Compensation of interfering fields in NMR measurements in the earth's magnetic field
US5578920A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 1995 |
| Grant date | Nov 26, 1996 |
| Priority date | — |
| Expiry date | Jul 10, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/44
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In an apparatus having at least one detection coil (1) for the detection of nuclear magnetic resonance (NMR) from a sensitivity region of the detection coil (1) in the ground, whereby nuclear spins within the sensitivity region are excited by repeated coherent excitation, in each case, to precess in the earth's field and produce a small NMR induction voltage in the detection coil (1) which is introduced to a first amplifier (7), the detection coil (1) consists of at least two oppositely wound partial coils (2, 3) having parallel coil axes which are connected electrically in series and at least one compensation coil (8, 9, 10) is provided for additional compensation of spatially inhomogeneous interfering fields whose induction signal is introduced to a second amplifier (18, 19, 20) having adjustable amplification. In this fashion, in addition to the homogeneous portion, an inhomogeneous portion due to distant disturbances can be eliminated from the measured signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.