CCD细分技术在望远系统出瞳直径与出瞳距离测量中的应用

Application of CCD subdivision technology in diameter and distance of exit pupil of telescope system

为解决某种望远系统的出瞳直径与出瞳距离的测量而专门设计并研制了一个测试系统。该系统采用了一种将CCD成像技术及计算机图像处理技术等技术相结合对望远系统的出瞳直径和距离进行测试的新方法。详细介绍了测试系统中图像预处理所采用的CCD像元细分技术,根据CCD的工作原理分析了CCD的像元细分技术,提出了一种基于相关双采样和D/A转换的变阈值二值化方法,叙述了变阈值二值化的细分原理的实现方法。实验证明:该系统的测量误差小于0.02mm,重复性精度为±0.02mm,出瞳直径及出瞳距离的测量范围为0～100mm。该方法可实现数字化测量,从而可消除传统测试方法的易疲劳、人为影响等诸多缺陷,提高了检测的准确度,使检测更为直观、明确。

One test system systems was specially designed for measurement of the exit pupil and manufactured. A new method diameter and distance of telescopic was presented that combines CCD imaging, computer image processing, and some other techniques. The image pre-processing method based on CCD subpixel technology used in the test system was introduced in detail in this paper. From the operation principle of CCD, its subpixel technology was analyzed. A kind of binary quantization method with a variable threshold that was based on double correlative sampling and D/A conversion was presented. The means for implementing the subpixel principle based on the variable threshold binary quantization was illustrated. Experimentally, it is shown that the measurement error of the system is less than 0.02 mm, its repeatability is ±0.02 mm, and the measurement of the exit pupil diameter and distance ranges from 0 to 100 mm. Since the measurement method is digital, the disadvantages such as easy fatigue of eyes and personal effect in conventional tests can be dispelled so that the test veracity is improved while the test is more straight forward and definite.