In this paper, a calibration method for a camera with focus-related intrinsic parameters based on the thin-lens model is proposed to realize highly accurate measurement for small objects with extended depth of field (DOF). It mainly solves inaccurate calibration and small DOF problems at high magnification of vision systems. The mathematical camera model, initial camera calibration based on the iterative radial alignment constraint (IRAC) and optimization strategy are presented. The effectiveness, accuracy and practicality of the proposed calibration method are verified by both simulations and experiments. The root mean square errors of measured points in the 3D world coordinates with the proposed calibration method decrease from 22.02 μm to 1.66 μm when the magnification of the vision system increases from 0.12× to 0.66×. With the proposed calibration method based on the thin-lens model, accurate measurement, extended DOF and low calibration workload can be achieved.

中文翻译：

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基于薄透镜模型的聚焦相关内在参数相机标定方法

本文提出了一种基于薄透镜模型的具有聚焦相关内在参数的相机标定方法，以实现对扩展景深（DOF）的小物体的高精度测量。它主要解决了视觉系统高倍放大时校准不准确和自由度小的问题。提出了数学相机模型，基于迭代径向对准约束（IRAC）的初始相机校准以及优化策略。通过仿真和实验验证了所提出校准方法的有效性，准确性和实用性。根均方误差与所提出的校准方法减少3D世界坐标测量点的从22.02微米至1.66微米当视觉系统的放大倍率从0.12倍增加到0.66倍时。利用所提出的基于薄透镜模型的校准方法，可以实现准确的测量，扩展的自由度和较低的校准工作量。