Contrast transfer function: Difference between revisions

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[[Image:Contrast transfer function.jpg|thumb|Typical contrast transfer function observed from an electron micrograph]]

The '''contrast transfer function'''<ref name=":0">{{Cite journal|url = http://www.sciencedirect.com/science/article/pii/0304399192900118|title = A brief look at imaging and contrast transfer|last = Wade|first = R. H.|date = October 1992|journal = Ultramicroscopy|doi = 10.1016/0304-3991(92)90011-8|pmid = |access-date = |volume=46|pages=145–156}}</ref><ref name="Spence1982">Spence, John C. H. (1988 2nd ed) ''Experimental high-resolution electron microscopy'' (Oxford U. Press, NY) ISBN 0195054059.</ref><ref name="Reimer97">Ludwig Reimer (1997 4th ed) ''Transmission electron microscopy: Physics of image formation and microanalysis'' (Springer, Berlin) [http://books.google.com/books?id=3_84SkJXnYkC preview].</ref><ref name="Kirkland1998">Earl J. Kirkland (1998) ''Advanced computing in electron microscopy'' (Plenum Press, NY).</ref> mathematically describes how aberrations in a [[transmission electron microscope]] modify the image of a sample. This '''contrast transfer function''' '''(CTF)''' sets the resolution of '''[[High-resolution transmission electron microscopy|High-Resolution Transmission Electron Microscopy (HRTEM)]],''' also known as phase contrast TEM.

By considering the recorded image as a CTF-degraded true object, describing the CTF allows the true object to be reverse-engineered. This is typically denoted CTF-correction, and is vital to obtain high resolution structures in three-dimensional electron microscopy, especially [[cryo-electron microscopy]]. Its equivalent in light-based optics, is the [[optical transfer function]].