变基线综合孔径望远镜基线测量方法的研究

The technique of synthetic aperture telescope takes use of multiple telescopes to collect light and making cophasing imaging to achieve the high resolution of large aperture telescope. It could not only reduce the difficulty and risk of building large aperture telescope, but also could diminish the lunch weight and volume, thus it exhibits significant potential in astronomy observation and earth remote detection..Based on the testbed of synthetic aperture telescope we have built, this work would perform researches on the relative methods and techniques of baseline-changed synthetic aperture telescope. A theoretical model would be derived for predicting the relation of the pupil mapping error and the actual imaging quality, from which we could determine the requirement on the accuracy of baseline measurement, and some relative simulations and experiments would be conducted for validation. Then, two different baseline measurement methods would be present and adopted, one is based on the central circle fitting of diffraction rings from the screen imaging, and the other is based on the spatial frequency of the cophasing interferogram. The uncertainty of two methods would be analyzed, and then a serious of contrast would also be performed correlating with the measurement speed, dynamic range, noise sensitivity, complexity and in-situ measurement capability, for optimizing the superb method. And finally, the optimized method would be used for calibration of baseline’s position, for using the signal of electric sensors to realize dynamic measurement.

综合孔径望远镜采用多个望远镜收集光线并进行合光成像以达到大口径望远镜的分辨能力，不仅可以有效降低大口径望远镜制造难度和风险，还可以降低空间望远镜的发射重量和体积，因此在未来的天文观测、对地观测等领域具有重要的应用前景。.本课题拟基于实验室建成的综合孔径望远镜原理样机，开展变基线综合孔径望远镜相关技术和方法的研究，首先建立成像视场与基线映射偏差的理论关系模型，以此确定基线测量精度需求，并进行物理光学仿真验证和基于原理样机的实验验证；然后分别提出并采用基于投射光屏成像衍射环圆心拟合法和基于合光成像干涉条纹空间频率的方法对点光源成像的基线进行精密测量；之后进行测量不确定度分析，并从测量速度、测量动态范围、噪声敏感度、光路复杂程度、在位测量可行性等方面分析和对比两种方法的优缺点，择优并进一步优化，最后采用优化方法对基线数据进行标定，以采用电子学器件实现动态实时测量。

项目背景：综合孔径望远镜采用多个望远镜收集光线并进行合光成像以达到大口径望远镜的分辨能力，不仅可以有效降低大口径望远镜制造难度和风险，还可以降低空间望远镜的发射重量和体积，因此在未来的天文观测、对地观测等领域具有重要的应用前景。.主要研究内容：首先建立了成像视场与子望远镜放大率一致性和基线映射偏差对合成孔径成像视场的理论关系模型，然后进行了基于ASAP的物理光学仿真验证，得到存在子望远镜放大率公差和基线映射公差下不同视场成像效果，验证了理论模型有效性。然后提出投射光屏成像衍射环圆心拟合法和干涉条纹空间频率法对点光源成像的基线进行测量，后者精度可达到百微米量级；又提出了一种基于点阵光源的基线映射误差测量方法，通过不同视场上点光源的成像计算得到光程差的斜率拟合得到基线的映射误差，可以达到10微米量级的测量精度，满足合成孔径系统基线映射误差测量需求，并进行了实验测试，得到现有系统经过长时间放置后，基线映射误差在200微米量级。最后，分析了多种基线映射误差的测量方法，确定了采用干涉条纹空间频率的方法进行粗调，并采用基于点阵光源的基线映射误差测量方法作为精调的测量方案。.重要结果：(1) 子望远镜的放大率公差和基线映射公差对合成孔径干涉成像视场有线性影响关系；(2) 通过干涉条纹空间频率的方法进行基线的粗调，精度达到百微米量级；(3) 采用基于点阵光源的基线映射误差测量方法进行精调，精度可达十微米量级，满足应用需求。.关键数据：以现有样机参数为例：(1)子望远镜放大率需要达到0.2%；(2) 基线映射误差达到41.24μm；(3)基于点阵光源的基线映射误差测量方法可以达到11.5μm的测量精度，满足合成孔径系统的基线映射误差的测量需求。.科学意义：本课题基于实验室建成的综合孔径望远镜原理样机，开展变基线综合孔径望远镜相关技术和方法的研究，对未来变基线合成孔径的空间化应用提供了可靠的技术支撑。