Reply by author to discussion by William C. Kellogg

Geophysics ◽  
1966 ◽  
Vol 31 (4) ◽  
pp. 826-826
Author(s):  
Nelson C. Steenland
Keyword(s):  
High Sensitivity ◽  
Oil Fields ◽  
Aeromagnetic Anomalies ◽  
Geophysical Exploration ◽  
New Frontier

Those of us engaged in the pursuit of “high sensitivity” aeromagnetics are fully aware of, undoubtedly most aware of, the problems in its development. Some of these appear in Mr. Kellogg’s letter of 18 March 1966. It should be equally obvious that the advantages outweigh the disadvantages. Solutions to the problems Mr. Kellogg describes are being sought rather than simply accepting them as inalterable. “Oil Fields and Aeromagnetic Anomalies” made no attempt to describe these solutions, but set forth the problem as a new frontier in geophysical exploration.

On: “OIL FIELDS AND AEROMAGNETIC ANOMALIES,” BY NELSON C. STEENLAND; “INSTRUMENT DETAILS AND APPLICATIONS OF A NEW AIRBORNE MAGNETOMETER,” BY HOMER JENSEN; AND “SOME RESULTS OF AEROMAGNETIC SURVEYING WITH A DIGITAL CESIUM VAPOR MAGNETOMETER” BY RAOUL I. GIRET (GEOPHYSICS, OCTOBER 1965)

Geophysics ◽  
1966 ◽  
Vol 31 (4) ◽  
pp. 824-826 ◽  
Author(s):  
William C. Kellogo
Keyword(s):  
High Sensitivity ◽  
Oil Fields ◽  
Petroleum Exploration ◽  
Cesium Vapor ◽  
Aeromagnetic Anomalies ◽  
Magnetic Methods

Three articles appearing in the October 1965 edition of Geophysics, which was devoted to magnetic methods, deserve comment. These are papers by Steenland, Jensen, and Giret. Perhaps the following remarks will lead to better understanding of certain concepts in aerial magnetic surveying. All three authors discuss (and presumably advocate) the use of “high sensitivity magnetometers”. This advocation has considerable merit in certain instances of petroleum exploration. However, each paper has certain oversights or omissions to which I will draw attention. I will also discuss certain other related subjects which seem pertinent.

EXPLORATION WORK IN MEXICO

Geophysics ◽  
1953 ◽  
Vol 18 (1) ◽  
pp. 188-200
Author(s):  
Antonio Garcia Rojas
Keyword(s):  
United States ◽  
Gulf Coast ◽  
Geophysical Methods ◽  
The United States ◽  
Oil Fields ◽  
Present Level ◽  
Geophysical Exploration ◽  
Petroleos Mexicanos ◽  
The Difference

Since 1940 Mexico has increased exploration work in search of new oil fields. Most of the exploration has been done in the Gulf Coast area where all existing Mexican oil fields are located. A brief résumé is given of the main problems of the different provinces under exploration and a list of the fields discovered by Petróleos Mexicanos in the different provinces of the country. Geophysical methods have been responsible for location of a very large percent of the new fields. To compare the intensity of exploration in the United States and Mexico, the amount of seismic and gravity‐meter work and of wildcat drilling per million barrels of production is given for both countries. The data shows that Mexico’s level of geophysical exploration, per million barrels of oil produced, is very close to that of the United States. A very marked increase in the intensity of exploration is shown for both countries. Wildcat drilling in Mexico has been less intensive than in the United States but shows a definite tendency to increase; its present level is very close to that of the United States during 1940. The writer is of the opinion that the difference in intensity of wildcat drilling shown in the data presented is actually smaller than appears as there is a certain amount of duplication in the United States because of leaseholding problems.

New frontiers for infrared

2015 ◽  
Vol 23 (1) ◽  
Author(s):  
C. Corsi
Keyword(s):  
Energy Savings ◽  
High Sensitivity ◽  
Wide Band ◽  
Quantum Cascade ◽  
Submillimeter Wavelengths ◽  
New Frontier ◽  
Laser Sources ◽  
New Sensors ◽  
Ir Bands ◽  
Key Questions

ÀbstractInfrared (IR) science and technology has been mainly dedicated to surveillance and security: since the 70’s specialized techniques have been emerging in thermal imaging for medical and cultural heritage diagnostics, building and aeronautics structures control, energy savings and remote sensing. Most of these applications were developed thanks to IR FPAs sensors with high numbers of pixels and, actually, working at room temperatures. Besides these technological achievements in sensors/ receivers, advanced developments of IR laser sources up to far IR bands have been achieved in the form QCL (quantum cascade laser), allowing wide band TLC and high sensitivity systems for security. recently new sensors and sources with improved performances are emerging in the very far IR region up to submillimeter wavelengths, the so called terahertz (THz) region.A survey of the historical growth and a forecast of the future developments in Devices and Systems for the new frontier of IR will be discussed, in particular for the key questions: “From where and when is IR coming?”, “Where is it now?” and “Where will it go and when?”. These questions will be treated for key systems (Military/Civil), key devices (Sensors/ Sources), and new strategic technologies (Nanotech/TeraHertz).

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM

1988 ◽  
Vol 46 ◽  
pp. 204-205
Author(s):  
Kazumichi Ogura ◽  
Michael M. Kersker
Keyword(s):  
High Resolution ◽  
Layer Structure ◽  
High Sensitivity ◽  
Beam Current ◽  
Electron Beam Current ◽  
Lattice Structures ◽  
Super Lattice ◽  
Different Types ◽  
Backscattered Electron ◽  
Electron Imaging

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.

An x-ray microprobe based upon a close-coupled focal-spot / glass capillary arrangement

1992 ◽  
Vol 50 (2) ◽  
pp. 1758-1759
Author(s):  
D. A. Carpenter ◽  
M. A. Taylor
Keyword(s):  
Imaging Techniques ◽  
Fluorescence Analysis ◽  
High Sensitivity ◽  
Specimen Preparation ◽  
X Rays ◽  
Glass Capillary ◽  
Close Coupling ◽  
X Ray ◽  
Point To Point ◽  
Beam Damage

The development of intense sources of x rays has led to renewed interest in the use of microbeams of x rays in x-ray fluorescence analysis. Sparks pointed out that the use of x rays as a probe offered the advantages of high sensitivity, low detection limits, low beam damage, and large penetration depths with minimal specimen preparation or perturbation. In addition, the option of air operation provided special advantages for examination of hydrated systems or for nondestructive microanalysis of large specimens.The disadvantages of synchrotron sources prompted the development of laboratory-based instrumentation with various schemes to maximize the beam flux while maintaining small point-to-point resolution. Nichols and Ryon developed a microprobe using a rotating anode source and a modified microdiffractometer. Cross and Wherry showed that by close-coupling the x-ray source, specimen, and detector, good intensities could be obtained for beam sizes between 30 and 100μm. More importantly, both groups combined specimen scanning with modern imaging techniques for rapid element mapping.

Ultrastructural identification of three types of sensory setae on copepod antennae

1995 ◽  
Vol 53 ◽  
pp. 956-957
Author(s):  
T. M. Weatherby ◽  
P.H. Lenz
Keyword(s):  
Phase Locking ◽  
Membrane Surface ◽  
Reaction Times ◽  
High Sensitivity ◽  
Structural Features ◽  
Calanoid Copepods ◽  
Marine Food Webs ◽  
Dendritic Membrane ◽  
Ultrastructural Characterization

Crustaceans, as well as other arthropods, are covered with sensory setae and hairs, including mechanoand chemosensory sensillae with a ciliary origin. Calanoid copepods are small planktonic crustaceans forming a major link in marine food webs. In conjunction with behavioral and physiological studies of the antennae of calanoids, we undertook the ultrastructural characterization of sensory setae on the antennae of Pleuromamma xiphias.Distal mechanoreceptive setae exhibit exceptional behavioral and physiological performance characteristics: high sensitivity (<10 nm displacements), fast reaction times (<1 msec latency) and phase locking to high frequencies (1-2 kHz). Unusual structural features of the mechanoreceptors are likely to be related to their physiological sensitivity. These features include a large number (up to 3000) of microtubules in each sensory cell dendrite, arising from or anchored to electron dense rods associated with the ciliary basal body microtubule doublets. The microtubules are arranged in a regular array, with bridges between and within rows. These bundles of microtubules extend far into each mechanoreceptive seta and terminate in a staggered fashion along the dendritic membrane, contacting a large membrane surface area and providing a large potential site of mechanotransduction.

Slow-Scan CCD Observation of Backscattering Patterns in SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1308-1309
Author(s):  
F. Ouyang ◽  
D. A. Ray ◽  
O. L. Krivanek
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Dynamic Range ◽  
High Sensitivity ◽  
Lens System ◽  
Wide Dynamic Range ◽  
Peltier Cooler ◽  
Diffraction Patterns ◽  
Scanning Electron

Electron backscattering Kikuchi diffraction patterns (BKDP) reveal useful information about the structure and orientation of crystals under study. With the well focused electron beam in a scanning electron microscope (SEM), one can use BKDP as a microanalysis tool. BKDPs have been recorded in SEMs using a phosphor screen coupled to an intensified TV camera through a lens system, and by photographic negatives. With the development of fiber-optically coupled slow scan CCD (SSC) cameras for electron beam imaging, one can take advantage of their high sensitivity and wide dynamic range for observing BKDP in SEM.We have used the Gatan 690 SSC camera to observe backscattering patterns in a JEOL JSM-840A SEM. The CCD sensor has an active area of 13.25 mm × 8.83 mm and 576 × 384 pixels. The camera head, which consists of a single crystal YAG scintillator fiber optically coupled to the CCD chip, is located inside the SEM specimen chamber. The whole camera head is cooled to about -30°C by a Peltier cooler, which permits long integration times (up to 100 seconds).

Exit-surface wave reconstruction using a focal series

1992 ◽  
Vol 50 (2) ◽  
pp. 988-989
Author(s):  
W.J. de Ruijter ◽  
M.R. McCartney ◽  
David J. Smith ◽  
J.K. Weiss
Keyword(s):  
Surface Wave ◽  
Spherical Aberration ◽  
Data Extraction ◽  
High Sensitivity ◽  
Geometric Distortion ◽  
Variation Method ◽  
Objective Lens ◽  
Immediate Reconstruction ◽  
Exit Surface ◽  
Electron Microscopes

Further advances in resolution enhancement of transmission electron microscopes can be expected from digital processing of image data recorded with slow-scan CCD cameras. Image recording with these new cameras is essential because of their high sensitivity, extreme linearity and negligible geometric distortion. Furthermore, digital image acquisition allows for on-line processing which yields virtually immediate reconstruction results. At present, the most promising techniques for exit-surface wave reconstruction are electron holography and the recently proposed focal variation method. The latter method is based on image processing applied to a series of images recorded at equally spaced defocus.Exit-surface wave reconstruction using the focal variation method as proposed by Van Dyck and Op de Beeck proceeds in two stages. First, the complex image wave is retrieved by data extraction from a parabola situated in three-dimensional Fourier space. Then the objective lens spherical aberration, astigmatism and defocus are corrected by simply dividing the image wave by the wave aberration function calculated with the appropriate objective lens aberration coefficients which yields the exit-surface wave.

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