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Phase detection limits in off-axis electron holography from pixelated detectors: gain variations, geometric distortion and failure of reference-hologram correction
Microscopy ( IF 1.8 ) Pub Date : 2020-08-03 , DOI: 10.1093/jmicro/dfaa044
Martin Hÿtch 1 , Christophe Gatel 1
Affiliation  

We investigate the effect that recording off-axis electron holograms on pixelated detectors, such as charge-coupled devices (CCD) and direct-detection devices (DDD), can have on measured amplitudes and phases. Theory will be developed for the case of perfectly uniform interference fringes illuminating an imperfect detector with gain variations and pixel displacements. We will show that both these types of defect produce a systematic noise in the phase images that depends on the position of the holographic fringes with respect to the detector. Subtracting a reference hologram from the object hologram will therefore not remove the phase noise if the initial phases of the two holograms do not coincide exactly. Another finding is that pi-shifted holograms are much less affected by gain variations but show no improvement concerning geometric distortions. The resulting phase errors will be estimated and simulations presented that confirm the theoretical developments.

中文翻译:

像素化探测器离轴电子全息的相位检测极限:增益变化、几何失真和参考全息图校正失败

我们研究了在像素化检测器(如电荷耦合器件 (CCD) 和直接检测器件 (DDD))上记录离轴电子全息图对测量幅度和相位的影响。将针对完美均匀的干涉条纹照射具有增益变化和像素位移的不完美检测器的情况发展理论。我们将证明这两种类型的缺陷都会在相位图像中产生系统噪声,这取决于全息条纹相对于检测器的位置。因此,如果两个全息图的初始相位不完全重合,则从物体全息图中减去参考全息图将不会消除相位噪声。另一个发现是 pi 位移全息图受增益变化的影响要小得多,但在几何失真方面没有改善。将估计由此产生的相位误差并提供模拟以确认理论发展。
更新日期:2020-08-03
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