Apparatus for recording oscillation properties of a Penning ionization gauge at very high frequencies

Recording equipment for very high frequency oscillations in Penning ionization gaug

New Directions in Scanning Electron Microscopy Cathodoluminescence Microcharacterization

The general principles of the low-temperature spectroscopic cathodoluminescence (LTSCL) technique in the scanning electron microscope (SEM) are outlined. CL microscopy and spectroscopy are now being extended in new directions. Analysis of the intrinsic CL from quantum well materials by LTSCL is proving valuable for microcharacterization and such work can be expected to expand rapidly. The main, early CL results in this exciting field are summarized here. In geology, CL microscopy, without spectroscopy, is widely used via electron-beam attachments to light microscopes and the addition of spectral analysis to these studies is overdue. Much CL from minerals and ceramics comes from trace amounts of rare earth or transition metal ions, so the nature of this important type of emission is briefly described. Results on ceramic materials illustrating the advances in the field and the distinctive nature of the rare earth and transition metal ion emission bands are reviewed. The fascinating high Tc superconducting ceramics emit CL and there are a number of papers reporting the emission spectra of these materials, but no theoretical interpretation of the information is yet available. A new factor in the situation is the commercial availability of complete LTSCL systems, removing one of the main obstacles to the adoption of the technique by more laboratories

The Role of Defects in Semiconductor Materials and Devices

This literature review leads to the conclusion that recently the basis for an understanding of the electrical and optical properties of structural defects in semiconductors, especially in silicon, has begun to emerge. This is due largely to the ability of scanning electron microscopy (SEM) electron beam induced current (EBIC) and cathodoluminescence (CL) to determine the properties of single, well-defined defects in state of the art material. However, there are still major differences concerning the physical models to be used to explain different forms of dislocation EBIC contrast variation with temperature and beam current. Basic ideas in this field are emphasized. In contrast, there has been little systematic fundamental study of the role of defects in devices. Well-known correlations of properties with dislocation densities show that defects in materials and devices are undesirable, although the numbers that can be tolerated are often large and vary greatly from one material to another. Proposals to exploit defects in devices have not been adopted in practice. The few particular cases of the physical mechanisms of the influence of defects on device performance that have been studied are outlined. The role of defects in devices is ripe for the application of scanning beam techniques

Scene simulation for passive IR systems

The development of large mosaic detector arrays will allow for the construction of staring long wave infrared (LWIR) sensors which can observe large fields of view instantaneously and continuously. In order to evaluate and exercise these new systems, it will be necessary to provide simulated scenes of many moving targets against an infrared clutter background. Researchers are currently developing a projector/screen system. This system is comprised of a mechanical scanner, a diffuse screen, and a miniature blackbody. A prototype of the mechanical scanner, which is comprised of four independently driven scanners, has been designed, fabricated, and evaluated under room and cryogenic vacuum conditions. A large diffuse screen has been constructed and tested for structural integrity under cryogenic/vacuum thermal cycling. Construction techniques have been developed for the fabrication of miniature high-temperature blackbody sources. Finally, a concept has been developed to use this miniature blackbody to produce a spectrally tailorable source

SEASAT synthetic-aperture radar data user's manual

The SEASAT Synthetic-Aperture Radar (SAR) system, the data processors, the extent of the image data set, and the means by which a user obtains this data are described and the data quality is evaluated. The user is alerted to some potential problems with the existing volume of SEASAT SAR image data, and allows him to modify his use of that data accordingly. Secondly, the manual focuses on the ultimate focuses on the ultimate capabilities of the raw data set and evaluates the potential of this data for processing into accurately located, amplitude-calibrated imagery of high resolution. This allows the user to decide whether his needs require special-purpose data processing of the SAR raw data

Description and flight tests of an oculometer

A remote sensing oculometer was successfully operated during flight tests with a NASA experimental Twin Otter aircraft at the Langley Research Center. Although the oculometer was designed primarily for the laboratory, it was able to track the pilot's eye-point-of-regard (lookpoint) consistently and unobtrusively in the flight environment. The instantaneous position of the lookpoint was determined to within approximately 1 deg. Data were recorded on both analog and video tape. The video data consisted of continuous scenes of the aircraft's instrument display and a superimposed white dot (simulating the lookpoint) dwelling on an instrument or moving from instrument to instrument as the pilot monitored the display information during landing approaches

Recent Developments in Electrical Microcharacterization Using the Charge Collection Mode of the Scanning Electron Microscope

There are six distinguishable types of charge collection (CC) signal. Consequently specially designed CC detection systems are needed to obtain e.g. true EBIC and EBIV measurements and make quantitative electrical microcharacterization possible. EBIC and EBIV can arise from fields due to barriers such as p-n junctions or due to changes in doping e.g. p to p+. Materials, defect and device parameters are calculable from these signals. Hot-cold stages are important for temperature dependence studies of contrast, for improving signal to noise ratios and reducing leakage currents. Image processing and pattern recognition methods are vital for rapidly locating and evaluating the information in CC micrographs of large scale circuits. Some recent applications of these techniques to junctions and Schottky barriers in devices, to dislocations and grain boundaries, to microplasmas and to the location of defects in large scale intergration (LSI) devices are presented

Preliminary flight tests of an oculometer

A remote sensing oculometer has been successfully operated during flight tests. This device was able to track the pilot's eye-point-of-regard (lookpoint) consistently and unobtrusively in the flight environment. The instantaneous position of the lookpoint was determined to within approximately 1 degree. Data were recorded on both analog and video tape. The video data consisted of continuous scenes of the aircraft's instrument display and a superimposed white dot (simulating the lookpoint) dwelling or moving from instrument to instrument as the pilot monitored the display information during landing approaches

Equivalence-based Security for Querying Encrypted Databases: Theory and Application to Privacy Policy Audits

Motivated by the problem of simultaneously preserving confidentiality and usability of data outsourced to third-party clouds, we present two different database encryption schemes that largely hide data but reveal enough information to support a wide-range of relational queries. We provide a security definition for database encryption that captures confidentiality based on a notion of equivalence of databases from the adversary's perspective. As a specific application, we adapt an existing algorithm for finding violations of privacy policies to run on logs encrypted under our schemes and observe low to moderate overheads.Comment: CCS 2015 paper technical report, in progres

The Cathodoluminescence Mode of the Scanning Electron Microscope: A Powerful Microcharacterization Technique

By detecting cathodoluminescence (CL) in a scanning electron microscope (SEM), pan and monochromatic micrographs and CL spectral analyses analogous to x-ray mode point analyses can be obtained. Complete microcharacterization requires alternate examination of both micrographs and spectra. New techniques for near infra-red CL and low-temperatures to produce sharp spectra are of increasing importance. CL emission is due to electron transitions between quantum mechanical states so the radiative defects present can be unambiguously identified at liquid helium temperatures. Strongly luminescent impurities can be detected to below one part in 108. This is 104 times as sensitive as the x-ray mode (electron probe microanalysis). Only luminescent impurities can be detected and quantitative analyses by CL have not yet been attempted. There is a rapidly increasing use of the CL mode for the study of industrially important problems and for the study of the electronic effects of dislocations in semiconductors