Showing papers on "Electron tomography published in 1970"
TL;DR: It has been known for many years that there are two distinct ways of designing an electron microscope as discussed by the authors, i.e., two distinct methods of designing a single electron microscope, and one of them is the one proposed in this paper.
Abstract: It has been known for many years that there are two distinct ways of designing an electron microscope.
116 citations
TL;DR: In this article, it was shown that redundancies in structures can be used in the analysis of aperiodic structures. But the theory is developed in the language of the crystallographer, mainly using the concept of modifying functions.
Abstract: An electron microscope equipped with conventional electron optics can be used as a `diffractometer' for structure research on individual aperiodic objects. The resolution limit of the electron microscope is not the resolution limit of the `diffractometer' and electron structure research with atomic resolution is possible. The advantage is that a diffractometer of this type can measure amplitudes and phases. The theory is developed in the language of the crystallographer, mainly using the concept of modifying functions. It is shown that, as in crystallography, redundancies in structures can be used in the analysis.
74 citations
TL;DR: With normal electron incidence, the resolution of the backscattered electron image in the scanning electron microscope (SEM) is approximately equal to the classical electron pentration depth as discussed by the authors.
Abstract: With normal electron incidence, the resolution of the backscattered electron image in the scanning electron microscope (SEM) is approximately equal to the classical electron pentration depth. With oblique electron incidence, a significant number of plurally scattered electrons leave the specimen in an apparently specular direction after penetrating for a distance that is an order of magnitude smaller than this. Thus with 15‐keV electrons incident onto Al at 45°, a significant number of backscattered electrons leave the specimen after penetrating to less than 500‐a.u. depth. These electrons can be collected over an angle that is close to the plane of the specimen surface. Other electrons leave the specimen more nearly at right angles to the surface, and these have been scattered from a greater depth. The image in the SEM can change completely if the position of the collector is changed.
51 citations
TL;DR: In this article, a fast and accurate matrix method is used for calculating and mapping electron microscopy contrast around lattice defects, which can be used for defects of any geometry of any dimension.
Abstract: A fast and accurate matrix method is used for calculating and mapping electron microscopy contrast around lattice defects. As each contrast point is calculated separately the method can be used for defects of any geometry.
43 citations
TL;DR: In this paper, a wave mechanical description of the electron beam in a mirror electron microscope is given, from which the probability current density is derived, which turns out to be a useful expression to clarify the formation of the image on the screen.
Abstract: A wave mechanical description of the electron beam in a mirror electron microscope is given. First the Schrodinger equation of the electron beam is set up, from which the wave function is obtained. Then the probability current density is derived, which turns out to be a useful expression to clarify the formation of the image on the screen.
14 citations
TL;DR: In this article, the reciprocity principle is invoked to relate both image contrast and instrument design in scanning electron microscopy to that in conventional transmission electron microscope, and possible modes of operation employing deflexion systems and an energy analyser are discussed with reference to light and dark-field microscopy, convergent beam diffraction and conventional focused diffraction patterns.
Abstract: The use of scanning electron microscopy for the study of thin specimens by transmission has advantages over conventional transmission electron microscopy in terms of simplicity and cheapness, reduction in damage to irradiation-sensitive specimens and convenience for electron diffraction, energy analysis and the electronic measurement and recording of images. These advantages are specially important for microscopes operating in the range 200 kV to 1 MeV. The design of a 600 kV instrument to exploit these advantages is described. The possible modes of operation employing deflexion systems and an energy analyser are discussed with reference to light- and dark-field microscopy, convergent beam diffraction and conventional focused diffraction patterns. The reciprocity principle is invoked to relate both image contrast and instrument design in scanning electron microscopy to that in conventional transmission electron microscopy. Examples are given of light- and dark-field images and diffraction patterns obtained with the instrument.
12 citations
TL;DR: A mechanism is described for changing the signal detector in the Cambridge ``Stereoscan'' scanning electron microscope without breaking the vacuum, which makes it possible to optimize detectors by comparing different versions of the same basic design.
Abstract: A mechanism is described for changing the signal detector in the Cambridge ``Stereoscan'' scanning electron microscope without breaking the vacuum. This has three main advantages. First, it makes it easier to compare the back scattered electron image, the secondary electron image, and the luminescent image, which can help the interpretation in some cases. Second, a spare secondary electron detector can be kept in reserve for high resolution work, thus avoiding the degradation of scintillator performance that occurs after prolonged use. Finally, it makes it possible to optimize detectors by comparing different versions of the same basic design.
10 citations
TL;DR: This technique enhances minor topographic features which are poorly reproduced in the technique, because the brightness of the oscilloscope is modulated by a signal obtained by mixing the signal from secondary electrons or targets current with its first derivative.
Abstract: A technique is described for topographic images on the scanning electron microscope and the scanning electron probe microanalyzer. In this technique, the brightness of the oscilloscope is modulated by a signal obtained by mixing the signal (from secondary electrons or targets current) with its first derivative. This enhances minor topographic features which are poorly reproduced in the technique.
7 citations
TL;DR: In this article, a theoretical model of two-dimensional secondary electron noise has been derived and the maximum capacity content per picture element of the S.E.M. has been computed as a function of its geometrical resolving power.
Abstract: Information theory formalism has been applied to the scanning electron microscope. A theoretical model of two‐dimensional secondary electron noise has been derived and the maximum capacity content per picture element of the S.E.M. has been computed as a function of its geometrical resolving power. According to the theory, it is shown that the maximum number of grey levels on the picture varies between 2 and 8 (varying with the maximum secondary electron yield) with a resolving power of 200 A for a S.E.M. equipped with a tungsten filament gun, and 30–40 A is equipped with a lanthanum‐hexaboride gun. However, these figures are established with the assumption that the object does not present any redundant properties. The knowledge of the statistics of a general class of objects will permit the use of adapted coding to increase the information content in the object area of interest.
6 citations
TL;DR: A simple tilting stage has been constructed which can be mounted in conventional Philips EM 200 and EM 300 electron microscopes and guarantees high resolution and is able to rotate the object 180° in the electron beam.
Abstract: A simple tilting stage has been constructed which can be mounted in conventional Philips EM 200 and EM 300 electron microscopes. The stage guarantees high resolution and is able to rotate the object 180° in the electron beam.
TL;DR: In this article, the authors present several applications of new instrumentation which have been developed for the electron microprobe analyzer and the scanning electron microscope, including signal modulation techniques and phase sensitive detection.
Abstract: This paper reviews several applications of new instrumentation which have been developed for the electron microprobe analyzer and the scanning electron microscope. By using signal modulation techniques and phase sensitive detection, the information from the scanning electron microscope is made more quantitative. Digital techniques applied to photomultiplier outputs allow more sensitive and quantitative measurements of cathodoluminescence intensities and secondary electron emission. The technique of pulse rate analysis is used to enhance the information contained in x-ray scanning micrographs from an electron microprobe analyzer. Several examples of these techniques are discussed.
TL;DR: In this paper, a specimen rotation of 360° on an axis normal to the electron beam in a conventional electron microscope has been obtained with a specially designed stage, which is primarily intended for use with fine wires to measure thermal groove angles.
Abstract: Specimen rotation of 360° on an axis normal to the electron beam in a conventional electron microscope has been obtained with a specially designed stage. Although primarily intended for use with fine wires to measure thermal groove angles, minor modifications for holding other specimen forms could easily be carried out.