Contrast transfer function

Typical contrast transfer function observed from an electron micrograph

The contrast transfer function is a type of optical transfer function that affects images collected in an transmission electron microscope. The contrast transfer function must be corrected in the images in order to obtain high resolution structures in three-dimensional electron microscopy, especially cryo-electron microscopy.

The oscillations of contrast transfer function has the form (not including the envelope function):

$CTF(r) = - sin{ \left( \frac{\pi}{2} C_s \lambda^3 r^4 + \pi f \lambda r^2 \right) }$

where r is the radius from the center of the image, C_s is the spherical aberration, λ is the wavelength of the electron beam (usually converted from the potential difference voltage) and f is the amount of defocus.^[1]

See also

• Contrast transfer function (CTF) correction

References

1. ^ Maxim V. Sidorov. "What Is CTF (Contrast Transfer Function)?". ctfExplorer. http://www.maxsidorov.com/ctfexplorer/webhelp/background.htm. Retrieved July 29, 2011. 

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