X‐ray near‐field speckle‐based phase‐sensing approaches provide efficient means of characterizing optical elements. Presented here is a theoretical review of several of these speckle methods within the framework of optical characterization, and a generalization of the concept is provided. As is also demonstrated experimentally in a parallel paper [Berujon, Cojocaru, Piault, Celestre, Roth, Barrett & Ziegler (2020), J. Synchrotron Rad.27, (this issue)], the methods theoretically developed here can be applied to different beams and optics and within a variety of situations where at‐wavelength metrology is desired. By understanding the differences between the various processing methods, it is possible to find and implement the most suitable approach for each metrology scenario.

中文翻译：

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X射线光学和使用随机调制的光束表征：理论

X射线基于近场散斑的相位感应方法提供了表征光学元件的有效方法。本文介绍的是在光学表征框架内对其中几种散斑方法的理论综述，并对概念进行了概括。正如在平行论文中的实验所证明的[Berujon，Cojocaru，Piault，Celestrere，Roth，Barrett＆Ziegler（2020），J。Synchrotron Rad。27，（本期）]，理论上在此开发的方法可以应用于不同的光束和光学器件，并且可以用于需要进行波长计量的各种情况。通过了解各种处理方法之间的差异，可以为每种计量方案找到并实施最合适的方法。