光学精密工程2017，Vol.25Issue(3)：603-610,8.DOI:10.3788/OPE.20172503.0603
角膜地形图仪中Placido盘及投射照明系统的设计与实现
Design and implementation of Placido disk and projection lighting system for corneal topography
摘要
Abstract
In order to detect the cornel surface topography,a projection lighting system of corneal topography was designed based on Placido disk.Firstly,LED backlight was designed according to the visual spectral luminous efficiency of human eyes,the spectral response curve of CCD element and requirements for illumination and uniformity of the light source opposite to the instrument.Secondly,based on detection principles of corneal topography,the advantages and disadvantages of spherical Placido disk were compared with those of ellipsoidal Placido disk.Lighting conditions of the two Placido disks were analyzed in the backlight illumination.The analysis shows that the maximum irradiance of ellipsoidal Placido disc is larger than the sperical one.The mathematical model of the ellipsoidal disc was established with inverse extrapolation,thus the distributions of black and white loops on the disk were determined by solution with Matlah software.Finally,a ellipsoidal Placido disk was processed in terms of the design parameters.Furthermore,the experimental devices of projection and lighting were set up and then detected with the standard model eyes.Experimental results show that in the illumination of AlGalnP red LED area light source with dominant wavelength of 625 nm,white and black loops on CCD projected from achievable 24-ring ellipsoidal Placido disk meets the requirement of uniform distribution with equal interval.The detection precision can reach 0.05 m-1,meeting the requirements of high contrast and precision for projection lighting system of corneal topography.关键词
角膜地形图仪/投射照明系统/Placido盘/LED背光源Key words
corneal topography/projection lighting system/Placido disk/LED backlight分类
医药卫生引用本文复制引用
隋成华,沃圣杰,徐丹阳,高楠,张玉民..角膜地形图仪中Placido盘及投射照明系统的设计与实现[J].光学精密工程,2017,25(3):603-610,8.基金项目
浙江省重大科技专项资助项目(No.2011C11048) （No.2011C11048）
