發(fā)布時間：2018-06-24 09:18

  本文選題：摻鉈碘化銫薄膜 + 抗潮解��； 參考：《電子科技大學》2017年碩士論文

【摘要】：閃爍體X射線探測器在醫(yī)用檢測和安檢等方面都有很重要的應用。而其中摻鉈碘化銫由于它的光學性能很好、成本低和易于生長等優(yōu)點成為了熱門的閃爍體材料。就材料本身而言,雖然摻鉈碘化銫性能出眾,但是由于它易潮解的特性,當它暴露在潮濕空氣中時會使得其光轉換性能下降,因此對抗潮解摻鉈碘化銫的研究就顯得非常重要;就閃爍體X射線探測器件而言,X射線經過閃爍體后轉化為發(fā)散的可見光并且由于閃爍體存在轉換效率,部分X射線會直接進入CCD并對CCD造成輻射損傷。因此需要設計光轉換組件來收集可見光信號及分離X射線與可見光。因此,本文從理論與實驗上研究了潮解對摻鉈碘化銫薄膜結構與性質的影響并且設計出針對摻鉈碘化銫薄膜的抗潮解方案,并對X射線探測器光轉換組件進行了設計及優(yōu)化。首先,本文從通過對摻鉈碘化銫薄膜傅里葉紅外光譜的測試,證實了其暴露于潮濕空氣中的潮解現(xiàn)象。然后研究了摻鉈碘化銫薄膜暴露于不同濕度的潮濕空氣對其結構以及熒光光譜的影響并分析了原因,結果表明摻鉈碘化銫薄膜暴露在相對濕度更高的潮濕空氣中更長時間,其光轉換性能下降越多。其次,針對摻鉈碘化銫薄膜易潮解的特性設計了多種抗潮解方案。最終選擇了鋁保護膜層、二氧化硅保護膜層以及氮化硅保護膜層作為摻鉈碘化銫薄膜的保護膜層。為了確保保護膜層能盡量地使得可見光信號透過,對三種保護膜層對可見光的透射圖譜做了仿真并設計了達到對目標波長光的高透過率需要的膜層具體厚度。最后運用磁控濺射法與PECVD技術制備了三種保護膜層,并測試分析了它們對摻鉈碘化銫薄膜的抗潮解效果,結果表明鋁抗潮解保護膜的綜合性能最好。之后,根據對X射線探測器光轉換組件設計的要求并通過成像計算公式計算得到了基礎光轉換組件的設計參數。根據設計參數在ZEMAX上搭建了基礎光轉換組件的光路圖并對基礎光轉換組件的成像質量進行了全面的評價。最后,由于設計的基礎光轉換組件的成像質量并不理想,利用ZEMAX建立合適的優(yōu)化函數對基礎光轉換組件的成像質量進行了優(yōu)化。雖然優(yōu)化后光轉換組件的綜合像差、波前光程差、像散等均有了較大的改善,但是彌散斑和衍射能力上仍存在較大不足。在受到三片式物鏡的啟發(fā)下對光轉換組件進一步優(yōu)化,設計出了三透鏡光轉換組件。在對優(yōu)化后的三透鏡光轉換組件的成像質量的評價中,發(fā)現(xiàn)其在各個方面均有了很大的改善,成像質量已經基本達到了要求。因此將使用這一優(yōu)化后的三透鏡光轉換組件設計作為實際光轉換組件設計的重要參考模型來完成后續(xù)的整體X射線探測器的設計。
[Abstract]:Scintillator X-ray detectors have important applications in medical detection and security inspection. Among them, thallium-doped cesium iodide has become a popular scintillator because of its good optical properties, low cost and easy growth. As far as the material itself is concerned, although the properties of thallium iodide doped cesium iodide are outstanding, it is very important to study the resistance of thallium iodide doped cesium iodide when exposed to moist air. As far as scintillator X-ray detector is concerned, X-ray is transformed into divergent visible light after it passes through scintillator. Because of the conversion efficiency of scintillator, some X-ray rays will enter CCD directly and cause radiation damage to CCD. Therefore, a light conversion module is needed to collect visible light signals and separate X-ray from visible light. Therefore, in this paper, the influence of tidal decomposition on the structure and properties of thallium-doped cesium iodide films is studied theoretically and experimentally, and the anti-moisture scheme for thallium-doped cesium iodide films is designed, and the X-ray detector photoconversion module is designed and optimized. Firstly, the FT-IR spectra of thallium iodide doped cesium iodide films are measured and the results show that they are exposed to moist air. Then the effects of thallium-doped cesium iodide film on the structure and fluorescence spectrum of the thin film exposed to moist air with different humidity were studied. The results show that thallium doped cesium iodide film is exposed to higher relative humidity in humid air for a longer time. The more the optical conversion performance decreases. Secondly, according to the characteristics of thallium iodide-doped cesium iodide film, a variety of anti-moisture solution schemes are designed. Finally, aluminum protective film, silica protective film and silicon nitride protective film are selected as the protective film of thallium-doped cesium iodide film. In order to ensure that the protective film can make the visible light signal pass through as much as possible, the transmission spectra of the visible light of the three protective coatings are simulated and the specific thickness of the film to achieve the high transmittance of the target wavelength light is designed. Finally, three kinds of protective coatings were prepared by magnetron sputtering and PECVD technique. The results showed that the comprehensive properties of the protective films were the best for thallium iodide doped cesium iodide films. After that, the design parameters of the basic optical conversion module are calculated according to the requirements of the design of the X-ray detector photoconversion module and the imaging calculation formula. According to the design parameters, the optical circuit diagram of the basic optical conversion module is built on ZEMAX and the imaging quality of the basic optical conversion module is evaluated comprehensively. Finally, because the imaging quality of the designed basic optical conversion module is not ideal, the imaging quality of the basic optical conversion module is optimized by using ZEMAX to establish an appropriate optimization function. Although the synthesis aberration, wavefront optical path difference and astigmatism of the optimized optical conversion module have been greatly improved, the diffusivity and diffractive ability are still largely inadequate. A three-lens optical conversion module is designed by optimizing the optical conversion module inspired by a three-slice objective lens. In the evaluation of the imaging quality of the optimized three-lens optical conversion module, it is found that it has been greatly improved in all aspects, and the imaging quality has basically met the requirements. Therefore, this optimized three-lens optical conversion module is used as an important reference model for the practical optical conversion module design to complete the subsequent design of the overall X-ray detector.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TL816.1;O484

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