【作者】 于秋水；

【导师】 安志勇；

【作者基本信息】 长春理工大学 ， 仪器科学与技术， 2011， 博士

【摘要】 作为数字成像系统的关键技术之一,自动调焦技术发展迅猛,已广泛应用在照相机领域中并获得不断更新和完善,然而应用在测量仪器中还存在一定的局限性。在轻武器光学瞄具性能参数测试系统中,当CCD摄像系统倍率很高、焦距很短时,焦点便会出现模糊现象。为了获取清晰的分划板图像,进行准确调焦是性能参数测试的第一步,它是保障测量精度的前提和基础,因而具有至关重要的作用。本文在查阅大量关于自动调焦技术的国内外参考文献和资料的基础上,充分探讨了光学系统成像的基本原理,认真分析了基于图像处理的自动调焦的各个环节,深入研究了调焦评价函数、调焦窗口的选择以及自动调焦反馈控制这三个关键技术。在充分研究基于图像处理技术的光电自动调焦系统的工作原理的基础上,结合轻武器光学瞄具光学系统性能参数测试的基本要求,设计了一套基于图像处理技术的自动调焦系统。在该系统中,通过分析研究常用图像清晰度评价算法,对基于阈值的最大梯度平方和算法进行了改进,其结果提高了计算精度；通过分析研究离焦深度法和对焦深度法,提出了二者相结合的新的自动调焦法,充分利用离焦深度法速度快和对焦深度法精度高的优势,提高了自动调焦的效果。本论文首次把上述研究成果应用于轻武器光学瞄具光学系统性能参数测试中。通过反复实验证明,该自动调焦系统性能稳定,精度高,实时性较好,提高了轻武器光学瞄具光学系统性能参数的测量精度和效率,具有很好的实用价值。更多还原

【Abstract】 Auto-focusing technique, one of the key technologies in digital imaging system is developed rapidly which is employed in the cameras of all grades. The technique is updated and improved continually.However, the technique has some limitations in the measurement instruments. In the small arm optical sighting performance parameter testing system, the focus will be blurred when the CCD camera system magnification is high and the focal length is short. So the focusing accurately is very important, which is the first step of the testing to obtain the clear reticule pattern and guarantee the precision measurement.On the basis of a large number of domestic and international documents on auto-focusing technique, the paper fully explores the basic principle of the optical imaging system, carefully analyzes each link of the auto-focusing which is based on image processing and deeply researches the three key techniques, focusing evaluation function, focusing window selection and auto-focusing feedback control.On the basis of full research on the working principle of the photoelectric auto-focusing system, an auto-focusing system based on image processing is designed in this paper according to the basic requirements of the optical sighting performance parameter testing of small weapons. In this system, through the performance comparison of some image analysis operators, the maximum gradient squares algorithm based on threshold is improved. As a result,the computational accuracy is raised greatly. Through the analysis of Depth From Defocus and Depth From Focus,a new auto-focusing algorithm combining both algorithm is presented. It fully uses the high speed of Depth from defocus and the high accurate of Depth from Focus. The effect of Auto-focusing has a statistically significant increase.The conclusions of above researches are applied in the optical sighting performance parameter testing of small weapons for the first time. Experiments have repeatedly established that this auto-focusing system has stable performance、high precision and good real-time property. The precision and efficiency of the optical sighting performance parameter testing of small weapons are improved greatly. So this system has high practice value.更多还原