Axelrod Jeremy J, Petrov Petar N, Zhang Jessie T, Remis Jonathan, Buijsse Bart, Glaeser Robert M, Mȕller Holger
Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA.
Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA.
bioRxiv. 2023 Feb 13:2023.02.12.528160. doi: 10.1101/2023.02.12.528160.
We identify thermal magnetic field fluctuations, caused by thermal electron motion ("Johnson noise") in electrically conductive materials, as a potential resolution limit in transmission electron microscopy with a phase plate. Specifically, resolution loss can occur if the electron diffraction pattern is magnified to extend phase contrast to lower spatial frequencies, and if conductive materials are placed too close to the electron beam. While our initial implementation of a laser phase plate (LPP) was significantly affected by these factors, a redesign eliminated the problem and brought the performance close to the expected level. The resolution now appears to be limited by residual Johnson noise arising from the electron beam liner tube in the region of the LPP, together with the chromatic aberration of the relay optics. These two factors can be addressed during future development of the LPP.
我们将导电材料中由热电子运动（“约翰逊噪声”）引起的热磁场波动确定为带有相位板的透射电子显微镜中的一个潜在分辨率限制。具体而言，如果电子衍射图案被放大以将相位对比度扩展到更低的空间频率，并且如果导电材料放置得离电子束太近，就会出现分辨率损失。虽然我们最初实施的激光相位板（LPP）受到这些因素的显著影响，但重新设计消除了该问题，并使性能接近预期水平。现在的分辨率似乎受到LPP区域中电子束衬管产生的残余约翰逊噪声以及中继光学系统的色差的限制。在LPP的未来发展过程中可以解决这两个因素。
