Patent US5166620A successfully refreshed from Google Patents.
US5166620A
Expired / Lapsed
US
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Nmr frequency locking circuit
Assignee: Qualion Ltd
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Filing: 1990-11-07
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Granted: 1992-11-24
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Expires: 2010-11-07
Abstract
Abstract An NMR locking mechanism for use with not only electromagnets, superconducting magnets and permanent magnets, but also with ultrahigh energy product magnets such as neodynium. The circuit utilizes a single conversion superheterodyne receiver with a phase locked loop that forms a locking mechanism that depends upon a variable frequency. The resonant frequency of the nuclei is compared to a variable excitation frequency which is adjusted to maintain a control frequency with one unique value of the control frequency being zero at lock.
Inventors
- 👤 Richard L. Panosh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 04:09
CPC Classifications
G; G01; G01V; G01V3/00; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/32; G01R33/36; G01R33/3607; G01R33/38; G01R33/389
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
169 words
A device for use in nuclear magnetic resonance spectroscopy for locking to the resonant frequency of the nuclei of a test sample comprising: a permanent magnet for applying a fixed magnetic field to said nuclei; a transmitter, including a local oscillator, for generating a variable frequency signal for exciting said nuclei; an RF coil coupled to the transmitter for applying said variable exciting frequency signal to said nuclei to resonate said nuclei and cause a resonant frequency signal, offset from the local oscillator frequency, to be generated by said nuclei in the presence of the fixed magnetic field; receiver means coupled to said RF coil for combining the generated resonant frequency with the transmitter local oscillator frequency to obtain a free induction decay difference frequency; and a feedback loop coupled to said receiver combining means and said local oscillator for using said difference frequency to obtain said lock by adjusting the local oscillator frequency such to maintain the offset frequency such that the transmitter generates the variable exciting frequency.
Claim 2
Independent Claim
169 words
A device for use in nuclear magnetic resonance spectroscopy for locking to the resonant frequency of the nuclei of a test sample comprising: a permanent magnet for applying a fixed magnetic field to said nuclei; a transmitter, including a local oscillator, for generating a variable frequency signal for exciting said nuclei; an RF coil coupled to the transmitter for applying said variable exciting frequency signal to said nuclei to resonate said nuclei and cause a resonant frequency signal, offset from the local oscillator frequency, to be generated by said nuclei in the presence of the fixed magnetic field; receiver means coupled to said RF coil for combining the generated resonant frequency with the transmitter local oscillator frequency to obtain a free induction decay difference frequency; and a feedback loop coupled to said receiver combining means and said local oscillator for using said difference frequency to obtain said lock by adjusting the local oscillator frequency such to maintain the offset frequency such that the transmitter generates the variable exciting frequency.
Claim 3
Dependent Claim
38 words
A device as in claim 1 wherein said transmitter further comprises. means for generating the offset frequency; and means for combining said offset frequency and said local oscillator frequency to generate said variable frequency for exciting said nuclei.
Claim 4
Dependent Claim
42 words
A device as in claim 2 wherein said receiver comprises: means for amplifying said nuclei resonant frequency signal; and means for subtracting said amplified nuclei resonant frequency signal from said local oscillator frequency signal to obtain said free induction decay difference frequency.
Claim 5
Dependent Claim
54 words
A device as in claim 3 further comprising: means coupled to said free induction decay difference frequency and said means for generating said offset frequency to develop a control frequency; and means in said feedback loop utilizing said control frequency to adjust said local oscillator frequency to maintain said control frequency at a null.
Claim 6
Dependent Claim
14 words
A device as in claim 4 wherein local oscillator is a voltage controlled oscillator.
Claim 7
Dependent Claim
28 words
A device as in claim 5 further including means for converting said control frequency to a variable DC voltage for adjusting the frequency of said voltage controlled oscillator.
Claim 8
Dependent Claim
22 words
A device as in claim 6 wherein said means for applying a fixed magnetic field to said nuclei is a permanent magnet.
Claim 9
Dependent Claim
24 words
A device as in claim 6 wherein said means for applying a fixed magnetic field to said nuclei is an ultrahigh energy product magnet.
Claim 10
Dependent Claim
19 words
A device as in claim 8 wherein the ultrahigh energy product magnet is formed with a rare earth material.
Claim 11
Dependent Claim
17 words
A device as in claim 9 wherein the rare earth material is of the class including neodynium.
Claim 12
Dependent Claim
16 words
A device as in claim 1 wherein the receiver means is a single conversion superheterodyne receiver.
Claim 13
Independent Claim
144 words
A device for use in NMR spectroscopy for locking to the resonant frequency of the nuclei in a sample under test comprising: means for applying a fixed magnetic field to said nuclei; means including a local oscillator for exciting said nuclei with a variable frequency signal to cause a resonant frequency to be generated by said nuclei in the presence of the fixed magnetic field, the resonant frequency being offset from the oscillator frequency; means for combining the generated offset resonant frequency signal with the local oscillator signal to obtain a variable control signal; and a feedback loop coupled to said combining means and said local oscillator for utilizing said variable control signal to obtain said lock by adjusting the local oscillator frequency to maintain the offset frequency such that said nuclei excitation frequency is varied with a change in the variable control signal.
Claim 14
Independent Claim
144 words
A device for use in NMR spectroscopy for locking to the resonant frequency of the nuclei in a sample under test comprising: means for applying a fixed magnetic field to said nuclei; means including a local oscillator for exciting said nuclei with a variable frequency signal to cause a resonant frequency to be generated by said nuclei in the presence of the fixed magnetic field, the resonant frequency being offset from the oscillator frequency; means for combining the generated offset resonant frequency signal with the local oscillator signal to obtain a variable control signal; and a feedback loop coupled to said combining means and said local oscillator for utilizing said variable control signal to obtain said lock by adjusting the local oscillator frequency to maintain the offset frequency such that said nuclei excitation frequency is varied with a change in the variable control signal.
Claim 15
Independent Claim
156 words
A method for locking to the resonant frequency of nuclei in nuclear magnetic resonant spectroscopy comprising the steps of: applying a fixed magnetic field to said nuclei; generating a variable frequency signal with a local oscillator for exciting said nuclei; coupling an RF coil to said local oscillator for applying said variable exciting frequency signal to said nuclei in the presence of the fixed magnetic field to resonate said nuclei and cause a resonate frequency signal offset from the local oscillator frequency to be generated by said nuclei; coupling a receiver to said RF coil for combining the generated offset resonate frequency with the local oscillator frequency to obtain a free induction decay difference frequency; and coupling a feedback loop to said receiver combining means and said local oscillator for using said difference frequency to adjust the local oscillator frequency to maintain the offset frequency such that the local oscillator generates the variable exciting frequency signal.
Claim 16
Independent Claim
156 words
A method for locking to the resonant frequency of nuclei in nuclear magnetic resonant spectroscopy comprising the steps of: applying a fixed magnetic field to said nuclei; generating a variable frequency signal with a local oscillator for exciting said nuclei; coupling an RF coil to said local oscillator for applying said variable exciting frequency signal to said nuclei in the presence of the fixed magnetic field to resonate said nuclei and cause a resonate frequency signal offset from the local oscillator frequency to be generated by said nuclei; coupling a receiver to said RF coil for combining the generated offset resonate frequency with the local oscillator frequency to obtain a free induction decay difference frequency; and coupling a feedback loop to said receiver combining means and said local oscillator for using said difference frequency to adjust the local oscillator frequency to maintain the offset frequency such that the local oscillator generates the variable exciting frequency signal.
Claim 17
Dependent Claim
38 words
A method as in claim 13 further comprising the steps of: generating an offset frequency with a transmitter; and combining said generated offset frequency and said local oscillator frequency to generate said variable frequency for exciting said nuclei.
Claim 18
Dependent Claim
39 words
A method as in claim 14 further comprising the steps of: amplifying said nuclei resonant frequency signal; and subtracting said amplified nuclei resonant frequency signal from said local oscillator frequency signal to obtain said free induction decay difference frequency.
Claim 19
Dependent Claim
50 words
A method as in claim 15 further comprising the steps of: developing a control frequency with said free induction decay difference frequency and said generated offset frequency; and utilizing said control frequency in a feedback loop to adjust said local oscillator frequency to maintain said control frequency at a null.
Claim 20
Dependent Claim
20 words
A method as in claim 16 further comprising the step of using a voltage controlled oscillator as said local oscillator.
Claim 21
Dependent Claim
29 words
A method as in claim 17 further including the step of converting said control frequency to a variable DC voltage for adjusting the frequency of said voltage controlled oscillator.
Claim 22
Dependent Claim
23 words
A method as in claim 18 further comprising the step of applying a fixed magnetic field to said nuclei with a permanent magnet.
Claim 23
Dependent Claim
30 words
A method as in claim 19 further comprising the step of applying a fixed magnetic field to said nuclei with a magnet formed from an ultrahigh frequency energy product material.
Claim 24
Dependent Claim
23 words
A method as in claim 20 further comprising the step of forming the ultrahigh frequency energy product magnet from a rare earth material.
Claim 25
Dependent Claim
27 words
A method as in claim 21 further comprising the step of using rare earth materials of the class including neodynium to form the ultrahigh energy product magnet.
Claim 26
Dependent Claim
40 words
A method as in claim 13 further comprising the step of using a single conversion superheterodyne receiver for comparing the nuclei generated resonant frequency signal with the transmitter local oscillator frequency signal to obtain the free induction decay difference frequency.
Claim 27
Independent Claim
125 words
A method for locking to the resonant frequency of the nuclei in a sample under test for use in NMR spectroscopy comprising the steps of: applying a fixed magnetic field to said nuclei; exciting said nuclei with a variable frequency signal from a local oscillator to cause a resonant frequency to be generated by said nuclei in the presence of the fixed magnetic field, the resonant frequency being offset from the oscillator frequency; combining the nuclei generated offset resonant frequency signal with the local oscillator signal to obtain a variable control frequency; and utilizing said variable control frequency to adjust the local oscillator frequency to maintain the offset frequency and vary said nuclei excitation frequency with a change in the resonant frequency of the nuclei.
Claim 28
Independent Claim
125 words
A method for locking to the resonant frequency of the nuclei in a sample under test for use in NMR spectroscopy comprising the steps of: applying a fixed magnetic field to said nuclei; exciting said nuclei with a variable frequency signal from a local oscillator to cause a resonant frequency to be generated by said nuclei in the presence of the fixed magnetic field, the resonant frequency being offset from the oscillator frequency; combining the nuclei generated offset resonant frequency signal with the local oscillator signal to obtain a variable control frequency; and utilizing said variable control frequency to adjust the local oscillator frequency to maintain the offset frequency and vary said nuclei excitation frequency with a change in the resonant frequency of the nuclei.
Claim 29
Dependent Claim
36 words
A method as in claim 24 further including the step of utilizing a single conversion superheterodyne receiver to compare the nuclei generated resonant frequency signal with the local oscillator signal to obtain said variable control frequency.
Claim 30
Independent Claim
124 words
A device for use in NMR spectroscopy for locking to the resonant frequency of the nuclei of a test sample comprising: means for applying a fixed magnetic field to said nuclei; means for exciting said nuclei to resonate said nuclei and cause a resonant frequency signal to be generated by said nuclei; a single conversion superheterodyne receiver coupled to said nuclei and said exciting means for receiving said resonant frequency signal and generating a control signal; means for varying the magnetic field applied to said nuclei; and means coupled between said single conversion superheterodyne receiver and said means for varying the magnetic field applied to nuclei for using said control signal to vary the magnetic field applied to said nuclei and obtain said lock.
Claim 31
Independent Claim
124 words
A device for use in NMR spectroscopy for locking to the resonant frequency of the nuclei of a test sample comprising: means for applying a fixed magnetic field to said nuclei; means for exciting said nuclei to resonate said nuclei and cause a resonant frequency signal to be generated by said nuclei; a single conversion superheterodyne receiver coupled to said nuclei and said exciting means for receiving said resonant frequency signal and generating a control signal; means for varying the magnetic field applied to said nuclei; and means coupled between said single conversion superheterodyne receiver and said means for varying the magnetic field applied to nuclei for using said control signal to vary the magnetic field applied to said nuclei and obtain said lock.
Claim 32
Dependent Claim
58 words
A device as in claim 26 wherein said coupling means for using said control signal to vary the magnetic field further comprises: serially coupled first and second wide band filters receiving and reducing the frequency of said control signal; and means coupled to said second filter for converting said reduced frequency to current for varying said magnetic field.
Claim 33
Dependent Claim
59 words
A device as in claim 27 further comprising: an oscillator forming part of said nuclei exciting means; and a negative feedback loop coupled between the output of said first wide band filter and said oscillator to give greater accuracy in obtaining said lock and to cause the oscillator frequency to assume the frequency characteristics of the nuclei generated signal.
References Cited (Backward Citations)
US4875486A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-11-24 | 1996-05-25 | 1996-11-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-11-24 | 2000-05-25 | 2000-11-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-11-24 | 2004-05-25 | 2004-11-24 | $7700.00 | Window Closed / Lapsed |