大口径干涉仪系统传递函数的修正和校准
Revision and calibration of system transfer function for large-aperture interferometer
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摘要: 采用子孔径拼接法对传统系统传递函数校准方法进行修正。将大口径干涉仪视场分成若干个等晕区,采用标准台阶相位比较法分别测得每个等晕区的传递函数,然后将大口径干涉仪系统传递函数修正为每个等晕区传递函数的加权平均,其权重因子由对应等晕区内测试面的功率谱决定。实验结果表明:中心视场对应传递函数和修正后的系统传递函数在3 mm-1附近处差值大于0.2;修正后的系统传递函数校准方法能更准确地得到波前功率谱密度。Abstract: The large-aperture interferometer can not be regarded as shift-invariant linear imaging systems since for it has different forms of point-spread function at different field positions. It is necessary to revise the calibration of system transfer function by the method of subaperture stitching. The large field is divided into many isoplanatic regions and the transfer function of each isoplanatic region is measured by standard phase step. Then the revised system transfer function can be expressed as the weight average of the transfer function of each isoplanatic region, whose weight depends on power spectrum of the actual test surface at the corresponding region. The experiment shows that the difference between the revised system transfer function and the zero-field transfer function is large
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