本文關(guān)鍵詞：基于實(shí)驗(yàn)室光源的X射線相襯成像應(yīng)用研究　出處：《深圳大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： X射線 相襯成像 線焦斑源 光柵法成像 相位恢復(fù)

【摘要】：X射線相襯成像技術(shù)是近年來X射線研究領(lǐng)域的一個(gè)熱點(diǎn),它通過探測(cè)X射線穿過物體后相位的改變來對(duì)物體成像,克服了傳統(tǒng)吸收成像無法對(duì)弱吸收物體成像的缺點(diǎn),因而在醫(yī)學(xué)、無損檢測(cè)和材料學(xué)方面有很高的應(yīng)用價(jià)值。目前,比較成熟的相襯成像方法主要有:晶體干涉成像法、衍射增強(qiáng)法、同軸相襯成像法和基于光柵的相襯成像法。受到光源和晶體的限制,晶體干涉成像法和衍射增強(qiáng)法對(duì)設(shè)備的要求很高,適用性較差。相較而言,同軸相襯成像法和基于光柵的相襯成像方法,對(duì)光源和實(shí)驗(yàn)設(shè)備的要求較低,便于在實(shí)驗(yàn)室開展,所以本文將這兩種方法作為研究的主要內(nèi)容。同軸法相襯成像最初是在同步輻射源上開展的,但因?yàn)樗鼘?duì)于光源的時(shí)間相干性要求不高,所以也可以在微焦斑X射線源下進(jìn)行。微焦斑源的相干性較好,但因?yàn)榻拱咛?所以光通量很小。為了解決X射線成像中,光源光通量和相干性不可兼得的矛盾,我們使用了一種焦斑為線型的X射線源,間接的解決了這個(gè)問題。線焦斑源在線寬方向的相干性較好,但在線長方向不具有空間相干性,會(huì)丟失線長方向上的物體細(xì)節(jié),所以我們采用旋轉(zhuǎn)物體的方式,將多個(gè)方向的物體圖像進(jìn)行疊加,從而重構(gòu)出能反應(yīng)物體(芯片)細(xì)節(jié)的高分辨率圖像。我們將此結(jié)果分別與微焦斑X射線源類同軸成像以及大焦斑源成像結(jié)果進(jìn)行對(duì)比,給出了基于線焦斑源成像在相干性和通量方面具有優(yōu)勢(shì)的實(shí)驗(yàn)驗(yàn)證。基于光柵的相襯成像方法,發(fā)展至今有Talbot-Lau和逆Talbot-Lau方法,Talbot-Lau干涉儀法對(duì)光柵要求高,光柵制作較為困難;逆Talbot-Lau法受限于光源的相干長度,成像系統(tǒng)的距離很長,不利于實(shí)用。本文研究了光柵相襯成像方法中基于探測(cè)器積分效應(yīng)的位移曲線在無分析光柵情況下的實(shí)驗(yàn)采集技術(shù),通過對(duì)于Talbot-Lau干涉儀中分析光柵作用的分析,得出了分析光柵的主要作用是分割自成像條紋和選擇積分區(qū)域,并由此得出在無分析光柵情況下,位移曲線產(chǎn)生的充分條件。通過實(shí)驗(yàn)驗(yàn)證了不同像素下位移曲線的存在性,在實(shí)測(cè)位移曲線的基礎(chǔ)上,研究了像素優(yōu)化讀出方法,并成功的對(duì)聚乙烯棒進(jìn)行了相位恢復(fù)。然后利用此方法對(duì)生物樣品(雞爪)進(jìn)行了成像實(shí)驗(yàn),最終獲得了比以往所發(fā)表過的論文中成像襯度更清晰且結(jié)構(gòu)信息更豐富的相襯圖像。利用此方法可以極大的縮短成像系統(tǒng)的長度,具有一定的實(shí)用性。
[Abstract]:X-ray phase contrast imaging technology is a hot spot in the field of X-ray research in recent years. It detects the change of phase after X-ray passing through an object to image an object. It overcomes the shortcoming that traditional absorption imaging can not image weakly absorbing objects, so it has high application value in medicine, nondestructive testing and materials science. The relatively mature phase contrast imaging methods mainly include crystal interferometry, diffraction enhancement, coaxial phase contrast imaging and raster-based phase contrast imaging, which are limited by light source and crystal. The requirements of crystal interferometry and diffraction enhancement are very high and the applicability is poor. Compared with coaxial phase contrast imaging and grating based phase contrast imaging, the requirements of light source and experimental equipment are lower. Coaxial contrast imaging is initially carried out on synchrotron emitter, but the time coherence of light source is not high. So it can also be carried out under the micro-focal X-ray source. The micro-focal spot source has good coherence, but because the focal spot is too small, so the luminous flux is very small. In order to solve the X-ray imaging. Because of the contradiction between the luminous flux and coherence of the light source, we use a focal spot as a linear X-ray source, which indirectly solves this problem. The linear focal spot source has good coherence in the wide direction on line. But there is no spatial coherence in the long direction of the line, and the details of the object in the long direction of the line will be lost, so we use the method of rotating the object to superposition the image of the object in multiple directions. In order to reconstruct the high-resolution image which can reflect the details of the object (chip), we compared the results with the results of micro-focal X-ray source coaxial imaging and large focal spot source imaging. The experimental verification based on linear focal spot source imaging is given in terms of coherence and flux. The phase contrast imaging method based on grating is presented. Up to now, Talbot-Lau and inverse Talbot-Lau methods have been developed, which require the grating to be high, so it is difficult to fabricate the grating. The inverse Talbot-Lau method is limited by the coherent length of the light source and the distance of the imaging system is very long. This paper studies the experimental acquisition technology of the displacement curve based on the integral effect of the detector in the grating phase contrast imaging method without analyzing the grating. Through the analysis of the effect of grating in Talbot-Lau interferometer, it is concluded that the main function of the analysis grating is to divide the image fringes and select the integral region. The sufficient conditions for the generation of displacement curves without analyzing gratings are obtained. The existence of displacement curves in different pixels is verified by experiments, on the basis of the measured displacement curves. The pixel optimization readout method is studied and the phase recovery of polyethylene rod is successfully carried out. Then the imaging experiment of biological sample (chicken claw) is carried out by using this method. Finally, a phase contrast image with clearer contrast and more abundant structure information is obtained, which can greatly shorten the length of the imaging system and has certain practicability.
【學(xué)位授予單位】：深圳大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O434.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 干慧菁;朱化鳳;陳建文;高鴻奕;李儒新;徐至展;朱佩平;王[鐫，

本文編號(hào)：1357854