Editing Electron microscope (section)

== Aberration corrected instruments ==
[[File:Stem1.JPG|thumb|Scanning transmission electron microscope equipped with a 3rd-order spherical aberration corrector]]
{{Main|Aberration-corrected transmission electron microscopy}}
Aberration-corrected transmission electron microscopy (AC-TEM) is the general term for electron microscopes where [[Electro-optics|electro optical]] components are introduced to reduce the [[Optical aberration|aberrations]] that would otherwise reduce the [[Image resolution|resolution]] of images. Historically electron microscopes had quite severe aberrations, and until about the start of the 21st century the resolution was limited, able to image the atomic structure of materials if the [[Atom|atoms]] were far enough apart.<ref>{{Cite journal |last=Smith |first=David J |date=1997-12-01 |title=The realization of atomic resolution with the electron microscope |url=https://doi.org/10.1088%2F0034-4885%2F60%2F12%2F002 |journal=Reports on Progress in Physics |volume=60 |issue=12 |pages=1513–1580 |doi=10.1088/0034-4885/60/12/002 |issn=0034-4885}}</ref> Around the turn of the century the electron optical components were coupled with computer control of the lenses and their alignment, enabling correction of aberrations. The first demonstration of aberration correction in TEM mode was by [[Harald Rose]] and [[Maximilian Haider]] in 1998 using a hexapole corrector, and in STEM mode by [[Ondrej Krivanek]] and Niklas Dellby in 1999 using a quadrupole/octupole corrector.<ref name=":12">{{Cite journal |last=Pennycook |first=S. J. |date=2012-12-01 |title=Seeing the atoms more clearly: STEM imaging from the Crewe era to today |url=https://www.sciencedirect.com/science/article/pii/S0304399112001076 |journal=Ultramicroscopy |series=Albert Victor Crewe Memorial Issue |volume=123 |pages=28–37 |doi=10.1016/j.ultramic.2012.05.005 |issn=0304-3991 |pmid=22727567}}</ref>

As of 2024 correction of geometric [[Spherical aberration|aberrations]] is standard in many commercial electron microscopes, and they are extensively used in many different areas of science.<ref>{{Cite book |last=Erni |first=Rolf |url=https://www.google.com/books/edition/Aberration_corrected_Imaging_In_Transmis/Gsw7DQAAQBAJ?hl=en&gbpv=0 |title=Aberration-corrected Imaging In Transmission Electron Microscopy: An Introduction (2nd Edition) |date=2015-03-23 |publisher=World Scientific Publishing Company |isbn=978-1-78326-530-5 |language=en}}</ref><ref>{{Cite journal |last=Rose |first=Harald |date=2006-07-01 |title=Aberration correction in electron microscopy |url=https://www.degruyterbrill.com:443/document/doi/10.1515/ijmr-2006-0143/html |journal=International Journal of Materials Research |language=en |volume=97 |issue=7 |pages=885–889 |doi=10.1515/ijmr-2006-0143 |issn=2195-8556}}</ref> Similar correctors have also been used at much lower energies such as for [[LEEM]] instruments.<ref>{{Cite journal |last1=Tromp |first1=R.M. |last2=Hannon |first2=J.B. |last3=Ellis |first3=A.W. |last4=Wan |first4=W. |last5=Berghaus |first5=A. |last6=Schaff |first6=O. |date=June 2010 |title=A new aberration-corrected, energy-filtered LEEM/PEEM instrument. I. Principles and design |url=https://linkinghub.elsevier.com/retrieve/pii/S0304399110000835 |journal=Ultramicroscopy |language=en |volume=110 |issue=7 |pages=852–861 |doi=10.1016/j.ultramic.2010.03.005 |pmid=20395048}}</ref>