空间相机相关法实时检焦技术研究

Study of Real-time Autofocusing Technique Using Correlation Method for Space Camera

自动检调焦技术是保证空间相机拍摄出高质量图像的重要技术手段 ,本文介绍了一种自准直法实时检焦系统。该系统用两块小口径五棱镜代替其他空间相机常用的大平面反射镜 ,用半导体激光器做光源 ,用CCD作为光电转换器件 ,通过测量两光斑在CCD上的移动量 ,从而计算出离焦量。本文采用相关法处理数据 ,并通过合理选取阈值和数据拟和技术 ,实现了亚像素测量精度。该系统具有结构紧凑 ,稳定性好等特点 ,实验结果表明检焦分辨率≤ 10 μm。

Autofocusing technique is an important method to ensure the high quality image of space camera. In order to refocus the lens system in flight for space camera, a precise autofocussing system with auto collimatic method is introduced, in which two pentagonal prisms are substituted for a large mirror, a low power laser is used as the light source and CCD as photoelectric converting device. The resolution of the whole measuring system has been improved by use of the signal processing techniques such as correlation method, choosing threshold and data smoothing. The experiments show that the measuring resolution is less than 10μm. This system has compact structure and reliable properties.