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相比传统角膜曲率仪引入双像棱镜进行角膜屈光度的测量,提出一种新型的基于光标成像原理的角膜曲率仪光学系统,其结构紧凑,操作简单,具有满足要求的屈光度测量精度和测量范围。光学系统包括成像系统和照明系统两部分,成像系统由投影物镜、角膜、摄影物镜三部分构成,采用了外调焦方式;照明系统采用了柯勒照明方式,可以实现环形光标、角膜前表面和CCD接收器像面的均匀照明。成像系统的像面分辨率达到133lp/mm,畸变小于1%,角膜屈光度测量精度为0.25D(曲率半径测量精度0.02mm),测量范围为30～60D(曲率半径测量范围5.5～11mm)。设计结果表明,该系统在满足角膜屈光度测量精度高和测量范围广的前提下,有效地实现了结构紧凑,操作简单的目的。
Compared with the traditional corneal curvature instrument, the double prism is introduced to measure the corneal refractive power. A novel corneal curvature optical system based on the principle of cursor imaging is proposed, which has the advantages of compact structure, simple operation, and satisfying refractive index measurement accuracy and measuring range. The optical system consists of an imaging system and an illumination system. The imaging system consists of a projection objective, a cornea, and a photographic objective. The illumination system uses a Coke illumination method, which can realize a circular cursor, an anterior corneal surface, CCD receiver image plane uniform illumination. Imaging system resolution of 133lp / mm, distortion less than 1%, corneal refractive accuracy of 0.25D (curvature radius measurement accuracy of 0.02mm), the measurement range of 30 ~ 60D (radius of curvature measurement range of 5.5 ~ 11mm). The design results show that the system can effectively realize the objective of compact structure and simple operation under the premise of high precision of corneal refractive power measurement and wide measuring range.