|
Circular Functions/Aperture Function in EMs
- Practical Electron Microscopy and Database -
- An Online Book -
|
https://www.globalsino.com/EM/
|
This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
|
=================================================================================
A point object produces a spherical wavefront with a uniform amplitude distribution. After passing through a system, the wavefront is cut by the circular edge of the aperture, and the distribution A(x,y) is given by a circular function defined by,
---------------- [3746a]
where,
ρ is the radius of the aperture.
If the system is an objective aperture in EMs, the circular function (sometimes called aperture function) is given by
---------------- [3746b]
where,
α -- The semi angle subtended by the objective aperture.
For practical HRTEM imaging, a sufficiently large objective aperture is normally used such that no loss of imaging information originates from the aperture and the effect of circular function, A(k), can be ignored.
|
=================================================================================
The book author (Dr. Liao) welcomes your comments, suggestions, and corrections, please click here for submission. You can click How to Cite This Book to cite this book. If you let Dr. Liao know once you have cited this book, the brief information of your publication will appear on the “Times Cited” page. This appearance can help advertise your publication.
|
|