【摘要】：角膜地形圖儀是現(xiàn)代眼科醫(yī)學(xué)檢測中重要的測量儀器，其主要用作人眼角膜表面形貌特征的定量檢測，可將眼角膜表面的形貌信息用數(shù)據(jù)或處理圖像的形式給出，為眼科醫(yī)生對角膜測量提供方便，普遍應(yīng)用與角膜病癥的檢查（如圓錐角膜），激光近視手術(shù)前的角膜形貌檢查，硬性透氣性隱形眼鏡（RGP）以及角膜塑形鏡（OK鏡）驗配時的角膜測量中。 本課題是基于placido盤的角膜地形圖儀開發(fā)中的角膜圖像采集部分的研究，主要包括：角膜圖像采集系統(tǒng)中CCD的選型及驅(qū)動設(shè)計、圖像采集系統(tǒng)中投射系統(tǒng)設(shè)計、角膜圖像采集系統(tǒng)光學(xué)系統(tǒng)設(shè)計與實現(xiàn)三個部分。本文將對以上三個部分分別進行探討。 針對角膜圖像采集要求，選用索尼公司ICX424AL面陣CCD作為圖像采集系統(tǒng)的圖像傳感器。分析了ICX424AL的驅(qū)動時序要求，在應(yīng)用高性能模擬前端處理芯片AD9949A和ALTERA公司的MAX2系列EPM240T100C5N共同為CCD提供驅(qū)動脈沖信號的基礎(chǔ)上，采用Verilog硬件描述語言實現(xiàn)驅(qū)動時序的邏輯設(shè)計，利用ALTERA公司的軟件QuartusⅡ軟件進行功能仿真，并針對EPM240T100C5N芯片進行了硬件適配，最終實現(xiàn)了對ICX424AL驅(qū)動設(shè)計。投射系統(tǒng)設(shè)計包括placido盤和背光源的設(shè)計，要實現(xiàn)角膜表面形貌的采集首先要使投射系統(tǒng)在人眼角膜上產(chǎn)生清晰、均勻、柔和的圓環(huán)像，為此對placido盤的結(jié)構(gòu)和制作工藝進行了深入的探討，并設(shè)計了背光源的電源驅(qū)動。 根據(jù)系統(tǒng)設(shè)計要求選用一種初始的光學(xué)透鏡結(jié)構(gòu)，用CODEV光學(xué)設(shè)計軟件對該光學(xué)結(jié)構(gòu)進行了優(yōu)化設(shè)計，實現(xiàn)了焦距為20mm，視場角20°，入瞳直徑為2mm的光學(xué)系統(tǒng)。 通過研制的角膜圖像采集系統(tǒng)對眼角膜圖像進行采集，placido盤在眼角膜上投射的同心圓環(huán)滿足了上位機對角膜圖像進行計算的精度要求。實現(xiàn)了對人眼角膜圖的清晰采集，采集圖像的分辨率為640（H）×480（V），圖像的采集速率為60fps，通過與意大利CSO型角膜地形圖儀中的圖像采集系統(tǒng)進行對比，證明設(shè)計的圖像采集系統(tǒng)達(dá)到了圖像處理軟件對角膜表面采樣點的提取要求。
[Abstract]:Corneal topography is an important measuring instrument in modern ophthalmological examination. It is mainly used for the quantitative detection of the surface morphology of human cornea. The topography information of the corneal surface can be given in the form of data or image processing. It is convenient for ophthalmologists to measure cornea. It is widely used in the examination of corneal diseases (such as keratoconus), and in the examination of corneal morphology before laser myopia surgery. (RGP) and OK were used to measure the cornea of rigid gas permeable contact lens. This subject is a part of corneal image acquisition in the development of corneal topography instrument based on placido disc. It mainly includes the selection and driving design of CCD in corneal image acquisition system, and the design of projection system in image acquisition system. The optical system of corneal image acquisition system is designed and implemented. The above three parts will be discussed in this paper. According to the requirement of corneal image acquisition, Sony ICX424AL array CCD is selected as the image sensor of the image acquisition system. The driving timing requirements of ICX424AL are analyzed. Based on the application of high performance analog front-end processing chip AD9949A and MAX2 series EPM240T100C5N of ALTERA Company to provide the driving pulse signal for CCD, the logic design of driving timing is realized by Verilog hardware description language. The software Quartus 鈪，

本文編號：2347353