角膜地形图仪中Placido盘及投射照明系统的设计与实现

发布时间：2018-03-07 01:18

本文选题：角膜地形图仪　切入点：投射照明系统　出处：《光学精密工程》2017年03期 　论文类型：期刊论文

【摘要】：为了实现检测角膜的表面形貌,设计了基于Placido盘的角膜地形图仪投射照明系统。首先,根据人眼的明视觉光谱光视效率、CCD元件光谱响应曲线以及仪器对面光源照度与发光均匀性的要求,进行了LED背光源设计。其次,根据角膜地形图仪检测原理,比较了球形和椭球形Placido盘的利弊,在背光源照明下分析了这两种面型Placido盘的光照情况。分析显示,椭球形Placido盘的最大辐照度优于球形盘。采用反向逆推法建立数学模型,利用Matlab软件求解确定了盘上黑白条纹环的分布。最后,根据上述设计参数进行了Placido盘加工,搭建了投影照明实验装置,并利用标准模型眼对所获得的投射照明系统进行检测。实验结果表明:在主波长为625nm的AlGalnP红色LED面光源照明的情况下,采用所设计的24环椭球型Placido盘成像到CCD上的黑白条纹环满足等间隔均匀分布的要求,检测精度可达到0.05m~(-1),较好地满足了角膜地形图仪对投射照明系统的高对比度、高精度的要求。
[Abstract]:In order to detect the surface morphology of cornea, the projection illumination system of corneal topography based on Placido disc is designed. According to the spectral response curve of LED component and the requirement of illumination and uniformity of light source on the other side of the instrument, the design of LED backlight source is carried out. Secondly, according to the detection principle of corneal topography, The advantages and disadvantages of spherical and ellipsoidal Placido disks are compared, and the illumination of these two surface Placido disks under backlight illumination is analyzed. The results show that the maximum irradiance of ellipsoidal Placido disks is better than that of spherical disks. The distribution of black and white stripe rings on the disk is determined by using Matlab software. Finally, according to the above design parameters, the Placido disk is machined, and the experimental device of projection illumination is built. The projective illumination system was detected by standard model eyes. The experimental results show that: the main wavelength of 625nm AlGalnP red LED surface illumination, Using the designed 24-ring ellipsoidal Placido disk to image the black and white stripe rings on CCD to meet the requirements of uniform distribution at equal intervals, the detection accuracy can reach 0.05mT-1, which can meet the requirements of high contrast and high precision of corneal topography for projection lighting system.
【作者单位】：浙江工业大学理学院;浙江工业大学计算机学院;
【基金】：浙江省重大科技专项资助项目(No.2011C11048)
【分类号】：TH786;R770.4

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