Methods and apparatus for examination and measurement by means of nuclear magnetic resonance phenomena

Claim 2

Magnetic resonance apparatus comprising resonance detecting means having a sensing coil arranged to surround a test material sample and including means to induce oscillation in the sensing coil to provide an alternating magnetic field, means for establishing a unidirectional magnetic field perpendicular to said alternating magnetic field in the region of said sensing coil, and modulation means effective to sweep said unidirectional field causing the resultant magnetic field to pass through the resonance condition for the sample and hence generate an output signal indicative of resonance at successive time instants which are spaced at intervals such that the sum of two successive time intervals is not constant.

Claim 3

Apparatus as claimed in claim 1, in which said modulation means modulates the intensity of said unidirectional field and includes generator means providing at least one modulation component having a peak-to-peak amplitude many times greater than the resonance line width.

Claim 4

Apparatus as claimed in claim 1, in which said modulation means comprises first and second windings positioned adjacent to said sensing coil in the unidirectional field, and first and secOnd waveform generators respectively connected to said first and second windings, said first waveform generator being arranged to energize said first winding to superimpose a primary modulation of a first amplitude on said unidirectional field and said second waveform generator being arranged to energize said second winding to superimpose a secondary modulation of a second amplitude on said unidirectional field.

Claim 5

Apparatus as claimed in claim 3, wherein said first generator and said second generator both provide cyclic modulation waveforms.

Claim 6

Apparatus as claimed in claim 3, wherein said first generator provides a cyclic modulation waveform and said second generator provides a random modulation waveform.

Claim 7

Apparatus as claimed in claim 1, wherein said modulating means comprises a winding located adjacent to the sensing coil in the unidirectional magnetic field and a generator connected to said winding and arranged to supply a single modulation of complex noncyclic waveform.

Claim 8

Apparatus as claimed in claim 3, wherein said first generator is arranged to provide a triangular waveform and said second generator is arranged to provide a sinusoidal waveform.

Claim 9

Apparatus as claimed in claim 1, wherein said modulating means comprises a winding located adjacent to the sensing coil in the unidirectional magnetic field, a generator connected to said winding and arranged to supply a cyclic modulation waveform thereto, and means connected to said generator and arranged to vary the frequency of the cyclic waveform produced thereby.

Claim 10

Apparatus as claimed in claim 1, wherein said modulating means comprises at least one element of magnetic material positioned adjacent to said means establishing a magnetic field and arranged to be movable relative thereto to produce the modulation of the field strength of the unidirectional magnetic field.

Claim 11

Magnetic resonance apparatus comprising resonance detecting means having a sensing coil arranged to surround a test material sample and including means to induce oscillation in the sensing coil to provide an alternating magnetic field, means for establishing a unidirectional magnetic field perpendicular to said alternating magnetic field in the region of said sensing coil, and modulation means effective to sweep the frequency of the alternating magnetic field causing the resultant magnetic field to pass through the resonance condition for the sample and hence generate an output signal indicative of resonance at successive time instants which are spaced at intervals such that the sum of two successive time intervals is not constant.

Claim 12

Magnetic resonance apparatus comprising resonance detecting means having a sensing coil arranged to surround a test material sample and including means to induce oscillation in the sensing coil to provide an alternating magnetic field, means for establishing a unidirectional magnetic field perpendicular to said alternating magnetic field in the region of said sensing coil, and modulation means effective to sweep the frequency of the alternating magnetic field causing the resultant magnetic field to pass through the resonance condition for the sample and hence generate an output signal indicative of resonance at successive time instants which are spaced at intervals such that the sum of two successive time intervals is not constant.

Claim 13

Apparatus as claimed in claim 10, in which said sensing coil is connected as part of the resonant tank circuit of a self-oscillating nuclear magnetic resonance detector, and said modulation means comprises means connected to the detector and operative to modulate the frequency of the detector in first and second modes.

Claim 14

Magnetic resonance apparatus comprising resonance detecting means having a sensing coil arranged to surround a test material sample and including means to induce oscillation in the sensing coil to provide an alternating magnetic field, means for establishing a unidirectional magnetic field perpendicular to said alternating magnetic field in the region of said sensing coil, and first and second modulation means respectively effective to sweep the unidirectional field and the frequency of the alternating magnetic field causing the resultant magnetic field to pass through the resonance condition for the sample and hence generate an output signal indicative of resonance at successive time instants which are spaced at intervals such that the sum of two successive time intervals is not constant.

Claim 15

Magnetic resonance apparatus comprising resonance detecting means having a sensing coil arranged to surround a test material sample and including means to induce oscillation in the sensing coil to provide an alternating magnetic field, means for establishing a unidirectional magnetic field perpendicular to said alternating magnetic field in the region of said sensing coil, and first and second modulation means respectively effective to sweep the unidirectional field and the frequency of the alternating magnetic field causing the resultant magnetic field to pass through the resonance condition for the sample and hence generate an output signal indicative of resonance at successive time instants which are spaced at intervals such that the sum of two successive time intervals is not constant.

Claim 16

Apparatus as claimed in claim 12, in which said first modulation means modulates the intensity of said unidirectional field and includes generator means providing a modulation having a peak-to-peak amplitude many times greater than the resonance line width.