并利用數(shù)字圖像處理技術(shù)對(duì)編碼圖像進(jìn)行解碼,以達(dá)到系統(tǒng)性能的提升。WFC系統(tǒng)中,相位掩膜板實(shí)現(xiàn)波前的相位調(diào)制,如何設(shè)計(jì)及優(yōu)化相位掩膜板是WFC系統(tǒng)設(shè)計(jì)的關(guān)鍵。基于此,本文致力于WFC系統(tǒng)的相位掩膜板研究,力求獲取更為優(yōu)越的擴(kuò)展DOF成像性能。開展了擴(kuò)展DOF的非對(duì)稱相位掩膜板研究。從空域和空間頻域分析了非對(duì)稱相位掩膜板WFC系統(tǒng)的成像特性,說(shuō)明了非對(duì)稱相位掩膜板設(shè)計(jì)過(guò)程中需考慮的約束條件,建立了非對(duì)稱相位掩膜板WFC系統(tǒng)像質(zhì)評(píng)價(jià)模型。針對(duì)非對(duì)稱相位掩膜板編碼和解碼特性,為獲取更為穩(wěn)定的編碼過(guò)程離焦不變的成像特性,并在解碼過(guò)程有效抑制偽像和噪聲,研究了非對(duì)稱相位掩膜板相位函數(shù)。依據(jù)相位函數(shù)研究結(jié)果,獲取了四種新形式的非對(duì)稱相位掩膜板,并展開了性能比對(duì)研究,驗(yàn)證了新形式相位掩膜板在擴(kuò)展DOF成像中的優(yōu)越性能。開展了擴(kuò)展DOF的共軛非對(duì)稱相位掩膜板研究。單一非對(duì)稱相位掩膜板產(chǎn)生的點(diǎn)擴(kuò)散函數(shù)(PSF)在理論焦面存在偏移,則解碼圖像中包含偽像,成像質(zhì)量有一定的下降,這嚴(yán)重影響了系統(tǒng)的擴(kuò)展DOF性能�；诖�,提出了基于共軛非對(duì)稱相位掩膜板對(duì)的擴(kuò)展DOF成像方法,該方法可產(chǎn)生幾乎隨離焦不變的PSF,使系統(tǒng)離焦不變特性獲得提升。該共軛成像方法可在保證離焦不變特性的同時(shí),有效改正偽像。開展了擴(kuò)展DOF的徑向?qū)ΨQ相位掩膜板研究。由于徑向?qū)ΨQ相位掩膜板產(chǎn)生的PSF具有對(duì)稱特性,因而復(fù)原后的圖像不會(huì)存在偽像,但其離焦不變特性較徑向?qū)ΨQ相位掩膜板有所下降�；诖�,為提升對(duì)稱相位掩膜板WFC系統(tǒng)的離焦不變特性,在徑向?qū)ΨQ相位掩膜板WFC系統(tǒng)成像特性研究的基礎(chǔ)上,研究了徑向?qū)ΨQ相位掩膜板的相位函數(shù),提出了兩種新形式的徑向?qū)ΨQ相位掩膜板,并通過(guò)仿真實(shí)驗(yàn)驗(yàn)證了提出的相位掩膜板可獲取更為穩(wěn)定的離焦PSF和調(diào)制傳遞函數(shù)(MTF)。
[Abstract]:The large depth of Field (DOF) optical imaging system can capture more information about objects and bring them closer to the real world, in the last half century, People are looking for various ways to expand the optical system DOF.Wavefront coding (WFC) technology is a new optical imaging technology in recent years, one of its important applications is the extended optical system DOF.WFC technology as an optical digital hybrid imaging technology. The coded image is recorded by phase modulation in the pupil position of the traditional incoherent imaging system, and the coded image is decoded by digital image processing technology, so as to improve the performance of the system. How to design and optimize the phase mask board is the key to the design of WFC system. Based on this, this paper focuses on the study of phase mask plate in WFC system. In order to obtain better imaging performance of extended DOF, the asymmetric phase mask of extended DOF is studied. The imaging characteristics of asymmetric phase mask WFC system are analyzed in spatial and spatial frequency domain. The constraints to be considered in the design of asymmetric phase mask are explained, and the image quality evaluation model of asymmetric phase mask WFC system is established. The encoding and decoding characteristics of asymmetric phase mask are analyzed. In order to obtain more stable defocus invariant imaging characteristics of the coding process and effectively suppress artifacts and noises in the decoding process, the phase function of asymmetric phase mask is studied. Four new types of asymmetric phase mask are obtained, and the performance ratio studies are carried out. The excellent performance of the new type of phase mask in extended DOF imaging is verified. The conjugate asymmetric phase mask of extended DOF is studied. The point diffusion function generated by the single asymmetric phase mask is offset in the theoretical focal plane. Then the decoded image contains artifacts and the imaging quality decreases, which seriously affects the extended DOF performance of the system. Based on this, an extended DOF imaging method based on conjugate asymmetric phase mask pair is proposed. This method can produce PSF with almost defocus invariance, and improve the system defocus invariance. The conjugate imaging method can guarantee the defocus invariant property at the same time. Effective correction of artifacts. The radial symmetrical phase mask plate of extended DOF is studied. Because the PSF produced by radial symmetric phase mask plate has symmetry characteristics, there is no artifacts in the reconstructed image. However, the defocus invariance is lower than that of the radial symmetrical phase mask. In order to improve the defocus invariance of the symmetrical phase mask WFC system, the imaging characteristics of the radial symmetric phase mask WFC system are studied. The phase function of radial symmetric phase mask is studied and two new types of radial symmetric phase mask are proposed. The simulation results show that the proposed phase mask can obtain more stable defocus PSF and modulation transfer function (MTF).
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN919.81
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本文編號(hào)：1547869