为了能精确得到被测物体的几何参数,设计了一种采集物体图像的双远心光学系统,并通过数字图像处理技术对物体尺寸进行测量。用Zemax对系统进行优化,分析了系统的像差和传递函数,所设计系统的工作距离大于74 mm,物方视场直径达到80 mm,畸变小于0.11%,CCD全视场190 lp/mm处传递函数大于0.3。分析了光学系统的放大倍率稳定性和测量误差,并对小零件进行了测量,测量误差在允许的范围内,符合测量要求。

In order to accurately get the geometric parameters of an object, we designed a bilateral telecentric optical system to collect images of the object and measured the size of object by digital image processing techniques. We used Zemax to optimize the system, analyzed the aberration of the image and the transfer function of the system. The system had a long working distance which was greater than 74 mm. The field-of-view was 80 mm. The largest distortion was less than 0.11 percent and MTF was larger than 0.3 at 190 lp/mm for full field region of the CCD sensor. We analyzed the stability of the magnification and measurement deviation, and measured the small parts. The deviation was in the required range.