Topic
Contrast transfer function
About: Contrast transfer function is a research topic. Over the lifetime, 934 publications have been published within this topic receiving 26533 citations.
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TL;DR: In this paper, the effect of contrast transfer function (CTF) imposition on two-dimensional crystals of Rous sarcoma virus capsid protein has been investigated, showing that the morphology of the crystal in calculated projection maps from incorrect CTF imposition was utterly distorted in comparison to an appropriately CTF-corrected image.
Abstract: Transmission electron microscopy (TEM) is an excellent tool for studying
detailed biological structures. High-resolution structure determination is
now routinely performed using advanced sample preparation techniques and
image processing software. In particular, correction for contrast transfer
function (CTF) is crucial for extracting high-resolution information from
TEM image that is convoluted by imperfect imaging condition. Accurate
determination of defocus, one of the major elements constituting the CTF, is
mandatory for CTF correction. To investigate the effect of correct estimation of image defocus and
subsequent CTF correction, we tested arbitrary CTF imposition onto the
images of two-dimensional crystals of Rous sarcoma virus capsid protein. The
morphology of the crystal in calculated projection maps from incorrect CTF
imposition was utterly distorted in comparison to an appropriately
CTF-corrected image. This result demonstrates critical importance of CTF correction for producing
true representation of the specimen at high resolution.
2 citations
23 May 2012
2 citations
TL;DR: T theoretical estimates of the mean coefficients of spherical and chromatic aberration for low energy photoemission electron microscopy (PEEM) are presented to allow more precise correction of aberration in PEEM in experimental situations where the aberration coefficients and precise electron energy distribution cannot be readily measured.
2 citations
2 citations
01 Jan 1994
TL;DR: In this paper, the authors discuss the principle of bright-field imaging and a drawback of the bright field technique and present the graphical presentation of bright field hollow-cone transfer functions at optimum focus for various values of Γ 2.
Abstract: Publisher Summary
This chapter discusses the principle of bright-field imaging and a drawback of the bright-field technique. It reviews the bright-field image formation in terms of transfer functions. The chapter explains the phase contrast and amplitude contrast transfer function and discusses the spectral distributions of the illumination. It further focuses on the imaging of weakly scattering specimens in axial bright-field imaging conditions and presents the graphical presentation of bright-field hollow-cone transfer functions at optimum focus for various values of Γ2. The linear transfer theory depends essentially on the assumption that the unscattered beam is considerably stronger than the scattered beam, but this may well not be true for crystalline specimens, where the electrons are concentrated in spots in the back-focal plane of the objective.
2 citations