發(fā)布時(shí)間：2018-06-15 19:07

  本文選題：大物成像 + 自動(dòng)聚焦��； 參考：《南京郵電大學(xué)》2016年碩士論文

【摘要】：本文旨在進(jìn)行數(shù)字全息關(guān)鍵技術(shù)研究。利用理論推導(dǎo)和實(shí)驗(yàn)探究相結(jié)合的方法,通過對國內(nèi)外數(shù)字全息技術(shù)領(lǐng)域進(jìn)行深入調(diào)研與分析,本文對數(shù)字全息的三個(gè)關(guān)鍵技術(shù)進(jìn)行了研究:(1)為了簡化無透鏡大物體傅里葉變換數(shù)字全息實(shí)驗(yàn)光路設(shè)置,本文深入研究了一種無透鏡大物體合成孔徑數(shù)字全息成像方法,該方法通過改進(jìn)馬赫-曾德爾干涉儀,將原始參考光分成兩束,其中一束進(jìn)行重定向,作為第二束物光,兩束物光照在大物體不同部位,與參考光干涉在CCD上成像后,利用合成孔徑技術(shù),實(shí)現(xiàn)了一次曝光大物體數(shù)字全息成像;(2)在數(shù)字全息自動(dòng)聚焦重建中,為了降低重建過程中重建像均值漂移對部分自動(dòng)聚焦判據(jù)函數(shù)的影響,本文提出了一種新型強(qiáng)適應(yīng)性自動(dòng)聚焦判據(jù)函數(shù),即基于高頻分量的標(biāo)準(zhǔn)差對比度法,該方法僅利用原始全息圖高頻能量計(jì)算判據(jù),減小了以往方法中存在的均值漂移問題,且更簡單、高效,在不同像質(zhì)的數(shù)字全息圖重建過程中,表現(xiàn)出強(qiáng)適應(yīng)性;(3)在數(shù)字全息重建過程中,重建像會因?yàn)樯咴肼暥沟孟褓|(zhì)降低,為了提高數(shù)字全息重建像像質(zhì),本文提出了一種有效的像質(zhì)增強(qiáng)算法,即大物體低像質(zhì)數(shù)字全息重建像在衍射極限下的頻率外延增強(qiáng)算法,該算法將原始全息圖+1級傅里葉濾波光譜重建像進(jìn)行自適應(yīng)高斯濾波后,降低散斑噪聲,作為原始光譜,對其通過連續(xù)梯度迭代分析,得到預(yù)測光譜,最后將預(yù)測光譜對原始光譜進(jìn)行校正,恢復(fù)出重建像的高頻信息。
[Abstract]:The purpose of this paper is to study the key techniques of digital holography. By using the method of combining theoretical derivation and experimental inquiry, through the in-depth investigation and analysis of the domestic and foreign digital holographic technology field, In this paper, three key techniques of digital holography are studied. (1) in order to simplify the arrangement of optical path of lensless large object Fourier transform digital holography experiment, a lensless large object synthetic aperture digital holographic imaging method is studied in this paper. By improving the Mach Zehnder interferometer, the original reference light is divided into two beams, one of which is redirected as the second beam of object light, and the two beams of object light are illuminated in different parts of the large object, and the light is interfered with the reference light on the CCD. In order to reduce the influence of the mean shift of reconstruction image on partial autofocus criterion function in digital holographic autofocus reconstruction, a large object digital holographic imaging with a single exposure is realized by using synthetic aperture technology. In this paper, a new strong adaptive autofocus criterion function, standard deviation contrast method based on high frequency components, is proposed. This method only uses the criterion of calculating the high frequency energy of the original hologram, and reduces the mean drift problem existing in the previous methods. In the process of digital holographic reconstruction, the reconstructed image will be reduced because of speckle noise. In order to improve the image quality of digital hologram reconstruction, In this paper, an effective image enhancement algorithm is proposed, that is, the frequency epitaxy enhancement algorithm for large objects with low image quality digital holographic reconstruction under the diffraction limit. In this algorithm, the speckle noise is reduced by adaptive Gao Si filtering after the spectral reconstruction of the original hologram is reconstructed by Fourier filter, and the predicted spectrum is obtained by continuous gradient iterative analysis, and the speckle noise is reduced as the original spectrum. At last, the original spectrum is corrected by the predicted spectrum, and the high frequency information of the reconstructed image is restored.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：O438.1;TN26

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