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Employing scanning transmission electron microscope as interferometer, relative phases of diffraction maximums can be determined by analysis of dark field images. Synthetic aperture technique and Fourier-transform computer processing of amplitude and phase information provide high resolution images at approximately one angstrom.
Quality assurance mechanical inspection, anticipating the need for improved measuring techniques for the various laboratory programs, has perfected a modification of the Leitz microscope for the Moore measuring machine that has the capability of significantly reducing inspection time with increased reliability.
Computer image processing techniques have been applied to particle counting and sizing in electron microscope images. Distributions of particle sizes were computed for several images and compared to manually computed distributions. The results of these experiments indicate that automatic particle counting within a reasonable error and computer processing time is feasible. The significance of the results is that the tedious task of manually counting a large number of particles can be eliminated while still providing the scientist with accurate results.
Microscopic aspects of interfacial reactions are discussed, such as interdiffusion, formation of intermetallic phases, generation and annihilation of lattice defects, effect of temperature, grain size, etc., which normally occur in diffusion bonding processes. Relationships between properties and microstructure in thin film couples are examined utilizing a unique combination of contact resistance measurements and characterization by transmission electron microscopy.
The various mechanisms which contribute to sound absorption in the atmosphere are identified and a technique for computing the contribution from each is presented. The similarities between sound absorption, laser fluorescence measurements, and the opto-acoustic effect are discussed. Finally, experimental sound absorption results are compared to predictions to test the microscopic energy transfer approach.
An electron microscope including an electron source, a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen, and an objective lens having an annular objective aperture, for focusing electrons passing through the specimen onto an image plane are described. The invention also entails a method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques.
Application of electron and optical microscopic techniques to the study of growth spirals on quartz crystal faces is described. Attention is centered on the centers of the spirals and on screw ledges; overhanging kinks are revealed on one side of the spiral centers. The possibility that these special features may have developed after growth of the crystals went to completion is explored. The conjecture is raised that such structures might result from adsorption of growth-inhibiting impurities at the center of the growth spiral on the quartz habit faces.
Microscopic tubes have been observed in several igneous rocks and may be quite common. They occur in single crystals and have either elliptical or circular cross-sections 1 to 5 microns in diameter and are ten to hundreds of microns long. Microtubes may be hollow or partially or completely filled with another phase, but are distinct from acicular crystals of accessory minerals such as rutile. Microtubes can form by at least three processes: (1) the partial annealing of microcracks, (2) the natural etching of dislocations, or (3) the primary inclusion of fluid material during crystal growth.
Viking lander cameras have returned stereo and multispectral views of the Martian surface with a resolution that approaches 2 mm/lp in the near field. A two-orders-of-magnitude increase in resolution could be obtained for collected surface samples by augmenting these cameras with auxiliary optics that would neither impose special camera design requirements nor limit the cameras field of view of the terrain. Quasi-microscope images would provide valuable data on the physical and chemical characteristics of planetary regoliths.
A standard procedure for the determination of the minority carrier diffusion length by means of a scanning electron microscope (SEM) consists in scanning across an angle-lapped surface of a P-N junction and measuring the resultant short circuit current I sub sc as a function of beam position. A detailed analysis of the I sub sc originating from this configuration is presented. It is found that, for a point source excitation, the I sub sc depends very simply on x, the variable distance between the surface and the junction edge. The expression for the I sub sc of a planar junction device is well known. If d, the constant distance between the plane of the surface of the semiconductor and the junction edge in the expression for the I of a planar junction is merely replaced by x, the variable distance of the corresponding angle-lapped junction, an expression results which is correct to within a small fraction of a percent as long as the angle between the surfaces, 2 theta sub 1, is smaller than 10 deg.
It is pointed out that the conventional iterative analysis of nonlinear plasma wave phenomena, which involves a direct use of Maxwell's equations and the equations describing the particle dynamics, leads to formidable theoretical and algebraic complexities, especially for warm plasmas. As an effective alternative, the Lagrangian method may be applied. It is shown how this method may be used in the microscopic description of small-signal wave propagation and in the study of nonlinear wave interactions. The linear theory is developed for an infinite, homogeneous, collisionless, warm magnetoplasma. A summary is presented of a perturbation expansion scheme described by Galloway and Kim (1971), and Lagrangians to third order in perturbation are considered. Attention is given to the averaged-Lagrangian density, the action-transfer and coupled-mode equations, and the general solution of the coupled-mode equations.
The quasi-microscope has been used for stereo pictures using a small aperture placed at the right and left over the entrance aperture. A 16-degree stereo view angle yields an enhanced stereo effect. When viewed upward through a transparent support, all grains come into focus. The technique may be used for determining mineral constituents on the basis of cleavage and fracture patterns, grain details, and surface slopes used in estimating single-particle albedo and the illumination of scattering profiles.
In scanning electron microscope (SEM) injection measurements of minority carrier diffusion lengths some uncertainties of interpretation exist when the response current is nonlinear with distance. This is significant in epitaxial layers where the layer thickness is not large in relation to the diffusion length, and where there are large surface recombination velocities on the incident and contact surfaces. An image method of analysis is presented for such specimens. A method of using the results to correct the observed response in a simple convenient way is presented. The technique is illustrated with reference to measurements in epitaxial layers of GaAs. Average beam penetration depth may also be estimated from the curve shape.
Samples mounted on rotatable microscope stage consisting of aluminum hemisphere resting in hemispherical cavity of polytetrafluoroethylene base is viewed at various angles. Stage permits operator to orient sample at selected fixed angles.
Dark glass in eyepieces lets welder look at fine parts without eye damage. Previously welder had to repair barely visible crack without magnification, because necessary goggles kept eyes too far from microscope eyepieces.
Convenient, miniature, spring-loaded clamp holds specimens for scanning electron microscope. Clamp is made out of nesting sections of studded angle-aluminum. Specimens are easier to mount and dismount with vise than with conductive adhesive or paint.
Scanning electron microscopy was used to characterize the erosion of annealed copper and aluminum surfaces produced by both single- and multiple-particle impacts. Macroscopic 3.2 mm diameter steel balls and microscopic, brittle erodant particles were projected by a gas gun system so as to impact at normal incidence at speeds up to 140 m/sec. During the impacts by the brittle erodant particles, at lower speeds the erosion behavior was similar to that observed for the larger steel balls. At higher velocities, particle fragmentation and the subsequent cutting by the radial wash of debris created a marked change in the erosion mechanism.
An analytical electron microscope study of dispersed interplanetary dust aggregates collected in the earth's stratosphere shows that, in spite of their similarities, the aggregates exhibit significant differences in composition, internal morphology, and mineralogy. Of 11 chondritic particles examined, two consist mostly of a noncrystalline chondritic material with an atomic S/Fe ratio equal to or greater than 2 in places, one consists of submicron metal and reduced silicate 'microchondrules' and sulfide grains embedded in a carbonaceous matrix, and another consists of submicron magnetic-decorated unequilibrated silicate and sulfide grains with thick low-Z coatings. Although the particles are unmetamorphosed by criteria commonly applied for chondritic meteorites, the presence of reduced chemistries and the ubiquity of mafic, instead of hydrated, silicates confirm that they are not simply C1 or C2 chondrite matrix material. The observations indicate that portions of some particles have not been significantly altered by thermal or radiation processes since their assembly, and that the particles probably contain fine debris from diverse processes in the early solar system.