长基线干涉仪测量中由延迟和二向衰减引起的偏差
Biases induced by retardance and diattenuation in the measurements of long-baseline interferometers
AI总结：
本文推导了光学干涉仪中由延迟和二向衰减引起的条纹对比度与可见度相位偏差的理论表达式，分析了不同偏振光下的偏差性质，指出天体测量偏差取决于偏振特性与(u,v)采样，并在特定条件下提出校准方法。
摘要：
本文推导了光学干涉仪中条纹对比度和条纹可见度相位偏差的理论表达式，该干涉仪的偏振特性可通过光束旋转、延迟和二向衰减来描述。针对自然光、圆偏振和线偏振以及部分偏振光，讨论了这些偏差的性质。获得了针对小偏振度、小微分延迟和小二向衰减的展开式。条纹对比度的偏差已知。本文表明，延迟和二向衰减也是可见度相位及导出量的偏差来源。在某些情况下，偏差为零。如果延迟是无色差的，则微分相位不受影响。对于具有弱二向衰减和弱微分延迟的干涉仪，以及中等偏振源，无论光的类型如何，闭合相位都不受二阶影响。否则，需要校准程序。结果表明，在一般情况下天体测量测量存在偏差。该偏差既取决于干涉仪的偏振特性，也取决于(u,v)采样。在样本对齐于穿过空间频率平面原点的直线这一极端情况下，偏差是不确定的，并且可以任意大。在所有其他情况下，如果已知干涉仪的偏振特性，则可以对其进行校准。在低微分延迟和低偏振度的情况下，偏差位于一条穿过天体测量参考点的直线上。如果线偏振度在观测期间发生变化，则天体测量偏差具有显著特征，它描绘了该直线的一段。对于轻微偏振的干涉仪，会增加一个固定偏移量而不改变偏差的形状。
英文摘要：
I derive in this paper theoretical expressions for biases on fringe contrast and fringe visibility phase for optical interferometers whose polarizing properties can be described by beam rotation, retardance, and diattenuation. The nature of these biases is discussed for natural light, circular and linear polarization, and partially polarized light. Expansions are obtained for small degrees of polarization, small differential retardance, and small diattenuation. The biases on fringe contrasts are already known. It is shown in this paper that retardance and diattenuation are also sources of bias on the visibility phases and derived quantities. In some cases, the bias is zero. If the retardance is achromatic, differential phases are not affected. Closure phases are not affected to the second order for an interferometer with weak diattenuation and weak differential retardance and for moderately polarized sources whatever the type of light. Otherwise, a calibration procedure is required. It is shown that astrometric measurements are biased in the general case. The bias depends on both the polarization properties of the interferometer and on the (u,v) sampling. In the extreme case where the samples are aligned on a line crossing the origin of the spatial frequency plane, the bias is undetermined and can be arbitrarily large. In all other cases, it can be calibrated if the polarizing characteristics of the interferometer are known. In the case of low differential retardance and low degree of polarization, the bias lies on a straight line, crossing the astrometric reference point. If the degree of linear polarization varies during the observations, then the astrometric bias has a remarkable signature, which describes a section of the line. For slightly polarizing interferometers, a fixed offset is added without changing the shape of the bias.
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