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 article, it is shown that a system of interference fringes photographed on a photographic plate has very interesting properties when used as a diffraction grating and the nature of variation of spherical aberration between these zero-aberration positions is presented in the form of curves computed from the theory of these gratings.
Abstract: It is now well known that a system of interference fringes photographed on a photographic plate has very interesting properties when used as a diffraction grating. This paper considers two cases. One is when the photographic plate is a plane surface; the aberration properties of this are worked out as a function of wavelength. There are three positions for which the spherical aberration is zero. Of these, one is of little interest as this is simply zero-order position. Another case considered was that of a photographic plate in the form of a concave spherical surface. In this case, there are three positions at which the spherical aberration is zero. The nature of variation of spherical aberration between these zero-aberration positions is presented in the form of curves computed from the theory of these gratings.
23 citations
TL;DR: In this article, state-of-the-art deep ultraviolet steppers and some i-line steppers were compared by measuring the contrast transfer function, i.e., contrast versus linewidth.
Abstract: The aerial image contrast is a key parameter for the evaluation of the performance of optical projection systems. State‐of‐the‐art deep ultraviolet steppers and some i‐line steppers were investigated for comparison by measuring the contrast transfer function, i.e., contrast versus linewidth. Examples are shown how specific weaknesses of an imaging system like astigmatism and sensitivity from internal reflections can be quantified with this technique. For comparison the contrast transfer functions were also calculated, assuming ideal, purely diffraction limited image transfer of the optics, and with the numerical aperture and partial coherence as parameters. Interestingly none of the steppers meet the imaging performance which can be expected from theory.
23 citations
TL;DR: In this article, a method is presented to measure the spherical aberration constant of a transmission electron microscope with high precision based on the measurement of a series of beam-tilt-induced image displacements.
23 citations
TL;DR: This work makes use of the iterative data refinement (IDR) technique to ameliorate the effect of the CTF and demonstrates that the approach can be successfully applied to noisy data.
Abstract: Three-dimensional electron microscopy (3D-EM) is a powerful tool for visualizing complex biological systems. As with any other imaging device, the electron microscope introduces a transfer function (called in this field the contrast transfer function, CTF) into the image acquisition process that modulates the various frequencies of the signal. Thus, the 3D reconstructions performed with these CTF-affected projections are also affected by an implicit 3D transfer function. For high-resolution electron microscopy, the effect of the CTF is quite dramatic and limits severely the achievable resolution. In this work we make use of the iterative data refinement (IDR) technique to ameliorate the effect of the CTF. It is demonstrated that the approach can be successfully applied to noisy data.
23 citations
TL;DR: Under high-resolution operation conditions, it is found that a physical phase plate improves strongly low- and medium-resolution object contrast, while improving tolerance to defocus and C(s)-variations, compared to a microscope without a phase plate.
23 citations