为获得均匀光照，提高视觉测量系统图像的品质，对前置对称安装的矩形发光二极管(LED)光源布置问题进行了研究。考虑到解析法要求光轴与辐照面法线平行，提出采用优化的方法布置光源。根据光源的结构特征，以方差作为主要指标，建立优化目标函数。考虑到目标函数的非凸性，采用模拟退火算法（SA）对问题进行求解。搭建实验平台对照度分布进行了测量，考察均匀度在95%以上的区域，优化方法的结果与实验结果基本一致，误差在4%以内。结果表明，确定的优化目标合理，提出的光源优化布置方法有效。

Positioning of forward symmetrically installed square light-emitting diode (LED) arrays are studied to achieve uniform illumination with which high quality images can be gathered for machine vision measurement. The optimization method is used to solve this problem because the optical axes of the arrays are not perpendicular to the irradiated plane, which can′t be solved by analytic method. The variance is chosen to establish the mathematical model of goal function on the base of the structure characteristics of LEDs. The simulated annealing (SA) algorithm is chosen for solving the non-convex objective function. An experiment system is developed for illumination photometry. The sizes of area with 95% of uniformity of the analytic method are a little larger than those of the optimization based method. The maximum difference is within 4%. The results show that the optimization objective is reasonable and the method is feasible.