一种航摄相机纵走式焦平面快门研究

发布时间：2018-05-14 00:43

本文选题：电磁纵走式焦平面快门 + 曝光时间　；参考：《长春理工大学》2016年博士论文

【摘要】：航空相机快门作为控制成像曝光时间的主要部件,是决定成像质量的关键要素,在航空成像需求的牵引下发展日益成熟,随着相机成像器件的不同要求,形成了多种快门技术。我国由于发展起步较晚,与国外相比还有较大差距,尤其表现在面阵CCD相机对焦平面快门的需求,实际上,焦平面快门已经成为制约面阵CCD相机发展的瓶颈。根据快门在相机光学系统中安装位置和运动特点不同可分为物镜快门和焦平面快门两类。本文针对某面阵CCD航空相机技术指标要求,研制一种电磁纵走式焦平面快门,解决了大面阵CCD航空相机高频大幅面快门难题,快门频率达到每秒3帧,快门最短曝光时间1/500秒,曝光均匀性优于10%。该快门具有体积小、幅面宽(48mm×36mm)、频率高、寿命长等特点,且具备自动上紧、自动释放、自动调节曝光时间等功能,该快门主要由前帘、后帘两组叶片组成,每组包括四片叶片,曝光时通过前帘、后帘叶片组边缘形成的曝光狭缝使感光介质曝光。对本文研究的快门,其结构参数、驱动弹簧参数对快门的运动特性影响较大,直接决定了快门的曝光时间、曝光均匀性等性能,本文推导了快门叶片运动数学模型,快门曝光时间数学模型,并通过仿真分析给出了相机整个成像幅面内各位置快门曝光时间分布情况及通光效率,同时,通过Abaqus软件对快门叶片进行了动力学分析,模拟了快门叶片的运动过程,对快门叶片运动数学模型进一步验证,分析了快门叶片在运动过程中的应力变化情况,对叶片的易损部位进行了预测,为快门结构设计、参数优化、修改完善提供了理论依据。为分析电磁纵走式焦平面快门曝光过程对光学系统传递函数的影响,通过codeV软件分析了快门曝光过程中成像幅面内不同位置光学系统的静态传函,照度变化,以及快门运动对传递函数的影响,分析表明,快门帘尽可能的靠近像面,增大帘缝式快门的缝宽,提高快门移动速度可减小快门运动对传递函数的影响。论文分析了快门帘缝在曝光运动过程中对成像畸变的影响,结合帘缝式快门的工作特点,阐述相机成像畸变是由于像移补偿残差的存在及帘缝式快门分时曝光成像导致的,推导出相机在无姿态角变化时,相机在垂直、侧倾、前倾三种成像方式下及相机存在姿态角时像面上各点像移补偿速度残差及畸变量数学模型,并通过MATLAB仿真给出了在相机整个成像幅面内各位置像移补偿速度残差分布情况及畸变分布情况。最后,通过快门曝光时间测试试验和成像畸变测试试验,对快门的曝光时间进行测试,并对论文分析方法及结果进行验证,试验结果表明快门性能指标满足相机的使用要求。
[Abstract]:The aerial camera shutter, as the main component of controlling the imaging exposure time, is the key factor to determine the imaging quality. With the development of the aerial imaging demand, the shutter technology has been formed with the different requirements of the camera imaging device. Due to the late start of development in China, there is still a big gap compared with foreign countries, especially in the demand of focal plane shutter for planar CCD camera. In fact, focal plane shutter has become a bottleneck restricting the development of plane array CCD camera. The shutter can be divided into objective shutter and focal plane shutter according to the position and motion characteristics of the shutter in the camera optical system. According to the technical requirements of a certain plane array CCD aerial camera, a kind of electromagnetic longitudinal traveling focal plane shutter is developed, which solves the problem of high frequency and large format shutter for large plane array CCD aerial camera. The shutter frequency reaches 3 frames per second, and the shortest exposure time of the shutter is 1 / 500 seconds. The uniformity of exposure is better than that of 10. The shutter has the characteristics of small volume, wide width of 48mm 脳 36mm / m, high frequency and long service life. The shutter has the functions of automatic tightening, automatic release and automatic adjustment of exposure time. The shutter is mainly composed of two groups of blades: front curtain and rear curtain, each group includes four blades. Exposure through the front curtain, rear curtain blade group edge of the exposure slit to expose the photosensitive medium. For the shutter studied in this paper, its structural parameters and drive spring parameters have a great influence on the shutter motion characteristics, which directly determine the shutter exposure time, exposure uniformity and other properties. In this paper, the mathematical model of shutter blade motion is derived. The mathematical model of shutter exposure time is given, and the distribution of shutter exposure time and optical efficiency in every position of the camera is given through simulation analysis. At the same time, the dynamic analysis of shutter blade is carried out by Abaqus software. The movement process of the shutter blade is simulated, the mathematical model of the shutter blade motion is further verified, the stress change of the shutter blade during the movement process is analyzed, the vulnerable position of the shutter blade is predicted, and the shutter structure is designed. Parameter optimization and modification provide theoretical basis. In order to analyze the influence of electromagnetic longitudinal focal plane shutter exposure process on the transfer function of optical system, the static transmission function and illumination change of optical system at different positions in imaging format during shutter exposure are analyzed by codeV software. The effect of shutter motion on the transfer function is analyzed. It is shown that the shutter movement can reduce the effect of shutter motion on the transfer function by increasing the width of the slit shutter and increasing the speed of shutter movement. This paper analyzes the influence of the fast door shutter on the imaging distortion in the course of the exposure movement. Combined with the working characteristics of the shutter, the paper expounds that the imaging distortion of the camera is caused by the residual error of the image compensation and the time-sharing exposure imaging of the shutter. A mathematical model of the velocity residuals and distortion compensation of each point on the camera image plane under the three imaging modes of vertical tilting and forward tilting and when the camera has attitude angle is derived when the camera has no attitude angle. The residual distribution and distortion distribution of the image compensation velocity in the whole imaging area of the camera are given by MATLAB simulation. Finally, the shutter exposure time is tested by the shutter exposure time test and the imaging distortion test, and the analysis method and the results are verified. The test results show that the shutter performance meets the requirements of the camera.
【学位授予单位】：长春理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：V245.6

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