Contrast transfer function: Difference between revisions

Revision as of 22:56, 16 September 2015

Revision as of 19:49, 17 November 2015

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The contrast transfer function can also be given in terms of spatial frequencies, or reciprocal space. With the relationship <math display="inline">\theta =\lambda k</math>, the phase contrast transfer function becomes:

:<math>K(k) = sin[2\pi\lambda )W(k)]</math> <br /> <math>W(k) = -z\lambda k^2/2 + C_s\lambda^3 k^4</math>/4

<math>z</math> = the defocus of the objective lens (using the convention that underfocus is positive and overfocus is negative), <math>\lambda</math> = the relativistic wavelength of the electron wave, <math>C_s</math> = The [[spherical aberration]] of the objective lens, <math>k</math> = the spatial frequency (units of m⁻¹)