【摘要】：通過視網(wǎng)膜微血管形態(tài)檢查可以早期診斷內(nèi)分泌疾病。但是，由于人眼像差的存在，使臨床所用檢眼鏡的分辨率大幅下降，不能直接看到10μm以下的微細(xì)血管。自適應(yīng)光學(xué)技術(shù)能夠?qū)崟r補(bǔ)償人眼像差，得到接近衍射極限的視網(wǎng)膜視覺細(xì)胞圖像，但對視網(wǎng)膜微細(xì)血管成像時還存在一些問題。本論文針對準(zhǔn)確定位微細(xì)血管困難、圖像對比度難以達(dá)到臨床要求等問題，結(jié)合人眼的光學(xué)特性，進(jìn)行了一系列光學(xué)系統(tǒng)的創(chuàng)新設(shè)計(jì)。 采用視標(biāo)盯視方法進(jìn)行眼底方位定位。根據(jù)人眼焦深、調(diào)節(jié)誤差、視覺銳度和對顏色的敏感度，設(shè)計(jì)視標(biāo)的位置、形狀、照明波長等：確定眼前1D處的視標(biāo)滿足準(zhǔn)確性、普適性的要求；設(shè)計(jì)馬耳他十字視標(biāo)，調(diào)節(jié)支臂可滿足不同視力的人眼盯視；采用人眼最敏感的綠光照射視標(biāo)，有利于提高人眼盯視能力。根據(jù)視網(wǎng)膜結(jié)構(gòu)，定位方法分三步：1）選擇小凹中心為定位的基準(zhǔn)，2）橫向定位之后，按照系統(tǒng)放大倍率，將成像相機(jī)進(jìn)行軸向位移，聚焦到位于視網(wǎng)膜內(nèi)部幾層的血管，3）找到較粗血管后，可沿血管走勢有意識控制橫向定位，直至尋找到10μm以下微細(xì)血管。 設(shè)計(jì)了具有微細(xì)血管搜尋定位的自適應(yīng)光學(xué)成像系統(tǒng)。根據(jù)視網(wǎng)膜血管的吸收波長，，確定了高對比度視網(wǎng)膜血管的成像方法：1）先用785nm紅外光搜尋，以避免綠光長時曝光對人眼的強(qiáng)烈刺激，2）再使用561nm綠光數(shù)毫秒曝光成像。 通過理論計(jì)算得到具體的有利于提高對比度的途徑。利用血液與周圍組織結(jié)構(gòu)偏振性的差異，設(shè)計(jì)液晶偏振自適應(yīng)光學(xué)系統(tǒng)，利用微細(xì)血管的消偏光成像，對比度達(dá)到0.25，較原來提高約1.2倍。針對實(shí)際光路中由于光學(xué)器件的加工和光學(xué)系統(tǒng)裝調(diào)中的誤差，極限分辨率遠(yuǎn)遠(yuǎn)達(dá)不到理想設(shè)計(jì)值的問題，設(shè)計(jì)簡易化自適應(yīng)光學(xué)系統(tǒng)，大大減少所使用的光學(xué)元器件的個數(shù)。在保證系統(tǒng)校正功能的基礎(chǔ)上，提高了系統(tǒng)的能量利用率和調(diào)制傳遞函數(shù)。利用圖像配準(zhǔn)與疊加消除噪聲以提高對比度，使得獲得的圖像具有更高的臨床使用價(jià)值。
[Abstract]:Early diagnosis of endocrine diseases can be made by microvascular morphology of retina. However, due to the existence of human aberration, the resolution of ophthalmoscope used in clinic is greatly reduced, and the fine blood vessels below 10 渭 m can not be seen directly. Adaptive optics can compensate human eye aberration in real time and obtain retinal visual cell images close to the diffraction limit. However, there are still some problems in retinal microvascular imaging. In this paper, a series of innovative design of optical system is carried out based on the optical characteristics of human eyes in view of the difficulty of accurately locating fine blood vessels and the difficulty of image contrast meeting the clinical requirements. The eye fundus orientation was carried out by using the method of visual standard staring. According to the depth of human eye focus, adjustment error, visual acuity and sensitivity to color, design the position, shape, lighting wavelength, etc.; determine that the visual standard at 1D in front meets the requirements of accuracy and universality; design the Maltese cross visual standard, Adjusting the supporting arm can satisfy the different visual acuity of human eyes, and using the most sensitive green light to illuminate the visual standard is helpful to improve the ability of human eyes to stare. According to the structure of the retina, the localization method is divided into three steps: 1) selecting the fovea center as the datum for the location, 2) after the lateral positioning, the imaging camera is rotated in axial direction according to the magnification rate of the system. Focusing on the vessels located in several layers of the retina, 3) after finding the thicker vessels, we can consciously control the lateral orientation along the trend of the vessels until we find the microvessels below 10 渭 m. An adaptive optical imaging system with micro vascular search and location is designed. According to the absorption wavelength of retinal vessels, the imaging methods of high contrast retinal vessels were determined as follows: 1) search with 785nm infrared light first to avoid strong stimulation of human eyes by long exposure of green light, 2) then use 561nm green light in millisecond exposure imaging. Through theoretical calculation, a specific way is obtained to improve the contrast. Based on the polarization difference between blood and surrounding tissue structure, a liquid crystal polarization adaptive optical system is designed. The contrast is 0.25, which is about 1.2 times higher than that before, using depolarizing imaging of fine blood vessels. In order to solve the problem that the limit resolution is far from the ideal design value due to the processing of optical devices and the errors in optical system installation in the practical optical path, a simplified adaptive optical system is designed, which greatly reduces the number of optical components used. On the basis of ensuring the correction function of the system, the energy utilization ratio and modulation transfer function of the system are improved. Image registration and superposition are used to eliminate noise in order to improve the contrast and make the images have higher clinical value.
【學(xué)位授予單位】：中國科學(xué)院研究生院(長春光學(xué)精密機(jī)械與物理研究所)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：O439;R774.1

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