瞳孔直径自动测量系统设计

Design of Automatic Measurement System for Pupil Diameter

为了实现瞳孔直径的高精度测量,设计了一种无损伤、非接触式瞳孔直径测量系统。首先介绍了低相干干涉原理,运用低相干干涉测量技术对人眼不同结构表面进行精确定位,确定角膜顶点到瞳孔表面之间的距离用于瞳孔直径参数测量。然后对瞳孔直径的测量原理进行分析,提出了包括自动阈值分割、形态学运算、连通域检测、最小二乘圆拟合等算法在内的瞳孔直径计算方法,设计了由成像模块、干涉模块和测量模块组成的实验样机。最后,对测量系统进行实际测试。通过实验表明,该测量系统的测量精度达到±0.02 mm。

In order to achieve high precision measurement of pupil diameter,a non-invasive,non-contact pupil diameter measurement system is designed.Firstly,the principle of low coherence interference is introduced.Using the low coherence interference measurement technology,the optical path difference between the reference arm and the measuring arm of interference signals reflected by different surfaces of the human eye is obtained,and the distance between the cornea vertex and the pupil surface is determined for the measurement of pupil diameter parameters.Then,the measurement principle of pupil diameter is analyzed,and the calculation method of pupil diameter including automatic threshold segmentation,morphological operation,connectivity detection,least square circle fitting and other algorithms is proposed.A prototype consisting of imaging module,interference module and measurement module is designed.Finally,the measurement system is tested.The experiment shows that,compared with the traditional pupil diameter measurement system,the measurement accuracy of this measurement system reaches±0.02 mm,meeting the functional requirements of the system.