Walsh T M, Warner D N
Appl Opt. 1970 May 1;9(5):1097-104. doi: 10.1364/AO.9.001097.
An interferogram of the wavefront deformation to a flat wave caused by an aircraft or spacecraft window contains all the error contribution effects of the window. The interferogram may be analyzed to determine the slope of this wavefront at a given point, which yields the angular deviation to a line of sight through the point. The interferogram as used in this study is a two-dimensional photo representing the three-dimensional relationship of the transmitted wave relative to the flat reference wave. The progression from light to dark fringes is the progression of the third dimension normal to the photo, and the fringes are thus similar to contour lines on a topographic map. To demonstrate the ability to obtain interferograms, to analyze interferograms, and to achieve sufficient accuracy, an aircraft window and spacecraft window were studied in an experimental test. The deviations to a line of sight were derived from transmitted wave interferograms obtained in the laboratory and were also measured precisely by an autocollimator system. The standard deviation of the transmitted wave deviations derived from interferograms relative to directly measured deviations was 0.7 sec of arc, indicating that the transmitted wave interferogram method is a good tool for window error determination.
由飞机或航天器窗口导致的波前相对于平面波的变形干涉图包含了窗口所有的误差贡献效应。可以对该干涉图进行分析，以确定波前在给定点的斜率，这会得出通过该点的视线的角偏差。本研究中使用的干涉图是一张二维照片，它表示了透射波相对于平面参考波的三维关系。从亮条纹到暗条纹的变化是垂直于照片的第三维度的变化，因此这些条纹类似于地形图上的等高线。为了展示获取干涉图、分析干涉图以及达到足够精度的能力，在一次实验测试中对飞机窗口和航天器窗口进行了研究。视线偏差是从实验室获得的透射波干涉图中推导出来的，并且也通过自准直仪系统进行了精确测量。从干涉图得出的透射波偏差相对于直接测量偏差的标准偏差为0.7角秒，这表明透射波干涉图方法是确定窗口误差的一个良好工具。
