Automated interpretation of horizontal magnetic gradient profile data

Geophysics ◽  
1992 ◽  
Vol 57 (2) ◽  
pp. 288-295 ◽  
Author(s):  
D. L. Marcotte ◽  
C. D. Hardwick ◽  
J. B. Nelson
Keyword(s):  
Vertical Gradient ◽  
Horizontal Gradient ◽  
Two Dimensional ◽  
Total Field ◽  
Profile Data ◽  
Magnetic Gradient ◽  
Inversion Methods ◽  
Automated Interpretation ◽  
A New Technique ◽  
Magnetic Gradients

A new technique has been developed to estimate the vertical magnetic gradient [Formula: see text] along a profile from measurements of the two orthogonal horizontal magnetic gradients [Formula: see text]. In addition, a means of identifying two‐dimensional anomaly sources and the angle of the structure relative to the profile direction is shown to be a function of [Formula: see text]. This angle can be used to correct interpretations from vertical gradient or total field inversion methods which assume source structures oriented perpendicular to the profile direction. A modified Werner deconvolution algorithm for vertical gradient data incorporating these features has been applied to both real and simulated horizontal gradient data.

An alternate derivation of the three‐dimensional Hilbert transform relations from first principles

Geophysics ◽  
1986 ◽  
Vol 51 (4) ◽  
pp. 1014-1015 ◽  
Author(s):  
J. Bradley Nelson
Keyword(s):  
Hilbert Transform ◽  
Magnetic Field Intensity ◽  
Three Dimensional ◽  
Gradient Methods ◽  
Vertical Gradient ◽  
Horizontal Gradient ◽  
Implicit Assumption ◽  
Limited Applicability ◽  
Magnetic Gradients ◽  
The Magnetic Field

Several techniques for determining the location, geometry, and strength of a source are based on a knowledge of the magnetic gradients generated by that source. Hood (1965), Bhattacharyya (1966), and Rao et al. (1981) detailed three of these gradient methods. For many years, geophysicists have used the two‐dimensional (2-D) Hilbert transform to approximate the vertical gradient from measurements of the horizontal gradient in the magnetic‐field intensity (Nabighian, 1972; Stanley and Green, 1976; Stanley, 1977; Mohan et al., 1982). This technique is of limited applicability because of the implicit assumption that the source is a linear, 2-D body oriented at right angles to the profile direction.

THE GEOMAGNETIC GRADIOMETER

Geophysics ◽  
1967 ◽  
Vol 32 (5) ◽  
pp. 877-892 ◽  
Author(s):  
Howard A. Slack ◽  
Vance M. Lynch ◽  
Lee Langan
Keyword(s):  
Magnetic Field ◽  
Vertical Gradient ◽  
Diurnal Variations ◽  
Resolving Power ◽  
Magnetic Intensity ◽  
Geophysical Prospecting ◽  
Total Field ◽  
Optically Pumped ◽  
Magnetic Gradient ◽  
The Difference

The geomagnetic gradiometer is a new geophysical prospecting tool which measures directly the vertical gradient of the earth’s magnetic field and the total field intensity. The system is composed of two simultaneously recording, optically pumped and monitored magnetometer sensors suspended from a helicopter. The sensors are separated vertically by a known distance so that the magnetic gradient can be determined from the difference in total magnetic intensity between the two sensors. Since the gradient is measured directly, the gradiometer allows geophysicists to make better use of LaPlace’s and Euler’s equations. The gradiometer increases the value of magnetic prospecting by: (1) greatly increasing resolving power, (2) discriminating between intrabasement and suprabasement anomalies, and (3) eliminating problems caused by diurnal variations.

DESIGN OF SPATIAL FILTERS AND THEIR APPLICATION TO HIGH‐RESOLUTION AEROMAGNETIC DATA

Geophysics ◽  
1972 ◽  
Vol 37 (1) ◽  
pp. 68-91 ◽  
Author(s):  
B. K. Bhattacharyya
Keyword(s):  
High Resolution ◽  
Field Data ◽  
Vertical Gradient ◽  
Double Fourier Series ◽  
Two Dimensional ◽  
Total Field ◽  
Spatial Filters ◽  
Aeromagnetic Survey ◽  
Potential Field Data ◽  
High Frequency Response

Methods for the design of spatial filters are discussed in this paper. For a given response of a one‐dimensional filter, the weighting coefficients are calculated by solving a set of simultaneous equations with a simple matrix inversion procedure. In the case of a two‐dimensional filter, the method for obtaining the coefficients of a double Fourier series representing a set of given values is used to design the spatial operator. The problems connected with the length of the operator and the choice of a suitable decay in the high‐frequency response are discussed in detail. In order to show the usefulness of these methods, the paper presents several examples of operators designed for computing the vertical gradient, the second vertical derivative, and downward continuation of potential field data. A two‐dimensional vertical gradient filter is applied to the total field data obtained during a high‐resolution aeromagnetic survey over an area in the Precambrian Shield of Northeastern Ontario. The calculated gradient maps are compared with maps showing measured gradient values. The quality of the calculated maps in defining trends, patterns, and detailed features of anomalies shows the feasibility of obtaining very accurate vertical gradient maps from observed total field data.

Two-Dimensional Local Deep-Level Transient Spectroscopy Imaging Using Super-Higher-Order Scanning Nonlinear Dielectric Microscopy

2016 ◽  
Author(s):  
N. Chinone ◽  
Y. Cho ◽  
R. Kosugi ◽  
Y. Tanaka ◽  
S. Harada ◽  
...  
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Higher Order ◽  
Trap Density ◽  
New Technique ◽  
Two Dimensional ◽  
Nonlinear Dielectric ◽  
Annealing Conditions ◽  
Transient Spectroscopy ◽  
A New Technique

Abstract A new technique for local deep level transient spectroscopy (DLTS) imaging using super-higher-order scanning nonlinear dielectric microscopy is proposed. Using this technique. SiCVSiC structure samples with different post oxidation annealing conditions were measured. We observed that the local DLTS signal decreases with post oxidation annealing (POA), which agrees with the well-known phenomena that POA reduces trap density. Furthermore, obtained local DLTS images had dark and bright areas, which is considered to show the trap distribution at/near SiCVSiC interface.

TWO-DIMENSIONAL NONLINEAR OPTICS SPECTROSCOPY: SIMULATIONS AND EXPERIMENTAL DEMONSTRATION

1996 ◽  
Vol 05 (03) ◽  
pp. 465-476 ◽  
Author(s):  
L. LEPETIT ◽  
G. CHÉRIAUX ◽  
M. JOFFRE
Keyword(s):  
Fourier Transform ◽  
Nonlinear Response ◽  
Two Dimensions ◽  
Second Order ◽  
Phase Matching ◽  
Two Dimensional ◽  
Experimental Demonstration ◽  
Spectral Interferometry ◽  
Dimensional Measurement ◽  
A New Technique

We propose a new technique, using femtosecond Fourier-transform spectral interferometry, to measure the second-order nonlinear response of a material in two dimensions of frequency. We show numerically the specific and unique information obtained from such a two-dimensional measurement. The technique is demonstrated by measuring the second-order phase-matching map of two non-resonant nonlinear crystals.

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